The content of the encyclopedia of biomass energy comes from: biomass energy refers to all kinds of organisms formed through photosynthesis, including all animals, plants and microorganisms. The so-called biomass energy is the energy form in which solar energy is stored in biomass in the form of chemical energy, that is, energy with biomass as the carrier. It comes directly or indirectly from the photosynthesis of green plants, and can be converted into conventional solid, liquid and gas fuels, which are inexhaustible. It is a kind of renewable energy and the only renewable carbon source. The original energy of biomass energy comes from the sun, so in a broad sense, biomass energy is a form of solar energy. Many countries are actively researching, developing and utilizing biomass energy.

Biomass energy is a form of energy in which solar energy is stored in organisms in the form of chemical energy. It is a kind of energy based on biomass, which directly or indirectly comes from photosynthesis of plants. Among all kinds of renewable energy, biomass is unique. It is the stored solar energy and the only renewable carbon source, which can be converted into conventional solid, liquid and gas fuels. The amount of energy contained in biomass is closely related to the following factors: variety, growth cycle, propagation mode and seed value, harvest mode, disease resistance and disaster resistance, sunshine time and intensity, environmental temperature and humidity, rainfall, soil conditions and so on. Among the various processes of direct conversion of solar energy, the efficiency of photosynthesis is the lowest, and the conversion rate of photosynthesis is about 0.5%-5%. It is estimated that the conversion rate of photosynthesis of plants in temperate regions is once a year. Biomass energy has great potential. There are about 250,000 kinds of creatures in the world. Under ideal environment and conditions, the highest efficiency of photosynthesis can reach 8 ~ 15%, and the average efficiency is about 0.5%.

It is estimated that the annual fixed carbon in photosynthesis of plants on the earth is 2x 101t, and the energy content is 3x 102 1J, so the solar energy stored in branches, stems and leaves by plants through photosynthesis is equivalent to/kloc-of the global annual energy consumption. Biomass is distributed all over the world with huge reserves. The energy produced by plants on the earth alone is equivalent to 20 times of the mineral energy consumed by human beings at present, or 160 times of the food energy of the existing population in the world. Although the biomass output per unit area varies greatly in different countries, every country on the earth has some form of biomass. Biomass energy is the source of heat energy and provides basic fuel for human beings.

Classification of Biomass Energy According to different sources, biomass suitable for energy utilization can be divided into five categories: forestry resources, agricultural resources, domestic sewage and industrial organic wastewater, urban solid waste and livestock manure. Forestry resources: forestry biomass resources refer to biomass energy provided by forest growth and forestry production, including firewood forest, loose wood, residual branches, leaves and sawdust in forest tending and thinning operations; Branches, sawdust, sawdust, tips, boards and truncations in the process of wood harvesting, transportation and processing; Wastes from forestry by-products, such as shells and stones. Agricultural resources: agricultural biomass energy refers to crops (including energy crops); Wastes in agricultural production, such as crop straw (corn straw, sorghum straw, wheat straw, rice straw, bean straw, cotton straw, etc.). ) left in the farmland when the crops are harvested; Wastes produced by agricultural processing industry, such as rice husk left over from agricultural production. Energy plants generally refer to all kinds of plants used to provide energy, which usually include herbal energy crops, oil crops, hydrocarbon-producing plants and aquatic plants.

Domestic sewage and industrial organic wastewater: Domestic sewage is mainly composed of various kinds of drainage from urban residents' lives, businesses and services, such as cooling water, bath drainage, toilet drainage, laundry drainage, kitchen drainage and fecal sewage. Industrial organic wastewater is mainly the wastewater discharged in the production process of alcohol, wine making, sugar making, food, pharmacy, paper making, slaughter and other industries. , rich in organic matter. Municipal solid waste: Municipal solid waste is mainly composed of municipal household waste, commercial and service waste and a small amount of construction waste. Its composition is complex, influenced by the average living standard of local residents, energy consumption structure, urban construction, natural conditions, traditional habits and seasonal changes. Livestock manure: Livestock manure is the general name of livestock manure, which is the transformation form of other forms of biomass (mainly grain, crop straw, pasture, etc.). ), including livestock manure, urine and their mixture with bedding grass.

