7.1 China

7.1.1 Background

With rapid economic development, energy demand increases rapidly also in China. China’s total energy consumption already occupies the second place in the world. Fig.1 shows the trends of China’s oil consumption and net imports from 1990 to 2006. Since 1993 when China became a net import country of petroleum, the dependency of petroleum upon import increased from 7.6% in 1995 to 47.0% in 2006. It is forecasted that in 2020 the petroleum consumption and import in China will amount to 450 million tons and 250 million tons, respectively, with 55% dependency of petroleum upon petroleum import. It’s expected that transportation will contribute the most oil consumption growth in future. Compared to the transportation oil consumption in 2000 which accounts for about 1/3 of the total petroleum consumption, it is forecasted that the ration will rise to 43% and 57% by 2010 and

Fig. 7.1.1. Trends of China’s oil consumption and net imports from 1990 to 2006

The status of biomass utilization in Japan is shown in Fig. 7.13.1. Livestock waste is used as compost etc., food waste as compost and animal feed, lumber-mill residue as energy and fertilizer, construction-derived wood residue as paper production, particleboard production, animal bedding material, combustion etc., sewage sludge as construction material and compost, non-edible portions of farming crops as compost, animal feed, animal bedding material etc. paper waste as recycle and heat production, black liquor as combustion use. Forestry residue is not any used.

Bio diesel fuel from waste cooking oil is produced around 3,000 t/year. Bio-ethanol production is almost in R&D stage, and bio-ethanol is produced commercially 1,400 kL from waste wood in 2007. Test sales of ETBE-mixed gasoline (3%-EtOH equivalent) and E3 just started in 2007.

Energy crops is not tried yet. Introduction is limited due to the limited land and high labor cost, although test production of sugarcane and ethanol production is going on in Okinawa.

7.13.2 Successful example

The First Energy Service Co., Ltd., commercially collects waste wood and produces electricity. They established 3 power generation companies using waste wood; 10,000 kW at Iwakuni Wood Power Co., Ltd., 11,500 kW at Shirakawa Wood Power Co., Ltd., and 12,000 kW at Hita Wood Power Co., Ltd.

7.13.3 Other comments

Non

Further information

MAFF webpage: http://www. maff. go. jpAi/biomass/index. html

Utilization □ Non-utilization I

Globally, increase in emission rates of greenhouse gases, e. g., CO2, present a threat to the world climate. As an estimate in the year 2000, over 20 million metric tons of CO2 were expected to be released in the atmosphere every year (Saxena et al., in press). If this trend continues, some extreme natural calamities are expected such as excessive rainfall and consequent floods, droughts, and local imbalances. Biomass is a carbon neutral resource in its life cycle and the primary contributor of greenhouse effect. Biomass is the fourth largest source of energy in the world after coal, petroleum, and natural gas, providing about 14% of the world’s primary energy consumption (Saxena et al., in press). Biomass is being considered as an important energy resource all over the world.

In order to reduce greenhouse gas emissions from energy consumption, several policy alternatives such as emission taxes and tradable emission permits have been proposed. These mitigation policies are likely to enhance the competitive advantage of biomass energy over fossil fuels as the former can displace CO2 emissions from the latter. However, it is well understood that the conversion of biomass to bioenergy requires additional energy inputs, most often provided in some form of fossil fuel. The life cycle energy balance of a biomass compared to conventional fossil fuel should be positive, but depending on the processing choices, the cumulative fossil energy demand might, at times, only be marginally lower or even higher than that of liquid fossil fuels. Bioenergy systems should be compared to conventional fuel ones from a point of view of a life cycle basis, or using LCA.

(a) Plant taxonomy

The coconut palm (Cocos nucifera) belongs to Plant Kingdom under Magnoliophyta Division, Class Liliopsida, Order Arecales, Family Arecaceae and Genus Cocos.

