1.2.3.1 The feasibility of biomass gasification gas as fuel

As China’s energy situation becomes worse, the policy of national environmental protection has become stricter, and it is necessary to adapt to the actual situation of power generation tech­nology to reduce operation and maintenance costs (Dong et al., 2007). The safe operation of power generation enterprises has become more and more urgent. Using gas fuel especially some flammable industrial waste as a supplemental fuel cannot only help the power generation enter­prises to reduce the production costs but also reduce the NOx emissions of pollutants effectively.

Biomass is one of the earliest sources of energy, especially for the rural areas where biomass is the only accessible and affordable one. The waste from agriculture and industry can be used as raw material in biomass gasification for electric power generation. Gasification efficiency and system efficiency increase and tar content in fuel gas decreases when the gasification technology is put into operation. From the chemical point of view, the composition of biomass is a C-H compound. It exists in the conventional mineral sources of energy such as oil, coal and other similar sources (coal and oil are all biomass). Biomass generates organic compounds through photosynthesis by plants, including agriculture and forest waste (such as straw, straw, branches, etc.), firewood, crop residues from sugar industry, municipal organic waste, energy crops and animal waste. Their characteristics and utilization patterns have been very similar to those of fossils. Some biomass gas main compositions and low calorific values have been listed in Table 4.8.

China is rich in biomass resources, and except for firewood and livestock feed, most of them are burnt directly and with low utilization rate. Therefore, it is important to change the situation and to increase the energy utilization efficiency, which would promote the national economic development and environmental protection. Biomass energy utilization started in China late, but the development of boiler capacity has been very fast. More and more medium and large cities have formulated a corresponding demand. Regulations and restrictions on the use of fuel gas boilers, such as in Beijing, Shanghai, Xi’an, where construction of new coal-fired boiler room plant is no longer approved. After 10 years of development, from the pure laboratory research to pilot scale, biomass gasification has been successfully used in production practice. The Thermal Engineering Department of Harbin Institute of Technology has developed fluidized bed combus­tion technology for biomass energy utilization and has resulted in manufacturing of domestic combustion boilers, such as a 12.5 t/h bagasse fluidized bed boiler, a 4t/h rice husk fluidized bed boiler, and a 10 t/h wood and sawdust fluidized bed boiler. The efficiencies are very high, up to 99%.