Open Collections

UBC Undergraduate Research

Sustainability assessment of OSB and softwood plywood manufacturing in North America Chan, George 2012

You don't seem to have a PDF reader installed, try download the pdf

Item Metadata

Download

Media
[if-you-see-this-DO-NOT-CLICK]
Chan_George_WOOD_493_Project_2012.pdf [ 1.84MB ]
Metadata
JSON: 1.0103136.json
JSON-LD: 1.0103136+ld.json
RDF/XML (Pretty): 1.0103136.xml
RDF/JSON: 1.0103136+rdf.json
Turtle: 1.0103136+rdf-turtle.txt
N-Triples: 1.0103136+rdf-ntriples.txt
Original Record: 1.0103136 +original-record.json
Full Text
1.0103136.txt
Citation
1.0103136.ris

Full Text

    Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America  George Chan    WOOD 493 A Report Submitted in Partial Fulfillment of the Requirements for the Degree of Bachelor of Science in Wood Products Processing In The Faculty of Forestry  April 14, 2012  Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America   ii  Abstract The Canadian wood products industry, including structural panels, is very dependent on the US housing market. Since the US housing crisis in 2006, exports of Canadian wood products to the US significantly dropped annually at a devastating rate. With the growing trend for sustainable construction, the widespread influence of promotions from campaigns such as Wood First and Wood Works and as well as the building standards of the LEED rating system, the demand for wood products is steadily being restored. Amongst the primary construction materials, the manufacturing of structural products of OSB and softwood plywood has slightly higher environmental impact than the manufacturing of lumber due to the drying and pressing processes and the resins used as well. As the demand for structural panels is being slowly created, manufacturers in this industry need to lower the emissions generated from manufacturing to lower environmental impacts. This thesis contrasts and analyzes the emissions and emission control data from the Life Cycle Assessment and Life Cycle Inventory reports for OSB and softwood plywood. In general, between both structural panel products, plywood is the more sustainable product of the two with lower energy utilized and fewer emissions of CO2, SOx, NOx, VOC and particulate matter generated in the manufacturing process. To further reduce emissions associated with manufacturing of both panel products, the theoretically plausible solution is to combine the use of regenerative thermal oxidizer, which can remove 99% more VOC emissions than that of the wet electrostatic precipitator (NCASI, 1999), with an emissions trading legislature.    Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     iii  Table of Contents Abstract ......................................................................................................................................................... ii List of Tables ................................................................................................................................................. v List of Figures .............................................................................................................................................. vii 1 Introduction .......................................................................................................................................... 1 2 Canadian and US OSB Study .................................................................................................................. 4 2.1 OSB Manufacturing Process .......................................................................................................... 4 2.1.1 Log Preparation ..................................................................................................................... 5 2.1.2 Drying .................................................................................................................................... 5 2.1.3 Blending ................................................................................................................................ 6 2.1.4 Pressing ................................................................................................................................. 6 2.1.5 Finishing ................................................................................................................................ 6 2.2 Life Cycle Assessment of OSB ....................................................................................................... 7 2.2.1 System Boundaries ................................................................................................................ 7 2.2.2 LCA Results ............................................................................................................................ 7 2.3 Life Cycle Inventory of OSB ......................................................................................................... 13 2.3.1 System Boundaries .............................................................................................................. 13 2.3.2 Life Cycle Inventory Results ................................................................................................ 14 2.4 Contrast between Canadian and US mills ................................................................................... 24 2.4.1 Material Input ..................................................................................................................... 24 2.4.2 Energy ................................................................................................................................. 25 2.4.3 Material Output .................................................................................................................. 26 2.4.4 Emission .............................................................................................................................. 27 3 Canadian and US Softwood Plywood Study ........................................................................................ 29 3.1 Plywood Manufacturing Process ................................................................................................ 29 3.1.1 Green process, debarking ................................................................................................... 30 3.1.2 Green process, log conditioning and veneer peeling ......................................................... 30 3.1.3 Veneer drying ...................................................................................................................... 30 3.1.4 Veneer layup and pressing .................................................................................................. 31 3.1.5 Finishing .............................................................................................................................. 31 3.2 Life Cycle Assessment of Plywood .............................................................................................. 31 Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     iv  3.2.1 System Boundaries .............................................................................................................. 32 3.2.2 LCA Results .......................................................................................................................... 32 3.3 Life Cycle Inventory of plywood .................................................................................................. 38 3.3.1 System Boundaries .............................................................................................................. 38 3.3.2  LCI Results ........................................................................................................................... 39 3.4 Contrast between Canadian and US mills ................................................................................... 50 3.4.1 Material Input ..................................................................................................................... 50 3.4.2 Energy Input ........................................................................................................................ 52 3.4.3 Material Output .................................................................................................................. 53 3.4.4 Emission .............................................................................................................................. 54 4 Analysis ............................................................................................................................................... 55 4.1 Structural Panel Comparison ...................................................................................................... 55 4.1.1 Energy ................................................................................................................................. 56 4.1.2  Greenhouse Gases .............................................................................................................. 57 4.1.3 Other air emissions ............................................................................................................. 58 4.1 Emission Control System ............................................................................................................. 60 4.1.1 Oriented Strand Board ........................................................................................................ 60 4.1.2 Softwood Plywood .............................................................................................................. 62 5 Recommendation ................................................................................................................................ 63 5.1 Sustainable Structural Panel Product ......................................................................................... 63 5.2 Emission Control System ............................................................................................................. 64 6 Conclusion ........................................................................................................................................... 66 7 Appendix ............................................................................................................................................. 68 8 Bibliography ........................................................................................................................................ 70     Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     v  List of Tables Table 1: Energy utilization in production of 1 MSF 3/8 inch basis OSB in absolute value ............................ 7 Table 2: Energy utilization in production of 1 MSF 3/8 inch basis OSB in percentage ................................. 8 Table 3: Air Emissions generated in the production of OSB per MSF 3/8-inch basis ................................. 11 Table 4: Southeastern electricity allocation along the sub-unit processes of manufacturing for 1MSF 3/8- inch basis of OSB ......................................................................................................................................... 16 Table 5: Analysis of different emission systems used in US OSB mills ....................................................... 23 Table 6: Average material inputs in Canadian mills versus US mills for 1 MSF of 3/8 inch OSB ................ 24 Table 7: Average energy inputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of OSB .............. 25 Table 8: Average material outputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of OSB ......... 26 Table 9: Average main air emissions generated in Canadian mills versus US mills for 1 MSF of 3/8-inch of OSB .............................................................................................................................................................. 27 Table 10: Energy Utilization in production of 1 MSF 3/8-inch basis of plywood (Absolute Value) ............ 32 Table 11: Energy Utilization in production of 1 MSF 3/8-inch basis of plywood (Percentage) .................. 33 Table 12: Air emissions generated in the production of 1 MSF 3/8-inch basis of plywood (Absolute Value)  .................................................................................................................................................................... 35 Table 13: Air emissions generated in the production of 1 MSF 3/8-inch basis of plywood (Percentage) . 35 Table 14: Acidification, Eutrophication, Smog and Air-Mobile Emissions .................................................. 37 Table 15: Energy utilization per MSF 3/8-inch basis within softwood plywood manufacturing ................ 39 Table 16: Utilization of primary energy sources for the generation of electricity in the PNW region ....... 41 Table 17: PNW electricity allocation along the sub-unit processes of plywood manufacturing for 1 MSF 3/8-inch basis .............................................................................................................................................. 42 Table 18: Air emissions per MSF 3/8-inch basis generated from the production of plywood in the PNW region (percentage) .................................................................................................................................... 48 Table 19: Air emissions per MSF 3/8-inch basis generated from the production of plywood in the SE region (percentage) .................................................................................................................................... 48 Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     vi  Table 20: Carbon input per MSF 3/8-inch basis of plywood produced in the PNW region ........................ 45 Table 21: Carbon output per MSF 3/8-inch basis of plywood produced in the PNW region ..................... 45 Table 22: Carbon input per MSF 3/8-inch basis of plywood produced in the SE region ............................ 46 Table 23: Carbon output per MSF 3/8-inch basis of plywood produced in the SE region .......................... 