(b) Origin

There are two contrasting views on to the origin of coconut. One is that it originated in America as several species in the genus Cocosare found only in America and the occurrence of coconuts in America antedates recorded history. On the other hand, others said that coconut originated in Asia as shown by the discovery of nuts of Cocos species in the Pleiocene deposit in North Auckland, New Zealand, the presence in Southeast Asia of a greater range of coconut varieties than in America and other reasons (Banzon, 1982).

(c) Description

Early Spanish explorers called it coco, which means "monkey face" because the three indentations (eyes) on the hairy nut resembles the head and face of a monkey. Nucifera means "nut-bearing." The coconut palm is generally described as a perennial tree. The coconut palm has long trunk of the tree, and several stems or leaves come from upper trunk, with green foliage, inconspicuous white flowers, and brown fruits. The greatest bloom is usually observed in the indeterminate, with fruit and seed production starting in the year round and continuing until year round. Leaves are retained year to year. The coconut palm has a moderate life span relative to most other plant species and a moderate growth rate. At maturity, the typical coconut palm will reach up to about 20 m high.

(d) Ecology

Coconut is a sun-loving plant requiring sufficient sunlight for photosynthesis and raising the temperature of the air. It grows best at a mean temperature of 27oC and is sensitive to low temperatures. It is also observed that coconut does best at rainfall of 1,300 to 2,300 mm per year. It may even do well at 3,800 mm or more if the sol has good drainage. It does very well in humid climate. The best soil for coconut is a deep mellow soil such as sandy or silty loam or clay with granular structure.

(e) Fruiting

Different varieties come to bear fruits at different ages. The dwarf varieties start bearing fruits in 3-4 years after planting while the tall varieties start at 5-7 years. The complex of sunlight, rainfall and temperature result in periodicity of yield in the different months of the year. Results of studies showed that the heavier yields are obtained in March to June.

(f) The fruit

A coconut fruit is actually a one-seeded drupe. On the outside is the "husk", which is initially green but turns brown after being picked and dried. Inside the outer coat of the fruit lies the mesocarp, which is packed with vascular bundles. This fiber is called the "coir" and is used for making mats and rope. What we buy in the grocery store is the "stone" of this drupe, which has a hard "shell," the endocarp, and the seed, which is inside of the shell. The shell is used for containers and is widely employed by artisans to make ornaments and decorations. The thin seed coat is the next, and then there are the white flesh or “copra” and “coconut milk.” Both the copra and the milk are the endosperm of this seed. Yes, coconut is unique among plants in having copious liquid endosperm, which bathes the young embryo. Initially the milk is fairly sweet and the copra is thin, but as the seed matures, the liquid is converted into solid endosperm rich in oils (triglycerides). The solid endosperm, copra, is harvested, dried, and then pressed to release the oil, widely used for chief ingredients of shampoo and hair conditioners.

(g) Product forms of coconut

Coconut is called the tree of life because of its many uses. Primary coconut products include coconut oil, desiccated coconut, fresh coconut, and copra (dried mature coconut meat). The major coconut products produced in the Philippines are copra, copra cake, coconut oil, desiccated coconut, fresh young coconut and coconut coir. From this list, desiccated coconut, “buko” fresh young coconut meat and coconut oil are the most in demand products in foreign markets.

Of the estimated 14 million nuts produced in the country per annum during 2001-2005, about 90% is processed into copra. Annual copra production is estimated at two million MT. The remaining portion (10%) of the total coconut production is devoted to the manufacture of desiccated coconut (5%) and other coconut products namely coconut milk, “buko” and for household purposes. Out of the total amount of copra produced, 62% is processed into crude CNO — 60% of which goes to exports while 40% is left for domestic consumption. Copra cake or meal which is the by-product of copra production constitutes the remaining 34%.

Processing of coconut products produces other products such as detergent, bath soaps, shampoo, cosmetics, margarine, cooking oil, confectionery, vinegar, and nata de coco. Coconut intermediates include oleochemicals such as fatty acids and fatty alcohols

Recently, crude coconut oil is transformed into cocomethyl esther or more popularly known as cocobiodiesel. Throughout the conversion process, two by-products are generated namely copra meal and glycerin

(h) By-products of coconut

The major coconut by-products are coconut shell, coconut husk and coconut fronds. Coconut shell can be converted to activated carbon while coconut husk can be processed to produce coconut shell charcoal, coconut coir, and coir dust.

