Types and moisture content of wood residuals from wood processing plants like sawmills or plywood mills can vary widely. Larger residuals are chipped and sold for pulp or wood composites like log slabs from sawmills or peeled cores from plywood mills. Smaller residuals like bark, sawdust, planer dust, or veneer residuals are utilized as livestock bedding in nearby farms, as boiler fuel in the mill, or as compost. Only 7% of the estimated 12 million m3 of wood residuals produced in 2005 was uselessly burned or otherwise wasted.

In large scale mills, even zero emission production is possible by recycling residuals for electric power generation or steam for wood drying. But for small sawmills without drying facilities or precut mills, a residuals utilization system such as a small-scale round accumulation system, must be established. Recently, wooden pellet production from bark or sawdust, which is easy to handle and has higher energy density, has been increasing.

Fig. 2.12.1. Wood flow in Japan.

2.12.2 Residuals from wood utilization

In the 2005 estimates, 22 million m3 of residuals were produced in the construction, furniture, transportation, and civil engineering sectors. Residuals from civil engineering include trees felled during construction works.

Only 10% of residuals were recycled as materials; 1.6 million m3 for particle board etc., and 0.8 million m3 for pulp. The “Construction Recycle Law” mandates that construction-derived wood wastes from construction and civil engineering sectors are to be separated and recycled. In 2005, an estimated 62.8% of the 15 million m3 of residuals produced is recycled in some way, mostly, for energy generation, except for the volume reducing by incineration.

In the first commitment period of the Kyoto Protocol, the rise of petroleum prices has given many industries like power plants, steel mills, cement mills, and paper mills added incentive to start wooden residuals for energy production. Recycling companies also benefit easily, because they can collect a disposal fee for residuals from wood utilization. The objectives of the “Construction Recycle Law” will undoubtedly be achieved, and there may even be a shortage of wood residuals.

Material-recycling for conserving resources must have top priority. However, residuals with adhesives or paint cannot be used for pulp chips, and almost no waste wooden boards are material-recycled. Also small or composite wooden residuals, which cost much to be material-recycled, should be crushed and used as fuel chips. So, more than half of wood residuals could be energy-recycled without wasting, which in turn could reduce fossil fuel consumption by more than 1 million tons-C.

(a) What is co-firing?

Co-firing refers to the technology whereby biomass is fired with fossil fuels at thermal power stations and so on. The advantage of this technology is that, simply by making some minor revisions to existing equipment to enable biomass treatment, it becomes possible to fire biomass in highly efficient large-scale combustion facilities. Here, an introduction is given to research and development of coal and woody biomass co-firing technology that has been jointly implemented by The Chugoku Electric Power Co., Inc., Hitachi Ltd. and Babcock-Hitachi K. K.

(b) Goals

Upon burning around 5-10% of woody biomass in a coal fired power station (hereafter the proportion of mixed fuel is shown in terms of the calorific base), they aimed to secure stable operation and to clear environmental standards while at the same time minimizing any reduction in generating efficiency. Aiming for generating efficiency equivalent to approximately 40% the level in the existing coal fired power station, they held the reduction in efficiency at the sending end to within 0.5% when the mixed fuel firing rate was 5% (and within 0.8% when the mixed fuel firing rate was 10%).

(c) Feedstock

Based on component analysis of pine, cedar, cypress and bamboo, etc., woody biomass has greater volatile content than coal (bituminous coal), its fuel ratio (ratio of fixed carbon content to volatile matter content) is approximately 1/10 of that of coal, and its ash content is low. Upon conducting tests in a small hammer mill, etc., grinding power consumption for woody biomass was at least 10 times higher than that for the same weight of coal and simultaneous grinding testing of coal and woody biomass revealed that the grindability of coal is reduced a lot when the mixing ratio of wood is increased.

(d) Process flow

Figure 4.1.2 shows the flow diagram of the biomass pretreatment equipment. The woody biomass consisted of thinned timber and bamboo chips procured from the Chugoku region with a size of no more than 50 mm and water content of 50wt%. The chips were crushed to a size suitable for drying (no more than 20 mm) and dried to a water content of 20% or less. Next, two types of pulverizer were combined to regulate the pieces to a top size of 1~5 mm, and the materials were blown into the furnace by fixed quantity feeder. The mixed fuel firing rate was a maximum of 15%. Two types of burner were used: a coaxial coal and biomass mixed burner and a biomass dedicated burner (separately installed).