46 Table 24: Average material inputs in Canadian mills versus US mills for 1 MSF 3/8-inch of plywood ....... 50 Table 25: Average energy inputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of softwood plyood ......................................................................................................................................................... 52 Table 26: Average material outputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of softwood plywood ...................................................................................................................................................... 53 Table 27: Average main air emissions generated in Canadian mills versus US mills for 1 MSF of 3/8-inch of softwood plywood .................................................................................................................................. 54 Table 28: Sustainability comparison between OSB and softwood plywood for 1 MSF 3/8-inch basis ...... 56 Table 29: Comparison of average output between Canadian and US softwood plywood manufacturing for 1 MSF 3/8-inch basis ............................................................................................................................. 63 Table 30: Comparison of average output between Canadian and US OSB manufacturing for 1 MSF 3/8- inch basis ..................................................................................................................................................... 64 Table 31: Air emissions (per MSF 3/8-inch basis) generated ...................................................................... 68 Table 32: Air emissions (per MSF 3/8-inch basis) generated ...................................................................... 69 Table 33: Air emissions (per MSF 3/8-inch basis) generated ...................................................................... 69    Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     vii  List of Figures Figure 1: OSB manufacturing process ........................................................................................................... 4 Figure 2: Energy Utilization within the Manufacturing Process (Percentage) .............................................. 9 Figure 3: Emission of CO2 in the production of OSB per MSF 3/8-inch basis ............................................. 10 Figure 4: Air Emissions generated within the manufacturing process for 1 MSF 3/8-inch basis of OSB ... 11 Figure 5: Survey Region for Participating OSB Mills ................................................................................... 13 Figure 6: Energy utilization per MSF 3/8-inch basis of OSB within manufacturing (percentage) .............. 14 Figure 7: Utilization of primary energy Sources for the generation of electricity in the Southeastern Region US .................................................................................................................................................... 15 Figure 8: Sourtheastern electricity allocation along the sub-unit processes of manufacturing ................. 17 Figure 9: Air Emissions Generated On-site and Off-site during the manufacturing of 1 MSF 3/8-inch basis of OSB .......................................................................................................................................................... 19 Figure 10: Air emissions generated both On-Site and Off-Site during the manufacturing of 1 MSF 3/8- inch basis of OSB ......................................................................................................................................... 20 Figure 11: Air emissions generated On-Site during the manufacturing of 1 MSF 3/8-inch basis of OSB ... 20 Figure 12: Input of Carbon Raw Material for 1 MSF 3/8-inch basis of OSB ................................................ 21 Figure 13: Carbon Output per MSF 3/8-inch basis of OSB .......................................................................... 22 Figure 14: Average material inputs in Canadian mills versus US mills for 1 MSF of 3/8 inch OSB ............. 24 Figure 15: Average energy inputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of OSB ........... 25 Figure 16: Average material outputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of OSB ...... 26 Figure 17: Average main air emissions generated in Canadian mills versus US mills for 1 MSF of 3/8-inch of OSB .......................................................................................................................................................... 27 Figure 18: Plywood manufacturing process ................................................................................................ 29 Figure 19: Energy utilization within OSB manufacturing ............................................................................ 34 Figure 20: Emission of CO2 in the production of 1 MSF 3/8-inch basis of plywood ................................... 36 Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     viii  Figure 21: Acidification, Eutrophication, Smog and Air Mobile Emissions in manufacturing of plywood . 37 Figure 22: Energy utilization within plywood manufacturing ..................................................................... 40 Figure 23: PNW electricity allocation along the sub-unit processes of plywood manufacturing for 1 MSF 3/8-inch basis (Percentage) ........................................................................................................................ 42 Figure 24: CO2 emissions (percentage) per MSF 3/8-inch basis of plywood from sub-unit processes of manufacturing in the PNW region .............................................................................................................. 43 Figure 25: CO2 emissions (percentage) per MSF 3/8-inch basis of plywood from sub-unit processes of manufacturing in the SE region .................................................................................................................. 44 Figure 26: Average material inputs in Canadian mills versus US mills for 1 MSF of 3/8 inch of plywood .. 51 Figure 27: Average energy inputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of softwood plywood ...................................................................................................................................................... 52 Figure 28: Average material outputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of softwood plywood ...................................................................................................................................................... 53 Figure 29: Average main air emissions generated in Canadian mills versus US mills for 1 MSF of 3/8-inch of softwood plywood .................................................................................................................................. 54 Figure 30: Comparison of energy utiliztion between OSB and softwood plywood for 1 MSF 3/8-inch basis  .................................................................................................................................................................... 56 Figure 31: Comparison of CO2 emissions between OSB and softwood plywood for 1 MSF 3/8-inch basis 57 Figure 32: Comparison of SOx, NOx, VOC and particulate matter emissions between OSB and softwood plywood for 1 MSF 3/8-inch basis............................................................................................................... 58 Figure 33: COMBINED ON-SITE AND OFF-SITE EMISSIONS PRODUCED FOR 1 MSF OSB ........................... 60 Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America   1  1 Introduction Demand for oriented strand board and softwood plywood products were once steadily increasing in the Canadian wood exports industry before 2000 (Poon, 2010). Low strength variation and narrow allowable design stress are both engineered into these products (Ellis, 2010), which led them to become preferable single family housing construction sheathing materials. However, since the US housing crisis in 2006, demand for Canadian OSB and softwood plywood significantly fell. Exports of Canadian OSB to the US dropped at record high levels in the years of 2007 and 2008 at an average of 39.47% (Poon, 2010), while plywood exports dropped at a record high average of 30.12% from 2008 to 2009 (Poon, 2010). In the structural panel industry, plywood struggles to gain structural panel market share from OSB (Poon, 2010); nonetheless at the current decreasing rate of demand for plywood panels, plywood is not likely to be completely replaced by OSB. However, with the current growing trend in sustainable construction, wood products are promoted and demanded as construction material in North America. Noticeable campaigns include Wood First and Wood Works promote the use of wood products through public education and training. In Oregon, negotiation to pass a Wood First bill "to direct the state of Oregon to use wood as a preferred building material" (Holt, 2011) in 2011; although the negotiation was unsuccessful, Wood First will continue to involve the state of Oregon with their campaign (Andre, 2011). Other means of promotion takes place through financial incentives. LEED rates and scores buildings according to their potential impact in both the environment and human health. Grants are awarded to homeowners depending on the levels of certification their homes are qualified in. Aside from promotions, there exists pre-fab housing in the US that involves constructing the entire home within a plant and assembling the house on-site to primarily reduce cost and environmental impact. Demand for pre-fab housing was on a decline since 2006, but due to the events of hurricane Katrina, the demand was boosted as manufacturers were called upon to rebuild the many destroyed Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     2  homes in New Orleans (Moldvay, 2011). Mainly because of lower cost and environmental impact, pre- fab housing is currently well recognized and the demand is forecasted to grow annually by 6.5% until 2016 (Moldvay, 2011). In general, sustainable construction is an influential growing trend that will revive the wood industry through creating demand in North America. Amongst the primary construction materials of lumber, OSB and softwood plywood, the manufacturing of structural panel products has slightly greater environmental impact than the manufacturing of lumber, because of emissions generated from the drying and pressing processes and the resins used as well (Athena Sustainable Materials Institute, 2009). Yet, these products will be greatly demanded as sheathing materials with the increasing sustainability campaigns and pre-fab housing demands. OSB and softwood plywood utilize more available timber material in a tree than lumber, thus achieving higher wood fibre utilization within a tree. The more efficient, sustainable use of wood fibre in OSB and softwood plywood when compared to lumber offsets the slightly higher emissions. In addition, OSB and softwood plywood also serve as components in engineered products such as the web of I-joist. As a result, manufacturers in the structural panel industry need to lower the emissions generated from manufacturing to lower the associated environmental impacts. In this thesis, the environmental impact and emission control systems reported in Canadian life cycle assessment reports of OSB and softwood plywood are contrasted with the data provided in the US life cycle inventory reports to search for potential improvements in the manufacturing process.  The OSB manufacturing process is first described along with the subsequent emissions from each procedure. After process description, environmental impact data from Canadian life cycle assessment and US life cycle inventory reports are presented in the format of LCA impact categories. Following environmental impact from both reports, analysis and recommendations are discussed. Furthermore, the manufacturing process of softwood plywood is also described with the subsequent emissions. Environmental impacts from LCA and LCI reports on plywood Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     3  manufacturing are then provided. Lastly, an analysis and recommendations are discussed regarding the sustainability of the structural panel products, emission control systems and environmental impacts.      Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     4  2 Canadian and US OSB Study 2.1 OSB Manufacturing Process  The following section provides a brief description of the manufacturing processes and the subsequent emissions involved in the production of OSB.  Figure 1: OSB manufacturing process Source:  Smith, G. (2012). WOOD 487. Vancouver, British Columbia, Canada. Retrieved April 10, 2012 Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     5  2.1.1 Log Preparation Log debarking and stranding are the first processes in OSB manufacturing. Within the stranding process, knives of a strander cut the logs into strands.  