How to effectively utilize rural biomass resources in China.

The word biomass is unfamiliar to everyone. Let's explain the term first. Biomass refers to all kinds of organisms produced by photosynthesis in the atmosphere, water and land. That is, all living and growing organisms are collectively referred to as biomass. It includes plants, animals and microorganisms. Broad concept: Biomass includes all plants, microorganisms, animals that feed on plants and microorganisms and their wastes. Representative biomass, such as crops, agricultural waste, wood, wood waste and animal manure. Narrow concept: Biomass mainly refers to lignocellulose (lignin for short) such as straws and trees in the process of agricultural and forestry production, leftovers from agricultural products processing, agricultural and forestry wastes and livestock manure and wastes in the process of animal husbandry production. Features: renewable, low pollution, widely distributed. Because biomass contains energy, the word biomass energy is introduced. Biomass energy is an 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. Distribution of Biomass Resources in China Because biomass includes plants, animals and microorganisms, we only consider the distribution of plants when analyzing the distribution of biomass resources. China is rich in agricultural and forestry biomass resources, such as straw, rice husk, fuelwood, sawdust and bagasse. According to statistics, the collectable crop straw in China is about 450 million t/ year, equivalent to 65.438+0.8 billion t of standard coal and 50 million t of rice husk, equivalent to 20 million t of standard coal. The wood waste produced by forestry processing is about 24 million m3, equivalent to 65438+500,000 t standard coal; The reasonable supply of all kinds of natural fuelwood is 65.438+0.4 billion t, which is equivalent to 0.7 billion t standard coal. Agricultural Biomass Resources China is a big agricultural producer with abundant agricultural biomass resources. The annual output of agricultural production waste is about 650 million t, reaching 20 10, and the output can reach 730 million t, which can generate energy 12EJ. Agricultural biomass resources mainly include crop straws and agricultural product processing wastes. Crop straw is the traditional energy consumption in rural areas of China, in which rice, corn and wheat straw account for 84.3%; Agricultural product processing wastes include rice husk, corncob, peanut shell and bagasse. From 65438 to 0999, the total amount of agricultural available biomass in various regions of China reached 560 million tons, and the top 10 regions were: Shandong, Henan, Hebei, Jiangsu, Heilongjiang, Jilin, Sichuan, Hubei, Anhui and Inner Mongolia. Among them, the main flow direction of straw biomass is 15% returning to the field, 24% feeding, 2.3% industrial utilization, and nearly 60% burning wood or burning in the open air. Therefore, China's agricultural biomass resources have great application potential. Forestry Biomass Resources The existing forest area in China is 65.438+750 million hm2, and the forest volume is 65.438+245.6 million m3. In 2002, the national afforestation area was 7,776,5438 hectares, an increase of 56.8% over the previous year. The total biomass resources of terrestrial trees in China exceed180 billion t, and the main biomass energy sources are firewood forests, forestry wastes and stubble shrubs. Forestry biomass energy plays an important role in rural energy in China. In 2002, the forestry biomass energy resources consumed in rural areas of China were about 654.38 66 billion tce, accounting for 2654.38 0.2% of the total rural energy consumption. In hilly, mountainous and forest areas, more than 50% of farmers' living energy depends on forestry resources. 1999, the top areas of China's forestry biomass output 10 are: Heilongjiang, Inner Mongolia, Sichuan, Yunnan, Jilin, Jiangxi, Hunan, Guangxi, Guangdong and Shanxi. In addition, there are about 4,692,338+000 hm2 of barren hills and wasteland suitable for forest in China, which can be used for developing and planting high-yield energy plants. (Data from Baidu Encyclopedia) The current situation of biomass energy utilization in China is rich in biomass energy resources. However, the development and utilization of biomass energy in China started late. With the research and development in recent years, obvious results have been achieved. But in general, it is mainly used as fuel to provide heat energy or power generation, farmland organic fertilizer and various chemical products. As fuel or power generation (1), biomass directly burns more than 900 million rural people in China, and most of them rely on biomass energy. However, the thermal efficiency of direct combustion is low, and the direct combustion utilization of precursors focuses on the research and development of improving the thermal efficiency of combustion and reducing the emission of harmful substances, such as the research and development of various boilers and other energy-using equipment. Biomass combustion is used in foreign commercial power generation, but China needs to