The following discussions are referring to the combination of the three prominent coconut by-products: coconut husks, coconut shells and coconut fronds.

The amount of residue generated annually in a country is equal to the product of residue-to-product ratio (RPR) value for any specific residue and the annual production of the crop or product. RPR values for major crops are given in Table 2.9.1.

Table 2.9.2 shows the heating values of common coconut residues used in the industry.

(i)

Uses of coconut residues

Coconut shell is consumed mostly by commercial establishments for energy purposes due to its high heating value. Major users of coconut shells are by restaurants or food processors owners. Coconut shell is also used for drying of crops like copra and rubber. Other energy uses of coconut shells are in the ceramic industry and in heating.

Most of the coconut husk is used in drying of copra using the traditional method called “tapahan”. The rest of the coconut husk is used as fuel in bakeries, drying of fish, pottery, ceramics, brick making and in commercial food preparation.

Coconut frond is used as fuel for drying copra while others are in restaurants, bakeries, fish drying and others.

3.2.1 What are Pellet and Pelletizing?

Pelletizing is to compress the materials into the shape of a pellet. A large range of different raw materials such as solid fuels, medicine, feed, ore, and more are pelletized. On the solid fuel, we call them the wood pellet, ogalite(wood briquette), coal briquette or composite fuel. The wood pellet shown in Fig. 3.2.1(a) is made of wood waste such as sawdust and grinding dust. A diameter of a pellet is 6-12 mm, a length is 10-25mm. Figure (b) and (c) show a large size pellet (wood briquette and rice husk briquette). A diameter of briquette s 50-80 mm, and a length is 300 mm. Figure (d) shows CCB that is a kind of the Composite fuel of Coal and Biomass. We call it Biobriquette.

(a)Wood pellet (b) Ogalite (c) Rice husk briquette (d) CCB

Japan Japan Nepal Japan

Fig. 3.2.1. Various types of briquette.

(a) Wood pellet

Apart from a rice husk briquette, wood pellet and wood briquette are produced in the following manufacturing processes.

(1) drying process

Generally the original moisture content of wood is about 50%. It is necessary to dry the raw materials to moisture content 10-20% in order to obtain the optimum pulverizing and pelletizing conditions. Big particle size of raw material should be dried with the rotary kiln, and small particle size of raw material should be dried with the flash dryer.

(2) pulverizing process

The raw materials should be pulverized in accordance with size of the pellet. In case of whole wood or large size wastes, the raw materials should be crushed before drying process in order to prepare the moisture content uniformly. This process is needless in case of the raw material is rice husk.

(3) pelletizing process

Pelletizer consists of feeder, roller, dies as shown in Fig. 3.2.2-3.2.3. Fig. 3.2.2 shows the schematic drawing of pelletizer for wood pellet. This type of pelletizer is the most popular in the world. Fig. 3.2.3 shows the schematic drawing of briquetting machine for wood briquette and rice husk briquette.

(4) cooling process

Because the pellet of manufacture right after is high temperature and contains much moisture, it needs to cool off.

(5) screening process

Low quality pellets are removed in this process. They are utilized as energy for drying.

(b) CCB (Composite fuel of Coal and Biomass;Biobriquette)

In the second oil crisis, CCB was developed as kerosene substitute fuel in Japan. CCB is a kind of composite fuel of coal (<2 mm) and biomass (<2 mm) that is produced by the high pressure briquetting machine as shown in Fig.

