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Sustainble solar energy kiln to dry eucalyptus in Peru Alvarez, Mónica Apr 1, 2009

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 SUSTAINBLE SOLAR ENERGY KILN TO DRY EUCALYPTUS IN PERU      MÓNICA ALVAREZ    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     THE UNIVERSITY OF BRITISH COLUMBIA     April 2009   ii Abstract  The purpose of this report is to evaluate the suitability of producing value added products from eucalypts in Peru.  Information from FAO and INRENA was used to analyse the potential that Peru has to plant, grow and produce good quality eucalyptus wood.  The opportunities for eucalyptus wood in the market appear to be favourable especially for furniture and other interior products. While searching for sustainable solutions to process eucalypts to enhance the Peruvian wood industry, some problems were found during the manufacturing of this genus.  The main problems during the processing of eucalypts occur during the drying process.  Drying of eucalyptus requires care due to the tendency its wood cells have to collapse, which causes excessive shrinkage and fibre separation or checks. Eucalyptus wood needs to dry at low temperatures and in a high relative humidity environment at least during the first stages of the process.  The drying of eucalyptus has been a challenge, and research has been done around the world to find the optimal method according to the needs and resources of the individual countries.  Countries such as Australia, Argentina, and Brazil, have done studies to find the best trees, growing rates and drying methods to minimize the defects on the wood at the desired final moisture content.  Recently there has been an increasing interest in using solar kilns to dry eucalyptus especially in developing countries.  The drying of eucalyptus using a solar energy kiln in Peru can be the best alternative.  The solar kiln for hardwoods designed by Dieter Steinmann in 2006 seems to be a good fit for the Peruvian Industry.  Not only are the initial investment for construction prices low, but also the need for expertise and supervision during its performance is minimal. Many locations in Peru satisfy the environmental requirements that this kiln needs to be able to execute.  Key words:  Eucalypts, drying, solar kiln, moisture content, value added wood products        iii   Table of contents  SUSTAINBLE SOLAR ENERGY KILN TO DRY EUCALYPTUS IN PERU ................ i Abstract .................................................................................................................................... ii Table of contents .................................................................................................................... iii List of Tables .......................................................................................................................... iv List of Figures .......................................................................................................................... v Introduction ............................................................................................................................. 1 Peru and Eucalyptus ............................................................................................................... 1 Utilization of Eucalyptus ........................................................................................................ 5 Drying Eucalyptus wood ........................................................................................................ 7 Steinmann’s Solar Energy Kiln Design .............................................................................. 10 Steinmann Kiln ................................................................................................................... 11 Parts..................................................................................................................................... 13 Operation............................................................................................................................. 14 Advantages and Disadvantages ........................................................................................... 14 Conclusions ............................................................................................................................ 16 Literature Cited .................................................................................................................... 17 Appendices ............................................................................................................................. 19        iv List of Tables  Table 1.  Peruvian Forest and other wooded land  .................................................................... 2 Table 2.  Drying costs for spotted gum and blackbutt  ............................................................. 7      v List of Figures  Figure 1.  Front view of Steinmann’s Solar Energy Kiln  ...................................................... 