Wood particles and sawdust are the forms of particulates emitted from these processes. There are generally two particulate sizes produced, particulates with diameter of 10 microns or less, known as PM10, and particulates with a diameter of 2.5 microns or less, referred to as PM2.5 (Smith K. T., 2009). Additional particulates are also released from vehicle activities on the job site and wind dispersion of "uncovered bark or wood fines storage piles" (Smith M. , 2009) 2.1.2 Drying Drying is the most energy demanding and polluting procedure in the entire manufacture process. Through a dryer, the moisture of strands are reduced from an initial moisture content of roughly 50-60% to its final moisture content of 3-4% (Ellis, 2011). Three types of dryers used in the industry are the commonly used triple-pass rotary drum (Smith M. , 2009), single pass rotary drum, and conveyor dryers. Currently, direct-fired rotary drum dryers typically use wood residue as fuel, while "natural gas or oil fired rotary drum dryers" (Smith M. , 2009) are rarely used. Conveyor dryers differ from rotary drum dryers in that the former utilizes indirect fire to dry strands entering a conveyor. The result is reduced inlet temperatures of approximately 160oC, whereas rotary dryers have higher inlet temperatures of up to 870oC. During drying, the combustion of fuel and drying of strands generate harmful emissions. Depending on the fuel source, combustion typically generates "particulate matter, nitrogen oxide, carbon dioxide and carbon monoxide" (Smith M. , 2009). In addition, wood naturally contains volatile compounds that are released during the drying process as volatile organic compound (VOC) and hazardous air pollutants (HAPs). An emission known as blue haze is also generated from the dryer. This Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     6  is the result of certain VOCs and condensable PM being released in the form of vapor that is later condensed in ambient air temperature (Smith M. , 2009).  2.1.3 Blending  During blending, a blender mixes surface strands with liquid or powder phenol-formaldehyde (PF) and another blender mixes strands to be used for the core of the OSB panel with PF or diphenol methane diisocyanate (MDI) resin (Smith M. , 2009).  Emissions of VOC and HAPs within this process are released by the resins, although emissions from blending are much lower compared to drying and pressing processes (Smith M. , 2009). 2.1.4 Pressing  The strands are then laid and oriented perpendicular to the previous layer of strands being laid. After mat formation, the mat is trimmed and pressing follows. Heat and pressure are applied to the mat in order to "activate the resin and bond the strands" (Smith M. , 2009). To attain this heat at the press, heat generated by a boiler is transferred to the press via steam, hot water or oil (Smith M. , 2009). The fuel sources for the boiler vary from wood residue to natural gas or oil.  Similar to drying, pressing is also primarily responsible for emitting air pollutants due to the particulates generated from fuel combustion and the volatile compounds released from the pressing process.  The latter occurs through the release of vapor, consisting of formaldehyde and phenol, upon opening of the press (Smith M. , 2009).  2.1.5 Finishing  Finally, the panels are trimmed to their final dimensions and finished to customer preference. Particulate emissions are produced from the trimming procedure, and additional emissions are produced when sawdust piles are dispersed by wind (Smith M. , 2009). Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     7  2.2 Life Cycle Assessment of OSB The following is a summary of energy utilization and air emissions released from the manufacturing process of OSB production in Canada. 2.2.1 System Boundaries Four Canadian OSB manufacturing mills participated in this study. Their geographical locations are rather diversely distributed across the provinces of BC, Alberta, Ontario and Quebec (Athena Sustainable Materials Institute, 2008). These mills "represent slightly more than 10% of all [OSB] plants in Canada" (Athena Sustainable Materials Institute, 2008), and their annual production of 3/8-inch basis ranged approximately between 167 to 625 MMSF. 2.2.2 LCA Results  The following paragraphs and tables display the results of environmental impacts generated from the manufacturing of OSB.  Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Oriented Strand Board. Ottawa, Ontario: Athena Institute. Table 1: Energy utilization in production of 1 MSF 3/8 inch basis OSB in absolute value N n-renewable, fossil 308 184 2,112 2,604 No -renewable, nuclear 1 1 126 128 Renewable (SWHG) 1 0 331 332 Renewable (biomass) 0.05 0 2,399 2,399 Feedstock, fossil 0 0 899 899 Feedstock, biomass 0 0 10,612 10,612 Total Pri ary Energy 310 185 16,479 16,974 Manufacturing  (MJ) Energy Source Resource Harvesting (MJ) Total  (MJ) Resource & Material Transportation (MJ)Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     8   Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Oriented Strand Board. Ottawa, Ontario: Athena Institute. Table 2: Energy utilization in production of 1 MSF 3/8 inch basis OSB in percentage  Total Primary Energy In this cradle-to-gate life-cycle assessment (LCA), the production of OSB is divided into three production processes of resource harvesting, resource and material transportation, and OSB manufacturing (Athena Sustainable Materials Institute, 2008). Combining the primary energy requirements of these three production processes, the total is calculated to 17 GJ of energy, and the manufacturing process accounts to 97.1% of this total primary energy. As displayed in Table 1, OSB embodies biomass and feedstock energy as well, and with this energy of 11.5 GJ removed from the energy demand, only 5.46 GJ is required for OSB production. This input energy is evenly derived at 50/50 from two types of sources, renewable and non-renewable, because of the abundant use of biomass as a thermal fuel to dry raw wood furnish and hydro power as energy in resource harvesting and manufacturing. Consumption of this cumulative energy input is, however, unequal across the unit processes. As displayed in Table 2, the manufacturing process consumes the majority of primary energy, mainly due to the high energy consumption procedures such as drying and pressing. Even with the huge demand for energy from the manufacturing unit process, the entire manufacture of OSB is almost half self-efficient (Athena Sustainable Materials Institute, 2008).  Energy Source Resource Harvesting Resource & Material Transportation OSB Manufacturing Total Non-renewable, fossil 11.8% 7.1% 81.1% 100.0% Non-renewable, nuclear 0.9% 0.5% 98.6% 100.0% Renewable (SWHG) 0.4% 0.0% 99.6% 100.0% Renewable (biomass) 0.0% 0.0% 100.0% 100.0% Feedstock, fossil 0.0% 0.0% 100.0% 100.0% Feedstock, biomass 0.0% 0.0% 100.0% 100.0% Total Pri ary Energy 1.8% 1.1% 97.1% 100.0%Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     9   Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Oriented Strand Board. Ottawa, Ontario: Athena Institute. Figure 2: Energy Utilization within the Manufacturing Process (Percentage)  Shown in Figure 2, up to 48.3% of the energy consume on-site is derived from renewable biomass sources. While the other 42.5% is from the consumption of non-renewable fossil energy, which is mainly the result of converting fossil fuel into heat required for drying and pressing of the OSB mats. Thus, biomass is the dominant source of renewable energy, while fossil fuel is major source of non- renewable energy utilized in the manufacturing process.  42.51% 2.54% 6.66% 48.29% Non-renewable, fossil Non-renewable, nuclear Renewable (SWHG) Renewable (biomass)Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     10  Global Warming Potential  Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Oriented Strand Board. Ottawa, Ontario: Athena Institute. Figure 3: Emission of CO2 in the production of OSB per MSF 3/8-inch basis  As for global warming potential, a total of 154 kg of CO2 is produced per MSF of OSB (Athena Sustainable Materials Institute, 2008). Figure 2 displays the mass of CO2 produced across the three production processes. OSB manufacturing is the greatest impacting processes for producing over 100 kg of CO2, a mass that takes up 77.2% of the total CO2 produced, while resource harvesting amounts to 20% and transportation accumulates the least at 8.8%.   Carbon Balance In each MSF of OSB, there is a net carbon balance of 912 kg of CO2 sequestered within the product. Subtracting 154 kg of emissions from fossil derived sources, the carbon balance equates to a net positive carbon balance of 758 kg of CO2 (Athena Sustainable Materials Institute, 2008).  21.5 13.5 118.6 0 20 40 60 80 100 120 140 Resource Harvesting Resource & Material Transportation OSB Manufacturing Em iss io n  o f CO2  ( kg ) Stages of OSB Production Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     11  Other Air Emissions  Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Oriented Strand Board. Ottawa, Ontario: Athena Institute. Table 3: Air Emissions generated in the production of OSB per MSF 3/8-inch basis    Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Oriented Strand Board. Ottawa, Ontario: Athena Institute. Figure 4: Air Emissions generated within the manufacturing process for 1 MSF 3/8-inch basis of OSB  Acidification potential is measured on the basis of SO2 emissions. Sulfur dioxide is the product of fossil fuel combustion in the manufacturing unit process, where the drying and pressing processes consume the majority of fuel (Athena Sustainable Materials Institute, 2008). The manufacturing process accounts for 80% of SO2 emissions.  Resource Harvesting Resource & Material Transportation OSB Manufacturing Total Acidification (Kg of SO2) 0.31 0.11 1.74 2.16  Eutrophication (Kg of N) 0.002 0.001 0.004 0.007 Smog (Kg of Ethylene) 0.23 0.08 0.6 0.91 Air-Mobile (Kg of PM2.5) 0.04 0.02 0.53 0.59 80.6% 57.143% 65.934% 89.831% 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% Acidification (SO2)  Eutrophication ( N) Smog (Ethylene) Air-Mobile (PM2.5) Em is si o n  ( % ) Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     12  The combined nitrogen emissions from manufacturing and resource harvesting processes accumulate to 90% of the overall water eutrophication impact. Nitrogen is released from "both fossil fuel emissions and fertilizer use in the forest" (Athena Sustainable Materials Institute, 2008). The overall smog impact is mainly contributed by the manufacturing process at 65.9% of the total ethylene emission of 0.91 kg (Athena Sustainable Materials Institute, 2008).  Production of 1 MSF of OSB releases a combined mass of 5.9 kg of particulates at 2.5 micron in diameter from all three unit processes. Up to 89.8% of these particulates are emitted from the manufacturing process (Athena Sustainable Materials Institute, 2008).            Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     13  2.3 Life Cycle Inventory of OSB The following is a summary of energy utilization and air emissions released from the manufacturing process of OSB production in the Southeast region of US. 2.3.1 System Boundaries  Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Figure 5: Survey Region for Participating OSB Mills  An LCI survey on OSB production was conducted by 22 OSB manufacturing plants across the Southeast region of the United States (Kline, 2004). Figure 4 displays the states in which the participating mills are located. The annual production size of these mills ranged approximately between "340,000 to 380,000 MSF of 3/8 inch basis" (Kline, 2004). When surveyed, these plants produced 1.4 million MSF 3/8" OSB, which generally represented "18% of the total production in the South and 11.8% of the total US production" (Kline, 2004).    Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     14  2.3.2 Life Cycle Inventory Results The following paragraphs display results of environmental impacts generated from the manufacturing of OSB. Total Primary Energy   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Table 4: Energy utilization within manufacturing for 1 MSF 3/8-inch basis of OSB   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Figure 6: Energy utilization per MSF 3/8-inch basis of OSB within manufacturing (percentage) Wood Fuel 2113.03 57.44% Natural Gas 810.19 22.02% Liquid Propane Gas 68.95 1.87% Diesel 2.59 0.07% Fuel Oil 29.38 0.80% Gasoline 0.95 0.03% Electricity 653.76 17.77% Total Primay Energy 3678.85 100.00% Source: CORRIM, Southeastern OSB production, 2004 Energy Source Manufacturing (MJ) Energy Utilization per MSF 3/8" basis OSB within Manufacturing Percentage 57.44% 22.02% 1.87% 17.77% 0.80% 0.07% 0.03% 0.89% Wood Fuel Natural Gas Liquid Propane Gas Electricity Fuel Oil DieselSustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     15   Shown in Table 4, producing one MSF of OSB in the southeastern US region requires a total cumulative energy of 3680 MJ. Though OSB production in this region requires large amounts of energy, 57% of which is derived from combustion of wood fuel, consisting of bark, OSB dust, fines and trimmings generated from manufacturing processes (Kline, 2004). The remaining energy is derived from combustion of fossil fuels. In addition, 17.8% of this cumulative energy is primarily in the form of electricity utilized in the production processes within manufacturing. Natural gas is the next primary source of energy; though the consumption is relatively smaller, this is mainly used "for back-up or secondary heat generation, providing up to 12% of heating requirements" (Kline, 2004). Following natural gas is liquid propane gas, which is used in small volumes as the fuel is used by forklifts mainly in the finishing process and heat generation in the manufacturing process. In general, fossil fuel requirement is very low. Aside from its use in forklifts and log handling, fossil fuel is only used in emission control activities. Figure 6 exhibits the proportion of various fuel sources used across the unit processes of OSB manufacture. Electricity Utilization of primary energy sources for the generation of electricity in the Southeastern region  Figure 7: Utilization of primary energy Sources for the generation of electricity in the Southeastern Region US Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     16  From Figure 5, a total of 654 MJ of electricity is used to produce 1 MSF of OSB. However, the importance is not the amount of electricity used; the focus is the fuel source used to generate the electricity. Consumed up to 49.2%, coal is the dominating fuel source followed by nuclear energy, natural gas, petroleum and hydro. Analyzed with SimaPro 5 and the FAL database, significant environmental impacts have been shown to have been strongly correlated with coal, nuclear and as well as petroleum combustion (Kline, 2004). Natural gas, however, has relatively less impact on the environment (Kline, 2004).  