Forestry, Faculty of
DSpace
UBCV
Liu, Xiaoyu
Master of Science - MSc
University of British Columbia
Traditionally, the assessment of the carbon footprint of bamboo products has focused only on the final product (e.g. laminated bamboo or bamboo scrimber), ignoring the important contribution of intermediate products (e.g. bamboo strips or bamboo bundle) to the overall environmental impact. Recognizing the importance of providing a holistic perspective, this study extends the scope of analysis to intermediate products. By developing a comprehensive life cycle assessment (LCA) model, this study quantifies the carbon footprints of intermediate and final bamboo products, and the utilization of processing residues under different scenarios, including boiler fuel, charcoal, and toothpick production. The assessment results are compared with benchmark products, including wood-based products and non-renewable alternatives (e.g. steel and concrete), to gain insight into the relative environmental performance of bamboo products. The results show that bamboo products have higher carbon emissions at the manufacturing stage compared to some alternatives, such as wood-based products made in North America or Europe, due to bamboo products being made in China which uses coal as the major energy source for electricity. The major contributor to the manufacturing procedure of bamboo products is electricity. However, these emissions can be offset by the carbon storage of bamboo during the growth stage. Therefore, the net carbon footprints of bamboo products are comparable to those of wood products when both carbon sequestration and emission are considered. Intermediate products are the major contributors to the total carbon emission of bamboo structural products. The impact of residue utilization for bamboo products is between -9.30 and 2.91 kg CO₂ eq, contributing insignificantly to the overall carbon footprint of the product life cycle.
Carbon Footprint Analyses of Structural Bamboo Products by Xiaoyu Liu B.Sc., The University of British Columbia, 2021 B.Eng. Beijing Forestry University, 2021 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE in THE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES (Forestry) THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) August 2024 © Xiaoyu Liu, 2024 ii The following individuals certify that they have read, and recommend to the Faculty of Graduate and Postdoctoral Studies for acceptance, a thesis entitled: Carbon Footprint Analyses of Structural Bamboo Products submitted by Xiaoyu Liu in partial fulfillment of the requirements for the degree of Master of Science in Forestry Examining Committee: Dr. Chunping Dai, Associate Professor, Department of Wood Science, UBC Co-supervisor Dr. Qingshi Tu, Assistant Professor, Department of Wood Science, UBC Co-supervisor Dr. Taraneh Sowlati, Professor, Department of Wood Science, UBC Supervisory Committee Member Dr. Guangyu Wang, Associate Dean, Department of Forest Resources Management, UBC Additional Examiner iii Abstract Traditionally, the assessment of the carbon footprint of bamboo products has focused only on the final product (e.g. laminated bamboo or bamboo scrimber), ignoring the important contribution of intermediate products (e.g. bamboo strips or bamboo bundle) to the overall environmental impact. Recognizing the importance of providing a holistic perspective, this study extends the scope of analysis to intermediate products. By developing a comprehensive life cycle assessment (LCA) model, this study quantifies the carbon footprints of intermediate and final bamboo products, and the utilization of processing residues under different scenarios, including boiler fuel, charcoal, and toothpick production. The assessment results are compared with benchmark products, including wood-based products and non-renewable alternatives (e.g. steel and concrete), to gain insight into the relative environmental performance of bamboo products. The results show that bamboo products have higher carbon emissions at the manufacturing stage compared to some alternatives, such as wood-based products made in North America or Europe, due to bamboo products being made in China which uses coal as the major energy source for electricity. The major contributor to the manufacturing procedure of bamboo products is electricity. However, these emissions can be offset by the carbon storage of bamboo during the growth stage. Therefore, the net carbon footprints of bamboo products are comparable to those of wood products when both carbon sequestration and emission are considered. Intermediate products are the major contributors to the total carbon emission of bamboo structural products. The impact of residue utilization for bamboo products is between -9.30 and 2.91 kg CO2 eq, contributing insignificantly to the overall carbon footprint of the product life cycle. iv Lay Summary Bamboo products are popular and commonly perceived to be eco-friendly, but more in-depth research is needed to understand the true impact on the environment of their manufacture. This study examines the carbon footprint of structural bamboo products from bamboo growth and transportation through their different manufacturing stages. Although structural bamboo products can have high emissions during production, the stored carbon in the bamboo timber offsets these emissions, giving an overall carbon footprint comparable to that of wood-based alternatives. This study emphasizes the importance of assessing the life cycle of bamboo manufacturing for consumers and businesses to make informed decisions. By analyzing the carbon footprint of bamboo products at different stages, this study can help the public better understand the sustainability of bamboo products and their role in developing more sustainable construction materials. v Preface This thesis is an original and independent work by the author, X. Liu, and is conducted under the supervision of Dr. Chunping Dai and Dr. Qingshi Tu. Part of Chapter 2 has been published in: Gan, J., Chen, M., Semple, K., Liu, X., Dai, C., & Tu, Q. (2022). Life cycle assessment of bamboo products: Review and harmonization. The Science of the Total Environment, 849, 157937-157937. https://doi.org/10.1016/j.scitotenv.2022.157937. I was the fourth author and contributed to the investigation and data collection for the literature review of bamboo products and bamboo forest management. Jinlu Gan contributed to the writing of the original draft and some figures. Meiling Chen contributed to the data collection and figure drawing. Kate contributed to the manuscript review and modification. Dr. Chunping Dai and Dr. Qingshi Tu were the supervisory authors of this review and were involved throughout the project in funding acquisition, conceptualization, and editing. vi Table of Contents Abstract....................................................................................................................................iii Lay Summary ..........................................................................................................................iv Preface.......................................................................................................................................v Table of Contents ....................................................................................................................vi List of Tables ...........................................................................................................................ix List of Figures..........................................................................................................................xi List of Abbreviations .............................................................................................................xv Glossary.................................................................................................................................xvii Acknowledgments .................................................................................................................xix Chapter 1: Introduction ..........................................................................................................1 1.1 Background and Rationale.........................................................................................1 1.2 Objectives and Hypothesis ........................................................................................8 1.3 Outline of Thesis........................................................................................................9 Chapter 2: Literature Review ...............................................................................................11 2.1 Bamboo and engineered bamboo products ..............................................................11 2.2 Carbon footprint estimates.......................................................................................18 2.2.1 Carbon footprint of bamboo forest ..................................................................19 2.2.2 Carbon footprint estimates for structure bamboo materials ............................24 2.2.3 Carbon footprint estimates for bamboo buildings ...........................................31 2.2.4 Other miscellaneous bamboo products ............................................................34 2.3 Current bamboo LCA study overview.....................................................................35 vii 2.4 Research gaps ..........................................................................................................39 Chapter 3: Methodology and Models...................................................................................40 3.1 Scope of this study ...................................................................................................40 3.2 Data collection and Functional unit .........................................................................41 3.3 Model Development Method ...................................................................................42 3.4 Carbon storage in bamboo products ........................................................................46 3.5 General equations used for calculation LCI. ...........................................................46 3.6 Residue utilization ...................................................................................................47 3.6.1 Toothpicks .......................................................................................................49 3.6.2 Bamboo charcoal .............................................................................................50 3.6.3 Combustion ......................................................................................................52 3.7 Bamboo structural products .....................................................................................53 3.7.1 Laminated bamboo ..........................................................................................55 3.7.2 Bamboo scrimber .............................................................................................70 3.7.3 BLSL................................................................................................................77 Chapter 4: Chapter 4. Results and Discussion ....................................................................87 4.1 Carbon footprint and major contributors for four structural bamboo products .......87 4.2 Comparison with other research and EPDs .............................................................97 4.3 Other environmental impacts...................................................................................99 4.4 Discussion ..............................................................................................................101 Chapter 5: Conclusions and Recommendations ...............................................................105 5.1 Summary and conclusions .....................................................................................105 5.2 Recommendations for future research ...................................................................107 viii 5.3 Recommendations for the industry ........................................................................108 References .............................................................................................................................110 Appendices ............................................................................................................................142 ix List of Tables Table 2.1 Bamboo carbon projects submitted on Verra Registry System (up to September 25, 2023). .......................................................................................................................................21 Table 2.2 Carbon storage in the moso bamboo forest (Unit: t C/ha). ......................................23 Table 3.1 Recovery ratio of each stage for laminated bamboo................................................45 Table 3.2 Recovery ratio of each stage for bamboo scrimber. ................................................45 Table 3.3 Recovery ratio of each stage for BLSL....................................................................45 Table 3.4 General equations for harvesting, transportation, resin, and energy consumption. .47 Table 3.5 Model for bamboo culm. .........................................................................................58 Table 3.6 Model for bamboo bleached and carbonized strips. ................................................61 Table 3.7 Model for bamboo strip plank. ................................................................................64 Table 3.8 Model for final panel production. ............................................................................67 Table 3.9 Bamboo residues from laminated bamboo manufacturing procedure. ....................68 Table 3.10 Model for bamboo bundle......................................................................................73 Table 3.11 Model for bamboo scrimber beam model. .............................................................76 Table 3.12 Proportion of residues after bamboo scrimber production. ...................................77 Table 3.13 Model of flattened bamboo and flattened bamboo plank. .....................................81 Table 3.14 Model for BLSL.....................................................................................................85 Table 3.15 Inputs and outputs of a flattened bamboo factory..................................................86 Table 4.1 Results from residue utilization scenarios for 1 m3 of three bamboo products. ......97 Table 4.2 Carbon footprint harmonized model for 1 m3 of bamboo products (Unit: kg CO2 eq)...................................................................................................................................................98 x Table S1. Three bamboo product specifications of this study. ..............................................142 Table S2. Environmental impacts of bamboo products and benchmark products.................142 Table S3. Energy inputs for one m3 LSL. ..............................................................................143 Table S4. Detailed results of residue utilization scenarios of each product. .........................144 xi List of Figures Figure 1.1 Bamboo related materials in building and construction area applications: (a) an electric vehicle charging structure with laminated bamboo lumber in New York, USA, (b) laminated bamboo lumber, (c) city life shopping district in Milan, Italy, (d) bamboo scrimber beam, (e) bamboo roof, (f) flattened bamboo [Sources: (a) and (b): ReNüTeq (https://www.renuteq.com/); (c): Moso bamboo (https://www.moso-bamboo.com/bamboo-inspiration/bamboo-wood-citylife/); (d): Chen et al. (2021); (e) and (f): Bamboo U (https://bamboou.com/flattened-bamboo-roofing-in-bamboo-architecture/); ] .........................5 Figure 1.2 Number of publications and top 10 areas focusing on bamboo: (a) number of publications from 2013 to 2023; (b) the most popular areas of bamboo-related research, from left to right materials science multidisciplinary (MSM), environmental sciences (ES), materials science paper world (MSPW), forestry, plant sciences, polymer science, energy fuels, engineering civil, engineering chemical (EC), chemistry multidisciplinary (CM). Source from Web of Science. .........................................................................................................................7 Figure 2.1 2022 Global bamboo market size with a schematic representation of diversity in bamboo products and applications in eleven major areas. Images: 1. Bamboo bicycle 2. Handwoven bamboo car 3. Bamboo lotion 4. Bamboo pulp paper towels 5. Bamboo charcoal 6. Kentucky Fried Chicken Canada bamboo packaging 7. Bamboo laboratory at Casa Congo, Nicaragua 8. Bamboo paneling for concert space 9. Woven bamboo roof 10. Bamboo leaf tea 11. Pickled bamboo shoots in chili oil 12. Bamboo hand cream 13. Bamboo charcoal dust mask 14 Bamboo storage solution 15. Bamboo coaster 16. Bamboo furniture 17. Woven bamboo light shade. Note: OSB means oriented strand board. Photos of bamboo products reproduced xii with permission. [Image Credits: 1, 5, 9. INBAR (https://www.inbar.int/) 2. Birkner and Cobonpue (https://www.design-inspiration.net/inspiration/albrecht-birkner-pheonix/) 3, 12. Erborian (https://www.walmart.ca/en/c/brand/erborian) 4, 14, 16-17. X. Liu, 2024 6, 11, 13, 15. L. Binfield, personal communication, May 02, 2024, 7. Casa Congo (https://casacongo.org/projects-portfolio) 8. Dasso (https://www.dassogroup.com/project.html) 10.Y. Xia, personal communication, May 10, 2024.] .......................................................................................................................................14 Figure 2.2 Intermediate products of pretreatment bamboo products, from left to right: bamboo bundles (crushed bamboo strips), bamboo strips, flattened bamboo sheets (Y. Li, personal communication, March 20, 2024). ...........................................................................................16 Figure 2.3 LCA model analysis with (a) models built for different products in different areas, (b) percentage of models reported in different regions, (c) upward trend of model development from 2005 to 2023, and (d) type of models. ............................................................................38 Figure 3.1 System boundary of this study with three stages....................................................41 Figure 3.2 Byproduct generated from rough planing to make toothpicks and the machine used in this step. Left: toothpicks. Right: machine used for making toothpicks. [Source: Y. Xia, personal communication., June 18, 2024; Anji Qiancheng Bamboo and wood machinery factory, 2024]. ..........................................................................................................................49 Figure 3.3 Conceptual framework with three products and their intermediate products of this study. BLSL: known as Bamboo Laminated Strand Lumber, a new product generated by UBC Bamboo Application and Manufacturing Lab (Y. Li, personal communication, March 23, 2024.). ......................................................................................................................................55 xiii Figure 3.4 The manufacturing procedure of laminated bamboo. Products are in diamond shapes and manufacturing procedures are in rectangle shapes. Photos of bamboo products reproduced with permission. [Image Credits: 1. Guadua bamboo (https://www.guaduabamboo.com/). 2. Van der lugt, (2008). 3. Mesun bamboo (https://www.mesunbamboo.com/). 4. Moso bamboo (https://www.moso-bamboo.com/). 5, 6, 7, 8, 11, 15. Anos bamboo (https://anos-bamboo.com/). 9. X. Liu, 2024 12, 13, 17. Jiang & Liu, (2024).14, 19. Y. Li, personal communication, March 23, 2024. 20. Nkeuwa et al., (2022).] ................................................57 Figure 3.5 Two types of laminated bamboo strip plank. (a) plain pressing; (b) side pressing...................................................................................................................................................66 Figure 3.6 Manufacturing procedure of bamboo scrimber. Products are in diamond shape and manufacturing procedures are in rectangle shape. Photos of bamboo products reproduced with permission. Image Credits: 1. Guadua bamboo (https://www.guaduabamboo.com/blog/when-and-how-to-harvest-bamboo). 2. Van der lugt, (2008). 3. Mesun bamboo (https://www.mesunbamboo.com/about-us/production/). 4. Moso bamboo (https://www.moso-bamboo.com/). 5, 7, 8. Anos bamboo (https://anos-bamboo.com/how-to-make-bamboo-plywood/). 6. Li et al., (2020). 9. Chen et al., (2014). 10. Y. Li, personal communication, May 23, 2024. 12. Adjei and Yeboah, (2021). 13. Yang et al., (2021). 15. Huang et al., (2019)..................................................................................................................71 Figure 3.7 Manufacturing procedure of bamboo laminated strand lumber (BLSL). Photos of bamboo products reproduced with permission. Image Credits:1. Guadua bamboo (https://www.guaduabamboo.com/blog/when-and-how-to-harvest-bamboo). 2. Van der lugt, (2008). 3. Mesun bamboo (https://www.mesunbamboo.com/about-us/production/). 5, 6, 8, 11. xiv Yuan et al., (2022). 7. Yuan et al., (2021). 9, 10. Anos bamboo (https://anos-bamboo.com/how-to-make-bamboo-plywood/). 13, 15. Yang et al., (2024). 14, 17, 20, 21. Y. Li, personal communication, May 20, 2024. 