11    1 Introduction Value added products are the present and the future for obtaining the major economic value from logs.  The Peruvian forest land is an asset with the potential to increase the economic growth of the country.  The heterogeneity of the native forests and the low investment in technology complicate harvesting and management plans limiting the traditional Peruvian wood industry to small scale production companies (FAO, 2008).  There is currently increasing interest in establishing plantations for wood production.  The majority of established plantations in Peru are from exotic species such as pine and some eucalyptus species (FAO, 2008).  Therefore, there is also interest in utilizing eucalyptus wood for value added products.  The drying of eucalyptus species however, is difficult and is one of the major concerns when considering its use for manufactured wood products such as furniture, flooring, and engineered products, amongst others.  Low temperatures need to be used when drying eucalyptus to avoid the collapse of wood cells, and this can be achieved with solar drying.  Other methods like air drying or conventional kiln drying can be used to dry Eucalyptus wood; but using solar energy kilns, particularly the design of Steinmann, can be a more economically feasible solution for Peru.  In this essay I will discuss the benefits of utilizing eucalyptus wood in Peru.  I will also present and compare the characteristics of using three different drying methods:  air drying, conventional kiln drying and solar energy kiln drying.  I will argue that choosing Steinmann’s ―Homebuilt Solar Kiln for Hardwoods‖ is the best and most sustainable option for drying eucalyptus in Peru during this early stage.  Peru and Eucalyptus Forest land covers about 53.5% of Peru.  Peru has three natural regions: the coast, the highlands and the jungle.  Peru has more than 1 million hectares of potential forest land in it’s the coastal  2 region.  The mountainous region has an even greater area ―suitable for forest use‖ (FAO, 2007), that has already been planted with exotic pine and eucalyptus species (Eucalyptus globulus, E. viminalis, E. bicostata, E. camaldulensis, and others) (FAO, 2007).  Peru’s forest can be divided into five main categories:  primary, modified natural, semi-natural, productive plantation and protective plantation (see table 1).  Table 1.  Peruvian Forest and other wooded land. (FAO, 2006) FRA 2005 categories Area (1000 hectares) Forest Other wooded land 1990 2000 2005 1990 2000 2005 Primary 62, 910 62, 188 61, 065 - 1, 912 2, 213 Modified Natural 6, 983 6, 310 6, 923 - 20, 220 19, 919 Semi-natural 0 0 0 - - - Productive plantation 263 715 754 - Protective plantation - - - - - - Total 70, 156 69, 213 68, 742 - 22, 132 22, 132  Peru has one of the biggest and richest tropical rainforests in the world with vast biological diversity and natural resources (WWF, 2009).  Due to the heterogeneity and diversity of species found in the Peruvian forest, the harvesting of wood for large scale industry is difficult. Transport within the forest is mainly by water or by air.  These ways of haulage add a constraint when doing business, especially for the wood industry. The majority of the wood manufactured products and the wood furniture produced in Peru are consumed by the national market.  The biggest international market for Peruvian sawnwood is the United States of America (USA),  3 which consumes 74.12% of Peru’s, valued at $83,597,000 in 2006 (FAO, 2009).  The USA is currently mainly interested in wood for construction, but the use of wood for furniture maybe a better use for Peru’s wood because highest value can be extracted from logs especially in the case of custom designs.  The opportunities for using eucalyptus wood to manufacture value added products could be a profitable solution for the Peruvian wood industry.  The comparably higher growth rate of Eucalypts, together with the opportunity to harvest it from homogenous plantation, can facilitate increased focus and efficiency for industry.  Eucalyptus species were introduced to Peru around 1860 (FAO, 2008).  Eucalyptus trees and resources are already a part of many Peruvian communities.  The Eucalyptus genus in the Myrtaceae family is native to Australia and consists of around 700 tree species (Grattapaglia, 2008).  Eucalypts are sources of hardwood, pulp and paper, oils and floral beauty.  Transforming eucalyptus wood into value added products has greater economic potential compared to its use for firewood and round timber.  The quality of the fibre produced in the early stages of tree growth is very suitable for the pulp and paper industry, but the pulp and paper industry requires a big initial and continuous investment that is beyond the means of Peru.  Hence the use of Eucalyptus as sawlogs for value added products maybe a better option for Peru.  It is now a matter of choosing the best genetic material, management and utilization of technologies to get the highest value from eucalyptus in Peru.  Eucalyptus globulus has been the most planted species in Peru (Luzar, 2007).  