(e) Results

Figure 4.1.3 shows some of the test results. As the proportion of mixed fuel was increased, the unburned matter and relative value of NOx fell in both the coaxial burner and separately installed burner. The reduction in the unburned matter indicates that mixing of the highly volatile biomass caused the ambient temperature to rise and the combustion efficiency of the fuel itself to increase. The rate of decline in NOx was lower than the value forecast from the rate of decline iel.

(f) Efficiency

Based on the results of the combustion tests, the basic equipment and system composition in the case of application to the existing coal fired power station (selecting three units of 75-500 MW) was examined and the power generating efficiency and generating cost were assessed. Factors that cause the mixed fuel firing to affect power generating efficiency are thought to be changes in boiler efficiency and auxiliary power. In the case where thinned wood chips having water content of 30% and chip size of 50 mm or less following natural drying of the forest land, etc. are introduced to the power station, this wood is converted to crushed biomass of 20% water content and 2-mm particle size following pulverization and conveyance, and this is combusted in the boiler, whereas the unburned matter of ash is lower than in the case of firing only coal, the boiler efficiency drops slightly due to the water content of the woody biomass. As for auxiliary power of the plant, from the pilot test findings and based on estimation of the crushing power in the case where a two-stage shock crusher is used, the drop in overall sending end efficiency is 0.44% and 0.77% when the proportion of mixed fuel is 5% and 10% respectively, and these values are within the respective targets of 0.5% and 0.8%. Furthermore, upon comparing costs between woody biomass-only firing (10 MW) and mixed fuel firing, since the mixed fuel firing was less expensive than dedicated firing (11.3 yen/kWh), the superiority of mixed fuel firing was confirmed.

The strains of bacteria utilized for industrial production of butanol were acetone-butanol producing bacteria and butanol-isopropanol producting bacteria which produce butanol and isopropanol, a reduced product of acetone. The reaction pathway is shown in Fig. 5.3.1. Glucose is decomposed to pyruvate, acetyl-CoA, and acetoacetyl-CoA via EMP pathway, and finally acetone, butanol, isopropanol and ethanol are produced. The stoichiometrical equation of acetone-butanol fermentation is shown in Eq. 5.3.1.

95C6H12O6 -► 6OC4H9OH + 3OCH3COCH3 + 1OC2H5OH + 220CO2 + 120H2 + 30 H2O (5.3.1) In acetone-butanol fermentation, butanol is gradually accumulated and cause production

inhibition at more than 3 kg/m3 (g/L) of the butanol concentration. When the production inhibition occurs, the growth of bacteria cells, consumption of substrates, and accumulation of products are suppressed. Final concentration of butanol reaches about 30 kg/m3 (g/L). After fermentation, the culture solution is distilled and products are separated by the difference in their boiling points, e. g. acetone (BP 56.3°C), ethanol (BP 78.3°C) and butanol (BP117°C).

4.1.6 Energy efficiency of acetone-butanol fermentation.

From Eq. 5.3.1, 60 mol butanol (170 MJ), 30 mol acetone (54 MJ), 10 mol ethanol (14 MJ) and 120 mol hydrogen (34 MJ) are produced from 95 mol glucose (273 MJ) in acetone-butanol fermentation. Almost all energy in glucose can be moved to butanol, acetone, ethanol and hydrogen.

Secondary energy (converted into electricity, heat, and liquid fuels using biomass resources through appropriate conversion technologies) cost is calculated. Annual installation cost is calculated based on the following assumptions: 1) interest rate is 5%, 2) lifetime is 30 years (20 years for pyrolysis and fermentation generation), 3) annual expenditure is 12% (10% for fermentation generation, 17% for pylorysis, 27% for ethanol fermentation). This analysis shows that integrated gasification generation is promising if it is well developed as predicted. Pyrolysis is also promising if its technology cost can reduce in the future. Furthermore, the cost evaluation includes uncertainty. Resource cost depends on local situation and technology cost is subjective to technology RDD. Therefore, for practical use, it is necessary to analyze the bioenergy cost based on the latest information.

Biomass Resource Cost($/GJ)

Fig 6.4.3 Biomass Cost (Generation).