19. Jiang and Liu (2024). ......................................................79 Figure 4.1 Carbon footprint of bamboo products (FU: 1 m3). LB (B): bleached laminated bamboo; LB (C): carbonized laminated bamboo; BS (B): bleached bamboo scrimber; BS (C): carbonized bamboo scrimber; BLSL: bamboo laminated strand lumber; P: plywood; na means North America; cn means China; LVL: Laminated veneer lumber; S: steel; eu means Europe; Con: concrete; glo means global. .............................................................................................88 Figure 4.2 Bamboo products and their intermediate product with major contributors. (a) Laminated bamboo; (b) Bamboo scrimber; (c) Bamboo laminated strand lumber. B: bleached; C: carbonized; PP: plain pressed plank; PS: side pressed plank; LB: laminated bamboo; BS: bamboo scrimber; FB: flattened bamboo; FBP: flattened bamboo plank; LSL: laminated strand lumber; BLSL: bamboo laminated strand lumber. ..................................................................91 Figure 4.3 Breakdown of electricity consumption during bamboo product production. (a) Bleached laminated bamboo; (b) Carbonized laminated bamboo; (c) Bleached bamboo scrimber; (d) Carbonized bamboo scrimber.............................................................................94 Figure 4.4 Fossil fuel depletion comparison between bamboo products and benchmark products. LB: Laminated bamboo; BS: Bamboo scrimber; BLSL: Bamboo laminated strand lumber; B: Bleached; C: Carbonized; P_cn: Plywood made in China; P_na: Plywood made in North America; LVL: Laminated veneer lumber; S_eu: Steel made in Europe; Con_glo: Average concrete emission in the global situation. ...............................................................101 xv List of Abbreviations BC province code for British Colombia defined in the EcoInvent database. BLSL bamboo laminated strand lumber. BS bamboo scrimber. CA country code of Canada defined in the EcoInvent database. CLT cross-laminated timber. CN country code of China defined in the EcoInvent database. CSG China South electricity grid. FB flattened bamboo. FU functional unit, 1 m3, which is the volume of any product mentioned in this study. GHGs Greenhouse gas emissions. GLO geographical location “global” defined in the EcoInvent database. IPCC Intergovernmental panel on climate change. LB laminated bamboo. LVL laminated veneer lumber. xvi RoW geographic location “rest of the world other than Europe” defined in the EcoInvent database. xvii Glossary APOS “allocation at the point of substitution”, an allocation method defined in the EcoInvent database. Biogenic CO2 is the carbon sequestered during biomass growth, such as wood and bamboo, and later released during product use (e.g., combustion) or end-of-life treatment (e.g., decomposition in a landfill). Carbon footprint is a commonly used metric to quantify the climate change impacts from the greenhouse gas emissions during the life cycle of a product in the unit of kg CO2 equivalent (CO2 eq). Carbon sequestration is the process of capturing and storing atmospheric carbon dioxide through photosynthesis. Cradle-to-gate describes a system boundary in the LCA assessment. It means the assessment covers the life cycle of the product from resource extraction to the gate of the final product which is ready for shipment to customers. Cradle-to-grave describes a system boundary in the LCA assessment. It includes the whole life cycle of the product from resource extraction to the end-of-life phase. CO2 eq. “carbon dioxide equivalent”, is a metric for comparing the climate change impacts from various greenhouse gas emissions, such as nitrous oxide (N2O) and methane (CH4). xviii Eco cost is a metric to quantify the environmental impact of a product, based on efforts to prevent that impact. These costs represent the (marginal) expenses required to mitigate environmental pollution and material depletion. EPD environmental product declaration is a standard document for displaying the environmental impacts of a product from a company or an industry. Life cycle assessment (LCA) is a common methodology used to evaluate the environmental impacts associated with all stages of the life cycle of the product, ideally from cradle to grave. Other than the carbon footprint methodology, the LCA method will assess not only the climate change impact of greenhouse gas emission (refer to Global Warming Potential), but also acidification, ecotoxicity, land occupation, ionizing radiation, depletion, and others. xix Acknowledgments First and foremost, I would like to express my sincere gratitude to Professor Chunping Dai and Professor Qingshi Tu for their guidance and supervision throughout my M.Sc. study and research. Thank you for your patience, enthusiasm and all the help especially when I felt lost in my research. Thank you for offering me this golden opportunity to perform this wonderful project. Your mentorship in research and the way to treat people inspire me to be a researcher and a better person. Being a student of yours is the best decision I have made: How can I ever thank you enough for choosing me to be one of your students? I also extend my gratitude to Dr. Taraneh Sowlati for being on my supervisory committee. Thank you for your knowledge of the product supply chain and advice on how to be more realistic in conducting my research. More thanks also go to two Postdocs in our group, Dr. Kate Semple and Dr. Yuan Hu. Many thanks to Dr. Semple for her help with writing and revising my thesis. My thesis would not be where it is without her tireless help and guidance. And thank you Dr. Hu for your help in modifying some of the figures in my thesis. Special thanks to Jialin Zhang, Jinlu Gan, Jinming Ke, Eric Li, Sol Rodriguez, Yeling Xia, Meiling Chen, Lucy Binfield, Shiva Zargar Ershadi, Bidhan Bhuson Roy, Tamara Britton, Zirui Tang for being my best friends during my M.Sc. life. Thank you for sharing your wisdom, advice, and useful suggestions for my research and my life. xx Finally, I would like to heartfully thank my parents for supporting me all these years. Many thanks to Ms. Yongli Wang and Dr. Qing Liu for giving birth to me and supporting me spiritually throughout my life. Your encouragement during tough times is much appreciated. 1 Chapter 1: Introduction 1.1 Background and Rationale An apt question behind the rationale for this work might be ‘Why do people need bamboo when there are so many other products in the world?’ The answer is both simple and complex. New and renewable materials can generally help reduce natural resource depletion and mitigate climate change, but what would be the differences between bamboo and wood? Climate change threatens the biosphere and human lives as evidenced by record-breaking heatwaves, wildfires, destructive floods, sea level rise, and other extreme weather conditions. Solutions are desperately needed to help mitigate climate change and must involve researchers, governments, and the public. The factors that impact climate change are well studied. Greenhouse gas emissions (GHGs) from human activities are the main drivers, including production from industry, energy consumption for electricity and transportation, and using nonrenewable materials (Intergovernmental Panel on Climate Change, 2022; Lu et al., 2022; Metz, 2009). Major GHGs include carbon dioxide (CO2), methane (CH4), and nitrous oxides (N2O) which have dramatically increased in recent decades (Metz, 2009; Casella, 2011). Net anthropogenic GHGs were estimated at around 59 Gt CO2 eq in 2019, which was 54% greater than the 1990 estimate (IPCC, 2022). 2 Governments release policy incentives, regulations, and sometimes binding legislation to help reduce emissions. For instance, the Canadian government has committed to a target to try to reduce Canada’s emissions by 40 to 45% by 2030 and reach net zero by 2050 (Environment and Climate Change Canada, 2021). The two largest emitters globally, China and the United States signed an agreement in 2014 to share information on clean coal power technology to help reduce their emissions (United Nations Climate Change, 2014). Under the recent European Climate Law (2021), Europe’s economy and society aim to cut greenhouse gas emissions by at least 55% by 2030 and reach carbon neutrality by 2050. Public sentiment has started to shift away from petroleum plastics which are a major environmental pollutant and take between 200 to over 1000 years to biodegrade in nature (Chamas et al., 2020). Universities, communities, and small businesses are all gradually switching to using biomaterials instead of plastics and other non-renewable or degradable products. Companies are keen to claim they are carbon neutral or environmentally friendly on their annual reports, environmental declaration of products (EPDs), and websites to attract investment customers and stakeholders, as examples of incremental societal changes towards sustainability. The construction industry remains a major contributor to GHGs, emitting an estimated 12 Gt CO2 eq. accounting for approx. 20% of total global GHGs in 2019 (IPCC, 2022). The construction industry is a high-priority area for change, with construction materials manufacturing being a major source of emissions and environmental pollution. It is therefore urgent to find appropriate biomaterials to partially or largely replace these traditional high-polluting materials. Wood products are the first option that comes to mind since societies have a very long history of using wood. The first wooden house is believed to have been developed 3 during the Young Stone Age (about 6,000 years ago) using logs (Grabner et al., 2018). North America and Asian countries also have a continuous and consistent culture of building houses with wood. The IPCC report (2022) recommends the use of wood products or other biomaterials to replace traditional construction materials. However, wood products are constrained by excess demand and decreased supplies stemming from their historic over-exploitation, slow replenishment rate, and increased impacts of natural disasters like wildfires. Wood products are universally used, ranging from paper and tissue products to construction materials, and as an important fuel energy source in some countries (Gajdačová et al., 2018). Governments are increasingly implementing policies and regulations to encourage increased adoption of wood-based alternatives to plastics and other unsustainable materials used in food and other packaging, grocery bags, furniture, kitchen utensils, etc. The projected demand for wood products increases as forest cover and the ability to grow wood decreases from other demands for land (agriculture, urbanization), and losses of timber estate to wildfires and extreme weather (IPCC, 2022; Morales-Hidalgo, 2015). Regrowth forests also have lower carbon density than mature original forests (IPCC, 2022). Planted or regrowth forests normally take 30 to 50 years to mature to harvestable age and size for lumber production (Jastrzębski & Paluch, 2022; Ligot et al, 2022). Pressures on forests from diseases, fires and lengthy harvesting cycles reduce wood supplies to industry in certain countries and regions. High demand but low supply creates a supply and demand crunch, affecting lumber and wood product prices. To help mitigate wood supply shortfall much research and commercialization effort has gone into developing alternative biomaterials such as bamboo, which produces ‘wood-like’ stem 4 tissue that once correctly seasoned has similar or better mechanical properties to many commodity lumber species. A benefit of bamboo is its much faster harvesting cycle (around 4 to 5 years), and several decades of successful research and development cultivation and commercialization in China now sees a wide range of viable bamboo products on the market (Li et al., 2016). Bamboo has excellent carbon absorption capacity due to its rapid growth cycle (Li et al., 2011; Wang et al., 2023). Bamboo can be used as a low-carbon material in buildings and construction (Silva et al., 2023). Companies and designers have completed several projects with bamboo in different countries: Fig. 1.1 highlights three of these. The first project is located in Germany featuring an electric vehicle charging station by ReNüTeq using laminated bamboo (Figure 1.1 (b)). The structure uses steel connectors and solar canopies on the roof, a concept that has been subsequently used in hotels, bridges, theaters, and treehouse resorts. The second project is a city shopping district in Milan, Italy designed by Zaha Hadid, showing the versatility of bamboo material (bamboo scrimber) with its impressively curved design. The bamboo floors and ceilings together provide a warm and dynamic feeling for customers (Figure 1.1 (c)). The third project is a roof made from flattened bamboo shingles in Indonesia. All projects are large public commercial buildings, designed and built to international standards. The charging station built by ReNüTeq was certified under ASTM 5456, Eurocode 5-EN 1995, and LEED V-4 – BREEAM (ReNüTeq, https://www.renuteq.com/structural). Many more bamboo houses have been built by companies that specialize in low-cost and specialty bamboo house design and building, such as Bamboo Living, Casa Congo, and IBUKU. 5 Figure 1.2 shows annual trends in the number of bamboo-related publications using data from the Web of Science from the keyword “bamboo”. The number of publications has more than doubled over the past ten years, covering a wide range of topics including materials, (c) (d) (e) (f) (a) (b) Figure 1.1 Bamboo related materials in building and construction area applications: (a) an electric vehicle charging structure with laminated bamboo lumber in New York, USA, (b) laminated bamboo lumber, (c) city life shopping district in Milan, Italy, (d) bamboo scrimber beam, (e) bamboo roof, (f) flattened bamboo [Sources: (a) and (b): ReNüTeq (https://www.renuteq.com/); (c): Moso bamboo (https://www.moso-bamboo.com/bamboo-inspiration/bamboo-wood-citylife/); (d): Chen et al. (2021); (e) and (f): Bamboo U (https://bamboou.com/flattened-bamboo-roofing-in-bamboo-architecture/). ] 6 environment, forestry, energy, and chemistry. Most articles focus on materials and modification of bamboo. From Figure 1.2, the number of bamboo-related research and publications grew rapidly after 2016, doubling in a decade. 7 (b) (a) 050010001500200025002013 2014 2015 2016 2017 2018 2019 2020 2021 2022 2023Number of publicationsFigure 1.2 Number of publications and top 10 areas focusing on bamboo: (a) number of publications from 2013 to 2023; (b) the most popular areas of bamboo-related research, from left to right materials science multidisciplinary (MSM), environmental sciences (ES), materials science paper world (MSPW), forestry, plant sciences, polymer science, energy fuels, engineering civil, engineering chemical (EC), chemistry multidisciplinary (CM). Source from Web of Science. 8 1.2 Objectives and Hypothesis This work aims to advance the understanding of the carbon footprint of bamboo structural products by developing practical models with individual sub-models for each major step during the manufacturing process. These models can help identify high carbon-intensive steps and improve the calculation of the carbon footprint for bamboo construction materials. The main objectives are to: 1) Develop module-based carbon footprint models for the two most common structural bamboo products: laminated bamboo and bamboo scrimber. Each product is analyzed using models for major intermediate products, their corresponding manufacturing processes, and related residue utilization. 2) Conduct a case study to validate and demonstrate the use of the models for calculating the carbon footprint of a new hybrid product composed of wood and bamboo. 3) Compare bamboo products to other benchmark construction materials, including steel, concrete, and wood-based products by estimating the carbon reduction potential of using bamboo structural products. 4) Analyze and compare carbon emissions of key processing stages between and within laminated bamboo and bamboo scrimber products and hence quantify their relative contributions to the carbon footprint. The main hypotheses investigated in this study are: 9 1) Bamboo structural products show better carbon storage ability compared with other benchmark products, even including certain wood-based materials. 2) Bamboo element product procedures, such as the production of bamboo strips, are the most carbon-intensive step in manufacturing engineered bamboo products. 3) Bamboo scrimber manufacture has higher overall CO2 emissions than laminated bamboo and flattened bamboo. 4) Transportation plays an important role in the total carbon emission of bamboo products. 5) Producing certain byproducts from bamboo residues can further increase the carbon footprint of bamboo products. 1.3 Outline of Thesis Chapter 1 provides a brief background and rationale for conducting carbon footprint analyses of structural bamboo products and states the objectives and hypotheses. Chapter 2 reviews the literature relating to carbon footprint analysis methods for bamboo and bamboo products for bamboo carbon accounting. Chapters 3 and 4 are related to model development; Chapter 3 presents the methodology of model development with two data collection methods. It presents the results from the models and discussion of which bamboo product manufacturing process has the highest emissions. Comparison is made with estimates made for typical wood structural materials from other published papers or reports and discusses reasons why bamboo products have a lower carbon footprint. Chapter 4 compares carbon footprint estimates for bamboo products with benchmark construction materials such as concrete, steel, and cement. Chapter 10 5 Conclusions discusses how the major findings accord with the general hypotheses and summarizes the main conclusions and future research directions. 11 Chapter 2: Literature Review 2.1 Bamboo and engineered bamboo products With over 1200 species, bamboo is widely distributed across the tropics and subtropical regions of the world i.e. the Asia-Pacific region, the American region, and the African region (Huang et al., 2022; Gu et al., 2019; Liu et al., 2016; Sharma et al., 2015). The Asia-Pacific region is the largest of the world’s bamboo-growing regions (Gao, 2021). Moso bamboo (Phyllostachys edulis) is the main commercial giant bamboo species in the Asia-Pacific region and is also called Phyllostachys pubescens and Phyllostachys heterocycla (Li et al., 2020; Yen and Lee, 2011; Hu et al., 2023; Gao et al., 2014; Zou et al., 2023). Hereafter referred to as moso, this fast-growing species can reach an average culm height of 13 m in about 1 month (Wang et al., 2017; Chen et al., 2022). The average diameter at breast height (DBH) of moso bamboo is 9.3 cm (Gao, 2021). Bamboo is used in many different applications including revegetation and landscape plants, foodstuffs (edible shoots, teas, fermented drinks), building materials, fuel, and medicine (Clark et al., 2015; Yu et al., 2008). Figure 2.1 showcases the large variety of bamboo uses and products available today, with the inner circle showing categories and the outer circle showing specific examples of bamboo products. The global market for bamboo products was worth an estimated 66.2 billion in 2022 (The Business Research Company, 2023). The outer layer represents the main materials used in each section and the second outer layer gives the product name. 12 Among all these categories, engineered bamboo products for construction contributes around US $25 billion with a projected 5% annual growth rate (Transparency Market Research, 2023). With growing demand for more eco-friendly materials, bamboo is gaining increased interest in the construction sector for its rapid growth rate and excellent mechanical properties. The mechanical properties (i.e., modulus, tensile strength) of bamboo fibers are nearly twice those of wood from Chinese Fir and Masson Pine (Yu et al., 2011; Yu et al., 2014; Xie et al., 2016). Raw bamboo culms are variable and contain nodes and a propensity for cracking. Reliable connection of bamboo poles can present problems that have hampered the growth of bamboo pole building (Sun et al., 2020; Hong et al., 2020; Huang et al., 2016; He et al., 2017). Compared with traditional bamboo buildings using round culms, engineered bamboo products are more consistent and reliable materials for modern construction. The development of engineered bamboo has benefitted greatly by adapting mature wood product processing technologies, scrimber being a good example (Sun et al., 2020). The curvature of the natural bamboo culm is a barrier to the utilization of bamboo (Yuan et al., 2022). Engineered bamboo requires milling flat rectangular strips, planing, and sanding to produce uniformly flat surfaces for gluing. Culm flattening technology is also used to create uniform sheets for gluing. Various techniques have been developed for flattening bamboo culms. The different circumferences of the outer and inner wall and gradational culm wall structure generate differential stresses during flattening leading to cracks and other damage (Fang et al., 2018). Bamboo flattening was first reported by Zhang (1988) in China with a half-culm flattening technique. The process used hot water to first soften the bamboo culm followed by hot pressing, testing three different strategies 1.) directly pressing the softened half bamboo 13 culm; 2.) gradually pressing the half bamboo culm to a flat strip; 3.) continuously pressing the bamboo culm through several rollers. Deep cracks occurred using the first method and the second method was time-consuming, while the third method required an appropriate continuous pressing machine to accommodate the non-standard shape of bamboo culms. Crack-free flattening methods have been developed in more recent years. Yuan et al. (2022) reported two methods including whole culm flattening with V-shaped protrusion nails and half or 1/3 culm flattening using arc-shaped flattening rollers. Fang et al. (2018) reported a more efficient method involving a set of rollers with diagonal knives on the surface to cut the inner surface of bamboo culm which could help to reduce the stresses on the culm wall and cracking. 