According to Waugh (1995), E. globulus is unsuitable for round timbers because of its propensity for end- splitting and surface checking during drying.  On the other hand, E .globulus is ―good‖ and ―acceptable‖ for the production of sawn engineering, and appearance products, engineering veneer, fibre composites and pulp and paper products (Waugh, 1995).  Nevertheless there is still  4 a need to develop appropriate technologies to process eucalyptus in developing countries and utilize its sawnwood for value added products.  Eucalypts plantations can be used in short rotations because of their rapid growth, especially in the first 10 to 15 years.   One of the issues with growing Eucalyptus in Peru is that it does not regenerate naturally; each tree needs to be individually planted (FAO, 1998).  The physical and mechanical wood properties of grown Eucalypt trees are controlled not only genetically, but also through the specific management practices and the trees’ environment (Sánchez Acosta, 1999). Research on wood processing and manufacturing techniques cannot be generalized for every Eucalyptus species; experiments and specifications should be done separately to obtain better and more accurate results.  The volumes of wood production by species collected in 2007 by the Instituto Nacional de Recursos Naturales of Peru (INRENA), places eucalypt (Eucalyptus spp) in the first place in the production of round wood with 333 170,36 m³(see Appendix A).  The volume of round wood produced is much greater than the volume of sawnwood, 54 334, 69 m³ (INRENA, 2008). Eucalypt species are used in large quantities by small communities for firewood and also as round timber for posts and power poles.  The economic value that can be obtained from sawmilled eucalyptus species and value added products could greatly exceed the current profits from round timber if appropriate policies and technologies were applied.  To be able to utilize Eucalypt wood, the government and/or the wood industry needs to believe in the benefits of the final products and invest in the necessary technology to produce good quality products in the most efficient way.   5 Utilization of Eucalyptus Conversion of eucalyptus to value added products can be difficult because of problems related to grading, drying, and milling.  One of the major concerns is the drying process (Oliver, 2000), which is necessary when preparing wood for manufacture furniture, flooring and engineered wood products.  Eucalyptus fibres from trees grown in plantations tend to have thin walls, which make the wood very suitable for the pulp and paper industry, but this characteristic is not very helpful for the manufacturing of wood products.  The thin walls suffer collapse if  specific requirements of temperature and humidity during drying are not followed.  The collapse of wood cells causes excessive shrinkage while drying and fibre separation or checks also develop (Oliver, 2000). Checking can be classified into internal checking (discovered during manufacturing), surface checking and separation of rings (shakes).  Defects during drying are more prone to occur in wood from young eucalypts, especially if they come from plantations (Hillis and Brown, 1984). This wood usually has lower density and wider growth rings.  Eucalyptus wood from plantations can also have many significantly different chemical and mechanical properties compared with wood from native forests.  Even within the same species, and grown under the same environmental characteristics, there is a large within species variability in wood properties (Hillis and Brown, 1984).  Advantage could be taken from this variation, and together with the advancements in process technologies there is opportunity to manufacture eucalypts for value added products.  Many countries see the drying of eucalyptus as a challenge, and have focussed on developing viable options to avoid the defects produced during drying.  For more than 60 years, studies have been taking place in Australia to reduce the excessive degrade during drying that appeared with  6 older and bigger diameter Eucalypts (Hillis and Brown, 1984).  Now, that the majority of Eucalyptus wood used comes from plantations and regrown forests.  As mentioned earlier, Eucalypts do not regenerate naturally in Peru; therefore the selection of trees to be planted should always be done carefully.  Neighbouring countries to Peru, like Brazil and Argentina, have been trying to find the most cost efficient techniques to dry Eucalyptus according to the end product.  Numerous studies have taken place in these countries to enhance the production and utilization Eucalyptus wood.  In Argentina, for example, the industry is not only producing, but also specializing in the production of, parquet from Eucalyptus wood (Sanchez Acosta, 1999).  This product has shown enormous development as a result of managing the difficulties during the different processing steps, including drying.  