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Biomass liquefaction is the partial or complete conversion of biomass into liquid fuel through thermochemical or biochemical methods. Liquefaction methods mainly include thermal decomposition method, direct liquefaction method, hydrolysis fermentation method and vegetable lipidization method. In addition to combustible gas and coke obtained by carbonization and pyrolysis of biomass, the volatile components contained in it can be used to synthesize gasoline and hydrolyze to produce alcohol. Crude wood vinegar, the liquid product of dry distillation, contains acids, esters, aldehydes, ethers, hydrocarbons and other organic compounds. Those with industrial application value include acetic acid, ethyl acetate, methanol, propanol, acetaldehyde, furfural, acetaldehyde, etc. Turpentine is also an important product of retorting. Due to the high energy density of liquid fuel, which is convenient for storage, transportation and use, and high-quality fuel can be obtained after refining, the liquid products of biomass pyrolysis have received much attention in recent years. Biodiesel technology has developed rapidly in recent years. There are more than 400 kinds of herbal and woody oil-containing plants in my country, and the oil contained in their seeds is mainly glycerol tricarboxylic acid ester. In order to make its combustion characteristics closer to that of diesel, methanol or ethanol is added to the oil in a quantitative manner. Under the action of a catalyst, an esterified fuel similar to diesel is obtained and glycerin and other by-products can be separated. The transesterification reaction is illustrated as follows:: Reaction: http://www.cntcw.com/Doc/data.WebNoteBooks2007/03/20070316144200/p6_44.jpg In the formula, R1, R2 and R3 are the hydrocarbon groups of fatty acids, and R4 is methyl or ethyl. Animal and vegetable oils have been studied as power fuels for a long time. In recent years, as petroleum resources are increasingly depleted, animal and vegetable oils and fats have once again attracted people's attention as alternative energy sources. The calorific value of vegetable oil is roughly equivalent to 87-89% of diesel of the same quality, and increases with the length of the carbon chain. Due to its high viscosity, it has poor atomization effect in the engine and is generally mixed with diesel. The large-scale use of alcohol as automobile fuel is a major development in the application of biomass energy in recent years. This can reduce dependence on petroleum energy and reduce vehicle exhaust pollution. 90% of cars in Brazil use alcohol fuel, a renewable biomass energy source. Starch or sugar in biomass or raw materials that can be converted into sugar can be further converted into alcohol after saccharification under the action of microorganisms. Available raw materials include starchy agricultural products (sweet potatoes, corn, etc.), molasses raw materials (waste honey from sugar factories, etc.), wild plants containing a certain amount of starch (lycoris, fern root, oak kernels, etc.), cellulose raw materials (wood chips, sawdust), etc. After crushing and cooking, distiller's yeast is added to saccharify the raw materials, and then fermented under the action of yeast to convert the sugar into alcohol while releasing carbon dioxide. The total reaction process can be expressed as: http://www.cntcw.com/Doc/data.WebNoteBooks2007/03/20070316144200/2_8_5.35.gifhttp://www.cntcw.com/Doc/data.WebNoteBooks2007/03/20070316144200/2_8_5.36.gif http://www.cntcw.com/Doc/data.WebNoteBooks2007/03/20070316144200/2_8_5.37.gif Humanity has a long history of developing and utilizing biomass energy. Due to the large amount of resources and strong renewable nature, with the development of science and technology, people continue to discover and cultivate high-efficiency energy plants and biomass energy conversion technologies. The rational development and comprehensive utilization of biomass energy will definitely improve human living standards and make more positive contributions to improving the global ecological balance and the human living environment.