Reproducibility of characteristic gasification combustion boiler 1)

Biomass energy belongs to renewable resources. Biomass energy can be regenerated by photosynthesis of plants, which belongs to renewable energy such as wind energy and solar energy. It is rich in resources and can ensure the sustainable utilization of energy.

2) Low pollution

The sulfur content and nitrogen content of biomass energy are low, and less SOX and NOX are produced in the combustion process; When biomass is used as fuel, because the carbon dioxide required for its growth is equivalent to the amount of carbon dioxide it emits, the net carbon dioxide emission to the atmosphere is close to zero, which can effectively reduce the greenhouse effect;

3) Widely distributed

Biomass energy can be fully utilized in coal-deficient areas;

4) The total biomass fuel is very rich.

Biomass energy is the fourth largest energy source in the world, second only to coal, oil and natural gas. According to biologists' estimation, the earth's land produces 1000 ~ 125 billion tons of dry biomass every year; The ocean produces 50 billion tons of dry biomass every year. The annual output of biomass energy far exceeds the total world energy demand in 2007, which is equivalent to 10 times of the total world energy consumption in 2007. By 20 10, the biomass resources that can be developed as energy in China will reach 300 million tons. With the development of agriculture and forestry, especially the promotion of firewood forest, there will be more and more biomass resources.

The application of biomass energy is mainly used in: biogas, solid fuel compression molding, gasification to make gas, gasification to generate electricity, fuel alcohol production, and biodiesel production by thermal cracking.

The development and utilization potential of biomass energy is huge. The following technical means seem to be the most promising at present:

The direct combustion of biomass produces heat, steam or electric energy.

Using energy crops to produce liquid fuel. At present, the energy crops with development potential are: fast-growing crops, sugar and starch crops (used for ethanol production), carbon oxidation cooperatives, herbal crops and aquatic plants.

Produce charcoal and charcoal.

Biomass (pyrolysis) gasification is used for power generation, such as integrated biomass gasifier and large /STIG combined power generation device.

Anaerobic digestion of agricultural waste, manure, sewage or municipal solid waste can produce biogas and avoid disposing of these substances in the wrong way, so as not to cause environmental harm.

Using gasification to burn boiler biomass energy has always been an important energy source for human survival. It is the fourth largest energy source in the world after coal, oil and natural gas, and occupies an important position in the whole energy system. Experts estimate that biomass energy is very likely to become an integral part of the future sustainable energy system. By the middle of the next century, all kinds of biomass alternative fuels produced by new technologies will account for more than 40% of the global total energy consumption. By 2007, mankind will use biomass energy, including crop straw and firewood directly used as fuel; Indirect fuels include agricultural and forestry wastes, animal manure, garbage and algae, which produce biogas through microbial action, or liquid and gas fuels through pyrolysis, or biochar. Biomass energy is the most extensive renewable energy in the world. It is estimated that the total biomass produced by photosynthesis alone on the earth reaches1440 ~18 billion tons (dry weight) every year, and its energy is about 3 ~ 8 times of the global total energy consumption in the early 1990s. However, it has not been reasonably utilized by people, and most of them are directly used as firewood, which is inefficient and affects the ecological environment. The utilization of modern biomass energy is to produce methane by anaerobic fermentation of biomass, to generate gas, bio-oil and biochar by pyrolysis, to produce ethanol and methanol fuel from biomass, to cultivate energy plants and develop energy farms by bioengineering technology.

Application Research of Biomass Energy By 2007, the research and development of biomass energy technology has become one of the main hot topics in the world, attracting the attention of governments and scientists all over the world. Many countries have made corresponding development and research plans, such as Japan's sunshine plan, India's green energy project, American energy farms and Brazil's alcohol energy plan, in which the development and utilization of biomass energy accounts for a considerable proportion. By 2007, most foreign biomass energy technologies and devices have reached the level of commercial application and realized large-scale industrial operation. Taking the United States, Sweden and Austria as examples, the utilization of biomass converted into high-grade energy has reached a considerable scale, accounting for 4%, 16% and 10% of the national primary energy consumption respectively. In the United States, the total installed capacity of biomass power generation has exceeded 10000 MW, and the single unit capacity has reached10 ~ 25 MW; The Staten Waste Treatment Station in new york, USA invested US$ 20 million to treat waste by wet method, recover biogas, use it for power generation and produce fertilizer at the same time. Brazil is the most distinctive country in the development and application of ethanol fuel, and has implemented the largest ethanol development plan in the world. By 2007, ethanol fuel has accounted for more than 50% of the national automobile fuel consumption. The United States has developed the technology of producing alcohol from cellulose waste, and established a demonstration project of 1 MW rice husk power generation with an annual output of 2500 tons of alcohol.