In Brazil, aside from their huge development of their pulp and paper industry, they have also been working on new alternative ways of processing the eucalypts wood. The production of E. grandis lumber as a replacement for tropical woods such as Brazilian cherry (Hymenaea courbaril), Muirapiranga (Brosimum rubescens), Tatajuba (Bagassa guianensis); has been one of the greatest advances in Brazil in the last 20 years (Jankowsky and Gonçalves Luiz, 2006).  Different Eucalypt species are suitable for different industries according to their origin and their management.  The transformations they undergo depend on their end use and their costs during the processing.  Some Eucalypt species are better for pulp and paper (E. globulus, E. regnans, E. nitens, E.grandis), other for round timber (E. maculata, E. cladocalyx, E. camaldulensis, E. sideroxylon), other for flooring or furniture (E. saligna, E. sideroxylon, E. maculate, E. nitens, E. cladocalyx, E. botryoides, E. grandis) (Waugh, 1995).  It is possible to obtain a good final  7 product quality from Eucalyptus, but the best methods for processing for individual species need to be determined.  Drying Eucalyptus wood Over time, the methods to dry wood have evolved and have been adapted to different situations according to the needs and resources of the industry.  Eucalyptus wood needs to be dried slowly at low temperatures and high relative humidity especially during the first stages of drying (Hillis and Brown, 1984).  Wood in general shrinks when it loses moisture below the fibre saturation point, but the amount of water and temperature are not homogeneous throughout the piece being dried.  The surface dries first and creates a gradient throughout the pieces that generates internal stresses that can lead to defects such as surface checks, separation of fibres and collapse (Oliver, 2000).  ―Tendency to collapse can be detected from measurements of shrinkage against moisture content‖ (Oliver, 2000, (Innes, 1997)).  Even though some of the defects can be removed during reconditioning, the best option is to avoid them from the beginning.  Methods that work better and faster might not be profitable enough due to the time to recover the investment costs.  The drying methods that will be presented and discussed here:  Air drying, conventional kiln drying and solar energy kiln drying.  Air drying is the method that takes the longest to dry eucalyptus wood, requiring from 3 up to 10 months, to obtain final moisture content (MC) of 12% to 20%.   The drying period and the final moisture content depend on the species, wood thickness and the environment’s arrangement and condition (Simpson, 1999).   The required MC for high end quality products ranges from 5% to 15% according to the relative humidity of the environment where the wood is dried (DeWitt, 2002).  Air drying can be a good and cheap starting point to pre - dry Eucalyptus wood, if the  8 cost of carrying inventory is not significant. It is quite a long process and the wood will most likely need to pass through another more sophisticated drying method to get to the desired final moisture content to machine it. Wood is usually transferred to a conventional kiln after air drying when its moisture content is between 20% and 25% (Simpson, 1999).    These two methods might need to be scheduled together with reconditioning or moisturizing processes, like steaming or spraying.  The most common wood drying method is conventional kiln drying.  Conventional kilns are built to work at temperatures between 40°C to 90°C, reached by a heating system that consists of pipes which are channels that use steam as a heating fluid.  Kilns have fans working on the movement of air through the wood stacks, and they also have vents which act as regulators exchanging the air from inside and outside the kiln.  It is very important that the kiln has a spraying system that moisturizes the air; this is a very important issue when drying Eucalyptus (Jankowsky and Gonçalves Luiz, 2006).  Wetting the surface of the wood is important to maintain the moisture gradient throughout the piece as homogeneous as possible.  Because of the high temperatures at which conventional kilns work, this method is not the best choice for drying Eucalyptus wood when the moisture content is still too high (Jankowsky and Gonçalves Luiz, 2006).  Low temperatures could be set to dry Eucalyptus inside a conventional kiln, but the process would take too long and it would also be a waste of energy and money.  Some costs per cubic meter of drying spotted gum (Corymbia macualata) and blackbutt are given below (Eucalyptus pilularis) (see Table 2).  This study was done by Davies and Palmer at the Department of Primary Industries and Fisheries in Queensland.  The input costs are:  financial variables, kiln design, process specification, energy consumption and prices, labour, land and others (Davies and Palmer, 2005).   9 Table 2.  