Further information

Yamamoto, H., et al., “Economic Analysis of Bioenergy Utiliztion Technologies”, The 18th Energy Systems, Economics, and Environmental Conference, pp..233-238, 2002 (in Japanese)

DeMeo, E. A., “Renewable energy technology characterizations”, Technical Report TR-109496, Electric Power Research Institute (EPRI) and U. S. Department of Energy, 1997 OECD, “Projected cost of generating electricity update 1998”, 1998

In line with the government’s intensified efforts to promote RE development and use, the Philippine Department of Energy (DOE) formulated the Renewable Energy Policy Framework which embodies its objectives, goals, policies and strategies as well as programs and projects to further develop the RE sector within the perspective of the sector’s supply and demand prospects and its current stage of development. Specifically, the identified long-term goals are the following: (i) increase RE-based generating capacity by 100 percent within the next ten years; and (ii) increase non-power contribution of RE to the energy mix by 10 MMBFOE in the next 10 years. Included in these goals is the increase in the contribution of biomass, solar and wind in power generation.

Resource Potential

Based on current projections of the Philippine Department of Energy (DOE), RE will provide at least 40 percent of the country’s primary energy requirements for the next 10 years beginning 2005. Other RE such as biomass, used mostly for non-power applications, will remain to be the largest contributors to the total share of RE in the energy supply mix with at least 30 percent share. According to the Power Development Plan, biomass will provide 30 MW capacity in 2007 and will increase to 55 MW in 2008.

Based on the study, “Power Switch and Strategies for Clean Power Development in the Philippines”, the country has a potential resource capacity of 235.7 MW from bagasse resources. Other studies as well, shows the potential of the country for several small 1-2 MW rice hull fired power plants just like 1 MW rice hull fired power plant currently installed in the Northern part of Luzon.

2.7.1 The herbaceous biomass means

Herbaceous biomass includes grasses and legumes growing on grasslands. It includes under utilized wild species as well as cultivated forages with higher forage quality. Broadly speaking, food crops, such as rice, wheat, maize, and sugarcane represent sources of herbaceous biomass. By-products or residues, such as rice straw, are also considered herbaceous biomass; however, their use as herbaceous biomass is dependent on quality issues. Bamboos (Phyllastachys spp.) and sasas (Sasa spp.) are considered gramineous woody-type biomass species. Tropical grasses grow faster than trees and produce higher biomass in a shorter period. Grasses are classified into annual species, which include many cereals, and perennial species, which include many forage grasses. Legumes consist of shruby, viny, and wood-types, of which the two former types are considered herbaceous biomass. An important component of legumes is their ability to fix nitrogen in symbiosis with Rhizobium bacteria located in root nodules. It is economically necessary that a reduction in the use of chemical nitrogen fertilizers will be a component of biomass production. By rotating or sowing a mix-culture of forage and leguminous species in biofuel production pastures, the application of nitrogen fertilizer can be minimized. Published biomass production of leguminous species is 8-17 t/ha/year for alfalfa (Medicago sativa) in temperate Aichi Prefecture and 5-19 t/ha/year for tropical legumes in the subtropical Ishigaki Island. This production level is much lower than that for tropical grasses.

In the late 1990s, problems related to dioxin motivated incinerator manufacturers to develop a pyrolysis (or gasification) system in addition to a melting system. Solid waste is heated at around 500°C in a scarce — or low-oxygen atmosphere, and the resulting combustible gas and solid residue is burned at between 1200 and 1500°C to melt ash. This process was expected to yield benefits such as low dioxin emission, high power generation efficiency, and recycling molten slag, and 77 facilities were in operation by 2005. However, recent studies have found that these facilities require high consumption of supplemental fuel and electricity, and produce a low slag recycling rate. To minimize these drawbacks, the first part of the pyrolysis-melting system is used as carbonization. The product, char, can be used as a charcoal alternative, soil conditioner, and powdered coal for blast furnaces. In contrast, in the European Union, pyrolysis is used as an alternative technology for energy from waste, but its target is pyrolysis gas.

Further information

R. Stegmann, “Landfill gas utilization: An overview” in Landfilling of waste: Biogas (ed. T.H. Christensen, R. Cossu, R. Stegmann), E&FN SPON (1996)

Tadashi Abe, “Beikoku ni-okeru Gomi-hatsuden no Hatten”, Waste Management Research7(4) „ 305-315(1996) (in Japanese)

Hideaki Fujiyoshi, “Toshi-gomi no Tanka-nenryo-ka Shisetsu”, ENERGY, 57-59 (2001-4) (in Japanese) Shigeo Shikura, Hideki Harada, “Toshi-haikibutsu no Kenkisei-shoka”, Waste Management Research 10(3b 241-250(1999) (in Japanese)

Website of Tokyo-to, http://www2.kankyo. metro. tokyo. jp/tyubou/ (in Japanese)