Electricity allocated to each sub-unit process  Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Table 4: Southeastern electricity allocation along the sub-unit processes of manufacturing for 1MSF 3/8-inch basis of OSB Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     17   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Figure 8: Sourtheastern electricity allocation along the sub-unit processes of manufacturing  As shown in Figure 6, the processes of log handling, drying, and screening have the most electricity demand at 25.5% and 29.5% respectively. Though this data is surveyed only from one mill, the data is still representative of all OSB mills as "similar types of equipment" (Kline, 2004) are used in the manufacturing process, with exceptions to emission systems. Table 4 displays the percentage and as well as absolute values of electricity allocated in the sub-unit processes of manufacturing. Log Handling/Stranding Electricity is the most demanded energy, as displayed in Figure 6. Though this huge demand is necessary, as powerful motors are needed to handle and cut green logs into strands. Drying and Screening Throughout the entire OSB production, drying and screening are the processes that demands energy to the highest degree. This demanded energy comes in the form of electricity and heat generated from the combustion of wood residues produced earlier in the log handling process (Kline, 0% 5% 10% 15% 20% 25% 30% 35% A llo catio n   Sub-Unit Processes Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     18  2004). Entire 59.2 kWh of electricity and 2.17 BTU of heat are used to process 712 kg of green strands into 608 kg of dry strands of roughly 5% MC for every MSF of OSB (Kline, 2004).  Blending and Pressing Although there is relatively less energy consumed in this process, blending and pressing are some of the relatively more energy demanding processes after drying and screening (Kline, 2004). A total of 28.4 kWh of electricity and 0.57 million BTU of self-generated heat are needed to mix 608 kg of dry strands with wax and resin and press them into 640 kg of OSB (Kline, 2004). Finishing Only small amounts of energy are utilized in this process as 640 kg of OSB mat is trimmed to its final dimension of 572 kg in mass (Kline, 2004).  As a result of trimming, 63.5 kg of OSB scrap is produced per MSF (Kline, 2004). The scrap would re-enter the manufacturing process as fuel supply for heating energy (Kline, 2004).           Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     19  Global Warming Potential   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Figure 9: Air Emissions Generated On-site and Off-site during the manufacturing of 1 MSF 3/8-inch basis of OSB  Air emission analysis is categorized into on-site (restricting scope of emissions released only from within the plant) and off-site (enlarging the scope to emissions contributed from production to "delivery of fuels, resin, wax and electricity" (Kline, 2004). All air emissions including CO2, CO, VOC and particulates are produced on-site, whereas methane, SOx, CO2 from fossil fuel combustion and NOX emissions are produced off-site, as Figure 7 displays. A close look into CO2 emission in both on-site and off-site reveals that 61% is released from biomass, and in term of on-site emissions, the biomass released CO2 accounts to 89% (Kline, 2004).   Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     20   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Figure 10: Air emissions generated both On-Site and Off-Site during the manufacturing of 1 MSF 3/8- inch basis of OSB   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Figure 11: Air emissions generated On-Site during the manufacturing of 1 MSF 3/8-inch basis of OSB Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     21  The release of air emissions in percentage from “only on-site” and “on-site and off-site” is displayed in Figures 8 and 9. From Figure 9 (on-site), drying is the primary contributor for emitting biomass CO2, but as for fossil fuel released CO2, the drying process released less than half of the total emission. Emission control system emitted half of all fossil fuel CO2 and as well as the majority of all other emissions. Seen from Figure 8 (on-site & off-site), every production process is involved with emission of each pollutant, because of the off-site impact that is included. Similarities shared in both figures are that emission control is primarily responsible for air emission across various air pollutants (Kline, 2004). Flaking and finishing processes have the least air emissions, and majority of CO2 emissions from fossil fuel and biomass is released by the drying process. Carbon Balance   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Figure 12: Input of Carbon Raw Material for 1 MSF 3/8-inch basis of OSB Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     22   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Figure 13: Carbon Output per MSF 3/8-inch basis of OSB  Figure 8 shows carbon content assumptions of various material and fuel inputs associated. Throughout the entire manufacture of one MSF of OSB, roughly 423 kg of total carbon from material and fuel is consumed (Kline, 2004). Of this carbon sum, 396 kg of carbon originates from wood raw material. Another 11.4 kg and 12.3 kg of carbon are from the input of resin, wax and fuel respectively (Kline, 2004). As for carbon output shown in figure 9, 273.3 kg of carbon is within the MSF of OSB panel itself. Co-products contain the other 4% of carbon, while the remaining carbon output is emitted to the atmosphere as CO2, VOCs and other emissions. Other Air Emissions Figure 9 displays the percentage of air emission from each substance that is produced on-site. Carbon monoxide and VOC are the next primary air emissions following carbon dioxide. Emission of VOC accounts to 0.23%, 0.06 kg and NOx follows with emission of 0.08%, 0.02 kg (Kline, 2004).  PM10 and SO2 are emitted 0.06% and 0.01% respectively (Kline, 2004).  Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     23  Emission Control Analysis   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Table 5: Analysis of different emission systems used in US OSB mills  From Table 5, the mills participating in this survey employed RTO, wet ESP or combination of RTO and wet ESP emission systems. This variation in employment of emission systems is the result of "Maximum Achievable Control Technology" (Kline, 2004), which is a regulation that was used at the time of this study. Thus, data inconsistency on air emissions and certain assumptions are evident in this section. Indicated in Table 5 is the comparison of reported emission values from the four participating mills with NCASI emission data. Mill 3 displays lowest emissions, and indeed "falls within the range found in NCASI data for RTO methods" (Kline, 2004). Mill 1 employs both wet ESP and RTO emission systems, but the emissions are significantly greater than the NCASI reported RTO emission data. Though Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     24  both Mills 3 and 4 employ wet ESP, Mill 4 emissions are almost doubled. This can only be assumed that both mills have different input portions of hardwood and softwood raw material.  2.4 Contrast between Canadian and US mills 2.4.1 Material Input   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Table 6: Average material inputs in Canadian mills versus US mills for 1 MSF of 3/8 inch OSB   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Figure 14: Average material inputs in Canadian mills versus US mills for 1 MSF of 3/8 inch OSB Roundwood (kg) 626 780 -24.5% PF Resin (kg) 18.1 19.2 -6.01% MDI Resin (kg) 0 3.7 Slack Wax (kg) 9.02 8.75 2.99% TOTAL 653 811 -24.2% Canadian Mills US MillsMaterial Inputs Difference (%) -30% -25% -20% -15% -10% -5% 0% 5% D if fe re n ce  ( % ) Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     25  Material inputs are generally higher in Canadian mills. These inputs include roundwood input at 5%, wax at 3% and the significantly higher usage of water at 57% (Kline, 2004). Though some inputs are less utilized in Canadian mills, US mills have overall used greater amounts of total resin and wax at 26% (Kline, 2004). Canadian mills only use PF resin, whereas US mills use PF and MDI resins (Kline, 2004). 2.4.2 Energy  Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Table 7: Average energy inputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of OSB   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Figure 15: Average energy inputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of OSB Electricity (MJ) 445 655 -47.1% Wood Fuel (MJ) 2050 3158 -54.1% Natural Gas (MJ) 65.5 240 -266% Liquid Propane Gas (MJ) 4.2 66.2 -1476% Diesel (MJ) 50.7 2.52 95.0% Fuel Oil (MJ) 6.45 30.1 -367% Gasoline (MJ) 0 1.05 -757% TOTAL 2622 4153 -58.4% Energy Inputs Canadian Mills US Mills Difference (%) -1600% -1400% -1200% -1000% -800% -600% -400% -200% 0% 200% D if fe re n ce  ( % ) Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     26  Energy inputs of various sources are generally higher in the southeastern US mills. The surveyed US mills have evidently greater input of electricity, wood fuel and natural gas by 47%, 54% and 266% respectively (Kline, 2004). Though consumption of wood fuel is greater in US mills, the difference should be smaller when wood density differences are accounted for (Athena Sustainable Materials Institute, 2008). Use of natural gas is significantly higher in US mills, which is a result of employing RTO (Kline, 2004). 2.4.3 Material Output  Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Table 8: Average material outputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of OSB  Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Figure 16: Average material outputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of OSB OSB (kg) 522 574 -10.0% Co-products (kg) 18.4 32.9 -78.5% Hog fuel (kg) 102 176 -72.8% Wood residue (kg) 7.2 0 100% Wood Waste (kg) 1.9 0.05 97.4% Boiler Ash Waste (kg) 4.2 1.91 54.5% TOTAL 656 786 -19.8% Material Outputs Canadian Mills US Mills Difference (%) OSB (including resins & wax) Co-products Hog Fuel Wood Residue Stockpiled Wood Waste Boiler Ash Waste TOTAL -100% -80% -60% -40% -20% 0% 20% 40% 60% 80% 100% 120% D if fe re n ce  ( % ) Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     27  Quantities of OSB product, co-products and hog fuel production are higher in the US, but "some of this difference is (...) due to raw fibre density differences between the two regions" (Athena Sustainable Materials Institute, 2008). As for boiler ash waste, US mills produce only half of production from Canadian mills. 2.4.4 Emission   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Table 9: Average main air emissions generated in Canadian mills versus US mills for 1 MSF of 3/8-inch of OSB   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Figure 17: Average main air emissions generated in Canadian mills versus US mills for 1 MSF of 3/8- inch of OSB Particulate matter (kg) 0.67 0.46 31.3% VOC (kg) 1.13 2.36 -109% NOx (kg) 0.677 1.49 -120% SOx (kg) 1.35 2.56 -89.6% CO (kg) 1.19 1.47 -23.5% CO2 Biogenic (kg) 261 382 -46.4% CO2 Fossil (kg) 124 241 -95.1% TOTAL 390 631 -62.1% Substances Canadian Mills US Mills Difference (%) -140% -120% -100% -80% -60% -40% -20% 0% 20% 40% D if fe re n ce  ( % ) Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     28   Use of different emission systems in the mills across the continent reflects the difference in air pollutant extraction efficiencies. Emission equipment used by Canadian mills is less efficient and this is displayed by higher particulate matter release (by 32%) in Canada (Kline, 2004). Interestingly, VOC including methane emissions are at least twice as low from Canadian mills, despite the use of RTO in the mills of southeast US. Emissions of NOx and CO, as well as biogenic and fossil CO2 are both lower in Canadian mills, which is a result of consuming less "biomass and thermal fossil fuels" (Athena Sustainable Materials Institute, 2008) in manufacturing.   Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     29  3 Canadian and US Softwood Plywood Study 3.1 Plywood Manufacturing Process The following section provides a brief description of the manufacturing processes and the subsequent emissions involved in the production of OSB.  Source: Smith, G. (2012). WOOD 487. Vancouver,  British Columbia, Canada. Retrieved April 10, 2012 Figure 18: Plywood manufacturing process Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     30  3.1.1 Green process, debarking Upon the arrival of logs to the plywood mill, the green logs are stored in a pond storage or cold deck, where the logs are sprayed with water (US EPA, 1983). After which, the logs are debarked and "cut into specifically sized blocks" (US EPA, 1983). The bark generated is usually used as fuel. By-products generated from debarking are generally too coarse to emit into the atmosphere, although some finer particles such as PM10 (US EPA, 2011) may be emitted during its transportation on conveyor systems (US EPA, 1983). 3.1.2 Green process, log conditioning and veneer peeling Utilizing spray chambers or hot water vats, the logs are conditioned via heat and moisture (US EPA, 1983). The conditioned logs are then cut into veneers with a veneer lathe. Afterwards, with a veneer clipper, the pieces of veneer are "cut to size" (US EPA, 1983). Furthermore, the veneer is sorted based on size, species, grade, heartwood and sapwood (US EPA, 1983). 