Drying costs for spotted gum and blackbutt (Davies and Palmer, 2005) Seasoning Method/Kiln Type Average cost Single- stage drying Conventional Kiln drying above 70ºC using LP gas fuel on a small scale $100.30/m³ Conventional Kiln drying above 70ºC using wood waste fuel on a large scale $149.50/m³ Conventional Kiln drying below 70ºC using LP gas fuel on a small scale $228.51/m³ Two- stage drying Exposed pre-drying in the air and conventional kiln final drying $52.73/m³ Covered pre-drying in the air and conventional kiln final drying $61.39/m³  The advantage of using CK in the last stages of drying is that the system makes it possible to obtain a low moisture content under the fibre saturation point.  Regardless of the stage of drying where CK operate, it should work hand in hand with a steaming process (see Appendix B) to recondition or prepare the wood before, after or during drying.  Even though the final product quality reached with conventional kilns when drying eucalypts can be satisfactory, the costs needed to build, adjust, supervise and combine it with other methods cannot be currently justified by the profits of the Peruvian Industry.  A solar energy kiln uses a system that collects the energy from the sun to heat up the space where wood is adequately stacked and ready to be dried.  Because the energy of the sun has a low intensity compared to the usual energy generators (electrical, gas, etc), its use is currently effective only for some applications (Wengert and Oliveira, 1985).  The highest temperature achieved in a solar kiln is a round 60°C, which is fairly low compared to the temperatures that can be attained using conventional drying (De Vore, Denny and Harper, 1999). Depending on the design, the amounts of energy lost can also be comparably higher (Wengert and Oliveira,  10 1985).  Solar kilns are usually less costly to build than conventional kilns.  The energy consumption costs can be almost zero if the fans run with solar energy.  From previous research done in countries like Brazil, an average saving on investment and electrical energy costs are about 50% compared to kiln drying (Jankowsky and Gonçalves Luiz, 2006).  For a country like Peru where large investments, especially in the wood industry are unlikely, building a solar kiln instead of a conventional kiln can reduce the costs for the industry.  It is not only the financial aspects that make solar kilns attractive.  As mentioned earlier, the drying rates and temperatures required to dry the majority of eucalyptus species need to be low to decrease the development of drying defects.  There are many solar kiln designs that work best for specific latitudes, weather conditions and species. Steinmann’s homebuilt solar kiln for hardwoods however, looks like it has many characteristics to make it suitable for the drying of eucalypts in Peru.  Steinmann’s Solar Energy Kiln Design Solar energy is the power that can be collected from the sun to perform a variety of functions. Solar energy systems can be roughly divided into passive and active solar systems.  Active solar systems collect and transform the energy with the assistance of mechanical equipment; while the passive systems utilize the intrinsic energy of the sun (orientation, movement, radiant energy) (Kadulski, 2009).  Solar kilns are categorized into three basic types:  greenhouse, semi- greenhouse and opaque walls.  These three types of kilns are mainly designed using a passive solar system, unless the profits justify investing in an active system (Wengert and Oliveira, 1985).   11 Usually, every solar kiln has a collecting system that needs to have a specific size and orientation towards the sun.   The collector needs to have a surface that receives the energy of the sun to be later used as heat to dry the stacks of wood.  The collecting surface is called glazing.  The collector can be the kiln chamber itself in the case of the greenhouse design, where the roof and 3 of the walls are made of the glazing material.  The collector can also be outside the kiln with the aid of an absorber, in the case of opaque kilns.  The glazing needs to be of a clear or almost transparent material such as glass, rigid sheets of fibreglass reinforced with polyester panels or polymer plastic films (Mylar®, Tedlar®, Kalwall®, and others) (Wengert and Oliveira, 1985). The glazing can be composed of one to three layers, depending on the drying expectations and the budget to be spent on construction (Wengert and Oliveira, 1985).  The solar kiln designed by Steinmann is a greenhouse type and uses two layers of ultra-violet stabilized transparent plastic sheet for the roof and sides.  This kiln does not need to face any specific direction.  Even though this design uses two layers of glazing, the kiln is cheap and easy to build, and has been designed with the drying of eucalyptus in mind.  Steinmann Kiln Steinmann, now with the Nelson Mandela Metropolitan University in George, South Africa, designed and built a solar kiln which is a good option for the drying of Eucalyptus in Peru.  This kiln is a good fit for Peru because:  (1), it does not need a large initial cost investment; (2), it gradually achieves higher temperatures according to the independent drying rate of the wood species; (3), it does not need much extra technology and manpower to supervise and regulate its temperature and humidity; (4), it has low energy costs and its size fits the present supply and demand of the industry.  