China is a country with a large population and rapid economic development, and will face the dual pressures of economic growth and environmental protection in the 2 1 century. Therefore, changing the way of energy production and consumption and developing and utilizing renewable clean energy such as biomass energy are of great significance for establishing a sustainable energy system and promoting national economic development and environmental protection. The development and utilization of biomass energy is of special significance to rural areas in China. 80% of China's population lives in rural areas, and biomass energy such as straw and firewood is the main living fuel in rural areas. Although the use of commercial energy such as coal has increased rapidly in rural areas, biomass energy still occupies an important position. From 65438 to 0998, the total domestic energy consumption in rural areas was 365 million tons of standard coal, of which 207 million tons were straw and firewood, accounting for 56.7%. Therefore, developing biomass energy technology to provide energy for life and production in rural areas is an important task to help these areas get rid of poverty and achieve the goal of a well-off society.

From 199 1 to 1998, the total rural energy consumption increased from 568 million tons of standard coal to 672 million tons of standard coal, an increase of 18.3%, with an average annual growth of 2.4%. In the same period, the number of rural households using liquefied petroleum gas and electric cookers increased from 654.38+0578 to 49.37 million, more than doubling, with an annual growth rate of 654.38+07.7%, which is more than six times the total. It can be seen that with the development of rural economy and the improvement of farmers' living standards, the demand for high-quality fuel in rural areas is increasingly urgent. The traditional way of energy utilization has been difficult to meet the needs of rural modernization, and the transformation and utilization of high-quality biomass energy is imperative.

The high-tech conversion technology of biomass energy can not only greatly accelerate the process of energy modernization of rural residents, but also meet the urgent demand of farmers for high-quality energy after they become rich, and can also be applied to production fields such as township enterprises. Because China has a vast territory and a large population, conventional energy cannot fully meet the growing demand of the vast rural areas, and because various international conventions on environmental issues are being formulated to limit the emission of greenhouse gases such as carbon dioxide, which is very unfavorable to China, which is dominated by coal. Therefore, based on the existing biomass resources in rural areas, it is not only the urgent need of rural development, but also the need of reducing emissions, protecting the environment and implementing the sustainable development strategy.

Peter Bethune, an amateur navigator and environmentalist in New Zealand, announced that he would sail around the world in the fat-powered speedboat Earth Race. It is reported that Bethune will set off from Valencia, Spain, on March 1 2008, and start a round-the-world voyage with a total length of about 45,000 kilometers. Bethune said that he intended to challenge the world record set by the British ship Wired and Wireless Adventure in 1998 for circumnavigating the world in 75 days. The fat-fueled "Earth Race" is known as the fastest ecological ship in the world, with a cost of 2.4 million US dollars and a number of high technologies. The "Earth Race" is about 23.8 meters long and looks like a swan spreading its wings. The hull is protected by a three-layer shell with two advanced engines inside. The top speed can reach 40 knots (about 74 kilometers), even if sailing in huge waves, the speed will not slow down. Although there are many kinds of animal fats, Bethune plans to complete a global environmental protection tour with 100% biofuels only as the power source of the "earth race".

In order to raise enough fat biofuel, Bethune took the lead and took the initiative to lie on the operating table. However, despite the plastic surgeon's great efforts, the fat extracted from his body is only enough to make 100 ml biofuel. The 10 liter of fat pumped by his two assistants can be made into 7 liters of biofuel for the "earth race" voyage 15 kilometers. However, Pete's "green" global travel needs 70,000 liters of biofuel if he wants to break the 75-day global travel record set by the British "wired and wireless adventurer" 1998. That is to say, Pete needs fat volunteers to donate about 70,000 kilograms of fat.

biomass energy

I. Forest energy

Forest energy is biomass energy provided by forest growth and forestry production, mainly fuelwood, including some forest industry residues. Forest energy plays an important role in rural energy in China. 1980 or so, the national rural forest energy consumption is about10 million tons of standard coal, accounting for more than 30% of the total rural energy consumption. In hilly, mountainous and forest areas, more than 50% of rural households rely on forest energy for energy consumption.