3.1.3 Veneer drying Through the drying process, the moisture content of green veneers is reduced to its target moisture content ranging approximately between 1% to 15% (US EPA, 2011). There are essentially two types of dryers employed in the industry, longitudinal veneer dryer that "circulates air parallel to the veneer" (US EPA, 1983) and jet dryers that use "direct hot, high velocity air (...) to create (...) a turbulent flow of air" (US EPA, 1983) on the veneer surface. Two types of heat generation are available in veneer dryers, direct-fired or indirect-heated. Direct-fired dryers generate heat through the combustion of "gas or wood" (US EPA, 1983) in a boiler to produce hot gases. For indirect gas dryers, steam coils warm the air circulating on the veneer surface. Alternatively, mills may also employ veneer kilns to dry veneers (US EPA, 1983) as well.  Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     31  Drying is the main process primarily responsible for air emissions. Through the combustion of fossil fuel or wood residue, both PM and PM10 are released into the atmosphere (US EPA, 2011). Two types of organic compounds, condensable and volatile, are also emitted in this process as well (US EPA, 2011). When these condensable compounds cool after its emission, it combines "with water vapor to form aerosols [that] can cause blue haze" (US EPA, 2011). 3.1.4 Veneer layup and pressing Through resin applicators such as curtain coaters or roll spreaders, the commonly used phenol formaldehyde (exterior applications) and urea-formaldehyde (interior applications) resins are spread along one side of a veneer (US EPA, 2011). Depending on the end product, the three or five veneers will be symmetrically and grain alternating laid into one panel before it's sent to the hot press. Pressing temperatures typically range between 132oC and 165oC for softwood plywood and 107oC and 135oC for hardwood plywood (US EPA, 2011). These high pressing temperatures are needed to activate the thermosetting resins.  The thermal process taken place is a source of both PM and PM10 and hazardous air pollutant emissions as well (US EPA, 2011). 3.1.5 Finishing Lastly, the panels are trimmed to final dimensions and finished to customer preference. Automated sanders along with pneumatic dust collectors are employed for the finishing process (US EPA, 1983). 3.2 Life Cycle Assessment of Plywood The following is a summary of energy utilization and air emissions released from the manufacturing process of plywood production in Canada. Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     32  3.2.1 System Boundaries Three BC softwood plywood mills that represent "25% of all [Canadian] plants" (Athena Sustainable Materials Institute, 2008) participated in this LCA study. The combined production of these mills is 675 MMSF 3/8" basis of softwood plywood, which is approximately "25% of the industry's annual production" (Athena Sustainable Materials Institute, 2008). The annual production of the participating mills is approximately between "152 to 257 MMSF 3/8-inch basis annually" (Athena Sustainable Materials Institute, 2008).  3.2.2 LCA Results  The following paragraphs display results of environmental impacts generated from the manufacturing of OSB. Total Primary Energy  Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Table 10: Energy Utilization in production of 1 MSF 3/8-inch basis of plywood (Absolute Value) Non-renewable, fossil 408 189 1,649 2,246 Non-renewable, nuclear 3.3 1 7 11 Renewable (SWHG) 2.8 0 500 503 Renewable (biomass) 0.006 0.028 1,713 1,713 Feedstock, fossil 0 0 297 297 Feedstock, biomass 0 0 13,289 13,289 Total Primary Energy 414 190 17,455 18,059 E rgy Source Resource Harvesting (MJ) Resource & Material Transportation (MJ) Manufacturing (MJ) Total (MJ)Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     33   Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Table 11: Energy Utilization in production of 1 MSF 3/8-inch basis of plywood (Percentage)  The entire product of plywood is categorized into three system processes, resource harvesting, resource and material transportation and plywood manufacturing (Athena Sustainable Materials Institute, 2008). Amongst these three unit processes, the manufacturing process is primarily responsible for the overall environmental impact. The total primary energy requirement of the entire production from cradle to gate accumulates to 18 GJ per MSF of plywood (Athena Sustainable Materials Institute, 2008). Although this energy sum includes a significant amount of feedstock energy of 13.6 GJ (75.2%) within the raw material and phenol formaldehyde resin as well, and with this feedstock energy disregarded from the equation, the total energy requirement reduces to 4.5 GJ per MSF. As for fossil feedstock energy, it is entirely used to in the production of phenol formaldehyde resin (Athena Sustainable Materials Institute, 2008). Energy Source Resource Harvesting Resource & Material Transportation OSB Manufacturing Total Non-renewable, fossil 18.2% 8.4% 73.4% 100.0% Non-renewable, nuclear 30.0% 6.4% 63.6% 100.0% Renewable (SWHG) 0.6% 0.0% 99.4% 100.0% Renewable (biomass) 0.0% 0.0% 100.0% 100.0% Feedstock, fossil 0.0% 0.0% 13.2% 100.0% Feedstock, biomass 0.0% 0.0% 100.0% 100.0% Total Primary Energy 2.3% 1.1% 96.7% 100.0%Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     34   Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Figure 19: Energy utilization within OSB manufacturing  As shown in Figure 19, within the 4.5 GJ of manufacturing energy requirement, almost 50% is derived from non-renewable fuel sources. This energy is mainly fossil fuel derived, while the remaining 50% is derived from renewable sources, primarily biomass, thus, with the significantly high utilization of biomass, production of plywood is 49.5% "energy self-sufficient" (Athena Sustainable Materials Institute, 2008).  42.62% 0.18% 12.92% 44.28% Non-renewable, fossil Non-renewable, nuclear Renewable (SWHG) Renewable (biomass)Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     35  Global Warming Potential  Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Table 12: Air emissions generated in the production of 1 MSF 3/8-inch basis of plywood (Absolute Value)   Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Table 13: Air emissions generated in the production of 1 MSF 3/8-inch basis of plywood (Percentage) Acidification (kg SO2) 408 189 1,649 2,246 Eutrophication (kg N) 3.3 0.7 7 11 Smog (kg ethylene) 2.8 0 500 503 Global Warming (kg CO2) 0.006 0.028 1,713 1,713 HH Air- Mobile (kg PM2.5) 0 0 13,289 13,289 Total Emissions 414 190 17,158 17,762 S bstances Resource Harvesting Resource & Material Transportation OSB Manufacturing Total Acidification (kg SO2) 18.17% 8.41% 73.4% 100% Eutrophication (kg N) 30% 6.36% 63.6% 100% Smog (kg ethylene) 0.56% 0% 99.4% 100% Global Warming (kg CO2) 0.0003% 0.0012% 76.3% 100% HH Air- Mobile (kg PM2.5) 0% 0% 100% 100% Total Emissions 2.33% 1.07% 96.6% 100% Sub tances S1: Resource Harvesting S2: Resource & Material S3: OSB Manufacturing TotalSustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     36   Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Figure 20: Emission of CO2 in the production of 1 MSF 3/8-inch basis of plywood  In terms of global warming potential, only human related fossil carbon is considered. For the production of each MSF of plywood, a total of 118.6 kg of CO2 is produced (Athena Sustainable Materials Institute, 2008). The manufacturing process mainly emits the majority of CO2 of up to 66.1%, 78.4 kg, as resource harvesting and transportation processes only contribute 22.2% and 11.6% respectively (Athena Sustainable Materials Institute, 2008).  Carbon Balance Each MSF of a plywood panel has 119 kg of CO2 emitted during production (Athena Sustainable Materials Institute, 2008). This emission is offset by 696 kg of CO2 that is already sequestered within the plywood, resulting to a positive net carbon balance of 577 kg of CO2 (Athena Sustainable Materials Institute, 2008).  21.5 13.5 118.6 0 20 40 60 80 100 120 140 Resource Harvesting Resource & Material Transportation OSB Manufacturing Em iss io n  o f CO2  ( kg ) Stages of OSB Production Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     37  Other Air Emissions   Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Table 14: Acidification, Eutrophication, Smog and Air-Mobile Emissions   Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Figure 21: Acidification, Eutrophication, Smog and Air Mobile Emissions in manufacturing of plywood  Measuring on the basis of SO2 emissions, acidification potential is generally "a function of fossil fuel combustion" (Athena Sustainable Materials Institute, 2008). As shown in table 11 majority of SO2 emissions, 75.6% are released from the combustions taken place within the manufacturing process.  Resource Harvesting Resource & Material Transportation OSB Manufacturing Total Acidification (Kg of SO2) 0.35 0.11 1.43 1.89  Eutrophication (Kg of N) 0.003 0.001 0.003 0.007 Smog (Kg of Ethylene) 0.25 0.08 0.056 0.386 Air-Mobile (Kg of PM2.5) 0.03 0.02 0.13 0.18 75.66% 42.86% 14.51% 72.22% 0% 10% 20% 30% 40% 50% 60% 70% 80% Acidification (SO2)  Eutrophication (N) Smog (Ethylene) Air-Mobile (PM2.5) Em is si o n  ( % ) Substances Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     38  Resource harvesting and manufacturing processes both contribute evenly at 44.3% and 45.9% respectively to the eutrophication impact potential (Athena Sustainable Materials Institute, 2008). This is the result of both fertilization in the forest and fossil fuel emissions in manufacturing (Athena Sustainable Materials Institute, 2008). The total smog impact from producing one MSF of plywood is the emission of 0.89 kg of ethylene (Athena Sustainable Materials Institute, 2008). The majority of this ethylene emission, two- thirds, is released from the manufacturing process, though almost one-third of ethylene emission is contributed from resource harvesting. The overall human health criteria impact is 0.18 kg of particulates at 2.5 micron in diameter (Athena Sustainable Materials Institute, 2008). A significant portion, 72.1%, of PM2.5 is generated in manufacturing, while the process of resource harvesting produces 19.2% and transportation produces 8.8% (Athena Sustainable Materials Institute, 2008).  3.3 Life Cycle Inventory of plywood The following is a summary of energy utilization and air emissions released from the manufacturing process of plywood production in both Pacific Northwest and Southeastern US. 3.3.1 System Boundaries The LCI data presented in the following paragraphs are provided by a survey completed by five plywood manufacturers in the Oregon and Washington states, Northwestern region of US. The combined annual production of the five participating manufacturers 1,233,424 MSF 3/8-inch basis plywood annually, representing 26% of the production from the region and 27% of the entire US plywood production (Wilson, 2004).  Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     39  Another five plywood manufacturers also participated from the states of "Alabama, Georgia, Louisana, Mississippi, Florida, Arkansas, and Texas" (Jim Wilson, 2010), Southern region of US. The combined production of these five manufacturers represents 14% of the plywood production from the Southern region (Jim Wilson, 2010). The total annual production of these participating manufacturers accumulates to 1,383,642 MSF 3/8-inch basis (Jim Wilson, 2010).  3.3.2  LCI Results The following paragraphs display results of environmental impacts generated from the manufacturing of plywood. Total Primary Energy   Source: Jim Wilson, M. P. (2010). Softwood Plywood - Pacific Northwest and Southwest. CORRIM. Table 15: Energy utilization per MSF 3/8-inch basis within softwood plywood manufacturing Wood Fuel 3053 79.9% Natural Gas 177 4.63% Liquid Propane Gas 35.0 0.92% Diesel 53.8 1.41% Electricity 500 13.1% Total Primay Energy 3818 100% Energy Utilization Manufacturing (MJ) PercentageEnergy SourceSustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     40   Source: Jim Wilson, M. P. (2010). Softwood Plywood - Pacific Northwest and Southwest. CORRIM. Figure 22: Energy utilization per MSF 3/8-inch basis within softwood plywood manufacturing (percentage)  The entire plywood manufacturing process in the Northwestern region of US requires a total of 3820 MJ of energy (Jim Wilson, 2010). Shown in Table 15 are the proportions of "electricity, diesel, liquid propane gas, bark-hogged fuel and steam" (Wilson, 2004) utilized in manufacturing. Electricity is a widely used form of energy, accounting to 13.1% of the total manufacturing energy, in every process of plywood manufacturing. Its usage in the operations of manufacturing includes "the debarker, bucker, lathe, pneumatic and mechanical conveying equipment, fans, hydraulic pumps, saws, and a radio- frequency redryer" (Wilson, 2004). Diesel is the next primary source of energy that is mainly used to power "log loaders" (Wilson, 2004) for debarking operations. As for its fossil fuel counterpart, liquid propane gas is only needed in relatively smaller quantities, as it is typically used to operate forklifts (Wilson, 2004).   79.94% 13.10% 4.63% 1.41% 0.92% 2.32% Wood Fuel Electricity Natural Gas Diesel Liquid Propane GasSustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     41  Electricity   Table 16: Utilization of primary energy sources for the generation of electricity in the PNW region  In producing each MSF of 3/8-inch basis plywood, an overall 500 MJ of electricity is consumed in all of the processes of manufacturing (Jim Wilson, 2010). Various fuel sources are utilized to generate electricity in the US Northwestern region, and displayed in Table 15 are the proportions of these fuel sources utilized. Hydro energy is the chief source of energy that accounts to 77.5% of all fuel sources utilized. In addition, impact analysis from the SimaPro software did not reveal any environmental impact related to hydro-generated electricity (Wilson, 2004). Though consumed at much lesser quantity, coal is the next chief source of energy accounting utilization of 7.8%, and non-utility follows at 7.1%. Unlike hydro source, coal combustion contributes "significant impact values" (Wilson, 2004).      Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     42  Electricity allocation PNW electricity allocation along the manufacturing processes  Table 17: PNW electricity allocation along the sub-unit processes of plywood manufacturing for 1 MSF 3/8-inch basis  Source: Jim Wilson, M. P. (2010). Softwood Plywood - Pacific Northwest and Southwest. CORRIM. Figure 23: PNW electricity allocation along the sub-unit processes of plywood manufacturing for 1 MSF 3/8-inch basis (Percentage)  Displayed in Table 16, drying is the primary process in electricity consumption due to the operations to "increase (...) heat and mass transfer rates during drying" (Jim Wilson, 2010). These 0% 5% 10% 15% 20% 25% 30% 35% 40% A llo catio n  Sub-Unit Processes Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     43  operations include the use of "high velocity fans (...) in longitudinal, cross-flow and jet dryers (Jim Wilson, 2010). Each of the remaining sources utilizes about 15% electricity, with exceptions to conditioning, where only 6.9% of electricity is allocated (Jim Wilson, 2010).  Global Warming Potential   Source: Jim Wilson, M. P. (2010). Softwood Plywood - Pacific Northwest and Southwest. CORRIM. Figure 24: CO2 emissions (percentage) per MSF 3/8-inch basis of plywood from sub-unit processes of manufacturing in the PNW region 17.2% 3.9% 0.0% 28.4% 48.5% 2.0% 0.0% 10.5% 0.0% 74.3% 15.2% 0.0% 0% 10% 20% 30% 40% 50% 60% 70% 80% Em iss io n  Sub-unit Processes CO2 (Fossil) CO2 (non-Fossil)Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     44    Source: Jim Wilson, M. P. (2010). Softwood Plywood - Pacific Northwest and Southwest. CORRIM. Figure 25: CO2 emissions (percentage) per MSF 3/8-inch basis of plywood from sub-unit processes of manufacturing in the SE region  In Pacific Northwestern plywood mills, non-fossil fuel associated CO2 emission is almost 6 times greater than emissions of CO2 associated with fossil fuel. Shown in table 16 proportions of non-fossil fuel CO2 emissions are greatest at almost 75% in the veneer drying process. Combustion of hogged fuel that consists of bark produced from debarking, wood residues created from various manufacturing processes and "some purchased hogged fuel" (Jim Wilson, 2010), is the source of non-fossil fuel CO2 emissions. Along with non-fossil fuel CO2 emissions, almost 30% of fossil fuel C02 is emitted during drying as natural gas is also combusted as well.  This large scale of fuel consumption makes veneer drying the process releasing almost 70% of CO2 emissions.  9.3% 4.7% 3.9% 42.2% 35.1% 4.9% 0.0% 10.9% 0.0% 74.0% 15.1% 0.0% 0% 10% 20% 30% 40% 50% 60% 70% 80% Em iss io n  Sub-unit Processes CO2 (Fossil) CO2 (non-Fossil)Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     45  As for the mills in the Southern US region, similar CO2 emission trend is also evident. However, there are exceptions to the quantity of emission as Southern mills release greater amounts of CO2. Southern mills release 56.5 kg and 34.3 kg of non-fossil fuel and fossil fuel associated CO2 emissions than mills from of PNW, a result of higher wood waste and natural gas consumption in the Southern mills (Jim Wilson, 2010). Veneer drying and pressing processes are also the primary sources of CO2 emissions. Carbon Balance   Source: Jim Wilson, M. P. (2010). Softwood Plywood - Pacific Northwest and Southwest. CORRIM. Table 18: Carbon input per MSF 3/8-inch basis of plywood produced in the PNW region  Source: Jim Wilson, M. P. (2010). Softwood Plywood - Pacific Northwest and Southwest. CORRIM. Table 19: Carbon output per MSF 3/8-inch basis of plywood produced in the PNW region Raw Materials Carbon % Carbon (kg) Percentage Round wood 51.2 415 93.2% Bark 51.2 23 5.16% Purchased Dry veneer 51.2 1.50 0.34% Green veneer 51.2 3.31 0.74% Hogged fuel 51.2 2.56 0.57% Total 51.2 446 100% PNW Plywood - Inputs Air Emissions Carbon (kg) Percentage HAP 0.033 0.0076% Other 0.14 0.0329% CO 0.38 0.0871% CO2 (biofuel) 35.2 8.14% Particulates 0.087 0.0201% PM 10 0.052 0.0120% VOC 0.30 0.0702% Soliid Output Plywood 218 50.4% Co-products 176 40.6% Waste 2.76 0.64% TOTAL 432 100% PNW Plywood - OutputsSustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     46    Source: Jim Wilson, M. P. (2010). Softwood Plywood - Pacific Northwest and Southwest. CORRIM. Table 20: Carbon input per MSF 3/8-inch basis of plywood produced in the SE region   Source: Jim Wilson, M. P. (2010). Softwood Plywood - Pacific Northwest and Southwest. CORRIM. Table 21: Carbon output per MSF 3/8-inch basis of plywood produced in the SE region  The 2010 LCI plywood report on PNW and SE region mills does not provide carbon balance data, therefore, the data from 2004 LCI plywood report are used for analysis instead. However, the 2004 LCI report only reported the carbon data for hogged fuel, other sources of fuel, resins and waxes utilization are not provided. This section is written with the assumption that only hogged fuel is used for manufacturing of plywood both in the PNW and SE regions. For every MSF 3/8” basis of plywood panel, Raw Materials Carbon % Carbon (kg) Percentage Round wood 51.2 508 91.7% Bark 51.2 30.2 5.45% Purchased Dry veneer 51.2 1.96 0.35% Green veneer 51.2 2.54 0.46% Hogged fuel 51.2 11.2 2.01% Total 51.2 554 100% SE Plywood - InputsAir Emissions Carbon (kg) Percentage HAP 0.026 0.0046% Other 0.148 0.026% CO 0.558 0.10% CO2 (biofuel) 52.6 9.15% Particulates 0.137 0.024% PM 10 0.026 0.0044% VOC 0.131 0.023% Solid Output Plywood 263 45.7% Co-products 254 44.3% Waste 4.23 0.74% TOTAL 575 100% SE Plywood - OutputsSustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     47  a total of approximately 446 kg of carbon is generated, and 443 kg and 2.56 kg of this cumulative carbon sum are produced from wood raw material and hogged fuel respectively in the PNW mills (Kline, 2004). Up to 50.4% (218 kg) of carbon is sequestered within the plywood product, while the remaining 40.6%, (176kg), resides within various co-products. As for air emissions, biofuel CO2 is the primary source of carbon emission at 8.14%, which is 35.2 kg of carbon (Jim Wilson, 2010). Carbon monoxide and VOC are the next primary sources, releasing 0.9% (0.38 kg) and 0.7% (0.3 kg) of carbon respectively.  In contrast, both carbon inputs and outputs are higher in plywood manufacturing mills from the Southeastern mills. A cumulative carbon sum of 554 kg is required for 1 MSF of plywood (Kline, 2004). Up to 543 kg of carbon from this total is stored in the input of wood materials, while 11.2 kg of carbon is contributed by hogged fuel (Kline, 2004). The plywood product sequesters 263 kg of carbon, 44.9 kg greater than the carbon sequestered within plywood produced from Pacific Northwestern mills, though this difference may be the result of different wood species used (Kline, 2004). Higher masses of carbon are also evident in the co-products, as 254 kg of carbon (44.3%) is stored. Carbon air emissions are greater in the SE mills as well (Kline, 2004). Biofuel carbon dioxide, carbon monoxide and VOC emissions account to 52.6 kg, 0.56 kg and 0.13 kg of carbon released to the atmosphere respectively (Kline, 2004).  Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     48  Other Air Emissions  Source: Jim Wilson, M. P. (2010). Softwood Plywood - Pacific Northwest and Southwest. CORRIM. Table 22: Air emissions per MSF 3/8-inch basis generated from the production of plywood in the PNW region (percentage)  Source: Jim Wilson, M. P. (2010). Softwood Plywood - Pacific Northwest and Southwest. CORRIM. Table 23: Air emissions per MSF 3/8-inch basis generated from the production of plywood in the SE region (percentage) Methane CH4 Plywood pressing and veneer drying are the primary contributors to methane emissions in the Pacific Northwestern mills. The pressing process releases the most methane emissions of 56.88%, while veneer drying releases 30.88% (Jim Wilson, 2010). Higher methane emission within pressing is the result of increased use of natural gas.  CO 1.44% 9.57% 0% 72.09% 16.91% 0% 100% Dust  (PM10) 0% 0% 1.71% 95.33% 0.48% 2.48% 100% Particulates 2.99% 0.90% 2.20% 65.39% 26.55% 1.96% 100% Meth ne (CH4) 3.19% 4.81% 2.27% 30.88% 56.76% 2.09% 100% Nitrogen Oxides 18.48% 4.45% 0.54% 31.83% 44.21% 0.49% 100% SO2 0% 0% 0% 99.49% 0.51% 0% 100% Sox 4.48% 4.81% 1.65% 31.41% 56.18% 1.48% 100% VOC 0% 0% 0% 70.28% 29.72% 0% 100% HAP 0.99% 0.37% 0.0% 26.87% 71.77% 0.0% 100% TOTAL 4.24% 5.59% 0.54% 59% 30% 0.52% 100% Air Emission Debarking Conditioning Peeling and Clipping Veneer Drying Lay-up and Pressing Trimming and Sawing Total CO 0.83% 10.13% 0.07% 71.31% 17.49% 0.16% 100% Dust  (PM10) 0% 0% 4.25% 19.16% 0.12% 76.46% 100% Particulates 2.41% 1.35% 0.87% 19.31% 30.63% 45.42% 100% eth ne ( H4) 5.19 5.93 4.13 35.66 43.89 5.19 100 Nitro en Oxides 11.14% 5.00% 1.49% 35.43% 45.09% 1.85% 100% SO2 0% 0% 0% 99.34% 0.66% 0% 100% Sox 5.28% 0% 3.54% 38.39% 48.31% 4.47% 100% VOC 0% 0% 0% 23.31% 76.69% 0% 100% HAP 0.83% 0.62% 0.001% 4.93% 93.62% 0% 100% TOTAL 3.47% 6.03% 1.10% 50.3% 33.1% 6.03% 100% Lay-up and Pressing Trimming and Sawing TotalAir Emission Debarking Conditioning Peeling and Clipping Veneer DryingSustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     49  In comparison, Southern mills release almost double the methane emissions produced from Pacific Northwestern mills. Increased methane emissions are the result of higher natural gas consumption in every manufacturing process, especially within plywood pressing, where natural gas consumption is 50% higher in Southern mills than in PNW mills (Jim Wilson, 2010). Nitrogen Oxides Nitrogen oxide emissions are higher in pressing than in veneer drying. The pressing process contributes 44.2% of NOX emissions, whereas drying contributes 30.9% of the emission (Jim Wilson, 2010).  Southern mills produce higher nitrogen oxide emissions than mills of PNW by 30% due to increased combustion of natural gas (Jim Wilson, 2010). SO2, VOC, CO and Particulates The veneer drying process is the chief contributor to the emissions of SO2 and VOC. Though emission of S02 is mainly higher with the combustion of natural gas (Jim Wilson, 2010), it is highest in the drying process at 99.49%, while the remaining 0.51% of SO2 emission is released from pressing. As for VOC, CO and particulate emissions, 70%, 72% and 65% are released from the veneer drying process respectively.  In comparison to emissions of CO and particulates from Southern mills, PNW mills have lower emissions at approximately 29% and 31% respectively. However, SO2 and VOC emissions much greater in PNW mills than in Sothern mills, as displayed in table 17.   Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     50  Emission Control Though emission control values are not provided in the LCI study, the typical emission control systems employed in plywood mills are identified in the following paragraphs. PM emissions Emission systems used to remove particulate emissions generated during veneer drying are absorption systems, electrified filter beds, wet electrostatic precipitators and oxidation systems (US EPA, 2011). VOC emissions Either regenerative thermal oxidizers or regenerative catalytic oxidizers are used to control VOC emissions from veneer drying (US EPA, 2011).  3.4 Contrast between Canadian and US mills 3.4.1 Material Input   Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Table 24: Average material inputs in Canadian mills versus US mills for 1 MSF 3/8-inch of plywood Roundwood (kg) 749 813 -8.56% Purchased veneer (kg) 16 9.34 41.7% PF Resin (kg) 10.9 7.21 33.9% Catalyst, extenders, fillers (kg) 3.58 4.55 -27.1% Water (L) 364 426 -17.1% TOTAL 1143 1260 -10.2% Material Inputs Canadian Mills US Mills Difference (%)Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     51   Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Figure 26: Average material inputs in Canadian mills versus US mills for 1 MSF of 3/8 inch of plywood  Information is provided by the Athena report in 2008, therefore the 2004 CORRIM report is used for this comparison. Canadian plywood mills generally have higher material inputs than their US counterpart. Purchased veneer and PF resin are the noticeably higher inputs at 42% and 34% difference respectively (Athena Sustainable Materials Institute, 2008). Roundwood input is also higher in Canadian mills, though the difference is very small at 5% (Athena Sustainable Materials Institute, 2008). As for catalyst, extenders and fillers and as well as water, US mills utilized much greater inputs at a difference of 27% and 17% respectively (Athena Sustainable Materials Institute, 2008).      -40% -30% -20% -10% 0% 10% 20% 30% 40% 50% D if fe re n ce  ( % ) Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     52  3.4.2 Energy Input   Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Table 25: Average energy inputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of softwood plyood   Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Figure 27: Average energy inputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of softwood plywood  Overall energy inputs are lower in Canadian mills. Electricity, wood fuel and diesel inputs are all lower in Canadian mills, though the diesel input difference is very small. Natural gas input, however, is Electricity (MJ) 440 500 -13.7% Wood Fuel (MJ) 1535 1701 -10.8% Natural Gas (MJ) 496 123 75.3% Liquid Propane Gas (MJ) 7.9 33.6 -325% Diesel (MJ) 52.5 53.9 -2.74% Gasoline (MJ) 1.05 0 100% TOTAL 2532 2412 4.77% Energy Inputs Canadian Mills US Mills Difference (%) -350% -300% -250% -200% -150% -100% -50% 0% 50% 100% 150% D if fe re n ce  ( % ) Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     53  substantialy greater in Canadian mills due to the on-site heat requirements of their thermal processes (Athena Sustainable Materials Institute, 2008). 