At present, biomass energy is second only to coal, oil and natural gas and ranks fourth in the world's total energy consumption. Biomass energy is a kind of renewable energy derived from solar energy and has the characteristics of low carbon content. The development and utilization of biomass energy with new technologies not only helps to reduce the greenhouse effect and the virtuous ecological cycle, but also replaces some fossil fuels such as petroleum and coal, becoming one of the important ways to solve energy and environmental problems. Biomass energy, as an important renewable energy resource, has the characteristics of a wide variety of resources and a wide range of resources. In today's increasingly scarce energy situation, biomass energy has attracted more and more attention.
The most important of the renewable energy development goals proposed by the European Union is biomass energy. The main utilization methods of biomass energy are power generation, heating, and liquid fuel production. Biomass energy is the energy source with the longest history of human utilization. The traditional direct combustion heat utilization is still the most important method at present, with an annual utilization of about 1.3 billion tons of coal equivalent. High-quality utilization is the direction of the development of biomass energy. At present, about 50 million kilowatts of electricity are used worldwide (mainly in Northern Europe), and the annual production of liquid fuels is about 20 million tons of oil equivalent (mainly in Brazil and the United States).
China is a large agricultural country with a large population. Changing the way of energy production and consumption, and the development and utilization of biomass resources are of special significance to the establishment of a sustainable energy system, the promotion of national economic development and environmental protection, especially the development of rural areas in China.
80% of China's population lives in rural areas, and agricultural biomass such as fuelwood, straw, and livestock is very rich. These are the main living fuels in rural areas. Although the use of coal and other commercial energy in rural areas is increasing rapidly, biomass energy still occupies an important position. In 1998, the total energy consumption in rural life was 365 million tons of standard coal, of which straw and fuel wood accounted for 207 million tons of standard coal, accounting for 56.7%. From 1991 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 rate of 2.4%.
Biomass refers to various organisms formed through photosynthesis, including all animals, plants and microorganisms. The so-called biomass energy is the energy form of solar energy stored in biomass in the form of chemical energy, that is, energy with biomass as a carrier. It is directly or indirectly derived from the photosynthesis of green plants and can be converted into conventional solid, liquid and gaseous fuels. It is inexhaustible and inexhaustible. It is a renewable energy source and the only renewable energy source. Carbon source. The original energy of biomass energy comes from the sun, so in a broad sense, biomass energy is a manifestation of solar energy.
At present, many countries are actively researching, developing and utilizing biomass energy. Biomass energy is stored in organic matter such as plants, animals and microorganisms that can grow, and it is converted from solar energy. Except for fossil fuels, all energy materials derived from animals and plants in organic matter belong to biomass energy, which usually include wood, forest waste, agricultural waste, aquatic plants, oil plants, urban and industrial organic waste, animal manure, etc. Biomass energy resources on the earth are relatively abundant, and it is a harmless energy source. The earth produces 173 billion tons of materials each year through photosynthesis, and the energy contained therein is equivalent to 10-20 times the total energy consumption of the world, but the current utilization rate is less than 3%.
From the perspective of energy demand, the advantages of obtaining energy from biomass are shown in the following aspects:
① Replace imported energy with local resources to reduce the country’s dependence on imported energy
②Diversify the country's fuel utilization and reduce dependence on one kind of energy.
③It is a relatively clean energy that can replace polluting energy (such as low-quality coal) or controversial energy (such as nuclear power, etc.).
The economic feasibility of obtaining energy from biomass depends largely on the price of biomass relative to other fuels. Compared with coal prices in the world market, biomass resources such as agricultural and forest waste wood processing industry residues and energy crops under study are not economical. In many parts of Europe, bark alone is the cheapest, comparable to coal prices. Therefore, from the current stage, biomass energy research is a contribution to future technological development and global environmental protection activities.
China has abundant biomass energy resources. According to estimates, China's theoretical biomass energy resources are about 5 billion tons of standard coal, which is about 4 times the current total energy consumption in China. Under collectible conditions, the biomass energy resources currently available in China are mainly traditional biomass, including crop straw, fuelwood, poultry manure, household garbage, industrial organic waste residue, and wastewater.
51% of agricultural output is converted into straw, with an annual output of about 600 million tons, about 300 million tons can be used as fuel, equivalent to 150 million tons of standard coal; the annual available forestry waste is about 900 million tons, about 300 million tons It can be used as energy, equivalent to 200 million tons of standard coal. Energy crops such as sweet sorghum, jatropha, pistacia, and tung tree can be planted in an area of more than 20 million hectares, which can meet the raw material demand for bio-liquid fuel with an annual output of about 50 million tons. The theoretically annual production of biogas from livestock and poultry breeding and industrial organic wastewater is about 80 billion cubic meters.