A rough indicator of the performance of this design is that 38mm thick  12 ironwood (denser than Eucalypts, but lower initial MC), can dry to 12% in 4 months (Steinmann, 2006).  The Steinmann kiln is designed to work in a sunny location that has a difference between day and night temperatures of approximately 10°C.  The design prevents the kiln from reaching extreme conditions.  It has a self-regulating feature that ―automatically adjusts the settings‖ of the kiln in response to the daily temperature and humidity differences between the wood pieces and the chamber (Steinmann, 2006).  The solar kiln is self regulated daily with the changes in temperature of the environment that affect the relative humidity of the interior of the kiln while drying the wood.  As the kiln warms up, the relative humidity drops.  The stacks of wood properly stickered need to be covered on the top and side with a tarpaulin that creates a tunnel where the air is forced to pass through back into the plenum chamber. The warm air is circulated through the wood stacks at 1.5m/s with the aid of a 3kw fan that is located in the wall that divides the plenum chamber from the rest of the kiln where the wood is dried.  The temperature of the wood rises and the water starts to evaporate from the surface.  The hot air rises to the top of the kiln and it is blown by the centrifugal fan located on the roof of the kiln into the space between the glazing layers.  During the night, the warm air between the glazing layers will eventually undergo condensation when the temperature outside the kiln reaches the inside’s dew- point.  The condensed water is drained out of the kiln through small weeping holes that are incised on the outer layer where the water accumulates (this would need to be done after observing where the accumulation happens.  The cooled air is then fed back into the kiln through feedback valves.  During the night, the temperature is lower and the relative humidity inside the kiln is still high.  The wood stops being heated and its moisture content gradient is reduced.  The high relative humidity affects the rate of evaporation from the wood surface (Steinmann, 2006). The progressive mild changes in the kiln conditions depend on the rate of moisture content (MC)  13 evaporated from the wood.  This self-adjusting rate does not allow steep gradients that cause stresses and drying defects in Eucalyptus wood (Steinmann, 2006).  This solar kiln is economical and easy to build compared to conventional kilns and even compared to other solar kilns.  The design is very simple and requires a low initial investment, even though the principles behind the operation of the kiln are quite sophisticated.   Specifications for the construction and the principles that explain the system are given in Appendix C.  Parts The main parts of the Steinmann solar kiln (these can be found in Figure 1):  Figure 1.  Front view of Steinmann’s Solar Energy Kiln  The structure that supports the shape of the kiln is made out of wood or pipe.  GLAZING  14 The approximate costs of parts of the kiln are as follows:  Tarpaulin:  $73.00  Glazing layer of 40*50 ft:   $64.87  Fan:  $550  Centrifugal fan of 65 watt:  $200.  Operation It is possible that because of environmental conditions in some regions, the initial temperatures in the kiln may be too high.  It is important that while the moisture content of the wood is above 30%, the temperatures of the kiln are measured and kept below 35°C.  The temperatures can be kept below this level by covering the kiln with a shade cloth (preferably not directly on top of the surface of the kiln, Steinmann, 2006).  Attempts to vent the kiln to lower its temperature would alter the drying cycle.  This solar kiln design can dry wood to 10% moisture content.  The drying time depends on the thickness of the wood, the species being dried and desired final moisture content.    Regardless of the drying method, the green wood needs to be immediately and properly stickered and stacked after cutting to avoid warping.  It is recommended to put the stacks under a shaded area while they are not being dried in the kiln.  Once the kiln is empty, the stacks of wood are loaded inside it with a small forklift.  The position of the wood pieces should be lengthwise perpendicular to the air circulation path.  Advantages and Disadvantages The kiln consumes electric energy due to the utilization of the fan and the centrifugal fan.  The use of a solar panel to generate energy to run the fans is not justified at present because of the  15 high cost of solar panels.  The small quantities of electric energy used can be justified economically.  It has been determined that the solar kiln will take about 20% longer to dry eucalyptus than conventional drying (Steinmann, 2006).  This extra drying time is not a big disadvantage, and is more than offset by the savings in the construction and operation of the kiln.  The cost of building this solar energy kiln is approximately $5 241.48.  