3.2.4. The fundamental raw materials mixing ratio of CCB is coal 70-90%, biomass 10-30% by the weight. When coal includes sulfur content, slaked lime or lime stone of equivalence ratio 1-2 is added as a desulfurizer. Coal can be utilized from a lignite to smokeless coal, and wood waste, agricultural waste and something like that can be utilized as biomass. Because biomass is mixed with coal and the combustion efficiency of fuel is high, ignitability and flammability is good, there is a little emission of smoke, the effect of energy saving is high. In particular the reduction of the carbon dioxide is easy so that CCB includes 10-30% of biomass. The sulfurous acid gas of 50-80% can be reduced by adding a desulfurizer with fuel The technology of CCB is one of the clean coal technology and transferred to many countries as alternative fuels production technology of firewood, kerosene and charcoal In particular, the technical support requests for energy saving, reduction of carbon dioxide and prevention of acid are increasing rain from China.

For biodiesel production, transesterification is applied for vegetable oils (Reaction 4.7.1) in which triglycerides, the esters of glycerin with fatty acids, and free fatty acids exist. Generally, oils are mixed with methanol using alkali catalyst such as potassium hydroxide or sodium hydroxide, and its mixture is stirred at 60-70oC for 1 h. After the reaction, the lower and upper portions are phase-separated with glycerin in the lower and estrified products in the upper which is washed to be fatty acid methyl esters as biodiesel. Since free fatty acids are contained in the waste oils, they can react with a catalyst to produce saponified products (Reaction 4.7.2), thus reducing the yield of biodiesel.

Due to such a disadvantage of the alkali catalyst method, it is reported that free fatty acids are first esterified by acid catalyst, followed by alkali catalyst method. As non-catalytic methods, ion-exchanged resin catalyst method, lipase catalyst method and supercritical
methanol method are proposed. In addition, to promote efficiency of esterification, the two-step supercritical methanol method is also proposed by hydrolyzing triglycerides with subcritical water followed by esterification of fatty acids with methanol in its supercritical state (Reactions

4.7.3

and 4.7.4, Fig. 4.7.1). This process is the only one to handle the low-grade waste oils with w

The impact assessment on LCA consists of three parts: classification, characterization and total evaluation. At the phase of classification, the resource consumption or emissions are classified to the impact categories based on the potential environmental impacts.

Table 6.1.1 shows the default environmental impact categories list of the Society of

A. Input related categories (“resource depletion or competition”)

1. abiotic resources (deposits, fund, flows) glob

2. biotic resources (funds) glob

3. land loc

B. Output related categories (pollution)

4. global warming

5. depletion of stratospheric ozone

6. human toxicological impacts

7. ecotoxicological impacts

8. photo-oxidant formation

9. acidification

10. eutrophication (incl. BOD and heat)

11. odour

12. noise

13. radiation

14. casualties

Pro Memoria: Flows not followed up system boundary

input related (energy, material, plantation, wood, etc.) output related (solid waste, etc.)

Environmental Toxicology and Chemistry (SETAC)-Europe that is the academic society leading LCA studies. It is necessary to be clear which environmental categories are studied, depending on the “Goal and Scope definition”. At the phase of characterization, each assigned LCI data for an impact category is multiplied by a “Characterization Factor” (quantifiable representation of an impact category) and the output is shown as a numerical indicator, “Category Indicator”.

Fig. 6.1.3 shows a general procedure of impact assessment, taking global warming and ozone layer depletion as an example. The numerical value expressing potential environmental impacts of emissions, like "Global Warming Potential (GWP)", is often used for the Characterization Factor. It is to be noted that ISO-14040 defines that “classification and characterization” are mandatory elements but “normalization, grouping and weighting” are optional elements. Although it is possible for a practitioner to make indexes based on carbon dioxide or chlorofluoro-carbon in such impact categories as "global warming" and "ozone layer depletion", but they decided that to integrate these different environmental impacts and to make a single index for decision making is not possible.

the development of other biofuel feedstock such as corn, sago palm, sugar palm and sweet sorghum for bioethanol and coconut for biodiesel, depends on region’s bioenergy potential. The potential land for special biofuel zone has been determined by the Government and is shown in Fig. 7.6.3.