further improve this aspect. Direct combustion mainly includes stove combustion, compression molding fuel combustion, combined combustion and garbage incineration. Stove burning is a traditional way of energy consumption for rural people, which is gradually eliminated because of its low efficiency. Compression molding fuel combustion is the compression molding of biomass, which makes its density increase and its performance close to that of coal, which is equivalent to direct coal combustion technology in boilers. Moreover, the tail gas emission pollution is small, and the power generation prospect is broad, in which particle molding combustion is especially suitable for heating in homes or greenhouses. Combined combustion is the combustion of coal and biomass, which can reduce the emission of sulfur dioxide and nitrogen oxides. Garbage incineration means that the boiler burns combustible components in garbage at a high temperature of 800- 1000℃, releasing heat for heating or power generation. At present, there are more than 200 high-efficiency combustion boilers that directly burn biomass energy in China, and the efficiency can reach 80%. There are dozens of garbage incinerators operating normally. As the name implies, garbage is an environmental pollutant, but it is actually a "misplaced wealth". Many countries and regions have formed a garbage industry. Recycling garbage can not only reduce environmental pollution, but also alleviate the shortage of resources. In recent years, foreign countries have continuously developed new power generation technologies, such as municipal solid waste power generation. According to experiments, burning 500 tons of garbage can generate electricity 1000 kw? Time. A large-scale garbage power plant built in Hungary has four garbage combustion chambers, each of which can burn 15t garbage? The power station not only generates electricity, but also provides steam up to 250℃ to nearby users. Garbage power generation has also been paid attention to and applied in Denmark, Sweden, Germany, France, Japan, Britain and other countries. Power generation by sludge, the University of Tokyo in Japan invented a method of solidifying sludge. After testing, the solidified sludge has 4000 calories per kilogram, which is equivalent to the calorific value of low-quality coal. Using it to generate electricity can not only save energy, but also protect the environment and health. However, the industrialization of garbage resources in China has not yet formed. China's biomass direct-fired power generation is still in its infancy and still has great development potential. The technology of burning waste wood, agricultural waste and other biomass in the United States has matured, and the installed capacity of its power generation equipment is 736MW. (2) The development and utilization of biomass energy by conversion technology can be divided into biomass liquefaction and gasification according to the forms of conversion products, and biotechnology and thermochemistry are usually used for liquefaction and gasification. Biomass liquefaction and pyrolysis liquefaction technology are still in the experimental research stage in China. Zhejiang University and other domestic universities have studied the pyrolysis characteristics of biomass waste in rotary kiln and the precipitation behavior of various alkali metals and related inorganic elements in biomass pyrolysis. University of Shanghai for Science and Technology and Southeast University are also studying material liquefaction technology from different angles. The purpose of post-graduate material liquefaction is to improve the yield of liquid products and reduce the amount of solid residues and gas products, so as to obtain higher quality liquid products. Liquid fuel obtained by pyrolysis and liquefaction of biomass is customarily called biodiesel, which can be directly used as fuel or converted into higher-grade liquid fuel or higher-value chemical products. The research and development of biodiesel started late and is expected to develop rapidly in the next few decades, forming a biodiesel industry. Statistics show that the ethanol production of China13 is based on cassava. In 2004, the output of ethanol in Guangxi was 300,000 t, of which the total amount of ethanol produced by cassava reached 654.38+10,000 t. Brazil and the United States made outstanding achievements in producing ethanol from biomass. The results show that cassava, as the raw material of fuel ethanol, has the second comprehensive benefit and is the first choice for producing bioethanol. At present, scientific and technological personnel have developed technologies such as continuous fermentation and differential pressure distillation, which are comparable to corn ethanol production. Heilongjiang, Jilin and Henan provinces have built the production project of converting aged grain into fuel ethanol. With corn and sweet potato as the main raw materials, the demonstration work of gasoline ethanol fuel blended with 10% ethanol has been carried out in more than ten cities across the country. The research work of biomass gasification and biogas