This amount is comparably lower than the cost of building a modern conventional kiln, which costs around $131,037.00 (Steinmann, 2006).  This solar kiln does not need to work in combination with any other drying method to obtain the desired final moisture content.  It only needs to follow the construction and operation guidelines (see Appendix C).             16 Conclusions  Eucalypt trees have rapid growth and can be exploited for multiple uses.  In response to the local conditions and international market demands, it appears that the most profitable opportunity for eucalyptus wood in Peru is to convert it into high quality solid hardwood furniture, flooring, and other interior products (Oliver, 2000).  Peru already has high end hardwood products from native species, but the availability of these specific species is declining and is inadequate to satisfy market demands.  From an environmental and economic point of view, the use of eucalyptus wood as a substitute to native Peruvian hardwood species makes sense (instead of only using it as for firewood, veneer, posts and sleepers).  For this new option to occur, there is a need to convince the industry that the wood from eucalypts can be processed, and that the technologies for processing can be adapted by the Peruvian industry.  Peru has the potential to increase its production of wood products and their quality if adequate processing and operating methods are adopted.  If the country wants to become a better competitor in the global market, it will require meeting basic economic, social and environmental responsibilities.  A good development would be the utilization of solar energy kilns to dry eucalyptus.  The Steinmann kiln is suited to the economic and environment conditions of many locations in Peru.  The installation of this kilns to dry Eucalyptus instead conventional kilns, will save Peru a lot of money in terms of initial investment and operating costs.    Building such solar kilns is a good and sustainable option for Peru.  Its construction will result in the expansion of the wood industry in Peru, increasing job opportunities in communities and companies, while it will also save the industry energy and other expensive and non renewable resources.  17 Literature Cited  Baso López, C. (2002).  Normalizar la madera de Eucalipto con destino estructural. Ponencia Invitada al Forum IBEROEKA 2002 ―Innovación y Competitividad  en la Comunidad Iberoamericana‖ 13-15 Octubre de 2002, Montevideo, Uruguay  De Vore, J.B., Denny, G.S. and Harper, T.S. (1999). A Commercially Viable Solar Wood Drying Kiln System, Drying Technology. Fayetteville, Arkansas, pp. 271-283  DeWitt, C. (2002). Wood Moisture Content.  Retrieved March 30, 2009 from http://www.rlcengineering.com/wmc.htm   FAO (2008). Forests and Forestry Sector.  Forestry Country Profiles  FAO (1998). Especies Arbóreas y Arbustivas para las Zonas Áridas y Semiáridas de América Latina. Red Latinoamericana de Cooperación Técnica en Sistemas Agroforestales  Grattapaglia, D. (2008). Genomics of Eucalyptus, a Global Tree for Energy, Paper, and Wood. Plant Genetics and Genomics:  Crops and Models. Volume 1, Brasilia, Brazil, pp. 259-298.  Hillis, W.E., and Brown, A.G. (1984). Eucalyptus for Wood Production. pp.259-356  Innes, T.C. (1997). Improved Seasoned Hardwood Timber Quality.  Unpublished thesis, University of Tasmania  INRENA. (2008). Perú forestal en Números Año 2007.  Ministerio de Agricultura, Instituto Nacional de Recursos Naturales, Intendencia Forestal y de Fauna Silvestre, Centro de Información Forestal-CIF, Lima, Perú  Jankowsky, I.P., and Gonçalves Luiz, M. (2006). Review of Wood Drying Research in Brazil: 1984-2004.  Department of Forest Sciences, ESALQ, University of Sao Paulo, Piracicaba, Sao Paulo  Kadulski, R. Solar Energy.  Retrieved March 15, 2009 from http://www.thecanadianencyclopedia.com/index.cfm?PgNm=TCE&Params=A1ARTA0007549  Luzar J. (2007). The political ecology of a “forest transition”: eucalyptus forestry in the southern Peruvian Andes. Ethnobotany Research & Applications 5, pp. 85-93.  Oliver, A.R. (2000). Advances in drying plantation-grown eucalypt timber: an overview of Tasmanian research.  A Regional Journal of Forestry Science and Forest Management, Glenorchy, Tasmania, pp. 248-251  PRONFOR. (2007). Inversiones en Empresas de Bosques Tropicales Naturales. Confederación Peruana de la Madera, Miraflores, Lima, Perú  Sánchez Acosta, M. (2005). Tecnología de la Madera de eucaliptos colorados: Propiedades – usos – posibilidades.  Jornadas Forestales de Santiago del Estero – Junio 2005  18  Sánchez Acosta, M. (1999). Experiencia Argentina en la producción y utilización de la madera de eucalipto, panorama a 1999.  Simpson, W.T. (1999). Drying and Control of Moisture Content and Dimensional Changes. Forest Products Laboratory. Wood handbook—Wood as an engineering material.Gen. Retrieved March 26, 2009 from http://www.fpl.fs.fed.us/documnts/fplgtr/fplgtr113/ch12.pdf  Steinmann, D. (2006). Homebuilt Solar Kiln for Hardwoods.  