Indonesia biomass resources are mainly from forestry (as an important natural resource because its tropical rain forest), estate crops, agriculture crops and municipal (city) waste. From estate crops, one the most important biomass resources (as well as for an energy alternative) is Oil Palm plantation (Elaeis gueneensis). Indonesia is the second largest producing palm oil country in the world, after Malaysia, (with the total land area of plantation of about 6 million hectares and Crude Palm Oil (CPO) production of 15 million tons in 2006, see Fig. 7.6.4. Area and production Indonesia oil palm plantation) representing 18% of the world-wide production. The

expand rapidly using large mills which produce hundreds of tons of waste on a year round basis. Considerable opportunity exists in Indonesia and other countries to produce significant quantities of biofuel, (for 100,000 tons of CPO will produce 100,000 tons of biodiesel and 12,000 tons of glycerol), and steam & electricity from the residual
biomass while mitigating environmental impacts both locally and globally.

The palm oil residues generated from the palm oil production process are : fresh fruit bunches (FFB) or the oil palm fruit produce Crude palm oil (CPO) and Kernel palm oil (KPO) which can be utilized to produce biodiesel or to generate steam and power.

The climate of Indonesia is also well-known for very suitable of sugarcane (Saccharum officinarum). Indonesia is the richest country for sugarcane genetics and is believed as the origin of the world sugarcane (Papua). At least 2 million hectares of land is suitable for cane field which scattered over Papua (majority), Kalimantan, Sumatera, Maluku and Java. By the appropriate planning, policy and development, it is very likely Indonesia in the future will become one of sugar exporter countries and also as a bioethanol producer (similar to Brazil).

Cassava (Manihot esculenta), known as one of bioethanol feedstock is cultivated intensively

nowadays by the farmers especially in Lampung, Java and NTT regions. The cultivated area is around 1.24 million hectares all over Indonesia and the production was 19.5 million tons in 2005. The conversion of cassava to bioethanol is 6.5:1 or 1 ton of cassava will produce 166.6 liter of bioethanol.

Jatropha curcas (English Physic nut — another biomass source for biofuel, unlike palm oil and cassava, the seed and hence the oil is non-edible, so there is no competition between food vs fuel.

During Japanese occupancy (1942-1945), planting of Jatropha is a compulsory for native people. That’s why Jatropha can still be found today in the eastern part of the islands, such as NTT and NTB provinces.

Various local names had been given to Jatropha Curcas, such as : nawaih nawas (Aceh) jarak kosta (Sunda), jarak gundul, jarak cina, jarak pagar (Java), paku kare (Timor), peleng kaliki (Bugis), etc.

Also, when the jatropha plantation is to be developed in the critical lands or barren lands has two important steps that have been achieved, i. e. afforestation or replanting and the conservation efforts which will result of the improvement of local/regional environment. And also the jatropha oil can be extracted and be used as fuel. Normally Jatropha seeds content average of 1,500 liter of oil/ha/year, with the productivity of 5 tons per ha of dry seeds and the oil yield of 30%.

The R&D of Agriculture Institute, Department of Agriculture has identified about 19.8 million ha of land (see map above, orange color) from various provinces in Indonesia are
suitable for Jatropha curcas plantation, in which 14.277 million ha of land is categorized as a very suitable and 5.534 million ha is suitable (green color). The suitable land is scattered within 31 provinces with the largest being in East Kalimantan, South East Sulawesi, East Java, South Kalimantan, Lampung, Papua and West Irian Jaya provinces. It is projected that jatropha cultivation areas in Indonesia will achieve to 3 million ha by 2015. It is expected that jatropha oil as fuel will play an important role in rural villages of Indonesia, so called “Energy Self Sufficient Villages”, and ultimately to achieve poverty & jobless alleviation goals.