14 Figure 2.1 2022 Global bamboo market size with a schematic representation of diversity in bamboo products and applications in eleven major areas. Images: 1. Bamboo bicycle 2. Handwoven bamboo car 3. Bamboo lotion 4. Bamboo pulp paper towels 5. Bamboo charcoal 6. Kentucky Fried Chicken Canada bamboo packaging 7. Bamboo laboratory at Casa Congo, Nicaragua 8. Bamboo paneling for concert space 9. Woven bamboo roof 10. Bamboo leaf tea 11. Pickled bamboo shoots in chili oil 12. Bamboo hand cream 13. Bamboo charcoal dust mask 14 Bamboo storage solution 15. Bamboo coaster 16. Bamboo furniture 17. Woven bamboo light shade. Note: OSB means oriented strand board. Photos of bamboo products reproduced with permission. [Image Credits: 1, 5, 9. INBAR (https://www.inbar.int/) 2. Birkner and Cobonpue (https://www.design-inspiration.net/inspiration/albrecht-birkner-pheonix/) 3, 12. Erborian 15 (https://www.walmart.ca/en/c/brand/erborian) 4, 14, 16-17. X. Liu, 2024 6, 11, 13, 15. L. Binfield, personal communication, May 02, 2024, 7. Casa Congo (https://casacongo.org/projects-portfolio) 8. Dasso (https://www.dassogroup.com/project.html) 10.Y. Xia, personal communication, May 10, 2024.] Manufacturing processes for the engineered bamboo products can be divided into three stages: 1) primary element milling and pretreatment, 2) panel manufacturing, and 3) final product. Bamboo is first converted to elements such as milled bamboo strips, ribbons, and flattened bamboo culms (Huang et al., 2022). These may be further processed into scrimmed bundles, stitched curtains, woven mats, laminated blocks, strands, or particles to which adhesive is applied and pressed into panel products such as bamboo fiberboard (Huang, 2019; Zhang et al., 2015), bamboo scrimber (Huang, 2019; Chung and Wang, 2018), bamboo particleboard (Huang, 2019; Karlinasari et al., 2021), laminated bamboo lumber (Sun et al., 2020; Sharma, et al., 2015; Mahdavi et al., 2012), bamboo laminated veneer lumber (Chen et al. 2014), glubam (Xiao et al, 2013), and plybamboo (Li et al., 2020; Zheng et al., 2020; Fadhlia et al., 2017). Most studies papers focus on one particular final product such as plybamboo, laminated bamboo, or bamboo scrimber flooring. A few studies cover primary elements or intermediate products (i.e. bamboo strip, bamboo bundle, bamboo plank, etc.). There are often separate companies that produce primary and intermediate products such as ribbons and woven mats, stitched curtains, or seasoned strips, and others that purchase these to fabricate final products such as Glubam or LBL. To calculate their product’s carbon footprint, the carbon footprint of the primary elements and intermediate products is required. Major bamboo products used in construction come in panel or lumber forms, including laminated bamboo, bamboo scrimber, and flattened bamboo products based on the primary a 16 and intermediate products: strips, bundles, and flattened bamboo, shown in Figure 2.2 (Hong et al., 2020; Tang et al., 2022; Sun et al., 2020). These three types of products are used for non-structural applications, such as flooring, furniture, beams, framing, or walls. Figure 2.2 Intermediate products of pretreatment bamboo products, from left to right: bamboo bundles (crushed bamboo strips), bamboo strips, and flattened bamboo sheets (Y. Li, personal communication, March 20, 2024). Laminated bamboo (LB) is based on milled strips glued into one layer or multi-layered rectangular cross sections. The LB fabrication process is described in Mahdavi et al. (2011) whereby culms are harvested and transported to factories where they are split longitudinally into strips that are then planed to remove the inner and outer skin. Strips are bleached or carbonized to adjust colour and then dried and re-dressed to dimension prior to adhesive application and assembly and pressing to form final products. Post-processing includes trimming, sanding, and planing (Sharma et al., 2015). Tang et al. (2022) introduced sand-17 blasting surface modification to the laminated bamboo manufacturing process to improve bonding. The sandblasted bamboo strips are oven-dried and applied with phenol formaldehyde resin, followed by layering and hot pressing to cure the adhesive. Another example of structurally engineered bamboo is Glubam (Xiao et al. 2013) manufactured using laminated layers of bamboo mats and curtains bonded with structural grade phenol formaldehyde (PF) resin. The product requires several intermediate element processing steps after splitting bamboo culm. The culms are converted to small narrow strips of 2 to 3 mm thickness with inner and out culm skin removed that are boiled to reduce starch levels, dried, and machine stitched together to form continuous rolls of flexible curtain stock that are trimmed to width. Mats are also made from thin woven ribbons for the product. These are dipped in PF resin, layered into a mat with other resin-coated veneers, and hot pressed. Slender bamboo strips exhibit better flexibility compared to the thick strips used in LB and require less precision in the arrangement. Bamboo scrimber (BS) is another major product class of engineered bamboo products, made from resin-coated scrimmed or ‘fluffed’ bamboo bundles. Bamboo bundles are an intermediate element type produced by flatting split culms through rollers that break up the wall tissue into attached splinters. The crushed bamboo bundles are saturated with PF resin by dipping, and hot pressed to a high-density (1000 g/m3 to 1200 g/m3) billet or panel (Sun et al., 2020; Chen et al., 2024; Wu et al., 2023). An improvement on BS, termed laminated veneer lumber (BLVL) introduced by Chen et al. (2014) stitches bundles measuring 5-7 mm in thickness together horizontally to form an even veneer sheet. This eliminates the gaps and overlaps that create heterogeneity in the mat structure, over and under compacted zones, and non-uniform 18 properties (Pineda et al., 2021) Bamboo LVL is formed with 3 to 5 parallel layers of stitched veneers coated with structural PF resin and hot pressed (Zhou et al., 2019; Xiao et al., 2013). 2.2 Carbon footprint estimates This thesis addresses the question of whether bamboo structural products have a lower carbon footprint compared to conventional materials used in construction. Carbon footprint estimates involve two important factors: 1) emissions generated during the manufacturing procedures of products and 2) the carbon sequestration potential of the materials, i.e. trees and bamboo sequester atmospheric CO2 during growth, whereas minerals involve CO2 released during mining. Forests and forest products have different methods to assess carbon footprint. Products are assessed by calculating the energy and material inputs during the manufacturing procedures whereas forest carbon sequestration is assessed based on various carbon pools, including aboveground biomass, belowground biomass, surface leaf and branch litter, and the soil (Mumcu, 2020). Accumulated carbon pools in different parts of forests are used to calculate carbon sequestration and storage in bamboo forests (see next section). Different methods are applied in carbon footprint calculations for bamboo products or forests. Life Cycle Assessment (LCA) is used to estimate the carbon footprint of a product. This literature review covers both LCA studies in bamboo products and carbon pool calculations for bamboo forests. 19 2.2.1 Carbon footprint of bamboo forest Bamboo absorbs carbon dioxide from the air via photosynthesis as it grows in the forest or plantation, and different species have different carbon sequestration and storage abilities. Moso bamboo (Phyllostachys edulis) as a major commercial bamboo species has much data reported from Japan, Taiwan, and mostly China (Zhang et al. 2015; Xu et al. 2011; Xu et al. 2018). Most studies focus on both above and below-ground carbon storage. Among these carbon pools, two-thirds of the total carbon is contained in the above-ground portion (Yuen et al., 2017). The carbon store increases with several factors including forest age, silviculture, and culm density (Xu et al., 2018; Chen et al., 2009), demonstrating that moso bamboo forests can serve as a carbon sink (Fu et al., 2023). Xu et al. (2018) found that carbon storage was largely dependent on culm density, age, and DBH, but not significantly influenced by environmental factors such as latitude, aspect, slope, or soil thickness. Chen et al. (2009) calculated the change in carbon stocks in bamboo stands in China from 1950 to 2003 with data derived from the National Forestry Inventory and forecasted that carbon stocks will increase over the next 50 years with an average 0.7% annual growth rate. Yen and Lee (2011) compared carbon sequestration between moso bamboo (8.13 t C/ha) and Chinese fir (Cunninghamia lanceolata) forests (3.35 t C/ha) in central Taiwan. The aboveground sequestered carbon of Chinese fir was greater than moso bamboo due to the larger size and greater age of the trees, however moso bamboo registered higher carbon sequestration rates per hectare per year over its first 5 years of growth. There is rapidly growing interest from society and governments in the carbon footprint of bamboo forests and plantations. A voluntary carbon credits trading market provides net carbon 20 emitters including corporations, organizations, governments, and individuals with the opportunity to purchase carbon offset credits to help achieve their carbon neutrality goals. Verra is a third-party organization that plays a major role in the carbon offset trading system and is the main platform for registering bamboo forest carbon projects to sell carbon offsets. As of September 2023, there were 15 bamboo forest projects registered on the Verra registry platform, with 6 located in Africa, 5 in Asia, 3 in Europe, and 1 project located in Latin America. Within Asia, India has 4 bamboo projects. China, as the earliest adopter of industrial cultivation and processing of bamboo, has developed its own registry and standards for bamboo projects and is currently not part of the Verra network. Other countries and areas have no national standards or requirements for bamboo forests and plantations. Bamboo projects registered on the Verra platform use carbon storage calculation methodologies for tree forests rather than methods specifically adapted to bamboo forests, necessitating a new methodology for bamboo forests. From 2020 to 2023 bamboo projects registered with Verra increased from 5 to 15, an increase of 200%. Details of these can be found in Table 2.1 and note that 7 projects are currently still in the development and validation phase, and two have been rejected. For example, EcoPlanet, a major bamboo project development company, has submitted five projects with one successfully registered. Projects face stricter registration requirements now due to changes in Verra’s reporting standards and requirements. Projects submitted before November 2022 were not required to be fully defined, but since then required the full definition of the first project submission. In the coming years, more bamboo-related projects for carbon credit eligibility are expected to be submitted and registered on the Verra platform. 21 Table 2.1 Bamboo carbon projects submitted on Verra Registry System (up to September 25, 2023). Name Methodology Status Total emission reductions (t CO2) Estimated Annual Emission Reductions (t CO2/yr) Total area (ha) Crediting period (yr) CO2 sequestration (t CO2/ha/yr) Basilicata bamboo (Italy) AR-AMS0007 Under validation 55346680 1383667 35 40 39533.34 SMG - Bamboo plantations for a better tomorrow (India) AR-ACM0003 Under validation 4430300 221515 10000 20 22.15 Bamboo Afforestation (Malawi) Methodology Under Development Under development 3486020 174301 3584 20 48.63 1MTN Uganda Bamboo Planting Project (Uganda) Methodology Under Development Under development 3783240 126108 10000 30 12.61 EVI Bamboo Afforestation Project (India) AR-AMS0007 Rejected by Administrator 2629200 26292 596 100 44.11 Eastern Cape Bamboo Forestry Project (South Africa) AR-ACM0003 On Hold / 195438 10000 / 19.54 Bamboo plantations by farmers and community in the country (India) AR-ACM0003 Under development 1833780 61126 4500 30 13.58 Bisgnano and Mesoraca Project of Afforestation of the Agricultural Company GAIA SRL Bamboo Plants (Italy) AR-AMS0007 Under development 8833832 315494 9 28 35054.89 Rimboschimento Progetto Della Societa' Agricola GAIA SRL Bamboo Plants (Italy) AR-AMS0007 Under validation 77788928 2430904 62 32 39208.13 Reforestation Project in Meghalaya by Shillong Bamboo (India) AR-ACM0003 Under development 2000000 100000 5000 20 20.00 Lanao del Sur Bamboo Reforestation Project (Philippines) ACM0003 Registration requested 5958340 315067 8421 20 37.41 22 North Bandai Bamboo Reforestation Project (Ghana) AR-ACM0003 Registration requested 2158140 107907 2863 20 37.69 Bandai Hills Bamboo Reforestation Project (Ghana) AR-ACM0003 Registration requested 3778520 188926 7819 20 24.16 Peri-urban bamboo planting around South African townships (South Africa) AR-AMS0002 Registered 320000 16000 50 20 320.00 EcoPlanet Bamboo Central America - Reforestation Project (Nicaragua) AR-ACM0001 Registered 816300 40815 3199 20 12.76 23 Methods have been developed for calculating carbon storage in natural and planted bamboo forests. This review mostly covers moso bamboo forest since the focus products are made from moso bamboo. The carbon storage data for moso forest was collected through the Web of Science with keywords of “moso bamboo forest/plantation”, “carbon storage”, “land use” and “biomass”. The methodology involves four carbon pools including aboveground carbon (AGC), belowground carbon (BGC), litter carbon, and soil organic carbon (SOC) (Zhou et al., 2011; Adu-Poku et al., 2023). The litter carbon pool only considers the fallen leaves from bamboo which contributes little carbon compared to the others. Zhao et al. (2022) reported litter carbon from moso bamboo forest at 0.37 t C/ha, compared to 33.2 t C/ha for AGC, and 14.8 t C/ha for BGC (Yuen et al., 2017). Since Yuen et al. (2017) reviewed global bamboo forest carbon sequestration before 2017, the value from Yuen et al. (2017) and other published papers from 2018 to 2023 are included here to estimate total carbon storage, shown in Table 2.2. Table 2.2 Carbon storage in the moso bamboo forest (Unit: t C/ha). Location AGC BGC SOC Mean Range Mean Range Mean Range China, Japan, Korea, Taiwan 32.54 18.16-40.6 12.65 10.5-116.7 121.3 118.5-269 Note: Mean value is calculated from 73 papers. 24 2.2.2 Carbon footprint estimates for structure bamboo materials To better evaluate the carbon footprint of structural bamboo products, researchers have collaborated with factories or laboratories to analyze the manufacturing processes using details of energy consumption, utilization of materials, and chemical treatments. These studies may be sorted into application fields, products, and regions. A review of relevant literature on the subject revealed 59 environmental analysis models for bamboo products, covering the categories of construction and furniture, building, packaging, household items, transportation, and bioenergy. The literature search uses the keywords “bamboo”, “LCA”, and “life cycle assessment” in Web of Science and Google Scholar. Based on the title and abstract, papers were chosen and read to extract information from bamboo LCA models. The search found LCA studies for non-building products such as bamboo toothbrushes (Lyne et al. 2020), bamboo bicycle frames (Agyekum, et al. 2017), bamboo grid packaging (Ma et al., 2021), and bamboo winding pipes (Shi et al., 2019). Since this study focuses on engineered bamboo products, only LCA for products is presented. Numerous LCA models have been developed for more basic products to more complex processed engineered bamboo and hybrid products combining bamboo and other materials. Products include bamboo culms (Vogtländer et al., 2010; Zuraida and Larasati, 2015; Gomes, et al. 2022; Zea Escamilla and Habert, 2014), laminated bamboo flooring (Yu et al., 2019), glue-laminated bamboo (Li et al., 2016; Zea Escamilla and Habert, 2014), laminated bamboo veneer board (Restrepo et al., 2016), bamboo scrimber flooring (Yu et al., 2019), plybamboo (Vogtländer et al., 2014; Vogtländer et al., 2010; Chang, et al. 2018), strandwoven bamboo 25 (bamboo scrimber) (Vogtländer et al., 2010; Zea Escamilla and Habert, 2014), bamboo fiberboard (Ogawa et al., 2010), and flattened bamboo (Zea Escamilla and Habert, 2014). Most of the LCA models are from Asia (Chang et al., 2018; Ogawa et al., 2010), especially China (Yu et al., 2019; Li et al., 2016; Vogtländer et al., 2010; Vogtländer et al., 2014). The studies are mainly LCA models for one or several final products and others estimated the eco costs of manufacturing the products, such as air and water pollution (Vogtländer et al., 2010; Zuraida and Larasati, 2015; Silva et al., 2023). Most models cover cradle-to-gate analysis. Using commercial products such as laminated bamboo and bamboo scrimber, Yu et al. (2019) reported LCA results of laminated bamboo flooring and bamboo scrimber flooring in China based on the functional unit of 1 m2. The manufacturing procedures were divided into three stages: unit production, panel production, and final product processing, including use and disposal stages, i.e. a cradle-to-grave analysis. The results did not show the actual value of each impact category but used the normalized method which transfers different categories with different units into a single unit and three major categories: human health, ecosystem quality, and resources. Laminated bamboo flooring was shown to be a less energy-intensive process with significantly reduced damage to the environment in all three categories compared with bamboo scrimber flooring. Bamboo scrimber flooring had a 1.61 times higher environmental impact overall than laminated bamboo and required greater energy consumption in manufacturing. Li et al. (2016) analyzed 3 layered straight joint glued-laminated bamboo for the energy, material, and environmental cost of the production procedures using a gate-to-gate model that 26 included specific manufacturing processes, such as carbonization, drying, planing for rough and finished dimensions, gluing, hot pressing, and packaging. Processes were categorized into four groups: Preparation, Sorting, Glued-laminated bamboo forming, and Goods. The effects of each procedure were broken down and the major contributor was the carbonization and drying step, which comprised 100.8 kg CO2 eq. due to the high energy consumption. Zea Escamilla and Habert (2014) reported several bamboo-based construction materials including laminated bamboo, using 1 m3 as the functional unit to compare different materials. Data was collected from various papers to calculate the average value for each manufacturing procedure. The results only apply to the final product with normalized values for three categories: Human health, Ecosystem quality, and Climate change. However, the study did not assess intermediate products. LCA models are reported for bamboo scrimber (also called strand woven bamboo). Vogtländer et al. (2014) introduced a novel LCA approach incorporating land-use change calculations in China. Their research was centered on assessing the carbon footprints associated with two structural bamboo products: plybamboo and bamboo scrimber, covering their entire life cycles from cradle to grave. The biogenic carbon that was stored in the plybamboo or bamboo scrimber was factored into the calculation. Compared with plybamboo, bamboo scrimber stores less biogenic carbon (0.55 kg CO2 per kg) due to its large requirement for petroleum-derived resin. Vogtländer et al. (2010) focused on the eco-costs during the manufacturing of bamboo culms, plybamboo, and bamboo scrimber. These bamboo products shipped to Europe were compared 27 with locally produced wood products and tropical hardwood-based products. LCA analysis showed that overseas shipped bamboo products had relevantly higher eco costs than the local wood alternatives. Transportation from harbor to harbor of bamboo products accounted for between 19% and 89% of the total eco cost, especially for less manufactured products (i.e. bamboo culms). While bamboo products were deemed a sustainable choice for regions with abundant bamboo forests, using locally made wood products was still a better solution for countries without bamboo forests as a resource. High-quality 3-layer plybamboo and strand woven bamboo had similar estimated eco-costs to tropical hardwood such as Teak. With a high yield value per year and a shorter harvesting cycle, bamboo products still had a competitive advantage compared with local wood products. A cradle-to-grave LCA study was conducted by Ogawa, et al. (2010) for bamboo fiberboard from Japan, using a functional unit of 1 kg of fiberboard. They compared the energy consumption and GWP during the manufacturing procedures between bamboo fiberboard and a benchmark product of glass fiber-reinforced plastic and included the disposal stage in their research. Their results showed the GWP from the bamboo fiberboard manufacturing procedure was higher than that of glass fiber-reinforced plastics, but this was offset by the much higher energy consumption of the disposal stage of the glass fiber reinforced plastics, which surpassed the manufacture of bamboo fiberboard. Some LCA models exist for bamboo culms. Zuraida and Larasati (2015) compared traditional and modern preservation methods for bamboo culms in Indonesia. Their study covered the cradle-to-gate analysis of bamboo culms, from harvesting to preservation. Two species of bamboo, Phyllostachys pubescens (Moso bamboo) and Dendrocalamus giganteus grown in 28 Brazil had LCA models developed for culms and strips by Gomes, et al. (2022). Culms from the same plantation were transported and processed into strips at locations with different transport distances between the factory and the plantation. The LCA showed that the Dendrocalamus giganteus culms had higher emissions (2.34 kg CO2 eq) compared with Moso bamboo (1.87 kg CO2 eq) per meter of the culm. Dendrocalamus giganteus also had higher CO2 emissions when processed to strips, averaging 2.8 kg CO2 eq compared with processing Moso bamboo to strips (1.54 kg CO2 eq) per meter of strips. Transportation and electricity were the major contributors to emissions, accounting for 59% and 23% respectively. Their GWP values were lower than those reported by other countries such as China, likely because of differences in electricity generation – China relies largely on coal whereas Brazil uses more renewable energy sources such as hydro-electric (Reichert et al., 2021). The study also reported the environmental-mechanical performance indicators of culms and strips, comparing emission/resistance factors. Results showed that longer transportation distances resulted in higher environmental impacts. LCA studies have been conducted on hybrid products containing bamboo and other materials, such as bamboo scrimber-steel frames (Zhang et al., 2021), bamboo-cement frames (Salzer et al., 2017), earth-based mortar with bamboo particles (Paiva et al., 2021; Paiva et al., 2022), pozzolanic cement made with bamboo leaf ash (Silva et al. 2023), bamboo bioconcrete (Caldas et al., 2020), bamboo and rice straw composites (Pang et al., 2022), and steel-glued laminated bamboo hybrid truss (Zhang et al., 2021). 