Stellenbosch University, Stellenbosch, South Africa  Waugh, G. (1995). Plantation Eucalypts for Solid Wood Products. Environmental Management: The Role of Eucalypts and other fast Growing Species. Proceedings of the Joint Australian/Japanese Workshop held in Australia October 1995  Wengert, E.M., and Oliveira, L.C. (1985). Solar Heated, Lumber Dry Kiln Designs.  Department of Forest Products, Brooks Forest Products Center, Virginia Polytechnic Institute and State University, Blacksburg, Virginia, U.S.A.  World Wildlife Fund. (2009). Progress and a Setback for Rain Forest Conservation in Peru. Retrieved March 24, 2009  from http://wwf.worldwildlife.org/site/PageServer?pagename=can_results_peruvian          19    Appendices             20  SPECIES  Round Wood (m³)  Scientific Name Common Name  Sawnwood (m³)  21  Appendix B SPECIES  Common Name  Scientific Name Round Wood (m³)  Sawnwood (m³)  22 Steaming process Steaming can be done before drying, between two drying stages or at the end of the whole drying process.  When wood has already gone through a drying process, steaming is called reconditioning.   Reconditioning is preparing the wood for the next stage, being drying at higher temperatures, or ready to cool down and be machined.   ―Reconditioning to remove collapse usually causes the surface checks to re-open during final drying.  This can severely degrade back-sawn timber. however, reconditioning tends to close internal checks‖ (Hillis and Brown, 1984).  Steaming previous to air or kiln drying helps to even out the moisture gradient in the wood pieces, and it can also accelerate the drying process (Hillis and Brown, 1984).  Appendix C The construction of a Solar Kiln  • The kiln floor should be level, sturdy and dry even during the rainy season. Drain water away from the kiln. Use a sheet of plastic as a moisture barrier against ground moisture and use a layer of bricks to lift the floor 50 to 100 mm above ground level. • Framework of wood or pipe is made to a suitable size to accommodate the stack of wood you intend to dry and allow for air circulation. • A tunnel shape is recommended for easy construction. • Cover both ends of the tunnel with any material. Allow for a door to load the kiln. • Cover top and sides with a double layer of ultra violet stabilized transparent plastic sheet sealed all around its 4 edges • Ensure that the kiln air can not leak out of the kiln!! • Stack the wood in the kiln in such a way that an electric fan can blow the kiln air through the stack. Baffle the stack to the fan to ensure that no air by-passes the stack. An air speed through the stack of 1,5 m/sec is sufficient. • Fit a small blower fan (50- 150 watt) to the inside of the kiln structure and use a suitable air duct to blow the air between the two skins of the kiln at a point near the top of the kiln and about halfway along its length. • Cut vent holes through the inner skin of the kiln, about 200 mm above ground level and at 2 metre spacing all along both sides of the kiln. These vent holes are required to feed the air from the small blower back into the kiln. • NB Make these holes small enough to allow a slight pressure build-up between the two skins to keep them apart when the blower is running.             23 PRINCIPLES OF OPERATION   Wood is stacked in a double skinned solar kiln with transparent roof and walls  The wood is covered to protect it from direct sunshine  The sun heats the inside of the kiln and the air  The warm kiln air is circulated by a fan through the wood stack to heat it.  The wood releases its moisture into the kiln air  A small blower blows this moist air into the space between the two skins and back into the kiln via vent holes in the inner skin.  When the temperature outside the kiln drops below the dew point of the kiln air, the moisture condenses on the inside of the outer skin  This condensate collects between the skins and is drained through weep holes to the outside of the kiln.  The above process removes the water from the wood and releases it outside the kiln  This process repeats itself in day/night cycles.  Principle #1 • During the day: •  Sun starts shining: •  Temperature inside kiln increases •  Relative humidity drops •  Wood starts drying from surface • Normally no condensation on a sunny day  Principle #2 • Removal of water by condensation on inside of outer skin: •  Night time, outside temperature drops •  Air between skins cools below dew-point •   temperature (once a day) •  Water condenses (inside of outer skin) – beer can! •  Water runs down •  Water collects at bottom where skins meet •  Removed through weeping holes •  Cooled air fed back through feedback valves into kiln  Principle #3 • During the night: • Lower absolute humidity • Relative humidity still high! •  Wood is still hot from heating during day •  Water still moves by diffusion to surface •  Very little evaporation from wood surfaces because of high relative humidity of        air •  Moisture content gradient in wood reduced during night •  Next morning : Principle # 1 repeated   24  Plan of Steinmann Solar Kiln (Steinmann, 2006)  25  Isometric view of Steinmann Solar Kiln (Steinmann, 2006)

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