Fuelwood comes from pruning branches during the growth of trees, scraps from wood processing, and firewood forests that provide fuelwood exclusively. 1979 The reasonable annual supply of firewood is 88.85 million tons, the actual consumption is 18 1 10,000 tons, and there are many fuelwood 1 time; 1995 can reasonably provide1432.29 million tons of forest energy, of which firewood forests can provide more than 20 million tons of fuelwood, and the rural consumption in China is 213.39 million tons, and the gap between supply and demand is about 70 million tons.

Second, crop straw.

Crop straw is a by-product of agricultural production and a traditional fuel in rural areas of China. Straw resources are closely related to agriculture, mainly planting production. According to the statistical data of 1995, the annual output of crop straw in China is 604 million tons, of which the loss of fertilizer returning to the field and its collection accounts for about 15%, and the rest is 513.4 billion tons. The available 513.4 million tons of crop straw can be used as feed and industrial raw materials, and most of the rest can also be used as fuel for farmers to cook and warm. At present, the consumption of straw as energy in rural areas in China is about 286.2 million tons, but most of it is burned directly on the wood stove in an inefficient way, and the conversion efficiency is only about 10%-20%. With the development of rural economy and the increase of farmers' income, the regional differences are gradually expanding, and the proportion of commodity energy in rural domestic energy consumption is increasing at a faster speed. In fact, the increase of farmers' income and the difficulty in obtaining commercial energy can be the opportunity and motivation for them to switch to commercial energy. Commercial energy (such as coal, liquefied petroleum gas, etc. ) becomes its main cooking energy near commercial energy producing areas or rich rural areas. Straw used in the traditional way has become the first object to be replaced, resulting in an increase in the amount of straw abandoned for direct combustion in the field year by year. In many areas, the amount of waste straw has accounted for more than 60% of the total straw, which not only harms the environment, but also wastes resources. Therefore, it is imperative to speed up the transformation and utilization of high-quality straw.

Third, livestock manure.

Livestock manure is also an important biomass energy source. Except for direct combustion in a few pastoral areas, livestock manure is mainly used as raw material for biogas fermentation. The main livestock and poultry in China are chickens, pigs and cows. According to the species, weight, fecal excretion and other factors of these livestock and poultry, the fecal resources can be estimated. According to estimates, the total amount of livestock manure resources in China is about 850 million tons, equivalent to more than 78.4 million tons of standard coal, including 578 million tons of cow dung, 48.9 million tons of standard coal, 259 million tons of pig manure, 22.3 million tons of standard coal, chicken manure/kloc-0.40 million tons, and 7/kloc-0.70 million tons of standard coal.

Among the fecal resources, the feces of large and medium-sized farms are more convenient for centralized development and large-scale utilization. At present, there are more than 6,000 large and medium-sized cattle, pigs and chicken farms in China, which discharge more than 800,000 tons of excrement and washing sewage every day. The annual fecal sewage resource in China is 65.438+600 million tons, which is equivalent to 654.38+065.438+57.5 million tons of standard coal.

Fourth, domestic garbage.

With the expansion of urban scale and the acceleration of urbanization, the generation and accumulation of urban garbage in China have increased year by year. 199 1 and 1995, the national industrial solid waste output was 588 million tons and 645 million tons respectively. In the same period, the amount of municipal solid waste increased at a rate of about 10% per year. 1995, the total number of cities in China reached 640, and the garbage removal capacity was10.75 million tons.

Urban domestic waste is mainly a mixture of domestic waste, commercial and service waste and a small amount of construction waste. Its composition is complex, which is mainly influenced by residents' living standards, energy structure, urban construction, green area and seasonal changes. The composition of garbage in big cities in China has shown the trend of transition to modern cities, which has the following characteristics: first, the organic matter content in garbage is close to 1/3 or even higher; Second, food waste is the main component of organic matter; Third, the content of degradable organic matter is high. At present, the calorific value of municipal solid waste in China is about 4. 18 MJ/kg (1000 kcal /kg).