29 Concrete frames reinforced with bamboo steel or conventional reinforcement for buildings were compared for LCA by Zhang et al. (2021). Their analysis covered the production, construction, operation, and end-of-life phases based on a three-story house as the functional unit. The operation stage considered the heating, cooling, and lighting requirements over a lifetime of 50 years. For the disposal stage, the LCA assessed the demolition work and waste transportation. A Monte Carlo simulation was conducted to investigate the influences of parameter uncertainty. The results showed that in the production phase, the metal materials were the major emitters. Bamboo scrimber emitted 27.9 t CO2, accounting for 17.4%. During the construction stage, the conventional reinforced concrete building had over 2 times higher emissions than the bamboo-steel frame building. The conventional reinforced concrete frame had a higher pollution index in the operation stage compared with the bamboo-steel frame, especially for heating which was 58% higher. The reinforced concrete frame had higher emissions in the end-of-life stage, especially waste transportation. While production emissions from conventional reinforced concrete frames and bamboo-steel frames were similar, the two product types diverged in the construction, operation, and demolition stages. The study showed that, overall, introducing bamboo materials could help reduce CO2 emissions over the life of the building. Restrepo et al. (2016) conducted an LCA analysis of the manufacturing process of bamboo boards in Colombia. The system boundary covered the entire production process plus residues. Two different energy sources for manufacturing the laminated bamboo veneer boards were considered, i.e. using bamboo residues or natural gas as the energy source. The results reported a negative value for the laminated bamboo veneer board of -117 kg CO2 eq if the factory used 30 bamboo residue as an energy source to generate heat for the boiling, drying, and hot-pressing processes. The CO2 emission value increased dramatically to 381 kg CO2 eq if natural gas was used as the energy source. The linear dependency between electricity consumption and the number of boards suggested factories should use bamboo residue as a major source of energy to reduce the environmental impacts incurred during manufacturing and utilize the high volume of residue produced by the factory. Xu et al. (2023) used an environmental tax as the environmental impact and economic indicator to analyze acceptance and willingness to purchase bamboo products in different regions in China. The results covered 10 environmental impacts of bamboo buildings from different provinces and major cities, including Beijing, Shanghai, Zhejiang, Sichuan, etc. Variations in CO2 emissions were observed across different regions due to differences in bamboo plantation locations and transport distances. For example, Zhejiang, the main bamboo-growing province registered a negative Global Warming Potential (GWP) value for the bamboo building. In contrast, since there are no bamboo plantations near Beijing, bamboo products registered a positive and higher level of CO2 emissions. Far-flung regions like Liaoning and Inner Mongolia registered higher emission values again than Beijing due to the long distances from bamboo plantations and also lengthy transport distances for products. The study also conducted an analysis of environmental taxation applied in different regions. Northern China had the lowest willingness to pay a premium for bamboo buildings, while Beijing imposed the highest environmental taxes for bamboo buildings at 266.30 yuan/m2. This is due to its long transport distances from bamboo factories relative to other cities, and the capital city’s stronger policies on pollution reduction. The study also compared results between bamboo materials 31 and C30 concrete which is the most common commercial building material used in construction in China. Overall, C30 concrete had higher environmental taxes imposed on it than bamboo materials, which still varied by region. For example, in Beijing, concrete had lower environmental taxes compared with bamboo material. The reason for this may be that the concrete industry has a well-organized short-transport distance supply chain in China’s northern cities whereas bamboo factories are mainly concentrated in the south of China far from Beijing with much longer product transport distances resulting in higher CO2 emissions. 2.2.3 Carbon footprint estimates for bamboo buildings Zea Escamilla and Habert (2017) developed a method to estimate the environmental impact of bamboo housing using a transport distance equation based on the total area of different countries. Estimates were made for bamboo housing in different countries in Latin America including Colombia, Panama, and Mexico. Five different houses were compared, including houses built from bamboo poles and manually flattened bamboo (esterilla), with both showing minimal environmental impact. The major contributor to climate change was the reinforcing steel used in their construction. Transportation was a major factor affecting the environmental impacts of bamboo houses compared with other types of houses. Transportation distance played a significant role in the variation of environmental performance. Overall, the study found bamboo houses had the lowest environmental impact and better structural performance than brick houses. 32 Rosse Caldas et al. (2020) conducted a cradle-to-grave LCA of bamboo bio-concrete in Brazil using a Dynamic Life Cycle Assessment. The team assessed six different cities in Brazil with different local climates, electricity matrices, and characterization factors. The results showed that the bamboo bio-concrete building was a good alternative to the conventional building system in Brazil. Overall, the 20 cm wall thickness of bamboo houses provided the best choice for mitigation of climate change. Bamboo houses were suggested as a solution for areas and countries to help address increasing housing demand. Zea Escamilla, et al. (2018) conducted an LCA on bamboo poles and glued laminated bamboo used in bamboo houses, involving production phases (including extraction of materials, transportation of materials, and manufacturing) and construction phases as the system boundaries. The study converted the portion value into an actual CO2 emission estimate per 1 m3 of bamboo poles or glued laminated bamboo. For example, carbon dioxide emissions during the manufacturing stages were included as a portion, representing 74.4% of 80 kg CO2 eq, allocated to the function unit that is used in the bamboo house (equivalent to 858 kg). Correal, et al. (2014) give an average density of glue-laminated bamboo made from Guadua angustifolia kunth, the same species used in the paper by Zea Escamilla, et al. (2018), of 730.55 kg/m3. Based on information from these two papers, the carbon dioxide emission during the manufacturing process of 1 m3 glue-laminated bamboo may be calculated as 74.4%*80* (1/ (858/ 730.55) = 50.68 kg, and manufacturing 1 m3 of the bamboo pole will emit 6.29 kg CO2 eq. Carcassi et al. (2022) prepared an LCA model for a novel bamboo bio-composite developed in Italy. The research contained three stages from bamboo cultivation to the retrofitting of 33 existing buildings with the bamboo composite. Their study considered 100 years as the service life of the plantation to calculate the GHG emissions from the entire cultivation process, from ploughing to the harvesting of phyllostachys edulis bamboo. In the second stage of the research, the production process of bamboo mycelium was analyzed with three main steps: inoculation, incubation, and deactivation at the lab scale. The bamboo-mycelium products used as exterior thermal insulation were also assessed. The functional unit was 1 m2 with a 30- or 60-year service life calculated. Emissions from the manufacturing processes were 84 to 85 g CO2 eq per unit. Considering the biogenic carbon stored in the products, the 60-year service life showed a slightly lower environmental impact with 30 g CO2 eq compared to the 30-year service life of 36 g CO2 eq. The replacement was also considered in the 30 and 60-year service life scenarios. A longer service life also means more replacements, which had a negative impact on the final net GWP value. The bamboo-mycelium products had a higher estimated GWP value compared with other materials due to the high volumetric mass and the extra materials needed to provide the same U-value. The renewable energy source resulted in a three-fold lower GWP than coal energy. Concrete frames reinforced with bamboo steel or conventional reinforcement were compared using LCA by Zhang et al. (2021). The analysis covered the production, construction, operation, and end-of-life stages based on the total house as the functional unit. A Monte Carlo simulation was conducted to investigate the influences of parameter uncertainty. For the operation stage, the heating, cooling, and lighting requirements over a lifetime of 50 years were considered. In the production stage, the metal materials used in the house were the major emitters. Bamboo scrimber emitted 27.9 t CO2, accounting for 17.4% of the total emission of 34 the product. During the construction stage, the conventional reinforced concrete building had over 2 times higher emissions than the bamboo-steel frame building. The conventional reinforced concrete frame had a higher pollution index in the operation stage compared with the bamboo-steel frame, especially for heating which was 58% higher. Interestingly the bamboo-steel frame structure resulted in 7.5% greater emissions than the conventional reinforced concrete frame due to the thinner walls used in the bamboo-steel frame increasing the relevant lighting floor area by 18.7 m2. For the disposal stage, the LCA assessed the demolition work and waste transportation. The reinforced concrete frame had higher emissions in the end-of-life stage, especially in waste transportation. While production emissions from the conventional reinforced concrete frame and the bamboo-steel frame were similar, the two building frame types diverged in the construction, operation, and demolition stages. The overall recommendation from the study was that introducing bamboo materials could help reduce CO2 emissions over the life of the building. 2.2.4 Other miscellaneous bamboo products Agyekum, et al. (2017) conducted a case study in Ghana for bamboo bicycle frames comparing the bamboo bike frame with the conventional aluminum and steel frames. The system boundary of the study included the whole life cycle of the bamboo bicycle frame. The study included environmental, social and socio-economic impacts in the analysis, considering the relationship between the company and the stakeholders, such as workers, local communities, consumers, and value chain actors. They collected data from three companies through 35 interviews. The results showed that the aluminum and steel bicycle frames had higher environmental impacts than bamboo bicycle frames in all categories, except freshwater aquatic ecotoxicity and terrestrial ecotoxicity. According to the GWP, the aluminum bicycle frames were over 6 times higher than the bamboo bicycle frames while that of steel frames was around 5 times higher. Lyne et al. (2020) compared toothbrushes made of different materials, including traditional plastic manual toothbrushes, plastic manual toothbrushes with replaceable heads, plastic and electric toothbrushes, and bamboo manual toothbrushes. The study covered the whole life cycle of toothbrushes from cradle to grave. Except for the bamboo toothbrush was manufactured in China, all other toothbrushes were produced in Europe. The result showed that the electric toothbrush had the greatest environmental impact while plastic manual replaceable-head and bamboo manual toothbrushes had the lowest environmental impact in most of the categories. Although bamboo toothbrushes were transported from China to the UK with the longest transportation distance compared with other toothbrushes, they still had a lower environmental impact in GWP, energy carriers, ozone depletion, and land use. Analysis of different LCA stages for bamboo toothbrushes, the manufacturing procedure, and usage phase (i.e., tap water usage) contributed the most. 2.3 Current bamboo LCA study overview Half of the LCA models found in the literature (50.85%) are related to construction and furniture materials, followed by bamboo building with 25.42% (Figure 2.3 a). LCA models 36 have also been developed for bamboo-based packaging including tableware, paper, and cardboard boxes, households and consumer items such as bamboo straws and toothbrushes, transportation and infrastructure including bamboo pipes and bicycles, and bioenergy (bamboo charcoal and biofuel). Most of the models reported come from Asia, especially China (> 40%) followed by South America with around 27% (Figure 2.3). There are numerous LCA models for bamboo products from other Asian regions (16.67%), including India, the Philippines, and Taiwan. Models reported from India are for mostly simple manufactured products, including household products (e.g. bamboo straws) and bioenergy products, such as bamboo biofuel feedstock (Rai et al., 2023; Patel et al., 2020). Philippines and Taiwan report structural products such as plybamboo and cement bamboo frames. Despite abundant bamboo resources in Indonesia, there is only one reported LCA model for a simple manufactured bamboo culm product (Zuraida and Larasati 2015). Half of all LCA models are from the last 3 years, compared with the previous 10 years (Figure 2.3 c), and may be categorized as LCA, LCA-Eco cost, and others (Figure 2.3 d). Over 78% include an environmental impact analysis with categories, such as GWP and ecotoxicity. Many are built using Sima Pro and OpenLCA software from the EcoInvent database. This study comes under the LCA model using OpenLCA software to assess the GWP of engineered bamboo products. Further details on the methodology are given in the next chapter. Some researchers focus on eco-cost analysis for bamboo products (over 15%) while others also include environmental payback periods or dynamic models. Most of the models cover the production phase which is the cradle-to-gate system boundary. Only a few studies include the whole life cycle of the product. 37 40.74%27.78%16.67%5.56%5.56% 3.70%China South America Asia (excluding China) EU Africa North America(b)50.85%25.42%6.78%6.78%5.08%5.08%Construction materials Building PackagingHouseholds Transportation Bioenergy(a) 38 (d) 78.85%15.38%5.77%LCA LCA - Ecocost Others051015202530352005-2010 2011-2015 2016-2020 2021-2023Number of modelYear(c) Figure 2.3 LCA model analysis with (a) models built for different products in different areas, (b) percentage of models reported in different regions, (c) upward trend of model development from 2005 to 2023, and (d) type of models. 39 2.4 Research gaps Existing models for bamboo products do not differentiate between intermediate production steps or units. Most structural bamboo products use similar procedures which could be classified under: 1) element production (such as strips, flattened bamboo, and bamboo bundles), 2) panel production (gluing small elements into a sheet), and 3) final product production (gluing the sheets into the final product). This study focuses on creating individual modules for unit production, panel production, and final product production for three products: laminated bamboo, flattened bamboo, and bamboo scrimber. This study also includes options for residue utilization in the factory with different scenario analyses. Common intermediate element production or residue uses procedures for different products means that the models in this study could be used for future research or commercial reports, and even evaluating novel products with a few adjustments as needed. 40 Chapter 3: Methodology and Models LCA can be used for the assessment of the environmental performance of any product (Zea Escamilla et al., 2018; Gan et al., 2022; the International Organization for Standardization 14040, 2006). LCA is a major tool to analyze the different environmental impacts of bamboo products (Xiao et al., 2013). This study focused on global warming potential (GWP), which is an indicator that estimates the cumulative climate change impacts from greenhouse gas emissions, including CO2, CH4, and N2O, for a specific period (100 years) after they are emitted to the atmosphere. 3.1 Scope of this study This study aims to evaluate the environmental impacts related to the production of structural bamboo products. The conceptual framework of this study is shown in Figure 3.1. LCA normally has five stages for product analysis, i.e., 1) raw material extraction and supply, 2) transport to the manufacturing site, 3) product manufacture, 4) usage, and 5) end-of-life stage, and this study focuses on the first three stages as seen in Figure 3.1. According to ISO 14040 (2006) and EN 15978 (2011), the life cycle of structural products can be broken down into the production stage (A1-A3), construction stage (A4-A5), use stage (B1-B7), and end-of-life stage (C1-C4). For bamboo products, in the context of this thesis, the scope mainly refers to 1) bamboo growth and harvesting, 2) manufacturing in the factory, 3) product use, 4) end-of-life, and 5) transportation included for products. This study considers the first three stages (A1-A3) and transportation between each stage, collectively termed ‘cradle-to-gate’. 41 The manufacturing procedures can be broken down into several subcategories, including base element or ‘unit’ production, panel production, and final product production. The main aims of the study are to: 1) Assess the environmental impacts of the manufacturing processes for three bamboo structural products using individual models for intermediate processing of elements, plank, and final products, including a new bamboo-wood product with individual models for intermediate products to demonstrate the function and the importance of the individual models, and 2) Compare the carbon footprints of the subject products. 3.2 Data collection and Functional unit Both primary and secondary data were used in this study. The primary data were collected from factories and laboratories, including Moso Bamboo Inc. in Zhejiang, China, Dasso Bamboo Inc. in Zhejiang, China, Indobamboo in Indonesia, and the Bamboo Application and Manufacturing (BAM) lab at the University of British Columbia in Canada. The secondary data were sourced from published papers or reports from research organizations such as the Figure 3.1 System boundary of this study with three stages. 42 International Bamboo and Rattan Organization (INBAR). The functional unit (FU) for the LCA is 1 m3 of materials, based on the literature and standard practice of developing LCA models for wood products and bamboo products presented in the EcoInvent database (Zea Escamilla and Habert, 2014; Frischknecht and Rebitzer, 2005). 3.3 Model Development Method With the data collected from different methods, individual models were developed using OpenLCA software and the EcoInvent v 3.7.1 database (https://ecoinvent.org/database/). OpenLCA is an open-source, industry-standard software package used in LCA modeling and sustainability assessment and is maintained by GreenDelta in Berlin, Germany. The EcoInvent database is a consistent and transparent life cycle inventory (LCI) database that is used worldwide. The impact assessment method used is ReCipe Midpoint (H), also one of the most widely used and recently updated impact assessment methods in LCA (Pittau et al., 2019). To compare the GWP results of structural bamboo products and other corresponding benchmark products, the total CO2 emissions from the manufacturing procedure are calculated using Equation 1. Each model is multiplied by the relative recovery rate, and these are then summed. 𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇𝑇 𝐺𝐺𝐺𝐺𝐺𝐺𝐵𝐵𝐵𝐵𝐵𝐵 = (𝐺𝐺𝐺𝐺𝐺𝐺𝐶𝐶𝐵𝐵 × 1/𝑅𝑅𝑒𝑒𝑒𝑒𝑇𝑇𝑣𝑣𝑒𝑒𝑣𝑣𝑣𝑣 𝑅𝑅𝑇𝑇𝑇𝑇𝑒𝑒𝐶𝐶𝐵𝐵) + (𝐺𝐺𝐺𝐺𝐺𝐺𝐸𝐸𝐵𝐵 × 1/𝑅𝑅𝑒𝑒𝑒𝑒𝑇𝑇𝑣𝑣𝑒𝑒𝑣𝑣𝑣𝑣 𝑅𝑅𝑇𝑇𝑇𝑇𝑒𝑒𝐸𝐸𝐵𝐵) +(𝐺𝐺𝐺𝐺𝐺𝐺𝐵𝐵𝐵𝐵 × 1/𝑅𝑅𝑒𝑒𝑒𝑒𝑇𝑇𝑣𝑣𝑒𝑒𝑣𝑣𝑣𝑣 𝑅𝑅𝑇𝑇𝑇𝑇𝑒𝑒𝐵𝐵𝐵𝐵) + (𝐺𝐺𝐺𝐺𝐺𝐺𝐹𝐹𝐵𝐵 × 1/𝑅𝑅𝑒𝑒𝑒𝑒𝑇𝑇𝑣𝑣𝑒𝑒𝑣𝑣𝑣𝑣 𝑅𝑅𝑇𝑇𝑇𝑇𝑒𝑒𝐹𝐹𝐵𝐵) −𝐺𝐺𝐺𝐺𝐺𝐺𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 (1) 43 Where: Total GWPBSP is the total GWP of bamboo structural products, kg CO2 eq/FU. GWPCP is the GWP value from the bamboo culm production, kg CO2 eq/FU. GWPEP is the GWP value from the element production, kg CO2 eq/FU. GWPPP is the GWP value from the plank production, kg CO2 eq/FU. GWPFP is the GWP value from the final product production, kg CO2 eq/FU. 𝐺𝐺𝐺𝐺𝐺𝐺𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 is the GWP value of the bamboo sequestration value in each forest-related product, kg CO2 eq/FU. Recovery Rate CP is the bamboo culm utilization ratio in the final product, %. Recovery Rate EP is the unit extraction ratio from the raw bamboo culms, %. Recovery Rate PP is the plank formation ratio from the small units, %. Recovery Rate FP is the final product production ratio from the panels, %. Data on the biogenic carbon and GWP from other stages was gathered from the literature review and summarized. These data sets undergo a process of harmonization and are analyzed to identify and address potential differences between GWP results attributable to the same bamboo product or manufacturing process. This harmonization process not only identifies and 44 mitigates uncertainties but also enhances the precision and reliability of environmental impact results (Gan et al., 2022; Heath et al., 2012). This is achieved by applying standardized methods and underlying assumptions across the entirety of the analysis. The recovery rates of each stage are estimated from Equation 2, and shown in Table 3.1, Table 3.2, and Table 3.3 below. All the numbers are calculated according to data from Moso Bamboo Inc. (Zhejiang, China) and literature reviews. 