3.4.3 Material Output   Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Table 26: Average material outputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of softwood plywood  Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Figure 28: Average material outputs in Canadian mills versus US mills for 1 MSF of 3/8-inch of softwood plywood  Both plywood products and co-products output are higher in US mills, although "some of this difference is due to raw fibre density differences between the two regions" (Athena Sustainable Plywood (kg) 392 450 -14.6% Co-products (kg) 277 350 -26.3% Wood residue (kg) 19.9 0 100% TOTAL 689 799 -16% Material Outputs Canadian Mills US Mills Difference (%) -100% -80% -60% -40% -20% 0% 20% 40% 60% 80% 100% 120% D if fe re n ce  ( % ) Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     54  Materials Institute, 2008). While Canadian mills produce 19.9 kg of wood residue, their US counterparts do not produce them at all.  3.4.4 Emission   Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Table 27: Average main air emissions generated in Canadian mills versus US mills for 1 MSF of 3/8-inch of softwood plywood   Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Figure 29: Average main air emissions generated in Canadian mills versus US mills for 1 MSF of 3/8- inch of softwood plywood Particulate matter (kg) 0.199 0.562 -182% VOC (kg) 0.696 0.594 14.7% NOx (kg) 0.572 0.577 -0.87% SOx (kg) 1.2 0.941 21.6% CO (kg) 3.5 1.846 47.3% CO2 Biogenic (kg) 135 253 -87.8% CO2 Fossil (kg) 89.9 69.1 23.2% TOTAL 231 327 -41.5% Substances Canadian Mills US Mills Difference (%) -200% -150% -100% -50% 0% 50% 100% D if fe re n ce  ( % ) Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     55   Because actual emission control systems employed in US mills are not provided in the LCI report, inferences cannot be made on emission differences between mills of Canada and US. Particulate matter emission is significantly lower in Canadian mills at a difference of 182% (Athena Sustainable Materials Institute, 2008). Volatile organic compound, SO2 and as well as CO emissions are higher in Canadian mills than in US mills at 15%, 22% and 47% respectively (Athena Sustainable Materials Institute, 2008). On the contrary, NOx emissions are lower, which may be the result of lower usage of biomass fuel in the manufacturing process of Canadian mills. Biogenic CO2 emission is lower in Canadian mills by 88% (Athena Sustainable Materials Institute, 2008). However, fossil CO2 emission is higher at 23% for Canadian mills (Athena Sustainable Materials Institute, 2008). This is due to the increased use of natural gas and lower use of hog fuel in thermal processes of Canadian mills (Athena Sustainable Materials Institute, 2008), although this may also be the result of a natural gas intensive Canadian mill that swayed the average (Athena Sustainable Materials Institute, 2008). 4 Analysis 4.1 Structural Panel Comparison   Sources: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Oriented Strand Board. Ottawa, Ontario: Athena Institute. Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     56  Table 28: Sustainability comparison between OSB and softwood plywood for 1 MSF 3/8-inch basis  4.1.1 Energy  Sources: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Oriented Strand Board. Ottawa, Ontario: Athena Institute. Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Figure 30: Comparison of energy utiliztion between OSB and softwood plywood for 1 MSF 3/8-inch basis   As displayed in Figure 30, the overall energy utilization in the manufacturing of OSB is greater than that of plywood. The contrast in energy utilization between OSB and plywood manufactured in Canada is relatively minor with approximately 90 MJ (3.4%) difference. On the contrary, the difference in energy utilization between US manufactured OSB and plywood is much more significant at approximately 1740 MJ (42%) greater in the manufacture of OSB.  0 500 1000 1500 2000 2500 3000 3500 4000 4500 Canada US Canada US En e rg y (M J)  Structural Panel Products OSB Plywood Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     57  4.1.2  Greenhouse Gases  Sources: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Oriented Strand Board. Ottawa, Ontario: Athena Institute. Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Figure 31: Comparison of CO2 emissions between OSB and softwood plywood for 1 MSF 3/8-inch basis  Shown in Figure 31, the manufacturing of OSB generates greater quantities of greenhouse gas emissions than the manufacturing of plywood. Although the CO2 generated in the Canadian manufacturing of OSB is relatively greater than the CO2 generated from plywood manufacturing at about 160 kg (42%), this difference is relatively insignificant in comparison to the difference of CO2 generated between US manufactured OSB and plywood. The CO2 produced from US manufactured OSB is 300 kg (48%) greater than the carbon dioxide produced from the manufacturing of plywood in US. 0 100 200 300 400 500 600 700 Canada US Canada US M ass ( kg ) Structural Panel Products Greenhouse Gases (CO2) OSB Plywood Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     58  4.1.3 Other air emissions  Sources: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Oriented Strand Board. Ottawa, Ontario: Athena Institute. Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Figure 32: Comparison of SOx, NOx, VOC and particulate matter emissions between OSB and softwood plywood for 1 MSF 3/8-inch basis  Emission of SOx Release of SOx emissions is higher in the manufacture of OSB than plywood, as displayed in Figure 32. The difference between US manufactured OSB and plywood is significantly greater than the difference between Canadian panel products. The Canadian manufacturing of OSB releases 0.15 kg (11%) more SOx emissions than that of plywood, whereas, US manufactured OSB releases 1.62 kg (63%) more than the manufacturing of plywood. 0 0.5 1 1.5 2 2.5 3 Sox Nox VOC Particulat Matter M as s (k g)  Air Emission Substances Canada US Canada US OSB OSB OSB OSB Plywood Plywood Plywood Plywood Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     59  Emission of NOx  From Figure 32, emissions of NOx are generally higher in the manufacturing of OSB than plywood. For Canadian panel products, the manufacture of OSB releases slightly more NOx emissions than the manufacture of plywood by approximately 0.11 kg (16%). As for US panel products, the NOx emission difference is much greater with the manufacture of OSB releasing 0.913 kg (61%) more than the manufacturing of plywood. Emission of VOC  As displayed in Figure 32, the manufacturing of OSB releases higher volatile organic compound emissions than that of plywood. VOC emissions are greater in the manufacture of OSB than plywood by 0.434 kg (38%) for Canadian panel products. In contrast, for US panel products, the VOC emission difference is considerably greater in the manufacture of OSB than plywood by 1.77 kg (75%). Emission of Particulate Matter  From Figure 32, the overall release of total particulate matter is greater in the manufacture of OSB than plywood. Specifically speculating Canadian panel products, manufacturing of OSB emits higher particulate matter than the manufacture of plywood by a significant difference of 0.471 kg (70%). However, in the US panel products, PM emissions released from the manufacture of OSB is lower than that of plywood by 0.10 kg (22%).   Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     60  4.1 Emission Control System 4.1.1 Oriented Strand Board 4.1.2 Emission Control Systems Utilized in US  Source: Wilson, J. B. (2004). Softwood Plywood Manufacturing. Corvallis: CORRIM. Figure 33: Combined on-site and off-site emissions produced in the manufacturing of 1 MSF 3/8-inch basis of OSB  The four southeastern plants participating in this study mainly employed two types of emission control systems, two plants used wet or dry Electro-Static Precipitator, ESP, and the other two used Regenerative Thermal Oxidizers, RTO (Kline, 2004). Figure 29 above displays the comparison between the results of air emissions in both on-site and off-site scenarios for each of the emission control systems. RTO is shown to be more effective than ESP at removing emissions of particulate, CO, and VOC by "34.1%, 75.8% and 57.9%" (Kline, 2004) respectively. On the contrary, the efficiency of RTO is countered by its increase of greenhouse gas emissions due to its utilization of natural gas. As a result, Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     61  RTO has much greater "biomass CO2, fossil fuelCO2, SOX, NOX and methane emissions" than its counterpart by "4.0%, 24.7%, 36%, 16.7% and 26.2%" (Kline, 2004) respectively.  4.1.3 Emission Control Systems used in Canadian and US mills Though the manufacturing process is the same, Canadian and US OSB mills typically employ different dust extraction systems. In Canadian mills, "electrified filter bed, Wet Electrostatic Precipitator, baghouse, multicyclone and dust collection" (Athena Sustainable Materials Institute, 2008) systems are used to remove particulates created in the manufacturing process. Conversely, US mills employ regenerative thermal oxidizers to extract particulates, CO and volatile organic compounds, and wet and dry Electrostatic Precipitator to collect particulates (Athena Sustainable Materials Institute, 2008). The use of different systems in mills of both countries leads to different extraction efficiency, as well as different energy utilization. With the use of RTO, Southeastern US mills have higher demand for energy in the form of fossil fuels, wood, purchased electricity, and natural gas (Athena Sustainable Materials Institute, 2008). In contrast, Canadian OSB mills consume less energy with 45% lower in electricity purchase, 73% lower in biomass fuel consumption and 2.5 times lower in the usage of natural gas (Athena Sustainable Materials Institute, 2008). However, lower energy consumption in Canadian mills came with the compromise of air emissions. On average, Canadian mills have 32% higher release of particulates than their US counterparts (Athena Sustainable Materials Institute, 2008). Fortunately, other air emissions are not compromised as the release of methane and VOC is 2 times lower and emissions of NOx and CO are lower than US mills, which may be the result of lower consumption of "biomass and thermal fossil fuel" (Athena Sustainable Materials Institute, 2008) in the manufacturing process in Canadian mills. There are 46% and 95% lower releases of biogenic and fossil fuel carbon Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     62  dioxide respectively from the lower usage of "biomass and fossil fuels in the manufacturing combustion process" (Athena Sustainable Materials Institute, 2008) in Canadian mills.  4.1.2 Softwood Plywood 4.2.1 Emission controls reported by the US EPA Stated in the US EPA report, the commonly employed VOC control system is the regenerative thermal oxidizer, but regenerative catalytic oxidizers are also used as well (US EPA, 2011). In an RTO, the temperature of preheated emissions is increased to a range between 778OC and 871OC (US EPA, 2011). This incineration process takes place in a "combustion chamber with sufficient gas residence time to complete the combustion" (US EPA, 2011).  Although both RCOs and RTOs remove VOCs in similar fashion, RCOs have catalytic media in the heat recovery beds (US EPA, 2011). The catalyst in the catalytic media increases the "rate of VOC oxidation" (US EPA, 2011). With the rate of oxidation increased, VOCs can be destroyed in temperatures lower than that of RTOs, "typically between 315 OC and 538OC" (US EPA, 2011). As a result, fuel consumption is also reduced.  4.2.2 Emission Control Systems used in Canada and US Canadian plywood mills typically use a wet or dry ESP, multicyclone, and round and square bag house. Emission systems are not discussed in US reports, therefore brief inferences are only drawn on emission control systems reported in the US EPA report on emission factors in plywood manufacturing.   Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     63  5 Recommendation 5.1 Sustainable Structural Panel Product In comparing the LCI profiles of both Canadian and US produced OSB and plywood products, manufacturing of the latter structural panel product from both regions is considerably more sustainable. Displayed in Table 28 are the major differences in energy utilization and air pollutant emissions of SOx, NOx, VOC and particulate matter generated in the manufacture of both panel products. Though the energy difference between the Canadian panel products is relatively minor, the energy utilized in the manufacture of OSB and plywood in the US differs by a significant amount of 1740 MJ. In addition, emissions of SOx, NOx and VOC are lower in the manufacture of plywood than OSB. The magnitude of these emissions differences is especially significant between the structural panel products manufactured in US with the manufacture of plywood releasing 1.62 kg, 0.913 kg and 1.77 kg less respectively. As for the emissions of particulate matter in the US manufacture of panel products, the manufacturing of plywood releases more PM emissions than the manufacturing of OSB. However, the opposite occurs in the Canadian manufacture of panel products, as the manufacture of plywood produces less PM emissions by 0.471 kg.   Source: Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute.  Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Ottawa: Athena Institute. Table 29: Comparison of average output between Canadian and US softwood plywood manufacturing for 1 MSF 3/8-inch basis  Mass (kg) Percentage Mass (kg) Percentage Plywood 379 49.8% 482 25.2% Co-products 383 50.2% 448 23.4% Waste 0 0% 23.4 1.2% TOTAL 762 100% 953 49.8% Average US Plywood Outputs Average Canadian Plywood OutputsProductsSustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     64     Sources: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM.  Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment  of Canadian Oriented Strand Board. Ottawa, Ontario: Athena Institute. Table 30: Comparison of average output between Canadian and US OSB manufacturing for 1 MSF 3/8- inch basis  Aside from lower energy utilization and air emissions, plywood has considerably lower product yield than OSB, which leads to poorer wood fibre utilization in the product (Smith G. , 2012). Displayed in Tables 29 and 30 are the percentages of product yield for both panel products. Amongst the panels manufactured in US, OSB panel yields approximately 29.8% more than plywood, while a similar difference is also evident in the panels manufactured in Canada with OSB yielding approximately 29.6% more than plywood. Though product yield is much lower in the manufacturing of plywood, almost 50% of the solid outputs are generated into co-products across both regions. These co-products include hog fuel, veneer, peeler cores and pulp chips that are sold for profit (Athena 2010). As for wastes, the difference in the amount of waste generated in the manufacturing of both panel products is minor at 0.31% and 0.76% for OSB and plywood respectively.  5.2 Emission Control System Canadian panel mills typically release higher quantities of particulate matter (from OSB manufacturing), VOC, NOx, SOX and CO (from plywood manufacturing) into the atmosphere, whereas US panel mills generally have greater CO2 emissions. Release of particulate matter has a significant impact on human health that can potentially damage "the human respiratory system" (Athena Sustainable Mass (kg) Percentage Mass (kg) Percentage Plywood 498 79.3% 546 37.2% Co-products 127.76 20% 119 17.9% Waste 1.93 0.31% 0 0% TOTAL 627 100.0% 665 100% Average Canadian OSB Outputs Average US OSB OutputsProductsSustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     65  Materials Institute, 2008). The overall impact of the remaining substances is environmentally associated. Volatile organic compound, NOX and CO emissions are contributors to smog, which can also potentially damage the human respiratory system (Athena Sustainable Materials Institute, 2008). As for SOX, high concentrations can lead to aquatic acidification, which impacts human health and fresh water within the affected region (Athena Sustainable Materials Institute, 2008). Lastly, the release of CO2 emission contributes to global warming that contributes to the increase in the average temperature of the Earth and may eventually leads to global climatic changes. Overall, considering the associated environmental and health impacts, the global warming impact from CO2 emission is relatively more gradual than the various impacts caused by VOC, NOX, SOX and CO emissions. Therefore, the impacts on human health criteria, smog and aquatic acidification should be considered before global warming potential. As a result, the removal of VOC, NOx, SOX and CO emissions should be the main concern in the structural panel manufacturing industry. Using of regenerative thermal oxidizers in panel manufacturing mills is theoretically preferable in removing VOC, NOx, SOX and CO emissions. Thermal oxidizers can "destroy VOCs and condensable organics by burning them at high temperatures" (US EPA, 2011), thus having the ability to achieve VOC removal efficiency of 99% (McFarlane, 2012). In addition, thermal oxidizers also lower CO emission via the process of complete combustion by oxidizing CO to CO2 in the "direct fired dryer exhausts" (US EPA, 2011). However, its counterpart, the regenerative catalytic oxidizer has a significant advantage over the use of RTO. The RCO generally functions in similar fashion as RTO, but the catalytic media in the heat recovery bed of the RCO increases the VOC oxidation rate, thus enabling the destruction of VOC at lower temperatures of typically between 316OC to 538OC (US EPA, 2011). The lower heat requirement of the RCO allows for reduced fuel utilization, a significant advantage over RTO. Although RCOs still have disadvantages that include "excessive downtime" (McFarlane, 2012) from plugged exchanger beds caused by buildup of residual ash, "higher maintenance cost" (McFarlane, 2012) from rapid Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     66  deterioration of the catalyst and relatively higher CO2 emission from increased fuel utilization, the latter disadvantage can be compensated with an emission trading legislature. An "economically efficient allocation mechanism" (McFarlane, 2012), emission trading can help redirect the available capital of panel manufacturers "towards more efficient projects via a market price for emissions" (McFarlane, 2012). Even though there is "difficulty in attaining uniform performance" (McFarlane, 2012) with RCO, the use of regenerative catalytic oxidizer in combination with the emission trading legislature is theoretically preferable. 6 Conclusion The influential trend of sustainable construction will indeed continue to change and innovate in single family homes from the overall design to the construction practice and choice of material. Even though, OSB and softwood plywood products are decreasing in demand since 2006, nevertheless these are essential products used as sheathing material and web of I-joist, which shall help increase the demand of OSB and softwood plywood with the growth of sustainable construction. Although the manufacturing of these products has utilized great amounts of hogged fuel and wood residue to improve carbon balance, there still are volatile and particulate emissions released from the manufacturing process. Aside from carbon dioxide, emissions of VOC, NOx, SOX, CO and particulates are the primary air pollutants mainly released from the processes of drying and pressing in the manufacturing of both structural panel products. Particulates specifically impact human health, while the remaining substances impact both health and the environment.  When contrasting OSB with plywood on the basis of sustainability, plywood is a more sustainable structural panel product between the two. Throughout the entire manufacturing process in Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     67  Canada and as well as in the US, production of plywood utilizes lower energy and generates fewer air pollutant emissions of CO2, SOx, NOx, VOC and particulate matter. Structural panel mills of both regions typically employ different emission control systems. Canadian mills mainly employ wet or dry electrostatic precipitators, multicyclones, round and square bag houses, electrified filter beds and dust collection equipments (Athena Sustainable Materials Institute, 2008), whereas US mills generally use regenerative thermal oxidizers and wet and dry electrostatic precipitators (Athena Sustainable Materials Institute, 2008). Overall, the systems used in the Canadian panel manufacturing mills are less efficient in removing air pollutants and produces lower CO2 emission. Conversely, the emission systems used in the US mills are significantly more efficient at air pollutant removal, but produce higher CO2 emission. Closely comparing the various emission control systems employed over the two regions, the combination of using regenerative catalytic oxidizer and emission trading legislature is theoretically preferable to lower the overall environmental impact generated from the OSB and softwood plywood manufacturing processes. In a world competing for sustainability, reducing environmental impacts of OSB and plywood will likely aid the Canadian panel manufacturers in gaining North American market shares of structural panels.   Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     68  7 Appendix   Source: Kline, D. E. (2004). Southeastern Orieted Strandboard Production.  Virginia Polytechnic Institute and State University. Blacksburg: CORRIM. Table 31: Air emissions (per MSF 3/8-inch basis) generated  from the manufacture of OSB on-site and off-site in the SE region      kg kg kg kg kg CO 1.44 0.0011 0.0004 0.0142 1.46 CO2 (Fossil) 225 1.7 0.939 1.66 229 CO2 (biomass) 375 2.83 0 3.94 381 CO2 (non-fossil) 0.0889 0.0007 0.0004 0.0006 0.091 CO2 11.6 0.088 0 0 11.7 Dust  (PM10) 0.304 0.002 0.0002 0.0034 0.310 Particulates 0.132 0.001 0.0009 0.0011 0.135 Meth ne (CH4) 0.626 0.005 0.002 0.0037 0.636 NOx 1.47 0.011 0.0036 0.0082 1.49 SO2 0.108 0.0008 0 0.0003 0.109 SOx 2.52 0.019 0.007 0.0156 2.56 VOC 0.975 0.073 0 0.0112 1.06 HAP 0.605 0.003 1.77E-06 0.0037 0.611 TOTAL 619 4.74 0.9534117 5.65 631 Total Substance OSB Dust Scrap Bark Screen FinesSustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     69   Source: Jim Wilson, M. P. (2010). Softwood Plywood - Pacific Northwest and Southwest. CORRIM. Table 32: Air emissions (per MSF 3/8-inch basis) generated  from the manufacture of softwood plywood in the PNW region     Source: Jim Wilson, M. P. (2010). Softwood Plywood - Pacific Northwest and Southwest. CORRIM. Table 33: Air emissions (per MSF 3/8-inch basis) generated  from the manufacture of softwood plywood in the SE region    kg kg kg kg kg kg kg CO 0.0196 0.131 0 0.984 0.231 0 1.37 CO2 (Fossil) 5.13 1.17 0.000644 8.48 14.5 0.594 29.8 CO2 (non-Fossil) 0.00129 19.8 0 140 28.6 0 188 Dust  (PM10) 0 0 0.00218 0.121 0.00060781 0.00315 0.127 Particulates 0.00685 0.00206 0.00503 0.15 0.0608 0.0045 0.229 Methane (CH4) 0.00205024 0.00309 0.00146 0.0199 0.0365 0.00135 0.0643 Nitroge  Oxides 0.0866 0.0209 0.00252 0.149 0.207 0.0023 0.469 SO2 0 0 0 0.000476 2.4313E-06 0 0.000479 Sox 0.015 0.0161 0.00553 0.105 0.188 0.00494 0.335 VOC 0 0 0 0.27 0.114 0 0.385 HAP 0.00124 0.000465 7.67E-09 0.0336 0.0899 6.76E-09 0.125 TOTAL 5.26 21.2 0.0174 150 44 0.61 221 Substance Debarking Conditioning Peeling and Clipping Veneer Drying Lay-up and Pressing Trimming and Sawing Total lb lb lb lb lb lb CO 0.0146 0. 78 0. 012 1.2 .307 0. 029 1.76 CO2 (Fossil) 5.94 3.01 2.48 27.1 22.5 3.13 64.1 CO2 (non-Fossil) 0. 018 26.7 0 181 36. 0 24 Dust  (PM10) 0 0 0.0021 0.0095 0.0001 0.0378 0.0495 Particulates 0.0073 0.0041 0.0026 0.0581 0.0921 0.137 0.3 Methane (CH4) 0.0064 0.0073 0.0051 0.0442 0.0544 0.0064 0.124 Nitrogen Oxides 0.068 0.0305 0.0091 0.216 0.275 0.0113 0.611 SO2 0 0 0 3.72E-05 2.46E-07 0 3.74E-05 Sox 0.0297 0 0.0199 0.216 0.272 0.0251 0.562 VOC 0 0 0 0.0345 0.113 0 0.148 HAP 0.0008 0.0006 6.38E-07 0.005 0.0953 0 0.102 TOTAL 6.07 29.9 2.52 210 60.6 3.35 312 Substa ce Debarking Conditioning Peeling and Clipping Veneer Drying Lay-up and Pressing Trimming and Sawing TotalSustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     70  8 Bibliography Andre, L. (2011, August 8). Wood-Frame Promoters Suffer Defeat in Oregon but Vow to Regroup. Retrieved from http://www.armca.net/FW_%20Just%20in.pdf Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Oriented Strand Board. Retrieved Febuary 2012, from http://www.athenasmi.ca/publications/docs/CIPEC_Canadian_OSB_LCA_final_report.pdf Athena Sustainable Materials Institute. (2009). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Lumber. Retrieved from http://www.athenasmi.org/publications/docs/CIPEC_Lumber_LCA_Final_Report.pdf Athena Sustainable Materials Institute. (2008). A Cradle-to-Gate Life Cycle Assessment of Canadian Softwood Plywood Sheathing. Retrieved from http://www.athenasmi.ca/publications/docs/CIPEC_Canadian_Plywood_LCA_Final_Report.pdf Ellis, S. (2010). Engineered Wood Products. Vancouver, British Columbia, Canada. Ellis, S. (2011). Oriented Strandboard. Vancouver, British Columbia, Canada. Energy, U. D. (2000). Energy Information Admin. State Electric Profiles 2000 . DC, Washington, United States of America. Retrieved from www.eia.doe.gov/cneaf/electricity/st_profiles/toc.html Ferrari, C. (2000). Life Cycle Assessment: Environmental modeling of plywood and laminated veneer lumber manufacturing.  Holt, T. (2011, April 11). Putting wood (naturally) back in Oregon's future. Retrieved March 30, 2012, from Oregon Live: http://www.oregonlive.com/opinion/index.ssf/2011/04/putting_wood_naturally_back_in.html Jim Wilson, M. P. (2010). Softwood Plywood - Pacific Northwest and Southwest. Retrieved from http://www.corrim.org/pubs/reports/2010/phase1_interim/05_Appendix_D.pdf Kline, D. E. (2004). Southeastern Orieted Strandboard Production. Retrieved from http://www.corrim.org/pubs/reports/2005/phase1/Module_E_Final.pdf McFarlane, P. (2012). Air Pollution Management Options. Vancouver, British Columbia, Canada. Moldvay, C. (2011). Prefabricated Home Manufacturing in the US. Retrieved from http://clients.ibisworld.com/industryus/default.aspx?indid=1105 NCASI. (1999). Volatile organic compound emissions from wood products manufacturing facilities, Part V - Oriented Strandboard. Research Triangle Park: National Council for Air and Stream Improvement, Inc. Sustainability Assessment of OSB and Softwood Plywood Manufacturing in North America     71  Poon, J. (2010). Wood Market Statistics Canada. Retrieved from http://www.fpinnovations.ca/pdfs/2010-WMS_CAN.pdf Smith, G. (2012). WOOD 487. Vancouver, British Columbia, Canada. Retrieved April 10, 2012 Smith, K. T. (2009). North American Oriented Strand Board Industry Review. Retrieved from http://digitalcollection.gov.mb.ca/awweb/pdfopener?smd=1&did=17133&md=1 Smith, M. (2009). North American Oriented Strand Board Industry Review. Retrieved from http://www.epa.gov/ttn/chief/ap42/ch10/final/c10s05.pdf US EPA. (2011, September 2). AP 42, Fifth Edition, Volume 1 Chapter 10: Wood Products Industry. Retrieved from Technology Transfer Network Clearinghouse for Inventories & Emissions Factors: http://www.epa.gov/ttnchie1/ap42/ch10/index.html US EPA. (1983). Control Techniques for Organic Emissions from Plywood Veneer Dryers. Retrieved from http://www.epa.gov/ttnnaaqs/ozone/ctg_act/198305_voc_epa450_3-83-012_plywood_dryers.pdf Wilson, J. B. (2004). Softwood Plywood Manufacturing. Corvallis: CORRIM.  

Cite

Citation Scheme:

    

Usage Statistics

Country Views Downloads
Canada 7 2
China 4 0
United States 4 0
India 1 0
Austria 1 0
City Views Downloads
Shenzhen 4 0
Unknown 4 1
Walnut 2 0
Vancouver 2 0
Ashburn 2 0
Vienna 1 0
Quesnel 1 0
Pilani 1 0

{[{ mDataHeader[type] }]} {[{ month[type] }]} {[{ tData[type] }]}
Download Stats

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.52966.1-0103136/manifest

Comment

Related Items