Of course Indonesia as a tropical country has many other biomass resources which can be developed and utilized as energy resources such as coconut (Cocos nucifera), corn (Zea mays), sorgum (Sorgum bicolor L.), arenga pinnata, rubber (Hevea brasillensis), sunflower

(Helianathus annuus), nipha (Nypa fruticans.), sweet potato (Ipomoea batatas L.), sago (Metroxylon p.) and many others.

Further information

Andi Alam Syah. Biodiesel Jarak Pagar. PT AgroMedia Pustaka. Jakarta. 2006.

Bambang Prastowo. Sustainable Production of Biofuel Crops. Indonesian Center for Estate Crops Research & Development. On Sustainable Aspect of Biofuel Production Workshop, Jakarta. June 21, 2007.

Joachim Heller. Physic nut. IPGRI. Germany. 1996.

Bambang Prastowo. Sustainable Production of Biofuel Crops. Indonesian Center for Estate Crops Research & Development. On Sustainable Aspect of Biofuel Production Workshop, Jakarta. June 21, 2007.

Paulus Tjakrawan. Indonesia Biofuels Industry. Indonesia Biofuels Producer Association (APROBI). On Sustainable Aspect of Biofuel Production Workshop, Jakarta. June 21, 2007.

Rama Prihadana et al. Bioethanol Ubi Kayu ‘■ Bahan Bakar Masa Depan. PT AgroMedia Pustaka. Jakarta. 2007.

Rama Prihadana & Roy Hendroko. EnergiHijau. Penebar Swadaya. Jakarta. 2007.

Soni S. W. Energy Generation Opportunities from Palm Oil Mills in Indonesia. 4th Asia Biomass

Workshop. Kuala Lumpur, November, 2007.

Sudradjat H. R. MemproduksiBiodiesel Jarak Pagar. Penebar Swadaya. Jakarta. 2006.

Tim Nasional Pengembangan BBN. Bahan Bakar Nabati. Penebar Swadaya. Jakarta. 2007.

Wahono Sumaryono. Palm Complex Model •’ An integrated preliminary concept for sustainable

plantation and CPQ-basedindustries. 4th Asia Biomass Workshop. Kuala Lumpur, November, 2007.

biodiesel (methyl ester).

2. Triglyceride and fatty acid which are still bonded in triglyceride in the oil is converted to methyl ester via transesterification. By this process, oil conversion to biodiesel (without glyceroyl) of 99.75% can be achieved.

Other feature of this process is the usage of methanol/ethanol reactant can be reduced to < 20% and HCl catalyst can be substituted with solid catalyst from natural substance (FKS) which is much cheaper and can be recycled.

From a production cycle, three grades estrans quality (Fig. 8.3.4) can be obtained : 1) Crude Jatropha Oil (CJO) — as a substitution of kerosene or residue which can be used for direct combustion; 2) Jatropha Oil (JO) — as diesel oil (ADO) substitution for engines with have low rpm (such as portable generator set, tractor/bulldozer, etc.; 3) Biodiesel as fuel (automotive).

Fig. 8.3.5 shows the typical process diagram for jatropha biodiesel production from the seeds. It can be seen, it involves washing, blanching and drying of seeds before proceeding into peeling process. The resulted seed meat is grinded with a grinding machine, the grinded powder is pressed by a hydraulic pressing machine (manual or electric). The crude jatropha oil (CJO) then can be extracted and the residue seed cake can be utilized for animal feedstock, biopesticides, etc.

The production of Jatropha Oil (JO) is carried out by using a estrans reactor where JO is heated at temperature between 50 — 60oC. Methanol as a solvent (5%) is used and HCl catalyst (10% v/v) is applied and then mixed them together. The esterification process will take 2 hours at 50oC. The mixture will direct to a glycerol separator where the aging process will take 4 hours. The glycerol (white paste) will stay at the bottom part whereas the top part JO can be extracted and feed to water separator and neutralization. In this water separator, JO is rinsed twice by using demineralization water, then neutralization is done by using 0.01% of NaHCO3 and finally the deminineralization

using water is carried out again. The final product will be pumped out to the storage tank.