𝑅𝑅𝑒𝑒𝑒𝑒𝑇𝑇𝑣𝑣𝑒𝑒𝑣𝑣𝑣𝑣 𝑅𝑅𝑇𝑇𝑇𝑇𝑒𝑒𝑖𝑖 = 𝑉𝑉𝑢𝑢𝑉𝑉𝑡𝑡 × 100% (2) Where: Recovery Ratei represents the recovery rate of each stage for each product, %. Vu is the volume of the utilized output materials, m3. Vt is the total volume of the raw input materials, m3. The recovery rates are shown in Table 3.1 for laminated bamboo, Table 3.2 for scrimber, and Table 3.3 for BLSL. Recovery Rate CP is the culm recovery rate during the harvesting in the bamboo forest. Culm utilization ratio is the ratio of bamboo culm harvesting in the bamboo forest or plantation not in the factory. The residue during harvesting is left in the forest to decompose. Natural decomposition is considered carbon neutral since very little carbon is released into the atmosphere while most of the carbon is retained in the slowly rotting dead bamboo and retained in the soil (Trettin, 2021). This portion of ‘harvest residue’ is therefore not considered further in this work. 45 Only the bottom 2/3 (around 66%) of the culm is transported to the factory to convert to products, whereby the recovery rate varies depending on the production stage. Before processing, the top and bottom 30 cm of the culm is docked to remove cracked or damaged ends (Xia, Pers. Comm., 2024). Most of the residue is then produced during the element production stage. Table 3.1 Recovery ratio of each stage for laminated bamboo. Stage Recovery rate (%) Recovery Rate CP 66.67a Recovery Rate EP 40b Recovery Rate PP 100b Recovery Rate FP 92b a Van der lugt, (2008), b Sharma et al., (2015). Table 3.2 Recovery ratio of each stage for bamboo scrimber. Stage Recovery rate (%) Recovery Rate CP 66.67c Recovery Rate EP 58c Recovery Rate FP 98b,c b Sharma et al., (2015). c N. Nicholson and Y. Xia, personal communication., March 05, 2024. Table 3.3 Recovery ratio of each stage for BLSL. Stage Recovery rate (%) Recovery Rate CP 66.67c Recovery Rate EP 52d Recovery Rate FP 95d c N. Nicholson and Y. Xia, personal communication., March 05, 2024. d Nkeuwa et al., (2022). 46 3.4 Carbon storage in bamboo products The bamboo used in structural bamboo products has a long-term carbon storage capacity, whereby the carbon release into the atmosphere is delayed until the end of the service life, presumed to be 15 years (Liang et al., 2023). The ISO 21930 standard suggests including biogenic carbon in a system which implies the carbon drawdown from the atmosphere as a result of carbon accumulating in biomass (ISO, 2017). For easier comparison with wood-based products, this study takes the carbon stored in the product into consideration as follows: 𝐺𝐺𝐺𝐺𝐺𝐺𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 = 𝐺𝐺𝑖𝑖 × 𝐶𝐶 × 3.67 (3) Where: 𝐺𝐺𝐺𝐺𝐺𝐺𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 is total carbon stored in one FU product, kg CO2 eq/FU. 𝐺𝐺𝑖𝑖 is the weight of one FU product, kg. 𝐶𝐶 is carbon content in bamboo products, 49.22% (Gan et al., 2023) used in this study. 3.67 is the molecular weight ratio between CO2 and carbon (Vogtländer et al., 2014). 3.5 General equations used for calculation LCI. General formulas and relevant explanations used for model development related to the harvesting, transportation, energy consumption, and unit transfer ratio are listed in Table 3.4. The energy consumption formula is applied to all the electricity usage and heating calculations 47 in this chapter. The resin consumption formula is also applied to every resin calculation in this study. Table 3.4 General equations for harvesting, transportation, resin, and energy consumption. 3.6 Residue utilization The material (culm) utilization ratio is low for many bamboo products (Wang et al., 2020). The recovery ratio of laminated bamboo is 35%-40%, flattened bamboo is around 50%, and bamboo scrimber is between 50% and 70% (Nkeuwa et al., 2022). Estimating the residues from manufacturing the different products in this study is based on the weight of one FU (1 Stages Equation Notes Harvesting 𝑇𝑇𝑖𝑖 = 1/(2.6 × 646𝑑𝑑𝑖𝑖 ) 𝑇𝑇𝑖𝑖 is machine operation hour (h); 𝑑𝑑𝑖𝑖 is the density of the bamboo species in this study (kg/m3). Transportation 𝑇𝑇𝑖𝑖 = 𝐺𝐺𝑖𝑖 × 𝐷𝐷𝑖𝑖 × 1.8 𝑇𝑇𝑖𝑖 is the total input of transportation (kg*km) which represents transporting the specific weight of product for a specific distance from site to site; 𝐺𝐺𝑖𝑖 is weight and 𝐷𝐷𝑖𝑖 is distance;1.8 is the factor to include empty backhaul for a truck. Energy 𝐸𝐸𝑖𝑖 = 𝐺𝐺𝑖𝑖 × 𝑇𝑇𝑖𝑖 × 𝑣𝑣𝑖𝑖 𝐸𝐸𝑖𝑖 is the energy consumption of the procedure (kWh); 𝐺𝐺𝑖𝑖 is the power rating of the machine (kW); 𝑇𝑇𝑖𝑖 is machine operation hour to produce 1 FU products (h); 𝑣𝑣𝑖𝑖 is the unit transfer ratio. Unit normalization ratio 𝑣𝑣𝑖𝑖 = 1/𝑉𝑉𝑖𝑖 𝑣𝑣𝑖𝑖 is the ratio to transfer the sample unit to FU (1 m3) for the convenience of carbon footprint comparison between different products; 𝑉𝑉𝑖𝑖 is the volume of one sample (m3) which is calculated by multiplying length, width, and thickness. Resin consumption 𝐶𝐶𝑖𝑖 = 𝐴𝐴𝑖𝑖 × 𝑛𝑛𝑖𝑖 × 𝑅𝑅𝑖𝑖 × 𝑣𝑣𝑖𝑖 × 𝑠𝑠 × 10−3 𝐶𝐶𝑖𝑖 is the resin consumption for one FU product (kg); 𝐴𝐴𝑖𝑖 is the resin applied area in one product (m2); 𝑛𝑛𝑖𝑖 is the number of glue llines; 𝑅𝑅𝑖𝑖 is the spread content of the resin in wet condition (g/m2); 𝑣𝑣𝑖𝑖 is the unit transfer ratio; s is the PF solid content. 48 m3) of the product and the known recovery ratio of the product used to estimate the initial mass of culms needed. It is noted that the weight of the final product also includes the weight of the resin, which in some cases such as scrimber is high, at 15% or more. Here the amount of processing residue is based on the weight of bamboo in the product without the resin content. In China, many factories burn all residue as boiler fuel, but some may sell a portion (the wet residues) to a nearby charcoal plant or produce toothpicks as value-added byproducts. In this study, these alternative residue pathways are evaluated for their energy contributions to production. The specific scenarios are discussed under each product’s model in section 3.3. For each product, the residue is calculated according to the recovery rate in the factory: 𝐺𝐺𝑤𝑤𝑖𝑖 = 𝐺𝐺𝐹𝐹𝐹𝐹 × (1− 𝑅𝑅𝑠𝑠𝑠𝑠𝑠𝑠𝑖𝑖𝑟𝑟 𝑖𝑖) × ( 1𝑅𝑅𝑠𝑠𝑅𝑅𝑠𝑠𝑅𝑅𝑠𝑠𝑠𝑠𝑅𝑅 𝑅𝑅𝑅𝑅𝑠𝑠𝑠𝑠𝑓𝑓𝑓𝑓 − 1) (4) Where: 𝐺𝐺𝑤𝑤𝑖𝑖 is the total weight of residue, kg. 𝐺𝐺𝐹𝐹𝐹𝐹 is the weight of one FU bamboo product, kg. 𝑅𝑅𝑠𝑠𝑠𝑠𝑠𝑠𝑖𝑖𝑟𝑟 𝑖𝑖 is the resin content of the product, %. (This information can be found in the Appendix Table S1). 𝑅𝑅𝑒𝑒𝑒𝑒𝑇𝑇𝑣𝑣𝑒𝑒𝑣𝑣𝑣𝑣 𝑅𝑅𝑇𝑇𝑇𝑇𝑒𝑒𝑓𝑓𝑖𝑖 is the overall recovery rate in the factory of one FU bamboo product, %. The carbon footprints of toothpicks and bamboo charcoal are calculated from OpenLCA software using EcoInvent database v 3.7.1. Combustion as a boiler fuel is calculated using Equation 4 for energy recovery. 49 3.6.1 Toothpicks The long, thin slices of bamboo left over from rough planing strips for LB are converted to toothpicks (Fig. 3.2). The machine’s power rating is 9.5 kW with a feed speed of 65 m/min. For each product with planed strips as the elements, the energy consumption for toothpick fabrication is estimated from the following equation: 𝐸𝐸𝑖𝑖 = 9.5 × 𝑇𝑇𝑖𝑖 (5) Where: 𝐸𝐸𝑖𝑖 is the energy consumption of the procedure, kWh. 9.5 is the power rating of the machine, kW. 𝑇𝑇𝑖𝑖 is machine operation time to produce one FU of toothpicks, h. This is calculated as follows: Figure 3.2 Byproduct generated from rough planing to make toothpicks and the machine used in this step. Left: toothpicks. Right: machine used for making toothpicks. [Source: Y. Xia, personal communication., June 18, 2024; Anji Qiancheng Bamboo and wood machinery factory, 2024]. 50 𝑇𝑇𝑖𝑖 = 𝑙𝑙𝑓𝑓 ×((𝑊𝑊𝑟𝑟𝑓𝑓×10%)/𝑊𝑊𝑠𝑠𝑓𝑓 )65×60 (6) Where: 𝑇𝑇𝑖𝑖 is the length of one strip generated in the product manufacturing procedure, m. 𝐺𝐺𝑠𝑠𝑖𝑖 is the weight of raw materials in the factory used to make the product, kg. 10% is the percentage of residue used for making toothpicks in the raw material. 𝐺𝐺𝑠𝑠𝑖𝑖 is the weight of one single bamboo strip generated in the product manufacturing procedure, kg. 65 is the feed speed of the machine, m/min. 60 is the transfer ratio between minute and hour. 3.6.2 Bamboo charcoal Bamboo charcoal is the second most common byproduct produced from bamboo processing residue in China. Bamboo charcoal is made from wet sawdust and shavings generated from docking green culms and other planing processes, before any element heat treatment, coloring or drying takes place. Anecdotal information from the factory manager suggests the residue ratio for wet sawdust is different for the three products in this study: 45-46% for LBL manufacture, 30-35% for scrimber, and 40-43% for flattened bamboo. The wet residue is sent to the closest charcoal factory (economically located within a 50 km radius of the bamboo 51 factory). The 50 km transportation distance is included in the carbon footprint calculation (W. Zhang, personal communication, June 28, 2024). The specific calculations for bamboo charcoal for each product are given in section 3.3. Bamboo residue is carbonized in a carbonization kiln producing charcoal, gas, and tar. The gas can be used as an energy source for the kiln, so producing bamboo charcoal only requires fossil fuel natural gas to preheat the boiler (requiring an input of 13 MJ for 1 m3 of bamboo charcoal), and once it generates enough gas, the kiln can continue to be heated using the gas from the bamboo carbonization process. From information obtained from the manager of Jizhu Bamboo Charcoal Company in Zhejiang, China, the transport input of bamboo residue is 20047.5 kg*km (W. Zhang, personal communication, June 28, 2024). One ton of wet bamboo residue generally produces 0.23 tons of bamboo charcoal (23%) and 16800 m3 of gas in 24 hours. The estimated carbon emissions (GWP) used to make bamboo charcoal from the wet sawdust generated from producing one FU of each product are: 𝐺𝐺𝐺𝐺𝐺𝐺𝐵𝐵𝐶𝐶𝑖𝑖 = 𝑅𝑅𝐵𝐵𝐶𝐶𝑖𝑖 × 𝐺𝐺𝐺𝐺𝐺𝐺𝐵𝐵𝐶𝐶 (7) Where: 𝐺𝐺𝐺𝐺𝐺𝐺𝐵𝐵𝐶𝐶𝑖𝑖 is the carbon emission of treating wet bamboo residues as bamboo charcoal for one FU of each product, kg CO2 eq. 𝑅𝑅𝐵𝐵𝐶𝐶𝑖𝑖 is the ratio of residue used for making bamboo charcoal of each product, %. 𝐺𝐺𝐺𝐺𝐺𝐺𝐵𝐵𝐶𝐶 is the total carbon emission of making one m3 bamboo charcoal, kg CO2 eq. 52 3.6.3 Combustion Energy recovery for boilers from burning the processing residues is calculated since this is the most common practice in bamboo factories. Calorific value is commonly used to describe the energy generated from burning biomaterials, averaging around 19.31 MJ/kg for moso bambo (Engler et al. 2012). The efficiency of thermal power is 42% (EPD International Advisory Board, 2020). The residue from bamboo culm harvesting is left in the forest. Only residues generated from the element, plank, and final production stages in the factory are used for energy. The energy recovery from factory residue for each product is calculated as follows: 𝐸𝐸𝑅𝑅𝑖𝑖 = 𝐺𝐺𝑤𝑤 × 19.31 × 42% 3.6⁄ (8) Where: 𝐸𝐸𝑅𝑅𝑖𝑖 is the amount of energy generated from burning bamboo residues, kWh. 𝐺𝐺𝑤𝑤 is the weight of residues from manufacturing, kg. 19.31 is the calorific value of moso bamboo, MJ/kg (Engler et al., 2012). 42% is the efficiency of thermal power in China (EPD International Advisory Board, 2020). 3.6 is the transfer ratio from MJ to kWh (U.S. Energy Information Administration, 2024). 𝐺𝐺𝑤𝑤 = 𝑊𝑊𝑓𝑓𝑅𝑅𝑠𝑠𝑅𝑅𝑠𝑠𝑅𝑅𝑠𝑠𝑠𝑠𝑅𝑅 𝑅𝑅𝑅𝑅𝑠𝑠𝑠𝑠𝑓𝑓𝑓𝑓 − 𝐺𝐺𝑖𝑖 (9) 53 Where: 𝐺𝐺𝑤𝑤 is the weight of residues from manufacturing, kg. 𝐺𝐺𝑖𝑖 is the weight of one FU bamboo product, kg. 𝑅𝑅𝑒𝑒𝑒𝑒𝑇𝑇𝑣𝑣𝑒𝑒𝑣𝑣𝑣𝑣 𝑅𝑅𝑇𝑇𝑇𝑇𝑒𝑒𝑓𝑓𝑖𝑖 is the recovery rate of the final bamboo product in the factory, %. While the combustion of bamboo residue replaces a portion of total factory energy consumption, it also generates CO2. However, the combustion of bamboo is considered carbon-neutral in this study since its bamboo rapidly absorbs CO2 from the atmosphere during its growth, (U.S. Energy Information Administration, 2024; Leturcq, 2014). 3.7 Bamboo structural products This study covers two commercial structural products made from bamboo, namely laminated bamboo and bamboo scrimber, and one experimental product termed ‘bamboo-laminated strand lumber (BLSL)’ produced in the laboratory at UBC. Models are developed for the major intermediate products in the manufacturing procedures of these three bamboo products. The conceptual framework of the study is shown in Figure 3.3, with six intermediate product models and three final product models ordered from low-value to high-value products. Low-value products are primary processed elements e.g. milled strips produced using simple machinery or by hand, while high-value products tend to be final-stage finished products produced in larger industries and requiring more sophisticated processing and machinery (Zea Escamilla and Habert, 2014). It should be noted that the final products included in this study 54 are only semi-finished base products that are commonly further manufactured for construction framing, flooring, and interior decor products. To build LCA models, input and output data are needed. The major inputs considered in this study are raw materials (such as raw bamboo and resins), energy (electricity and heat), other resources (such as water), and transportation. Laminated bamboo in this study included the dataset from Moso Bamboo Inc. in China. The manufacturing procedures of the laminated bamboo strips in these two different primary manufacturing factories are similar, starting with raw bamboo harvesting, transportation to a pretreatment factory to produce bamboo strips, and strip production including culm cutting to length, culm splitting, skin removal, rough planing, carbonization/bleaching, drying, and then transport to a secondary manufacturing factory to produce planks or final products. For bamboo scrimber, sometimes also called ‘strand woven bamboo’, the dataset also comes from Moso Bamboo Inc. Bamboo scrimber can be used indoors and outdoors depending on its density and adhesive content. Outdoor bamboo scrimber has a higher density (1080 kg/m3) with a higher resin content and compression level. Bamboo scrimber is also commonly used as flooring which is cut from bamboo scrimber beams (Van der lugt, 2008). Bamboo scrimber products intended for indoor use are lower in density and resin solid content and are used as flooring and decorative panels. BLSL is an experimental panel product made from flattened bamboo and wood laminated strand lumber (LSL). The manufacturing procedures for these three products are shown in the next section. Harvested raw bamboo culms are broken down into different small basic units that are pretreated before drying. Once dry they are applied with adhesive, hot pressed, and 55 sanded to intermediate panel layers, which are then assembled into final products such as laminated bamboo lumber beams. 3.7.1 Laminated bamboo The manufacturing procedure for laminated bamboo in this study is shown in Figure 3.4. It involves harvesting, transportation, splitting, planing, coloring, drying, gluing, pressing, sanding, and end cutting. The products are all above the arrows while all manufacturing Figure 3.3 Conceptual framework with three products and their intermediate products of this study . BLSL: known as Bamboo Laminated Strand Lumber, a new product generated by UBC Bamboo Application and Manufacturing Lab (Y. Li, personal communication, March 23, 2024.). 56 procedures are in rectangle shapes. Colouring uses two different strip pretreatments: bleaching or carbonization, and therefore two input models were used for bamboo strips. In total, there are 7 models for laminated bamboo-related procedures, including 6 intermediate models and one overall final product model. All the models were built according to the inputs of resources in each step. There are two transportation steps: first the transport of culms from the bamboo forest to the primary strip production and pretreatment factory, and second the transport of dried strips to the secondary panel manufacturing factory. This intricate transportation system is designed with a dual focus on optimizing both transportation and manufacturing efficiency. For transport efficiency, the impact factors can be sorted into two categories: 1) volume of materials, and 2) transport distance. The hollow culms impose constraints on the transportation capacity in the initial transport phase, but capacity and efficiency are greatly improved in the second transport phase of finished strips to the panel manufacturing facility. The distance between the bamboo forest and the manufacturing facility and between the primary and secondary manufacturing facilities are significant factors to be considered. In many cases, these factories are situated quite a distance away, often exceeding 300 kilometers (Van der lugt, 2008). Companies have an incentive to improve the efficiency of transportation, with one approach being to establish additional pretreatment factories near the bamboo growing areas. By doing so, companies can streamline the initial (inefficient) culm transport and processing steps of splitting, coloring, drying, and planing. This not only simplifies the manufacturing procedure but also enhances the flexibility of transportation. With pretreatment 57 factories strategically located at or very close to bamboo sources, companies can significantly improve the overall efficiency of the entire production process. This forward-thinking strategy ultimately leads to a more sustainable and economically viable approach to bamboo-based manufacturing. Figure 3.4 The manufacturing procedure of laminated bamboo. Products are in diamond shapes and manufacturing procedures are in rectangle shapes. Photos of bamboo products reproduced with permission. [Image Credits: 1. Guadua bamboo (https://www.guaduabamboo.com/). 2. Van der lugt, (2008). 3. Mesun bamboo (https://www.mesunbamboo.com/). 4. Moso bamboo (https://www.moso-bamboo.com/). 5, 6, 7, 8, 11, 15. Anos bamboo (https://anos-bamboo.com/). 9. X. Liu, 2024 12, 13, 17. Jiang & Liu, (2024).14, 19. Y. Li, personal communication, March 23, 2024. 20. Nkeuwa et al., (2022).] • Culm production The first model was built for bamboo culm which included the harvesting procedure (Table 3.4). The harvesting input is based on the running time of a power saw required to cut the culms. The plantation site is located in the Anji region of Zhejiang province, China. The 58 bamboo used for laminated bamboo is moso bamboo, which is the most commonly used woody bamboo species in China, reaching up to 15 m in height with a diameter of 10-12 cm (Van der lugt and Vogtlander, 2015). The average density of the culm of moso bamboo is 670 kg/m3 (Berndsen et al., 2014). According to Werner (2017), one operation hour can cut 2.60 m3 of bamboo culms harvested per productive machine hour with a density of 646 kg/m3. From the equation given in Table 3.4, the machine hour for 1 m3 moso bamboo culms is calculated as 1/(2.6×646/670) = 0.39 h. Table 3.5 Model for bamboo culm. *RoW means average data in the “rest of the world other than Europe”, see glossary. GLO means average global, see glossary. There are two transportation distances associated with LB: 1) from the plantation to the pretreatment factory (strip making in this model) and 2) from the pretreatment factory to the secondary panel-making factory. In the bamboo culm model, the first transportation is included. The average assumed distance from the plantation to the strip factory is 15 km with a 5-ton truck that can carry around 24 m3 Process Flow in database Input Unit Reference Harvesting Market for power sawing without catalytic converter | APOS, U-GLO* 0.39 hr Werner, F. (2017); Gan J., et al. (2022); INBAR (2015) From plantation to strip factory Transport, freight, lorry 3.5-7.5 metric ton, EURO 3, Cutoff, U | RoW* 18090 kg*km INBAR 2015; Abate (2014); Van der Lugt and Vogtlander (2015) From strip to panel factory Transport, freight, lorry 7.5-16 metric tons, EURO 3, Cutoff, U | RoW* 379998 kg*km INBAR 2015; Abate (2014); Van der Lugt and Vogtlander (2015) 59 of culms. When calculating the carbon emissions generated by transportation related to product manufacturing, it is necessary to consider not only the emissions from transporting raw materials but also those from the return backhaul whether full or empty. According to Abate (2014), research indicates that the carbon emissions from an empty backhaul on the same route are only about 20% less than those from a fully loaded journey. Therefore, a coefficient of 1.8 is applied to the carbon emissions of round-trip transportation. Transporting the FU of 1 m3 bamboo culm, a total round trip is calculated as follows: 670 ×15×1.8 = 18090 kg*km. Simplifications associated with the transportation calculation of bamboo culms include unaccounted-for taper and variable density, whereby the formula assumes a fixed cylinder shape and density value. • Element production-Strip Two models are created for bamboo strips due to their different coloring pretreatments: bleaching and carbonization (Table 3.6). The first step is splitting. An 8-m-long bamboo culm is first cut horizontally into three equal sections that are fed through a star splitter that divides it into a variable number of strips. Due to size, only the bottom two sections of the 8 m culm, (about 2/3 of its length) are used for products. The bottom section can yield approximately 10-12 strips, and the second section 8-10 strips (Van der lugt, 2008). Hence one bamboo culm yields an average of about 20 strips suitable for laminated bamboo production. Each rough strip is around 2.63 m long, 2.30 cm wide, and 0.80 cm thick. To produce 1 m3 strips, the splitter machine needs to run for 1.64 h. The power rating of the machine is 5.50 kW, and the estimated electricity consumption is 1.64×5.50 = 9.03 kWh. 60 The raw strips are then planed to remove the hard, curved outer and inner skin layers to give them a flat surface for gluing. The average power rating of the rough planer is 17.50 kW, taking 3.28 hours to process 1 m3 of strips for an estimated electricity consumption of 3.28×17.5 = 57.45 kWh per 1 m3 of strips. After selection, the strips are bleached to lighten the colour by boiling in a 27% concentration H2O2 solution at 70 to 80 ℃ (Van der lugt, 2008). The factory treats 3000 