The so-called biomass energy refers to the energy generated by biomass conversion. Commonly used biomass includes plant-crops, fuelwood, grass, wood, human and animal feces, industrial and agricultural organic waste, organic wastewater and so on. These biomass can be directly or indirectly derived from green plants and solar energy (through human and animal digestion or industrial and agricultural processing). Therefore, it is also called "green energy", which is essentially materialized solar energy. According to calculation, the biomass energy that can be produced by photosynthesis every year in the world is five times as much as the current global energy consumption.

Because the biomass energy is huge, and there are few or no pollutants produced in the conversion process, countries all over the world are developing conversion technologies for deep utilization of biomass energy with high efficiency, so that biomass can be used as fuel for heat energy, electric energy and power, and has a wide range of uses. There are two conversion techniques:

Convert biomass into alcohol by liquefaction. Burning 1 kg alcohol can release 29,726 kilojoules of heat, which is higher than that of ordinary coal. Moreover, alcohol is a liquid energy source, which is convenient to use, store and transport. Ordinary gasoline generators can use pure alcohol as fuel with a little modification. If you use a mixture of gasoline and alcohol to drive a car, the car generator can be used without modification. 1 liter of alcohol can drive a car on the highway 16 km.

Alcohol is produced by microbial fermentation of organic substances such as starch and sugar. There are many biomass containing starch and sugar, including sugarcane, beet, corn, sorghum, cassava, potato, aquatic plants and algae. Can be raw materials for producing alcohol.

Brazil has made great achievements in this regard. As early as 1975, Brazil formulated the "alcohol plan" to gradually replace oil with alcohol or a mixture of alcohol and gasoline, thus solving the problem of transportation energy supply. At present, 90% of cars in Brazil use alcohol as fuel. At present, 30% of gasoline in the United States is mixed with alcohol, and the amount of alcohol mixed is about 10%.

Methane-based biogas is produced by fermentation process. In China, 200 million tons of firewood and standard coal are burned as farm fuel every year, accounting for 65,438+05% of China's total energy consumption. But the energy efficiency is relatively low.

Using human and animal manure and straw as the main raw materials to develop biogas digesters not only solves the problem of domestic fuel, but also maintains the fertility of farmland and reduces the pollution of chemical fertilizers to water bodies. 1990, more than 4 million households in China used small biogas digesters, with an annual output of 10 billion cubic meters, and the installed capacity of biogas power stations was more than 2,000 kilowatts. At present, China has the largest number of household biogas digesters.

At present, many large-scale urban sewage treatment plants in China use the solid waste of the treatment plants for biogas fermentation, and the generated biogas is used for power generation. In more than 5000 sewage treatment plants in Britain, 1/3 is powered by biogas produced by fermentation. The French have built two garbage fermentation treatment stations in the south of limoges, which can treat 84,500 tons of garbage every year and produce 800 cubic meters of biogas every hour. These biogas have been used by some factories and gas companies.

For example, in the past 10 years, the capacity of bio-power generation in the United States has reached more than 4 million kilowatts, mainly using gaseous fuels after gasification of industrial wastes of wood and wood products. Combined with the control of urban environmental pollution, foreign countries began to use garbage to generate electricity, and the technology was mature. Japan alone operates about 100 garbage power stations, and plans to develop the installed capacity of garbage power stations to 4 million kilowatts. Therefore, using biomass energy to generate electricity is one of the new trends of new energy power generation.

China is an agricultural country with abundant material and energy resources. The annual resources are 30 million tons of fuelwood, 450 million tons of straw and 0./kloc-0. 50 million tons of rice husk. In addition, it also produces a large number of domestic sewage, garbage and industrial wastewater discharged by cities.

At present, the utilization of biomass energy to generate electricity in China is still small-scale and small-scale. The rice husk conversion power generation capacity is only 5000 watts, and the biogas power generation device is about 140, with a total capacity of only 2000 kilowatts. In addition, China has also introduced a garbage power station with a power generation capacity of 4,000 kilowatts.