Biodiesel production : JO is fed into an estran reactor with the temperature of 50 — 60oC. The mixture of methanol (10% v/v) and KOH catalyst (0.5% v/v) is then put into the reactor. Stir properly during transesterification process for 0.5 — 1 hour and keep the temperature at about 50oC. Separate the biodiesel from glycerol with the same procedure as JO making. Same procedure also for washing and neutralization process, but in here use 0.01% of CH3COOH instead of NaHCO3. Finally, the final product of Jatropha biodiesel is ready to be used as diesel fuel (ADO) substitution. The characteristic of Jatropha biodiesel is shown Table below.

(a) Cellulose

A polysaccharide in which D-glucose is linked uniformly by B-glucosidic bonds. Its molecular formula is (C6H12Oe)n. The degree of polymerization, indicated by n, is broad, ranging from several thousand to several tens of thousands. Total hydrolysis of cellulose yields D-glucose (a monosaccharide), but partial hydrolysis yields a disaccharide (cellobiose) and polysaccharides in which n is in the order of 3 to 10. Cellulose has a crystalline structure and great resistance to acids and alkalis. Fig. 2.3.1-a shows the structural formula of cellulose.

(b) Hemicellulose

A polysaccharide whose units are 5-carbon monosaccharides including D-xylose and D-arabinose, and 6-carbon monosaccharides including D-mannose, D-galactose, and D-glucose. The 5-carbon monosaccharides outnumber the 6-carbon monosaccharides, and the average molecular formula is (C5H8O4A. Because the degree of polymerization n is 50 to 200, which is smaller than that of cellulose, it breaks down more easily than cellulose, and many hemicelluloses are soluble in alkaline solutions. A common hemicellulose is xylan, which consists of xylose with 1,4 bonds. Figure 2.3.1-c shows the structural formula of xylan. Other hemicelluloses include glucomannan, but all hemicelluloses vary in amounts depending on tree species and the part of the plant.

(c) Lignin

A compound whose constituent units, phenylpropane and its derivatives, are bonded 3-dimensionally. Its structure is complex and not yet fully understood. Figure 2.3.1-d shows a constituent unit. Its complex 3-dimensional structure is decomposed with difficulty by microorganisms and chemicals, and its function is therefore thought to be conferring mechanical strength and protection. Cellulose, hemicellulose, and lignin are universally found in many kinds of biomass, and are the most plentiful natural carbon resources on Earth.

(d) Starch

Like cellulose, starch is a polysaccharide whose constituent units are D-glucose, but they are linked by a-glycosidic bonds. Owing to the difference in the bond structures, cellulose is not water-soluble, while part of starch (see Figure 2.3.1-b) is soluble in hot water (amylose, with a
molecular weight of about 10,000 to 50,000, accounting for 10%-20% of starch) and part is not soluble (amylopectin, with a molecular weight of about 50,000 to 100,000, accounting for 80%-90% of starch). Starch is found in seeds, tubers (roots), and stems, and has a very high value as food.

(e) Proteins

These are macromolecular compounds in which amino acids are polymerized to a high degree. Properties differ depending on the kinds and ratios of constituent amino acids, and the degree of polymerization. Proteins are not a primary component of biomass, and account for a lower proportion than do the previous three components.

(f) Other components (organic and inorganic)

The amount of the other organic components vary widely depending on specie, but there are also organic components with high value, such as glycerides (representative examples include rapeseed oil, palm oil, and other vegetable oils) and sucrose in sugarcane and sugar beet. Other examples are alkaloids, pigments, terpenes, and waxes. Although these are found in small amounts, they have very high added value as pharmaceutical ingredients. Biomass comprises organic macromolecular compounds, but it also contains inorganic substances (ash) in trace amounts. The primary metal elements include Ca, K, P, Mg, Si, Al, Fe, and Na. Substances and their amounts differ according to the feedstock type.

(c) Xylan sugar chain (d) Lignin structure unit (phenylpropane

Fig. 2.3.1. Chemical structures of major biomass components.