strips in 8 hours (Ashaari et al., 2004; Van der lugt, 2008). Bleaching 1 m3 strips requires 5.5 hours in total using 19.84 kg H2O2 solution. The power rating of the boiler is 2.30 kW for an estimated electricity energy consumption of 2.30×5.5 = 12.67 kWh. 61 Table 3.6 Model for bamboo bleached and carbonized strips. *Market for electricity indicates the average electricity available in China's Southern Power Grid, which is calculated based on the statistics from 2014 in the EcoInvent database. B: Bleached; C: Carbonized The strips are dried in a drying chamber with a power rating of 15 kW, taking 72 hours to dry 30000 bleached strips, which make up 14.52 m3 in volume, or equivalent to 4.96 hours per 1 m3 of strips. The steam used for the drier comes from the boiler which has a 1.64 kW power Process Flow in database Input Unit Reference Splitting Market for electricity*, medium voltage | Cutoff, U | CN-CSG 9.03 kWh Van der lugt (2008) Rough planing Market for electricity*, medium voltage | Cutoff, U | CN-CSG 57.45 kWh Van der Lugt and Vogtlander (2015); Van der Lugt (2008) Bleaching Market for hydrogen peroxide, without water, in 50% solution state | hydrogen peroxide, without water, in 50% solution state | Cutoff, U 19.84 kg Xu C., et al. (2010); Van der Lugt (2008); Steam production, as energy carrier, in chemical industry | heat, from steam, in chemical industry | Cutoff, U 12.67 kWh Van der Lugt (2008); Drying (B) Market for electricity*, medium voltage | Cutoff, U | CN-CSG 74.38 kWh Zhang et al. (2011); Van der Lugt (2008) Steam production, as energy carrier, in chemical industry | heat, from steam, in chemical industry | Cutoff, U 8.13 kWh Zhang et al. (2011); Van der Lugt (2008) Carbonization Market for electricity*, medium voltage | Cutoff, U | CN-CSG 9.19 kWh Van der Lugt (2008); Steam production, as energy carrier, in chemical industry | heat, from steam, in chemical industry | Cutoff, U 24.12 kWh Van der Lugt (2008); Drying (C) Market for electricity*, medium voltage | Cutoff, U | CN-CSG 220.42 kWh Zhang, et al. (2011); Van der Lugt (2008) Steam production, as energy carrier, in chemical industry | heat, from steam, in chemical industry | Cutoff, U 24.10 kWh Zhang, et al. (2011); Van der Lugt (2008) Transport from strip to panel factory Transport, freight, lorry 7.5-16 metric ton, EURO 3, Cutoff, U | RoW 379998 kg*km INBAR 2015; Abate (2014); Van der Lugt and Vogtlander (2015) 62 rating, with steam generation using an estimated 1.64×4.96 = 8.13 kWh of electricity. Total electricity consumption for the drying step is 15×4.96 = 74.38 kWh. The second strip pre-treatment model is carbonizing to darken the colour. Here strips are pressure-cooked in two stages: one before and one after drying to rectify deformation. The carbonization step before drying is around 2 hours according to the color shade required (Wu et al., 2023; Van der Lugt and Vogtlander, 2015), and can treat 500 strips per hour (Van der lugt, 2008). The second carbonization after drying also requires 2 hours to ameliorate the deformation induced by drying and can treat 750 strips per hour (Van der Lugt and Vogtlander, 2015). The power rating of the carbonization tank is 1.5 kW, using a steam boiler with a power rating of 3.94 kW. For 1 m3 strips, two-step carbonization takes a total of around 6.12 hours with an estimated energy consumption of 6.12×1.5 = 9.19 kWh and 6.12×3.94 = 24.12 kWh. It should be noted that the drying step for carbonized strips takes longer than for bleached strips (Sharma et al., 2018) because the carbonization procedure reduces the hemicellulose content and reduces the permeability of the bamboo tissue (Nguyen et al., 2019). Drying of 1 m3 carbonized strips takes 14.69 hours compared with 4.96 hours for bleached strips. The drying chamber is the same as used for the bleached strips, and so the estimated energy consumption of the drying step for carbonized strips is 14.69×15 = 220.42 kWh with a steam energy consumption of 14.69×1.64 = 24.10 kWh. Treated and dried strips are transported to the secondary panel factory with more advanced machines and technology. The distance between the pretreatment strip factory and the 63 secondary panel factory is around 300 km with a 10-ton truck. One m3 strip weighs approx. 703.70 kg, for an estimated transportation round trip of 703.70×300×1.8 = 379998 kg*km. • Plank production The next stage is the secondary manufacturing of dried, dressed strips into an intermediary product called bamboo strip plank, also referred to as 1-layer board (Table 3.7). A resin commonly used in laminated bamboo products is phenol formaldehyde (PF). Two configurations are used as shown in Figure 3.5 – side pressing (a) and plain pressing (b). Most LB beams are made using side pressing and thicker laminated boards are commonly made with one side-press plank in between two plain-press planks. The manufacturing procedure is similar for both types. Strips are first aligned and roller-coated with PF resin and then pressed together to form a board that is trimmed and sanded to finish. The liquid resin application rate is 200 g/m2 (Anokye et al., 2016). To produce 1 m3 of plain-pressed planks, the resin consumption is calculated as 10 kg of liquid resin with a solid content of 40.4% (Wahab et al., 2012) or 4.04 kg of dry active resin ingredient, from the equation listed in Table 3.4. 1 m3 side-pressed planks use 20 kg of liquid resin, based on the same solid content giving 8.08 kg resin solids. 64 Table 3.7 Model for bamboo strip plank. Process Flow in database Input Unit Reference Transport from strip to panel factory Transport, freight, lorry 7.5-16 metric ton, EURO 3, Cutoff, U | RoW 379998 kg*km INBAR 2015; Abate (2014); Van der Lugt and Vogtlander (2015) Gluing (plain) Market for phenolic resin | phenolic resin | Cutoff, U 4.04 kg Anokye et al. (2016); Gluing (side) Market for phenolic resin | phenolic resin | Cutoff, U 8.08 kg Hot pressing Market for electricity, medium voltage | Cutoff, U | CN-CSG 18.48 kWh Wang and Dai (2005); Van der Lugt and Vogtlander (2015); Van der Lugt (2008) Steam production, as energy carrier, in chemical industry | heat, from steam, in chemical industry | Cutoff, U 13.24 kWh Sanding Market for electricity, medium voltage | Cutoff, U | CN-CSG 5.1 kWh Van der Lugt (2008) The plank is hot pressed using a 5.5 kW steam-heated hydraulic press, with steam generated by a 3.94 kW boiler. According to Wang and Dai (2005), the pressing time required for laminated veneer lumber (LVL) is correlated with its thickness, averaging 28.74 s/mm. The pressing time for bamboo panels is determined by the density ratio between the LVL panel (535 kg/m3) and bamboo (670 kg/m3). Due to the higher density bamboo panels require a higher hot press rate of 38 s/mm for the core to cure. For panels measuring 20 mm in thickness and consisting of two types of planks—side pressed (10 mm) and plain pressed (5 mm)—the pressing durations differ. Accordingly, a side-pressed plank requires 6 minutes to cure, while a plain-pressed plank needs 3 minutes. However, since the size of one plain-pressed panel is twice that of a side-pressed panel, the overall time to press 1 m3 of a side or plain-pressed board is the same. The equation for calculating the press time for resin cure is: 65 𝑇𝑇𝑖𝑖 = 38 × 𝑑𝑑𝑖𝑖 360� × 𝑣𝑣𝑖𝑖 (10) Where: 𝑇𝑇𝑖𝑖 is the press operation time, h. 𝑑𝑑𝑖𝑖 is the panel or plank thickness, mm. 360 is the hour unit conversion from seconds to hours. 𝑣𝑣𝑖𝑖 is the unit transfer ratio from one board to one FU. To produce 1 m3 of side-pressed or plain-pressed panels takes 3.36 hours with the unit transfer ratio equation applied in Table 3.4 above. So the overall estimated energy consumption of one FU is 5.5×3.36 = 18.48 kWh and 3.94×3.36 = 13.24 kWh. Panels are then sanded using a sanding machine with an average power rating of 25.5 kW (range is 15 to 36 kW) and taking 1 hour to sand 250 m2 of surface, which means the sander can process 5 m3 of panels per hour. The energy consumption for one FU is 1/5×25.5 = 5.1 kWh. 66 • Final panel production Table 3.8 shows the model for the final product, i.e. a 3-layer laminated bamboo panel made up of two plain pressed strip planks and one side pressed strip plank. The resin used to make the 3-layer panel is PF resin, with a liquid resin spread rate of 200 g/m2. One 3-layer panel contains 2 glue lines, and from the equation shown in Table 3.4, the overall estimated resin consumption for one FU is 20 kg with 8.08 kg solids content. After resin application, the panel is pressed in a hot press with a power rating of 5.5 kW and heated by a boiler with a power rating of 3.94 kW. The final laminated bamboo product is 2440 mm long, 1220 mm wide, and 20 mm thick. One FU of panel requires 20×38/(60×60) ×1/(2.44×1.22×0.02) = 3.55 h, according to Equation 7. The energy consumption for the pressing step is calculated from the equation shown in Table 3.4, i.e. 3.55×5.5 = 19.53 kWh and 3.55×3.94 = 13.99 kWh. End trimming and sanding are the final two production steps. The table saw is rated at 5.5 kW with a processing rate of 56.25 m2/h. The electricity required for trimming is estimated as 1/56.25×1/0.02×5.5 = 4.89 kWh (equation shown in Table 3.4). The final step is sanding, in (b) (a) Figure 3.5 Two types of laminated bamboo strip plank. (a) plain pressing; (b) side pressing. 67 which the average power rating is 25.5 kW. The operation rate is 250 m2/h, using an estimated 1/250×1/0.02×25.5 = 5.1 kWh. Table 3.8 Model for final panel production. • Residue utilization Laminated bamboo contains about 2% resin (Khajouei-Nezhad et al., 2023) which was accounted for in the calculation of bamboo residue per m3 of product. The estimated amount of residues from manufacturing 1 FU of laminated bamboo using Equation 4 is shown in Table 3.9 below. Input in this table shows the amount of bamboo culm fed into the factory and output is the final product and residues after the manufacturing procedure. Process Flow in database Input Unit Reference Gluing Market for phenolic resin | phenolic resin | Cutoff, U 8.08 kg Anokye et al. (2016); Hot pressing Market for electricity, medium voltage | Cutoff, U | CN-CSG 19.53 kWh Wang and Dai (2005); Van der Lugt and Vogtlander (2015); Van der Lugt (2008) Steam production, as an energy carrier, in chemical industry | heat, from steam, in chemical industry | Cutoff, U 13.99 kWh End cutting Market for electricity, medium voltage | Cutoff, U | CN-CSG 4.89 kWh Van der Lugt and Vogtlander (2015); Van der Lugt (2008); Sanding Market for electricity, medium voltage | Cutoff, U | CN-CSG 5.1 kWh Van der Lugt (2008) 68 Table 3.9 Bamboo residues from laminated bamboo manufacturing procedure. Material Quantity (kg) Input Bamboo 1854.05 Output Laminated bamboo (without resin) 686 Bamboo residues 1168.05 There are three possible use scenarios for these: Scenario 1 – Boiler fuel, i.e. combustion only. Boilers are used to generate heat energy for the drying and carbonization steps, which may be partially or fully fueled by burning bamboo residues. Burning all bamboo residues on-site to fire boilers is a common practice in bamboo processing factories and helps reduce their reliance on coal or other fossil fuels. Scenario 2 – A value-added byproduct, i.e. toothpicks, is produced (Figure 3.3) from the long strips cut from milling strips to rectangular shapes, which comprises around 10% of total culm mass processed. The remaining residue is used for boiler fuel. Scenario 3 – If the factory is located close (within 50 km) of a charcoal plant, it may sell wet residues for bamboo charcoal. In this scenario, there are two byproducts: toothpicks (still assumed to use 10% of total raw material inputs) and bamboo charcoal (which accounts for around 45% of total raw material inputs). The remaining dry residues (about 10% of total raw material inputs) are burned as boiler fuel in the factory. 69 From equations 8 and 9, the combustion of all bamboo residues can generate (700/37%-700) ×19.31/3.6×42% = 2572.97 kWh. However, since the combustion of residues in the boiler generates steam to heat pipes, rather than generating electricity, the energy generated by burning bamboo residues can only be used to offset any electricity used to generate steam, and not any of the electricity used in other factory processes. Even in scenario 3, which involves burning a minimum amount of leftover residues from manufacturing, the total combustion of bamboo residues is 10%×700/37%×19.31×42%/3.6 = 257.30 kWh. The total steam usage from residue combustion is therefore calculated as follows for all three scenarios: 𝑆𝑆𝑇𝑇𝑖𝑖 = Σ(𝑆𝑆𝑖𝑖 × � 1𝑅𝑅𝑠𝑠𝑅𝑅𝑠𝑠𝑅𝑅𝑠𝑠𝑠𝑠𝑅𝑅 𝑅𝑅𝑅𝑅𝑠𝑠𝑠𝑠𝑓𝑓�) (11) Where: 𝑆𝑆𝑇𝑇𝑖𝑖 is the total steam usage, kWh. 𝑆𝑆𝑖𝑖 is the steam used during the manufacturing procedure, kWh. 𝑅𝑅𝑒𝑒𝑒𝑒𝑇𝑇𝑣𝑣𝑒𝑒𝑣𝑣𝑣𝑣 𝑅𝑅𝑇𝑇𝑇𝑇𝑒𝑒𝑖𝑖 is the recovery rate of each production stage, %. The total steam usage and estimated energy use offset if residues are burned for boiler fuel is (12.67+8.13)×(1/37%)+13.24×(1/100%)+13.99×(1/92%) = 83.18 kWh for bleached laminated bamboo and (24.12+24.10)×(1/37%)+13.24×(1/100%)+13.99×(1/92%) =155.34 kWh for carbonized laminated bamboo. Stean usage from combusted residues is greater for Carbonized laminated bamboo since carbonization requires more heat energy. The total usage of residue boiler steam (83.18 kWh for bleached LB and 155.34 kWh for carbonized LB) is much less than the total energy recovery from the manufacturing residues of 2572.97 kWh. This means 70 after offsetting the energy used to generate steam from the boiler, there is still over 1000 kWh of energy generated from the residues. The extra energy could be used as a substitute for natural gas for other factories in the industrial parks. 3.7.2 Bamboo scrimber The manufacturing process for bamboo scrimber beams is shown in Figure 3.6. Similar to laminated bamboo, products are above the arrows, and manufacturing procedures are shown in the rectangle. The size of the beam is 2.44 m long, 0.14 m wide, and 0.11 m thick, with a higher density of 1080 kg/m3 (Van der Lugt and Vogtlander, 2015). Bamboo scrimber is produced from crushed bamboo strips termed ‘bundles’ and contains 15% resin and 85% bamboo. Being a highly compressed product, its density is 1.19 times that of the bamboo parent tissue, i.e. 1080×85%/670 = 1.37. Each 1 m3 of scrimber requires 1.37 m3 of raw bamboo strips. Models associated with bamboo scrimber production include bamboo culm, transportation, strip, bundle, and bamboo scrimber beams. The models for culm harvesting and transportation from the plantation to the pretreatment factory are similar to the models for laminated bamboo products. 71 The bamboo scrimber production procedure is described as follows: bamboo culms are first crosscut into four 2-m-long sections which are then split into strips that do not need to be strictly uniform in size and shape. However, the manufacturing company, Moso Bamboo Inc., still selects the higher quality bamboo strips from the bottom two sections which produce more strips than the upper two sections. One bamboo culm generally produces 58 strips with 24 and 20 strips from the bottom two sections and 8 and 6 strips from the top two sections. The strip pre-treatment procedures are similar to those of laminated bamboo products but with the following additional procedures: 1) splitting thick strips into two thinner strips before coloring treatment and 2) crushing strips after drying. The bamboo scrimber model in this study is therefore built starting with the bundle model. Figure 3.6 Manufacturing procedure of bamboo scrimber. Products are in diamond shape and manufacturing procedures are in rectangle shape. Photos of bamboo products reproduced with permission. Image Credits: 1. Guadua bamboo (https://www.guaduabamboo.com/blog/when-and-how- to-harvest-bamboo). 2. Van der lugt, (2008). 3. Mesun bamboo (https://www.mesunbamboo.com/about -us/production/). 4. Moso bamboo (https://www.moso-bamboo.com/). 5, 7, 8. Anos bamboo (https://anos-bamboo.com/how-to-make-bamboo-plywood/). 6. Li et al., (2020). 9. Chen et al., (2014). 10. Y. Li, personal communication, May 23, 2024. 12. Adjei and Yeboah, (2021). 13. Yang et al., (2021). 15. Huang et al., (2019). 9 CrushingStart1 Harvesting 2 Transport from plantation to pretreatment factory4 Splitting3 Culm5 Rough planing 6 Strip cut in half 7 Coloring 8 Drying11 Transport from element factory to final product factory 10 Bundle12 Gluing14 End cuttingFinish13 Pressing15 BSCulm productionElement productionFinal production72 • Element production-Bundle The bundle model covers the production process from the culm splitting phase, using a splitting machine with a power rating of 5.5 kW which produces 1125 strips per hour (Table 3.10). A total of 4958 individual strips are needed to make up 1.37 m³ of raw bamboo with an average size of 2×0.02×0.006 m, which takes 4958/1125 = 4.41 h. The energy consumption of this step is 4.41×5.5 = 24.26 kWh. Strips are then planed to remove the outer and inner skin, using a planer with an average power rating of 17.5 kW that processes 562 strips per hour. The unit transfer ratio here is calculated by this equation: 𝑣𝑣𝑖𝑖 = 𝑁𝑁𝑅𝑅/𝑁𝑁𝐹𝐹𝐹𝐹 (12) Where: 𝑣𝑣𝑖𝑖 is the unit transfer ratio. 𝑁𝑁𝑅𝑅 is the number of strips processed according to machine feed speed. 𝑁𝑁𝐹𝐹𝐹𝐹 is the number of strips of one FU. 73 Table 3.10 Model for bamboo bundle. *Market for hydrogen peroxide represents the global average market data for hydrogen peroxide without Europe. The data not only includes the carbon footprint of the production of hydrogen peroxide but also considers the average transportation data related to hydrogen peroxide. B: Bleached; C: Carbonized. To process 1.37 m3 of strips through this step takes 4958/562 = 8.82 h, consuming 8.82×17.5 = 154.39 kWh of electricity. After planing the strips emerge with an average thickness of 6 mm and are then sliced into halves 3 mm in thickness. The slicing machine used in this step is 5.5 kW and processes 1200 strips per hour. To process 1.19 m3 of strips requires 4958/1200 = 4.13 h, and 4.13×5.5 = 22.72 kWh of energy. Process Flow in database Input Unit Reference Splitting Market for electricity, medium voltage | Cutoff, U | CN-CSG 24.26 kWh Data from Moso Bamboo Rough planing Market for electricity, medium voltage | Cutoff, U | CN-CSG 154.39 kWh Van der Lugt and Vogtlander (2015); Van der Lugt (2008) Cutting in Half Market for electricity, medium voltage | Cutoff, U | CN-CSG 22.72 kWh Van der Lugt (2008); Bleaching Market for hydrogen peroxide*, without water, in 50% solution state | hydrogen peroxide, without water, in 50% solution state | Cutoff, U-Row 23.61 kg Xu C., et al. (2010); Vogtländer et al. (2014); Van der Lugt (2008) Steam production, as an energy carrier, in chemical industry | heat, from steam, in chemical industry | Cutoff, U 30.41 kWh Drying (B) Market for electricity, medium voltage | Cutoff, U | CN-CSG 178.49 kWh Zhang et al. (2011); Van der Lugt (2008) Steam production, as an energy carrier, in chemical industry | heat, from steam, in chemical industry | Cutoff, U 19.52 kWh Carbonization Market for electricity, medium voltage | Cutoff, U | CN-CSG 24.79 kWh Van der Lugt and Vogtlander (2015); Van der Lugt (2008) Steam production, as an energy carrier, in chemical industry | heat, from steam, in chemical industry | Cutoff, U 65.12 kWh Drying (C) Market for electricity, medium voltage | Cutoff, U | CN-CSG 594.9 kWh Zhang et al. (2011); Van der Lugt (2008) Steam production, as an energy carrier, in chemical industry | heat, from steam, in chemical industry | Cutoff, U 65.04 kWh Crushing Market for electricity, medium voltage | electricity, medium voltage | Cutoff, U | CN-CSG 45.45 kWh Van der Lugt and Vogtlander (2015) 74 The colouring processes (either by bleaching or carbonization) are similar to those used for laminated bamboo. The smaller strips mean twice as many strips can be treated per run. For bleaching the strips are boiled in a 27% concentration of H2O2 at 70 to 80 ℃ (Van der lugt, 2008). Treating 6000 strips requires 23.61 kg of H2O2 solution, and (9916/6000) ×8 = 13.22 h The power rating of the boiler is 2.3 kW, and therefore the energy consumption is 2.3×13.22 = 30.41 kWh. For drying, the chamber can process 30000×2 = 60000 strips at once (twice the number of strips with half thickness). One drying round for bleached bamboo strips requires 72 hours, or a total of 9916/60000×72 = 11.90 h. The drying chamber is 15 kW which has one boiler for steam (1.64 kW). Total energy consumption is 15×11.90 = 178.49 kWh and 1.64×11.90 = 19.52 kWh. After drying, the strips undergo crushing by a 5.5 kW crushing machine, operating at a speed similar to that of planers (1200 strips/h). The electricity consumption is 9916/1200×5.5 = 45.45 kWh. Carbonizing the crushed strips uses the same treatment tank with similar steps used for laminated bamboo, i.e. a 1.5 kW tank and 3.94 kW boiler. The two rounds of carbonization each take 2 hours depending on the darkness of the strips. The first round can process 1000 strips per hour, and the second processes 1500 strips per hour. So, the energy consumption (9916/1000+9916/1500) ×1.5=24.79 kWh (round 1) and (9916/1000+9916/1500) ×3.94 = 65.12 kWh. 75 Carbonized strips are dried in two rounds: the first takes place after the first carbonization round and takes 168 hours, with a second drying round of 72 hours after the second carbonization round, for a total drying time of 240 hours. The capacity of the drying chambers is 60000 strips. One FU needs 9916/60000×240 = 39.66 h. The power rating of the drying chamber is 15 kW and uses a 1.64 kW boiler for heating steam. The energy consumption is 15×39.66 = 594.9 kWh (dryer) and 1.64×39.66 = 65.04 kWh (boiler). • Final production The dried bundles are dipped in phenol-formaldehyde (PF) resin with a resin application rate depending on the grade and application of the bamboo scrimber. For outdoor applications, the resin content of bamboo scrimber is around 15% (Khajouei-Nezhad et al., 2023). For 1 m3 of bamboo scrimber beam of 1080 kg/m3 density, the amount of the PF resin required is 15%×1080 = 162 kg with a solid content of 64.8 kg. After resin application, bundles are first compacted into a mold under 2200-ton pressure (around 114 MPa) and then cured in a tunnel oven at a temperature of around 150 ℃. Mold compaction