production from biomass has been carried out very well in China. Straw and manure are fermented to produce biogas, which is used for lighting and household fuel. At present, biogas digesters have been widely used in rural areas of China, especially in Sichuan. The development and utilization of biogas mainly includes agricultural biogas, industrial biogas, urban sewage biogas and urban garbage biogas. Biomass gasification products mainly include methane, ethane, hydrogen, carbon monoxide and carbon dioxide. These products can be used as writer's gas or industrial gas. Biomass gasification is the oldest and most practical technology in biomass thermal conversion technology, but the biggest weakness of biomass gasification gas is the low H2/ carbon monoxide ratio. Since 1960s, China has made a series of achievements in the development of technology and equipment. For example, it mainly focuses on hydrogen production from biomass by biological method and thermochemical conversion method. Various gasifiers developed by Guangzhou Energy Research Institute of Chinese Academy of Sciences can be used for clean heating, power supply and gas supply, and some products have been exported to Southeast Asian countries. At present, dimethyl ether is mainly synthesized from syngas obtained from coal gasification, natural gas gasification and heavy residue gasification. It is reported that the institute has developed a one-step method for the indirect liquefaction of biomass to synthesize dimethyl ether. The patent of the invention is a new method for synthesizing dimethyl ether by reforming biomass gasification gas with biogas, which relates to the field of efficient and clean utilization of biomass and provides a green synthesis method for fully utilizing biomass to efficiently and cleanly utilize synthetic fuel dimethyl ether. The solid waste research center of School of Environment and Chemical Engineering of Shanghai University uses hydrothermal technology to treat bagasse, leaves and vegetable skins. The transformation products and mechanism of biomass waste were studied. The results show that the biomass conversion products contain a lot of humic acid. This kind of humic acid can be used as ecological fertilizer, and its humic acid content can reach about 45%, which has good fertilizer efficiency and economic value. After two years of tackling key problems, researchers in biotechnology discipline of Guangxi University have successfully developed a technology to make efficient and pollution-free ecological organic fertilizer from sludge. The produced fertilizer can not only greatly increase crop yield, but also greatly improve the quality of fruits and vegetables, which is widely favored by farmers. In 2000, the technology was transferred to Guilin Miracle Group, a listed company, and was industrialized that year. In the process of biogas production in rural areas of China, anaerobic fermentation residues such as fermentation broth and slag are obtained at the same time, which are used as farmland organic fertilizers, with good results and full use of biomass energy. The technology of producing ethanol from cassava in China tends to be mature. Ethanol can not only replace gasoline as transportation fuel, but also produce glacial acetic acid, ethylene and its downstream products. Developed countries, such as the United States, Japan, Britain, France, Germany, Russia, etc., have already conducted technical research as early as 10 years ago. Zhu Lingfeng and others carried out this research work, which filled the gap in this research field in China. The results show that this method solves the problem of catalyst deactivation, and the low calorific value gas prepared by straw biomass thermochemical method can directly catalyze the synthesis of methanol after proper treatment. The research work of biomass energy has gradually turned to the deep processing and development of pyrolysis products, such as activated carbon, wood vinegar and other application research fields. Wood tar is an international tight product, and wood vinegar can form a variety of chemical products. (Source: Jiangxi Forestry Science and Technology News, No.5, 2006) The development and utilization of biomass energy has become an important measure for many countries in the world to increase revenue and reduce expenditure, turn harm into benefit and protect the environment. According to a survey report published by the United nations environmental protection agency, at least several industrialized countries have made remarkable achievements in the development and utilization of "green energy", and some of them have greatly alleviated the contradiction of energy shortage in their own countries by implementing the "green energy" plan? At the same time, the environment is effectively improved. While China is rich in biomass resources, we should rationally develop and utilize it, improve the utilization technology of biomass energy, improve the efficiency of energy utilization, make the utilization of biomass energy in China more perfect, and finally make biomass energy one of the important energy sources in China.