Toru Furuichi, Norio Nishi (ed), “Biocycle”, Kankyo-Shinbunsha (2006) (in Japanese)

Tsukasa Kagiya, “RDF Hokanji no Hatsunetsu to Kongo-no Taio”, Kankyo-Shisetsu 94, 48-55 (2003) (in Japanese)

“RDF Hatsuden-shisetsu o Kaku to-suru Gomi-shori Koiki-ka ni Kadai”, Kankyo-Shisetsu 94, 42-47

(2003) (in Japanese)

Hideaki Fujiyoshi, “Gasu-ka Yoyu-ro no Unten Kanri to Kaizen Jirei”, Kankyo-Gijutsu-Kaishi 129, 86-99 (2007) (in Japanese)

In Japan, charcoal is widely used as soil improver, fodder, moisture conditioner, etc. by making use of the adsorption capacity (so-called ‘charcoal for new uses’), in addition to solid fuel for cooking and heating. For liquid products, low boiling point fraction, pyroligneous acid, is on the market as agricultural materials, deodorant, etc. In contrast, high boiling point fraction, tar, has a limited practical utilization, like creosote as medicine. In a laboratory scale, the production of phenolic resin adhesive, the recovery of wood preservatives, conversion into electroconductive carbon, etc. has been reported. The use of gas fraction is a supplementary fuel for process.

4.4.3 Status-quo of the technology

A variety of reactors in scale and shape are developed in response of the diversification of material, and they are commercially operated, although the current system does not greatly differ from the earlier one. Nickel-catalyzed carbonization of wood at 900°C, which was conducted in a laboratory scale to obtain a functional carbon with conductivity and liquid phase adsorption in concurrence with hydrogen-rich gas, has attracted considerable attention.

Further information

Bridgwater, A. V.; Bridge, S. A.: “Biomass Pyrolysis Liquids Upgrading and Utilization”, Bridgwater, A.

V., Grassi G., Eds., Elsevier Applied Science, 1991, p. 22,

Lede, J. Reaction temperature of solid particles undergoing an endothermal volatilization. Application to the fast pyrolysis of biomass, Biomass Bioenergy, 7, 49-60 (1994)

Pomeroy, C. F. “Biomass Conversion processes for Energy and Fuels”, Sofer, S. S., Zaborsky, O. R. Eds., pp. 201-211, Plenum (1981)

Suzuki, T.; Miyamoto, M.; Luo, W.-M.; Yamada, T.; Yoshida, T. in “Science in Thermal and Chemical Biomass Conversion”, Vol. 2, Bridgwater, A. V; Boocock, D. G. B., Eds., CPL Press, 2006, pp. 1580-1591 Suzuki, T.; Suzuki, K.; Takahashi, Y.; Okimoto, M.; Yamada, T.; Okazakik N.; Shimizu, Y.; Fujiwara, M. Nickel-catalyzed carbonization of wood for coproduction of functional carbon and fluid fuels I., J. Wood Si, 53, 54-60 (2007)

Lactic acid for poly-lactate is requested to guarantee not only quite high optical purity but also its quite high purity as lactic acid. In lactic acid fermentation, any higher class purification technology to yield pure lactic acid is required because the fermentation broth contains a variety of compositions. Usually distillation technology is adopted for this purpose: In the purification of lactic acid from fermented kitchen garbage, butyl-lactate is separated by distillation after esterification of lactic acid with butanol. Moreover, ammonia can be recovered in the estirification reaction, which can be again used for pH adjustment in the fermentation. However, in this process more energy would be required to remove water to encourage the esterification reaction. When the energy would be supplied from fossil resources, it is neither ecologically nor economically suitable. Utilization of unused heat energy form incinerators should be an acceptable solution.

Further information

Morichi, T. Physiology and metabolism of lactic acid bacteria: Biseibutsu 6(1), 27-34 (1990) (in Japanese) Sakai, K.; Murata, Y.; Yamazumi, H.; Tau, Y.; Mori, M.; Moriguchi M.; Shirai, Y. Selective proliferation of lactic acid bacteria and accumulation of lactic acid during open fermentation of kitchen refuse with intermittent pH adjustment: Food Science and Technology Research, 6, 140-145 (2000)

Hassan, M. A.; Nawata, O.; Shirai, Y.; Nor’Aini A. R.; Phang L. Y.; Ariff, B. A.; Abdul Karim, M. I. A Proposal for Zero Emission from Palm Oil Industry Incorporating the Production of Polyhydroxyalkanoates from Palm Oil Mill Effluent: Journal of Chemical Engineering of Japan, 35 (1) 9-14 (2002)