uses 27.5 kW of electricity and the oven 50 kW. The compactor can compress 12 beams each hour; 1 m3 of scrimber requires 27.5×1/ (12×2.44×0.11×0.14) = 60.99 kWh. The tunnel oven requires 8 hours to cure 143 beams. For a 1 m3 beam, the energy consumption is 50×8/ (143×2.44×0.11×0.14) = 74.44 kWh. In total, bamboo scrimber beam production requires 60.99 + 74.44 = 135.43 kWh. 76 The final step is trimming, which uses a table saw to cut the edge of the beam. The power rating of the table saw is 11 kW. The input speed of the table saw is 30 beams per hour. The energy consumption of 1 m3 beam end cutting is 1/ (30×2.44×0.11×0.14) ×11 = 9.75 kWh. Table 3.11 Model for bamboo scrimber beam model. • Residue utilization The residues from bamboo scrimber manufacture (which recovers around 60% of the mass of processed culms) may be utilized under three scenarios: Scenario 1 – Combustion only as boiler fuel in the scrimber factory. Scenario 2 – 10% of total bamboo material inputs in the factory, i.e. from planing off the outer fiber-rich skin is converted to a value-added byproduct - toothpicks (Figure 3.3), and the remaining 90% is used as boiler fuel. Scenario 3 – Around 32% of total bamboo input is made up of wet sawdust and offcuts that are sold to a nearby (within 50 km) charcoal factory; The planed outer skin is used for toothpicks and the remaining dry sawdust (2% of total bamboo input for the factory) is used as boiler fuel. For scenarios 1 and 2, the energy offset from the combusted bamboo residues from producing one FU of bamboo scrimber is calculated using equation 11, as in laminated bamboo, i.e. Process Flow in database Input Unit Reference Gluing Market for phenolic resin | phenolic resin | Cutoff, U 64.8 kg Data from Moso Bamboo Hot pressing Market for electricity, medium voltage | Cutoff, U | CN-CSG 135.43 kWh Van der Lugt and Vogtlander (2015); Van der Lugt (2008) End cutting Market for electricity, medium voltage | Cutoff, U | CN-CSG 9.75 kWh Data from Moso 77 (30.41+19.52)×(1/58%) = 86.09 kWh used in bleached bamboo scrimber production and (65.12+60.04)×(1/58%) = 215.79 kWh required for carbonized bamboo scrimber. Carbonized bamboo requires significantly more energy during carbonization and drying. The total residues calculated from producing 1 FU of bamboo scrimber are shown in Table 3.12. Table 3.12 Proportion of residues after bamboo scrimber production. Product name Value (kg) Input Bamboo 2245.82 Output Bamboo scrimber (without resin) 918 Bamboo waste 1327.82 3.7.3 BLSL BLSL is a novel bamboo-wood hybrid product reported by Li (2023) and is used as an applied example of model application in estimating the carbon footprints of bamboo and wood construction products. BLSL is a sandwich comprised of two flattened bamboo planks glued to the surfaces of one LSL panel in the core. While the flattened bamboo planks were manufactured in the lab at the University of British Columbia and the LSL manufactured commercially in Canada, this study assumes both these intermediate products will be made in China from moso bamboo and the LSL made in China from locally grown Poplar logs, to estimate the carbon footprint of BLSL in the factory. The LSL energy consumption data is 78 gained from the EPD from the American Wood Council and Canadian Wood Council (2020), with the geographic location changed to China in the OpenLCA software. The total GWP of production for the hybrid panel is added together according to the content percentage of flattened bamboo and LSL in the product. The manufacturing procedure for flattened bamboo involves crosscutting to shorter (2 m) sections removing the nodes, and then ripping to cut a groove for culm flattening. The culms are then boiled in hot water at 85 ℃ for 4 hours to soften for flattening and the saturated culms are then flattened using a flattening machine. After flattening, the bamboo veneers are dried in the oven at 50 ℃ for 24 hours to reduce the moisture content to around 12% before planing to remove the uneven green outer skin and inner layers to create a flat surface for applying with PF resin and hot pressing together into a three-layer plank ready for BLSL panel production. Factories may use only flattened bamboo planks and glue them together with a low-density core material for nonstructural usage, such as forklift pallets. In the prototype product evaluated in this study, the prefabricated flattened bamboo planks are glued to LSL to produce higher mechanical performance panels for potential structural use. The size of the final product is 1050 mm long, 80 mm wide, and 80 mm thick, and 1 m3 of panel is the functional unit to assess the environmental impacts of the product. 79 Figure 3.7 Manufacturing procedure of bamboo laminated strand lumber (BLSL). Photos of bamboo products reproduced with permission. Image Credits:1. Guadua bamboo (https://www.guaduabamboo.com/blog/when-and-how-to-harvest-bamboo). 2. Van der lugt, (2008). 3. Mesun bamboo (https://www.mesunbamboo.com/about-us/production/). 5, 6, 8, 11. Yuan et al., (2022). 7. Yuan et al., (2021). 9, 10. Anos bamboo (https://anos-bamboo.com/how-to-make-bamboo-plywood/). 13, 15. Yang et al., (2024). 14, 17, 20, 21. Y. Li, personal communication, May 20, 2024. 19. Jiang and Liu (2024). • Element production – Flattened bamboo The flattened bamboo and flattened bamboo plank models are presented in Table 3.13. The factory uses a crosscutting machine with a power rating of 15.5 kW for 0.64 h/ton (Zhao et al., 2023). The density of the board is 700 kg/m3. Thus, for 1 m3 of flattened bamboo, it takes 0.45 h to crosscut all bamboo culms. Total energy consumption needs 0.45×15.5 = 6.98 kWh. After crosscutting, factories normally remove the nodes. The factory uses a 5.5 kW machine for 1.14 ton/h (Zhao et al., 2023). 1 m3 of flattened bamboo takes 0.80 h to remove all the nodes with a total energy consumption of 4.4 kWh. 80 A ripping saw with an 8.5 kW power rating cuts a groove along the bamboo culm to allow flattening and can process 1.18 tons/h (Zhao et al., 2023). 1 m3 of flattened bamboo requires 0.83 h to rip all culms required, with a total energy consumption of 0.83×8.5 = 7.06 kWh. In the lab, the thin-walled bamboo culms were softened in hot water at 80℃ for around 12 hours, whereas factories normally use hot water at 80-90℃ to soften culms for 4 hours (Fang et al., 2018; Cheng et al., 2013). The hot water bath can accommodate about 0.75 m3 of culms (Van der lugt, 2008). To soften 1 m3 of culms takes around 5.33 hours using a boiler with a power rating of 2.3 kW, and so the total estimated energy consumption for one FU is 5.33 ×2.3 = 12.26 kWh. The culm flattening machine has a power rating of 9.7 kW and a processing speed of 0.73 h/m3 (Zhao et al., 2023). The energy consumption for 1 m3 of flattened bamboo is 9.7×0.73 = 7.08 kWh. Flattened bamboo is then dried using a similar drying chamber and conditions as laminated bamboo and bamboo scrimber. In 24 h the chamber could dry 7.5 m3 of bamboo, equating to 3.2 h to dry 1 m3 of bamboo. The drying chamber power rating is 15 kW for the and 1.64 kW for the steam boiler, giving an estimated energy consumption of 1 m3 of 3.2×15=48 kWh and 3.2×1.64=5.25 kWh. Thickness planing uses a planer with a power rating range of 5.5 to 18 kW (Zhao et al., 2023; Van der Lugt, 2008). It takes 2.13 hours to process one ton (around 1.43 m3) of flattened bamboo. For 1 m3 of flattened bamboo, the operation time is 1.49 h for a total estimated energy consumption of 1.49× (5.5+18)/2 = 17.51 kWh. 81 Table 3.13 Model of flattened bamboo and flattened bamboo plank. * Market for electricity indicates the average electricity available in China's Southern Power Grid, which is calculated based on the statistics from 2014 in the EcoInvent database. • Plank production The factory uses liquid PF resin, with a spread rate of 200 g/m2 (Anokye et al., 2016) and solid content of 40.4% (Ab. Wahab et al., 2012). One flattened bamboo plank is made up of 2-3 layers of flattened bamboo with various thicknesses ranging from 7 to 10 mm (Yuan et al., Model Process Flow in database Input Unit Flattened bamboo Crosscutting Market for electricity, medium voltage | Cutoff, U | CN-CSG* 6.98 kWh Nodes removal Market for electricity, medium voltage | Cutoff, U | CN-CSG* 4.40 kWh Ripping Market for electricity, medium voltage | Cutoff, U | CN-CSG* 7.06 kWh Softening Market for electricity, medium voltage | Cutoff, U | CN-CSG* 12.26 kWh Flattening Market for electricity, medium voltage | Cutoff, U | CN-CSG* 7.08 kWh Drying Market for electricity, medium voltage | Cutoff, U | CN-CSG* 48 kWh Steam production, as an energy carrier, in chemical industry | heat, from steam, in chemical industry | Cutoff, U 5.25 kWh Planing Market for electricity, medium voltage | Cutoff, U | CN-CSG* 17.51 kWh Flattened bamboo plank Gluing Market for phenolic resin | phenolic resin | Cutoff, U-Row 6.46 kg Hot pressing Market for electricity, medium voltage | Cutoff, U | CN-CSG* 23.04 kWh Steam production, as energy carrier, in chemical industry | heat, from steam, in chemical industry | Cutoff, U 16.50 kWh Sanding Market for electricity, medium voltage | Cutoff, U | CN-CSG* 4.08 kWh 82 2022). According to the equation listed in Table 3.4, the consumption of resin is 6.46 kg for one FU of flattened bamboo plank. Hot pressing is the next step, which takes approximately 38 seconds per mm for the core of planks to cure (calculation is given in Table 3.4). The hot press has a power rating of 5.5 kW and heat is supplied by a steam boiler with a power rating of 3.94 kW. The average thickness of one flattened bamboo plank is 25 mm. The press accommodates a 2440×1220 mm area, allowing 30 planks each measuring 80×1050 mm to be pressed in one run. Every 1 m3 of flattened bamboo plank requires 4.19 h to press (from the equation in Table 3.4). The total energy consumption for one FU is 4.19×5.5 = 23.04 kWh and 4.19×3.94 =16.5 kWh. The final step is sanding, using a 25.5 kW sander. The operation rate is 250 m2/h (Van der Lugt, 2008), so sanding uses 1/250×1/0.025×25.5 = 4.08 kWh. • Final production Flattened bamboo planks may be used in a variety of applications or secondary manufactured products. The case study here is based on research by Li et al. (2023) uses the intermediate planks to enhance the mechanical properties of an engineered wood composite (LSL) for construction purposes. Since the estimated carbon footprint of production in the lab is normally higher than the same product produced on a larger economy of scale in a factory, this study uses factory data and a literature review to better estimate the manufacture of BLSL in a factory setting. This study assumes LSL with a density of 647.2 kg/m3 is made in China and shipped from one wood factory to another bamboo BLSL factory within the same province over a 83 distance of 145 km (Sahoo et al., 2021). To transport 1 m3 of LSL, the environmental input of transportation is 647.2×145 = 93844 kg*km (Table 3.14). LSL is cut to size (1050mm), requiring around 0.45 hours to cut the 1 m3 of LSL to the required size. The table saw used has a power rating of 15.5 kW, and energy consumption of 0.45×15.5 = 6.98 kWh. After cutting, the LSL is sanded in preparation for gluing. The total volume is around 0.9 m3. The 25.5 kW sander processes around 250 m2/h. The thickness of LSL is 44 mm before sanding, and so 0.9 m3 of LSL has a total sanded area of 20 m2. Each LSL piece goes through the sander twice, and the average operation time for 0.9 m3 of LSL is 20×2/250 = 0.16 h, with an energy consumption of 0.16×25.5 = 4.08 kWh. For the gluing step, PF resin with 40.4% solid content is used with a spread rate of 200 g/m2 over 20 m2 of 0.9 m3 LSL volume. The resin in each product is applied to two sides of the LSL consuming 200×20×2×40.4% ×10-3 = 3.23 kg in total. The next step is hot pressing. The core of BLSL is LSL with already cured resin so only the curing time for the two glue lines between the flattened bamboo plank and LSL, which are located around 25 mm in from the surface of BLSL. Therefore, although the BLSL board is 80 mm thick, an estimated curing time for a 50 mm thickness of bamboo plank is used. To press 1 m3 BLSL takes 4.19 h (equation in Table 3.4). The press power rating is 5.5 kW with a steam boiler of 3.94 kW, for an estimated energy consumption of 4.19×5.5 = 23.04 kWh and 4.19×3.94 = 16.5 kWh. 84 Sanding is the final step, using a 25.5 kW sander with a process rate of 250 m2/h, with one to two passes required, or an average of 1.5 passes. The estimated total sander operation time for 1 m3 of BLSL with a total sanded area of 12.5 m2 is 0.08 h (using a similar calculation for LSL sanding). The energy consumption for the sanding step is 0.08×25.5 = 2.04 kWh. The carbon footprint of LSL is gained from the environmental product declarations (EPDs) by the United States Department of Agriculture (Sahoo et al., 2021) and then calculated according to the volume percentage (60%) of LSL used in the final BLSL product. The total final product carbon footprint is the sum of the carbon footprint from the production of flattened bamboo, flattened bamboo plank, LSL, and BLSL. 85 Table 3.14 Model for BLSL. • Residue utilization Over half the total mass of bamboo culms processed into Flattened Bamboo is residue which has two end-use scenarios: Scenario 1 – Combustion only. Using residues as a boiler fuel is the most common scenario in bamboo processing factories (Y. Xia, persona communication, May 20, 2024). Scenario 2 – Bamboo charcoal and combustion. In this scenario, factories sell wet residue (around 43% of all bamboo culm input in the factory) to other factories that produce a value-added byproduct, bamboo charcoal, and burn the rest of the residue (around 8%). Process Flow in database Input Unit Transport, harbor to factory Market for transport, freight, lorry 16-32 metric ton, EURO3 | transport, freight, lorry 16-32 metric ton, EURO3 | Cutoff, U-Row 93844 kg*km Cutting Electricity voltage transformation from high to medium voltage | electricity, medium voltage | Cutoff, U | CN-CSG 6.98 kWh Sanding Electricity voltage transformation from high to medium voltage | electricity, medium voltage | Cutoff, U | CN-CSG 11.33 kWh Gluing Market for phenolic resin | phenolic resin | Cutoff, U-Row 3.23 kg Hot pressing Electricity voltage transformation from high to medium voltage | electricity, medium voltage | Cutoff, U | CN-CSG 23.04 kWh Steam production, as energy carrier, in chemical industry | heat, from steam, in chemical industry | Cutoff, U 16.50 kWh Sanding Electricity voltage transformation from high to medium voltage | electricity, medium voltage | Cutoff, U | CN-CSG 2.04 kWh 86 Similar to laminated bamboo, the combustion and release of sequestered carbon in both these scenarios are calculated from equation 11. The energy recovery from the combustion of the bamboo residues is (5.25+16.5)×(1/52%) + 16.5×(1/92%) = 59.76 kWh. The bamboo inputs and outputs in a typical flattened bamboo factory are shown in Table 3.15. Table 3.15 Inputs and outputs of a flattened bamboo factory. Material Quantity (kg) Input Bamboo culms 1357.14 Output Flattened bamboo (without resin) 665 Bamboo residues 692.14 87 Chapter 4: Chapter 4. Results and Discussion 4.1 Carbon footprint and major contributors for four structural bamboo products The results of the carbon footprint analyses for the four different final products are shown in Figure 4.1, comparing bamboo products with other benchmark construction products, including laminated veneer lumber (LVL), plywood, Glulam, steel, and concrete. The functional unit of 1 m3 was used. Positive values (grey bars) represent the carbon emissions during the production of bamboo products (A1-A3) and the negative values (white bars) represent the carbon storage value related to one FU of bamboo products. The data for the wood-based products, steel, and concrete were derived from EPD reports from the industry. The dashed line shows the net carbon footprint value of each product. The carbon footprints of steel and concrete are significantly higher than bamboo and wood products. Since biomaterials sequester carbon dioxide during their growth phase, they typically have a negative carbon footprint meaning they absorb more CO2 than they emit, resulting in a net reduction in greenhouse gas emissions if used in preference to metal and mineral products. This environmental benefit sets biomaterials apart from other benchmark products and contributes to their sustainability. 88 Figure 4.1 Carbon footprint of bamboo products (FU: 1 m3). LB (B): bleached laminated bamboo; LB (C): carbonized laminated bamboo; BS (B): bleached bamboo scrimber; BS (C): carbonized bamboo scrimber; BLSL: bamboo laminated strand lumber; P: plywood; na means North America; cn means China; LVL: Laminated veneer lumber; S: steel; eu means Europe; Con: concrete; glo means global. 89 It should be noted that the same product may have different carbon footprint values depending on where it is produced. For example, in the case of plywood, both North American plywood and Chinese plywood mentioned in this study are wood-based construction materials that both use PF glue. However, the carbon footprint of producing 1 m3 of plywood varies greatly between China (887 kg CO2 eq/m3) and North America (219.31 kg CO2 eq/m3) due to the difference in fuel used to generate industrial electricity. LSL which is made in China also has almost twice the carbon footprint of that made in North America. According to the United States Energy Information Administration (EIA) and the International Energy Agency (IEA) (2023), North American electricity generation is around 56% from fossil fuel (natural gas, coal, oil, etc.) while in China it is 64% coal-generated (EIA, 2023). Natural gas generates 36% of the USA’s electricity and produces up to 50% less greenhouse gases than coal when burnt (Waqar et al., 2022). All bamboo products in this study are manufactured in China and ¾ had negative net carbon footprints. The carbon footprints of bamboo products could be even lower than the results shown in this study if there was a greener electricity generation infrastructure where they are manufactured. Laminated bamboo and BLSL have low carbon emissions: Bleached laminated bamboo emits an estimated 534 kg CO2 eq/m3, carbonized laminated bamboo 678 kg CO2 eq/m3, and BLSL 660 kg CO2 eq/m3; all being net negative. Bamboo scrimber products have higher and net positive carbon emissions, which means the emissions during production are greater than the carbon sequestered and stored in the product. The contribution of the inputs for each product and its intermediate elements is shown in Figure 4.2. 90 (a) (kg CO2 eq/m3 ) (b) (kg CO2 eq/m3 ) 91 Figure 4.2 Bamboo products and their intermediate product with major contributors. (a) Laminated bamboo; (b) Bamboo scrimber; (c) Bamboo laminated strand lumber. B: bleached; C: carbonized; PP: plain pressed plank; PS: side pressed plank; LB: laminated bamboo; BS: bamboo scrimber; FB: flattened bamboo; FBP: flattened bamboo plank; LSL: laminated strand lumber; BLSL: bamboo laminated strand lumber. Prior to the fabrication of planks the intermediate products do not contain resins, meaning that electricity and transportation are the main contributors to the carbon footprint of intermediate elements and products. Transportation is the top contributor for culms, and for most of the elements and intermediate products, it is electricity. Electricity accounts for over half of the carbon emissions in bamboo products, with bamboo scrimber consuming more electricity than the other products, particularly carbonized bamboo (c) (kg CO2 eq/m3 ) 92 scrimber (997.23 kg CO2 eq/m3). In addition to the energy-intensive manufacturing procedure and high electricity consumption, the high resin content in bamboo scrimber also exacerbates its carbon footprint. Compared with LB and BLSL, bamboo scrimber contains up to 23% resin in the final product: markedly higher than LB (5%) or BLSL (4%). Note that due to the greater amount of compacted bamboo material in bamboo scrimber it also has a higher carbon storage value than un-densified products. Yu et al. (2019) also reported that the manufacturing of bamboo scrimber is highly energy-intensive compared with laminated bamboo. Further analysis of electricity usage for each manufacturing process was conducted and shown in Figure 4.3, which shows products using carbonized bamboo consume around twice the electricity of bleached or natural bamboo products. 93 (b) (a) 94 Figure 4.3 Breakdown of electricity consumption during bamboo product production. (a) Bleached laminated bamboo; (b) Carbonized laminated bamboo; (c) Bleached bamboo scrimber; (d) Carbonized bamboo scrimber. (d) (c) 95 For all three products, drying and hot pressing both use higher power-rated machines with a longer operation time and contribute the most to processing carbon emissions. Steam generation from electric or gas-fired boilers is another contributor to carbon emissions. Carbonized bamboo products take longer to dry which adds further to the carbon emissions of carbonized products compared with bleaching. Around 60% of the electricity used in the production of carbonized bamboo products is for drying. Li et al. (2016) analyzed 3 layered laminated bamboo with a gate-to-gate model and also reported the main contributors of laminated bamboo being drying and carbonization. For all three structural bamboo products considered in this study, the element production procedures consume most of the energy, contributing most to carbon emissions. Strips, bundles, and flattened bamboo account for 35-40%, 53-67%, and 27.46%, respectively of the total electricity consumption in producing LB, BS, and BLSL. The estimated energy from bamboo residues for each product is listed in Table 4.1. Using the residues as boiler fuel was considered carbon neutral in this study (as explained in Chapter 3), i.e. only energy recovery, excluding carbon emissions from combustion (U.S. Energy Information Administration, 2024; Leturcq, 2014). Scenario 1 considered using only the residues from laminated bamboo production for boiler fuel. It was noted that energy recovery from combustion in the factory could only offset any energy used to heat the boiler in drying, hot pressing, carbonization, and bleaching operations. It was also considered that products made from bleached bamboo require a smaller energy offset than carbonized products. 