The main ways of distributed utilization of biomass energy are molding to make materials and biogas (degassing and gasification). Biomass molding fuel and biogas are consistent with the use of traditional fossil fuel habits, is a good substitute for coal or natural gas, in line with the requirements of sustainable development, to achieve the transformation of low-grade fuels to high-grade, low-pollution fuels, can be widely used in a variety of small-scale hot-water boilers, hot air stoves, home heating stoves or fireplace, not only to solve the urban and rural families of the cooking and heating, but also can be used in small power generation and heating facilities, as the Small and medium-sized thermal power plants to create conditions for the adjustment of energy structure.

2.1 Current situation of distributed utilization of biomass energy in foreign countries

(1) molded fuel production and application of Europe and most other regions in the production of molded fuel is mainly wood biomass as raw material. At present, most of them are used in a variety of small hot water boilers, hot air stoves, home heating stoves or fireplaces, and some of them are used in small community cogeneration power supply stations to meet the heating needs of residents. China's new urbanization plan clearly put forward the rural renewable energy requirements in 10 years to reach 13%, which the use of biomass molding fuels for rural, small towns and households to provide cooking and heating energy, will be an important way.

(2) Biogas production and industrial use, biogas refers to the conversion of biogas from the biological must want to gas, including refined gas, split into gas and gas production, biogas currently has a greater cost advantage, so biogas is often referred to specifically biogas. According to the International Energy Agency, in 2012, there were more than 13,800 biogas power plants in operation in Europe, with an installed capacity of 7.5 GW. Most of them are cogeneration, and a small part of them are fed into the natural gas pipeline network, with power generation and heat supply amounting to 44.5 GWh and 1.1x105 GJ, respectively.At the end of 2013, Germany's biogas production plants had reached about 8,000, with an installed capacity of about 3.8 GW, 98% of which were used for power generation, and cogeneration was practiced, with power supply amounting to 2.7x104 GWh in that year, heat supply amounting to 1.2x104 GWh, respectively, accounting for 4.2% and 0.8% of the total national power supply and heat supply, it is estimated that by 2020, the total installed capacity of biogas power generation will reach 9500 MW. Another 169 biogas plants are supplying gas to the natural gas pipeline network, with a volume of 900 million cubic meters.

2.2 Status of distributed utilization of biomass energy in China

(1) molding hot material production and application, in recent years China began to pay attention to the development of biomass molding fuel industry, the National Development and Reform Commission in the "Renewable Energy Long-Term Development Plan" put forward, and strive to achieve in 2020 the annual utilization of 50 million tons of pellet fuels target. At present, the domestic biomass forming fuel is mainly used in the supply of high-temperature steam in the king industry, including copper and iron, textile, printing and dyeing, papermaking, food, chemical industry, etc. As the domestic biomass forming fuel industry is still in its infancy, the enterprises are scattered, and there is no uniform industry standard and product standard, it is difficult to count the specific industry scale, estimated to be about 5 million tons/year, and the National Energy Administration in the "2014 Energy Work (Guidance) emphasized that the new biomass industrial and civil heating within the year converted to 2 million tons and 800,000 tons (algae steam). And according to the Development and Reform Commission, the National Energy Board and the Ministry of Environmental Protection "on the issuance of energy industry to strengthen the prevention and control of air pollution work program notice", for 2017 biomass molding fuel utilization of more than 15 million tons.

(2) biogas production and application, China's biomass energy resources are abundant, can be used to produce biogas resource varieties, including crop straw, livestock and poultry manure, forestry waste and so on. According to statistics, the total amount of resources that can be used to produce biogas in China is about 700 million tons of standard coal (Table 1). If the technical feasibility and market competitiveness are taken into account, the amount of resources that can be utilized in the past is 250 million tons of standard coal, and the amount of biogas that can be produced is 199 billion cubic meters, which is equivalent to about 120 billion cubic meters of natural gas, equivalent to 2/3 of China's 2014 natural gas consumption of 80 billion cubic meters.

In recent years, China's biogas industry has made great progress, with biogas production reaching 15 billion m3/year, CO2 emission reduction of 7.65 million tons, and about 4,000 large and medium-sized biogas projects. However, in general, China's biogas projects dealing with agricultural organic waste are relatively small in scale and far away from cities and towns, and only a small amount of biogas generated is used for power generation and centralized gas supply (the amount of biogas used for power generation accounts for about 2.53% of the total gas production, and the centralized gas supply accounts for about 1% of the total gas production), and a large amount of biogas is used for the production of the farms themselves, and as a living fuel. The average capacity of agricultural biogas projects is only 283 cubic meters, and large-scale biogas projects with a capacity of more than 1,000 cubic meters only account for about 9%, so the development of biogas technology and industry is in urgent need of transformation and upgrading.

(3) Biomass gasification for power generation and gas application, biomass gasification for power generation and gas application is the distributed utilization of biomass energy with Chinese characteristics. Based on biomass pyrolysis gasification technology, China develops biomass pyrolysis gasification centralized gas supply system to meet rural residents' cooking and heating gas, and the related technology has been initially applied. Among them, using biomass pyrolysis and carbonization technology to build biomass charcoal, gas and oil multi-connected rigorous system to provide rural residents with living gas, and at the same time produce biomass charcoal and bio-tar, which has achieved better economic and social benefits, and has been preliminarily popularized in Measuring North, Anhui, and Henan, etc., and has a better prospect for development. In the area of biomass gasification for power generation, a variety of fixed-bed and fluidized-bed gasification furnaces have been developed using wood chips, rice husks, straw and other biomass as raw materials, and gasification power generation units of different specifications ranging from 400 kilowatts to 10 kilowatts have been successfully developed, and exported to Thailand, Myanmar, Laos and Taiwan, which is one of the countries with the largest number of small and medium-sized biomass gasification for power generation in the international arena.