Sakai, K.; Taniguchi, M.; Miura, S.; Ohara, H.; Matsumoto, T.; Shirai, Y. Novel process of poly-L-lactate production from municipal food waste: Journal of Industrial Ecology, 7(3, 4), 63-74 (2004)

Mori, T.; Kosugi, A.; Murata, Y.; Tanaka, R.; Magara, K. Ethanol and Lactic Acid Production from Oil Palm Trunk: Proceedings of Annual meeting of the Japan Institute of Energy, 16, 196-197 (2007) (in Japanese)

Because of the insufficient fuel supply and the requirements for energy saving and pollutants emissions reduction, China national government pays more and more attentions to research and development of bio-fuels. The People’s Republic of China Renewable Energy Law was issued in 2005.

Ethanol gasoline project started in 2001 in China. There are only four plants permitted by the government to produce food based fuel ethanol. The governments’ supports play an important role on simulating the ethanol gasoline development in China, especially at the initiation stage of the ethanol gasoline demonstration by preferential policies like incentives. The incentives include: 1) The excise tax of denatured fuel ethanol (5%) is free. 2) The value-added tax of denatured fuel ethanol is imposed first, and then given back to the ethanol provider. 3) The price of denatured fuel ethanol sold to the petroleum companies which are also the blending operators is (0.9111*manufacturer’s price of 90# gasoline). While the market prices of all kinds of E10 (90#, 93# or 97#) are the same as 90#, 93# or 97# gasoline. 4) An allowance is paid to the ethanol provider. These incentives will be executed until 2008. Now ethanol gasoline has been used in 9 provinces and the total consumption was 1.54 million tons in 2006. However, to ensure the food safety, no more food based fuel ethanol plants are permitted by the China national government any more. In the future, non-food feedstock including cassava, sweet potato, sweet sorghum and lignocellulose are potential for fuel ethanol production. A 200 000 tons/year fuel ethanol plant with cassava as feedstock in Guangxi province has been permitted by the government and is expected to start up soon. The four exiting fuel ethanol plants are encouraged to use non-food feedstock too.

There are more than 10 biodiesel plants in China. The amount of production is about 100 000 tons/year. <Biodiesel Blend Stock (BD100) for Diesel Engine Fuels> was issued in May 2007. But there is not yet regular policy for biodiesel sales like fuel ethanol. Some biodiesel are for non-engine utilization. One problem of biodiesel development in China now is the feedstock supply. China needs to import more than 6 million tons edible oil per year. It is impossible to use edible oil such as soybean oil and rape seed oil for bio-diesel production. Now most biodiesel plants in China are using waste oils as feedstock. However, with the development of biodiesel, the price of waste oils is higher and higher. Woody oils are getting more and more attentions. The “national bioenergy-directed forest construction program” and “Woody feedstock plantation plan for biodiesel during 11th Five-Year plan” were issued by State Forestry Administration of China, which indicate that 400 000 hectares of Jatropha curcas will be planted in Yunnan, Sichuan, Guizhou and Chongqing provinces; 250 000 hectares of Pistacia Chinensis will be planted in Hebei, Shanxi, Anhui and Henan Provinces; 50 000 hectares of Cornus Wilsoniana will be planted in Hunan, Hubei and Jiangxi Provinces; 133 333 hectares of Xanthoceras Sorbifolia will be planted in Inner Mongolia, Liaoning and Xinjiang provinces.

7.1.2 Conclusion

With the rapid economic development, the great insufficiency of energy supply has become the “Bottleneck” of sustainable development in China. Currently the important issue to be solved is to accelerate the development of biomass energy so as to relieve the pressure of resources and the environment. Moreover, as a responsible country, China should take the international responsibility to save energy and reduce pollution discharge. Hence, the biomass energy industry is promising with a fairly bright future in China. At present, the biomass energy consumption is 8% of the total fuel consumption. According to “Mid and Long Term Development Plan of Renewable Energies” issued on September 4th 2007, the percentages of biomass energy consumption will increase to 10% by 2010 and 15% by 2020. By 2010, annual consumption of non-grain based fuel ethanol shall reach 2 million tons, and that of biodiesel shall reach 200 000 tons in China; by 2020, annual consumption of fuel ethanol shall reach 10 million tons, and that of biodiesel shall reach 2 million tons in China.