96 Scenario 2 for laminated bamboo considered the outer skin diverted to toothpick production and the remainder used for boiler fuel. Scenario 2 for flattened bamboo residues considered bamboo charcoal production from the wet sawdust, and the remainder for combustion. Scenario 3 for laminated bamboo considered three residue streams: toothpicks, bamboo charcoal, and the remainder for combustion as boiler fuel. The GWP estimate for the residue conversion to value-added toothpicks and bamboo charcoal combines the two. Detailed data for each scenario can be found in Appendix Table S4. The GWP result of energy recovery is calculated according to the “heat, from steam, in chemistry” from the EcoInvent database 3.7.1 v. It was noted that most of the residue management scenarios have negative emissions which means burning bamboo residue could offset most of the primary energy required to produce the added byproducts from residues. According to the manager of the Jizhu Bamboo Charcoal Company, toothpicks, and bamboo charcoal production use very little energy if most of the energy used to make bamboo charcoal comes from gas generated (W. Zhang, personal communication, June 28, 2024). The toothpick machine has a low power rating with a short-time operation, meaning low energy is required during running (e.g. for carbonized laminated bamboo, 2.44 kWh compared with 220.42 kWh for drying). It was shown that if significant portions of residue were used to produce toothpicks and bamboo charcoal byproducts, then the small remainder would be insufficient to offset the emissions from their production, despite very small overall carbon emissions. With these low carbon footprint byproducts, factories could further boost their profits with relatively little impact on GWP. Restrepo et al. (2016) conducted an LCA analysis in Colombia comparing two different energy sources used for laminated bamboo boards: bamboo residue and natural gas. They found that 97 the combustion of bamboo residues could offset the energy usage and help reduce the environmental impact. Table 4.1 Results from residue utilization scenarios for 1 m3 of three bamboo products. Product name Scenario GWPemission (kg CO2 eq) GWPenergy recovery (kg CO2 eq) Total GWP residues (kg CO2 eq) Laminated bamboo Scenario 1-LB (B) / -3.58 -3.58 Scenario 1-LB (C) / -6.69 -6.69 Scenario 2-LB (B) 2.44 -3.58 -1.14 Scenario 2-LB (C) 2.44 -6.69 -4.25 Scenario 3-LB (B) 4.85 -3.58 1.27 Scenario 3-LB (C) 4.85 -6.69 -1.84 Bamboo scrimber Scenario 1-BS (B) / -3.71 -3.71 Scenario 1-BS (C) / -9.30 -9.30 Scenario 2-BS (B) 4.54 -3.1 0.83 Scenario 2-BS (C) 4.54 -9.30 -4.76 Scenario 3-BS (B) 6.62 -3.71 2.91 Scenario 3-BS (C) 6.62 -4.36 2.26 Flattened bamboo Scenario 1 / -2.57 -2.57 Scenario 2 1.69 -2.57 -0.88 4.2 Comparison with other research and EPDs Table 4.2 compares the results of this study and other studies or EPD reports conducted for similar bamboo products. The EPD reports are from different companies including Moso Bamboo Inc. and Hangzhou DASSO Technology Co., Ltd., and all products are compared under the same functional unit (1 m3). Since most of the data is reported only for the final products such as laminated bamboo and bamboo scrimber, very little data could be found for intermediate products. The models from this study are mostly within the range of past reports. Mean values are an average of all data from this study and data reported by others. The result for bamboo culm from this study is higher than other reports because it includes transportation in the calculation while most other bamboo culm models do not (Zea Escamilla 98 and Habert, 2014). Note from Figure 4.2 that transportation is the major contributor to the carbon emission estimate for bamboo culm, accounting for 77%. This study showed a lower emission estimate for flattened bamboo due to the commercial products given in the EPD by Hangzhou DASSO including carbonization and post-drying which are the most energy-intensive steps. This study reports two values for bamboo strips, laminated bamboo, and bamboo scrimber; i.e. bleached or carbonized. Table 4.2 Carbon footprint harmonized model for 1 m3 of bamboo products (Unit: kg CO2 eq). Note: The min and max values are calculated by interpreted models from the papers in the reference column. The mean number is gained by calculating the data of this study and the data obtained in the literature reviewProduct name Mean This study Min Max Reference Bamboo culm 3.44 13.21 1.80 5.76 Van der Lugt (2008); Zea Escamilla. & Harbert., (2014) Bamboo strips 196.70 131.92; 252.68 92.36 272.78 Van der Lugt (2008); Yu et al. (2019); Zhao et al., (2023); Flattened bamboo 138.65 92.54 92.57 230.86 Zea Escamilla, E. & Harbert, G., (2014); Zhao et al., (2023). Flattened bamboo plank 204.83 190.5 161 263 Zhao et al., (2023); EPD International Advisory Board (2020). Laminated bamboo 547.18 534; 678 230 746.72 Chang et al., (2018); Yu et al., (2019); Bamboo scrimber 1458.88 1116.7; 1557.8 1116.7 1901 Yu et al., (2019); 99 4.3 Other environmental impacts Greenhouse gas emission is not the only category that affects the environment. There are also other impact categories, including fossil fuel depletion, acidification, eutrophication, ozone depletion, etc. This study also compares different environmental impact indicators other than carbon footprint using the ReCipe 2016 midpoint (H) impact assessment method which estimates other environmental impact categories. The full table comparing bamboo products and other benchmark construction products is listed in Appendix Table S1. Impact values for bamboo products in this study and benchmark products are shown in Figure 4.4. Among all other impact categories, fossil fuel depletion is the highest impact indicator other than carbon dioxide emission. Fossil fuel depletion refers to the diminishing availability of fossil fuel resources over time as a result of extraction and consumption and is a significant environmental impact factor. It assesses fossil fuel-related resource scarcity in the future since fossil fuel is a nonrenewable energy source on human timescales. For bamboo products manufactured in China, fossil fuel depletion (in the form of coal to generate power) is another significant environmental impact factor in addition to CO2 emissions. 100 Note from Fig. 4.4 that while steel and concrete have the top two highest depletion values of all construction products, bamboo products generally have a higher value than wood-based products with products manufactured in China having a greater fossil fuel depletion value. For example, for the same product type (plywood) with the same PF resin and similar manufacturing procedures, the plywood made in China has a significantly higher fossil fuel depletion value than plywood produced in North America, mainly due to the reliance on coal-fired electricity. Laminated bamboo and bamboo scrimber products are also higher than the plywood made in China likely due to the lengthy drying, bleaching, and carbonization steps in bamboo product manufacture which do not apply to plywood production, according to the EPD report (EPD International AB, 2023). For the BLSL, the laboratory-based procedure did not involve bleaching or carbonization stages, which led to a lower depletion value than plywood made in China. For wood-based products that are manufactured in other regions, the fossil fuel depletion value is much lower. 101 Figure 4.4 Fossil fuel depletion comparison between bamboo products and benchmark products. LB: Laminated bamboo; BS: Bamboo scrimber; BLSL: Bamboo laminated strand lumber; B: Bleached; C: Carbonized; P_cn: Plywood made in China; P_na: Plywood made in North America; LVL: Laminated veneer lumber; S_eu: Steel made in Europe; Con_glo: Average concrete emission in the global situation. 4.4 Discussion This study presented a model to estimate CO2 emissions and other environmental impacts for three types of bamboo products from cradle to gate. Compared with past studies, this study not only generates estimates for the final products but also the intermediate elements such as strips, and products such as single-layer laminates, involving the major contributors from all of the inputs for both intermediate products and final products. This study uses a general region in the model, such as the rest of the world other than Europe (ROW) or the global region (GLO). 102 For transportation, the total assumed amount of bamboo is calculated based on a simplified cylinder shape rather than the normal tapered shape of bamboo culms. The analyses showed that electricity consumption, resin use, and transportation are the three main factors influencing the environmental impact of bamboo products. Since there is a lack of certain input values from China in the EcoInvent database, including resins, bleaching, vegetable oil used in power sawing, etc., this study uses the global value to estimate the carbon emissions. However, all the electricity data are derived from China's South Grid where most of the bamboo manufacturing facilities are located. Besides, since LSL is currently not made in China, the input data to the OpenLCA software is assumed based on the EPD report with a geographic switch from North America to China. The overall results of the models in this study could be more accurate if there were more detailed data available from China. Hypothesis 1 is that bamboo products have lower net carbon footprints compared with wood-based products which is partially confirmed in Chapter 4. In terms of overall production carbon emission, bamboo products actually emit more carbon dioxide than wood-based products, especially those manufactured in North America and Europe due to the greater reliance on coal-fired power. However, this may be partially offset by bamboo having faster carbon sequestration capacity due to its more rapid growth and harvest cycle compared with trees. Using bamboo has the benefit of storing carbon inside the products with a shorter harvesting cycle than wood. High-density bamboo products, such as bamboo scrimber, could store and offset more carbon inside the product. However, over time the carbon storage capacity of forest trees equalizes and surpasses bamboo due to the greater biomass volume in older forests (Van der lugt. 2008). 103 The study showed intermediate products, especially element production, are a major contributor to carbon emissions (Hypothesis 2). Hypothesis 3 is based on comparing the carbon footprints of three structural bamboo products, whereby bamboo scrimber has the highest carbon emission. This is verified in Chapter 4 (Figure 4.1). Bamboo scrimber has the most energy-intensive manufacturing procedure with the highest carbon emission. However, it also has the highest carbon storage in the product due to it containing a larger amount of bamboo (918 kg/FU) compared with the other two products (686 kg/FU for laminated bamboo and 665 kg/FU for flattened bamboo). Developing less energy-intensive drying and treatment processes for bamboo could help reduce carbon emissions. Hypothesis 4 considers the high transportation contribution to carbon footprint. In regions that have local bamboo forests or plantations, it makes sense to process it as a replacement material for wood-based construction materials. The analysis suggests the carbon footprint of bamboo-based materials compares unfavorably with wood products in regions with an established wood growing and processing industry, especially in Europe and North America. Shipping bamboo products from China to Europe or North America significantly exacerbates carbon emissions, exceeding those of locally produced wood products. The residue utilization further adds to the carbon footprints of bamboo products but not to a large extent due to lower power-rated machines used to make toothpicks (only 9.5 kW compared with 25.5 kW for the sanding machine), and the majority of energy source is gas-generated from burning bamboo itself for making bamboo charcoal (Hypothesis 5). Furthermore, this study uses moso bamboo which has lower carbon sequestration rates (8.1 t C/ha/yr) (Chiti et al., 2024) compared to Guadua angustifolia (25.92 t C/ha/yr) which is native to Central America (Rojas et al., 2013). If a factory in North America were able to source and use Guadua angustifolia or another US or South American-grown 104 bamboo type to manufacture bamboo products, then this would greatly help reduce the overall carbon footprint of bamboo construction products. 105 Chapter 5: Conclusions and Recommendations 5.1 Summary and conclusions Three models for estimating carbon emissions from final bamboo construction products and 11 sub-models for intermediate products were developed in this study, including the two major bamboo products on the market and one case study of a novel experimental product (BLSL) using a factory assumption for bamboo processing steps. As demonstrated with BLSL, the carbon footprint of the intermediate products could be used as input modules to calculate the overall carbon footprint of new products with any given layup configuration and substrate materials. In addition to carbon footprint estimates, this study also considered other environmental impacts. The environmental impact categories of bamboo products were compared with those of typical benchmark products in construction, such as engineered wood products (glulam, LVL, CLT), steel, and concrete. The models in this study were also compared with other models developed for the same products from the literature review. The major conclusions are as follows: 1) Nonrenewable material products have higher carbon footprints than bio-based materials such as bamboo and wood products, with steel producing the highest carbon emission. 2) Bamboo products made in China generally have higher carbon emissions than wood-based products made in Europe or North America. This is due to China's heavy reliance on brown coal to generate electricity, whereas Europe and North America have a higher proportion of natural gas and non-fossil fuel energy feeding their electricity grids. 106 3) Bamboo scrimber has the highest electricity consumption and resulting carbon emissions compared with the laminated bamboo and the hybrid bamboo and wood product evaluated in this study. Carbonized bamboo scrimber consumes over 1000 kWh of electricity, compared with 424.64 kWh for carbonized laminated bamboo. 4) The major contributor to carbon emission is electricity usage during manufacturing. Drying and hot pressing consume the most electrical energy, with drying accounting for 30-60% of the total energy consumption. This makes the element production stage more energy-intensive than some of the later manufacturing stages. 5) Transportation of bamboo and resin additives contributes significantly to the carbon emissions of bamboo products. Transportation depends largely on the distance between bamboo forests and production facilities. Overseas shipping incurs prohibitively high carbon emissions. 6) In general, despite their higher electricity consumption, the carbon footprints of bamboo products are similar to wood products if both carbon storage during growth and emissions during production are balanced out. Carbon storage in one m3 of bamboo or wood products is directly correlated to the density of the material. Since heavier products contain more bamboo and therefore more sequestered carbon, this makes the overall carbon footprint of bamboo scrimber more similar to lighter products such as laminated bamboo and bamboo-laminated wood strand lumber. 7) Residue utilization processes emit between -9.30 to 2.91 kg CO2 eq per m3 of bamboo products, depending on the utilization scenario. The toothpick machine used for value-added byproducts has a low power rating and bamboo charcoal consumes fuels generated from bamboo itself. 107 8) Bamboo and wood products made in China have higher fossil fuel depletion indices than wood products made in Europe or North America, due to the heavy reliance on coal-fired power. Bamboo scrimber is higher again due to its energy-intensive carbonizing and drying processes. Laminated bamboo and BLSL are lower in fossil fuel depletion than plywood despite all products being manufactured in China. 5.2 Recommendations for future research Most current LCA models for bamboo product processing only include A1 to A3 life cycle stages, which include raw material extraction, transportation, and manufacturing processes. However, detailed data on installation, use, dismantling, and recycling/reprocessing or disposal stages are often lacking. Future LCA studies should focus on supplementing these data gaps in order to gain a more comprehensive understanding of the environmental impacts of bamboo product life cycles. This includes collecting information on energy consumption, emissions, waste generation, and other environmental factors associated with the installation, use, dismantling, and end-of-life treatment of bamboo products. By extending the LCA model to include these additional life cycle stages and related data, researchers can make a more accurate assessment of the environmental sustainability of bamboo products. This will enable stakeholders to make more informed decisions on the selection, design, and disposal of bamboo products, ultimately contributing to more sustainable development of the bamboo and the construction industry. 108 Bamboo products are made from fast-growing, biodegradable materials that store carbon, however, research on carbon sinks in bamboo forests only considers the carbon sequestration capacity of bamboo forests themselves but lacks consideration of the carbon sequestration and storage potential of bamboo products. This aspect also warrants further research. Understanding the carbon sequestration and storage potential of bamboo products is essential to accurately assess their overall carbon footprint and environmental impact. This requires an assessment of the carbon storage of bamboo products throughout their life cycle, including the production, use, and disposal stages. Research efforts should aim to quantify the amount of carbon stored in different kinds of bamboo products (e.g., building materials, furniture, and packaging) and to assess the timing of sequestration of this carbon. By integrating the carbon sequestration potential of bamboo products into the broader framework of bamboo forest carbon sinks, researchers can gain a more comprehensive understanding of the role of bamboo in climate change mitigation. 5.3 Recommendations for the industry To reduce the environmental footprint of bamboo products, the bamboo product industry needs to consider upgrading their machinery to more energy-efficient models and improve the high-energy drying and carbonization processes. Upgrading drying, hot pressing, and planing machinery can reduce energy consumption and hence production costs as well as carbon emissions. Using bamboo residues as boiler fuel to generate heat for high energy-intensive procedures, such as boiling, drying, and hot pressing, could help factories offset some of their coal-fired power needs and be more environmentally friendly. 109 The most commonly used adhesives in the bamboo industry are phenol-formaldehyde (PF) resins which are high in carbon emissions during their production process. Therefore, exploring alternative, more environmentally friendly adhesives, such as methylene diphenyl diisocyanate (MDI) resin (Iglesias et al., 2023), should also be a priority. Starch-based binders are another option for helping reduce carbon footprints, especially in high resin content products like scrimber, being sourced from rapidly renewable agricultural wastes (such as soybean) and formaldehyde-free (Shao et al., 2022). 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Three bamboo product specifications of this study. Product name Density (kg/m3) Resin Content (%) Recovery rate in the factory (%) Laminated bamboo 700 2* 37 Bamboo scrimber 1080 15* 56 Flattened bamboo 700 2.4* 49 * Khajouei-Nezhad et al., 2023. Table S2. Environmental impacts of bamboo products and benchmark products. Product name Fossil depletion Eutrophication Acidification Ozone depletion Reference kg oil eq kg N eq kg SO2 eq kg CFC-11 eq LB(B) 158.05 8.440E-02 1.85 1.71E-05 This study LB(C) 209.99 1.2E-01 2.78 3.28E-05 This study BS(B) 364.25 1.81E-01 4.22 3.06E-05 This study BS(C) 455.92 2.4E-01 6.20 3.35E-05 This study BLSL 117.33 1.88E-01 5.46 3.18E-05 This study P_cn 237.29 9.28E-01 2.11 1.19E-05 EPD International AB, (2023) LVL 19.04 1.65 1.71 11.6E-05 American Wood Council & Canadian Wood Council, (2020) CLT 0.50 9.19E-02 2.37E-01 99.15E-06 EPD International AB, (2023) Steel_eu 1197.14 50.8 18.5 3.65E-09 EPD International AB, (2021) Concrete_glo 17.06 2.6E-01 1.24 1.24E-05 ConcreteBC, (2022) 143 Table S3. Energy inputs for one m3 LSL. Inputs Quantity Unit Reference Electricity 276.01 kWh Sahoo et al., (2021) Wood fuel 264.56 kg Sahoo et al., (2021) Propane 4.99 kg Sahoo et al., (2021) Natural gas, heat in the small-scale boiler 38.5 MJ Sahoo et al., (2021); Huang et al., (2022) Diesel, machine operation 1.89 h Sahoo et al., (2021); Ecoinvent database Transportation, log 287028 kg*km Sahoo et al., (2021); Lao et al., (2023). 144 Table S4. Detailed results of residue utilization scenarios of each product. Product name Scenario GWP toothpick (kg CO2 eq) GWP bamboo charcoal (kg CO2 eq) Energy recovery (kWh) Laminated bamboo Scenario 1-LB (B) / / 83.18 Scenario 1-LB (C) / / 155.34 Scenario 2-LB (B) 2.44 / 83.18 Scenario 2-LB (C) 2.44 / 155.34 Scenario 3-LB (B) 2.44 2.41 83.18 Scenario 3-LB (C) 2.44 2.41 155.34 Bamboo scrimber Scenario 1-BS (B) / / 86.09 Scenario 1-BS (C) / / 215.79 Scenario 2-BS (B) 4.54 / 86.09 Scenario 2-BS (C) 4.54 / 215.79 Scenario 3-BS (B) 4.54 2.08 86.09 Scenario 3-BS (C) 4.54 2.08 101.19 Flattened bamboo Scenario 1 / / 59.76 Scenario 2 / 1.69 59.76
Thesis/Dissertation
eng
Forestry
Vancouver : University of British Columbia Library
Attribution-NonCommercial-NoDerivatives 4.0 International
Graduate
Dai, Chunping, 1963-
Tu, Qingshi
Carbon footprint analyses of structural bamboo products
Text