Promote the green, low-carbon and circular development of the biomass power generation industry



In order to accelerate green and low-carbon development, jointly promote high-quality economic development and high-level protection of the ecological environment, according to the unified deployment and overall requirements of the Ministry's leading Party Group to carry out the theme education of "never forget the original intention, keep the mission in mind", combined with the central theme education and the designated help arrangement of atmospheric supervision, Xu Huaqing, director of the National Climate Center, led 5 people from the Strategic Planning Department and the Carbon Marketing Department to carry out special research activities on the green low-carbon cycle development of the biomass power generation industry to understand the development of the biomass power generation industry, the recycling of biomass resources, the transformation of ultra-low emissions of enterprises, the coordinated control of air pollutants and greenhouse gas emissions and other problems. The direction of green low-carbon cycle development of biomass power generation industry and the possibility and potential of realizing negative carbon dioxide emission in the future are discussed.

Basic understanding of biomass power generation industry

Biomass energy is an important renewable energy with basic features such as green, low-carbon and recycling. As an important way to build a low-carbon energy system in rural areas, biomass power generation industry plays an important role in promoting the transformation of green agricultural development and promoting the employment of rural labor force. It is of great significance to promote resource recycling, solve rural environmental pollution and explore potential negative greenhouse gas emission technologies.

First, although China's biomass resources are rich, the scale of biomass energy utilization is still relatively limited. The 13th Five-Year Plan for the development of biomass energy clearly points out that accelerating the development and utilization of biomass energy is an important part of promoting the revolution in energy production and consumption, and an important task of improving environmental quality and developing a circular economy. By 2020, biomass energy will basically achieve commercialization and standardized utilization, and the annual utilization of biomass energy will be about 58 million tons of standard coal. It is estimated that the total amount of biomass resources such as crop straw and agricultural product processing residues, forestry residues and energy crops, domestic waste and organic waste that can be used as energy resources in the country is equivalent to about 460 million tons of standard coal each year, of which 400 million tons of agricultural waste resources are converted into about 200 million tons of standard coal, and the amount of forestry waste resources is 350 million tons. Converted into about 200 million tons of standard coal, the remaining relevant organic waste resources are about 60 million tons of standard coal. 

In 2017, China's biomass energy for power generation and heating only 17.3 million tons of standard coal, as of 2018, China has put into operation 902 biomass power generation projects, connected to the grid installed capacity of 17.843 million kilowatts, annual power generation of 90.68 billion KWH, including: There were 321 agricultural and forestry biomass power generation projects, with a grid-connected installed capacity of 8.063 million kW and an annual generating capacity of 35.74 billion KWH. The average utilization hours of power generation equipment in the industry were 4,895 hours. There were 401 waste-incineration power generation projects, with a grid-connected installed capacity of 9.164 million kilowatts, an annual generating capacity of 48.81 billion kilowatt-hours, and an annual disposal of 130 million tons of garbage. There are 180 biogas power generation projects, with an installed capacity of 616,000 kilowatts and an annual generating capacity of 2.41 billion kilowatt-hours. From the perspective of geographical distribution, China's agricultural and forestry biomass power generation projects are mainly concentrated in North China, Northeast China, Central China and East China, where crops are rich. Due to the impact of industrial policies, some enterprises have converted to cogeneration, power generation subsidies have not been timely reissued, and some enterprises have been shut down due to tight capital chain. In 2018, the average utilization hours of power generation equipment in China's biomass power generation industry were 4,895 hours, a decrease of 774 hours compared with the previous year.

Second, China's biomass power generation is of great significance for promoting the green growth of agriculture and promoting labor employment. The Outline of Poverty Alleviation and Development in Rural China (2011-2020) clearly states that we will accelerate the development and utilization of renewable energy in poor areas, develop biomass energy according to local conditions, and promote the application of ecological energy projects such as biogas, energy-saving stoves, solid formed fuels, and centralized gas supply stations for straw gasification. Biomass power generation is an important carrier for the integrated development of agriculture, industry and service industry. It has the characteristics of long industrial chain and strong driving force. It can not only relieve farmers' worries about crop straw harvesting and disposal, but also realize clean production, waste resource utilization and ecological industrial model, improve agricultural sustainable development ability and effectively promote agricultural green growth. It is also conducive to solving the employment problem of some local rural labor force. It is estimated that according to the annual consumption of about 54 million tons of agricultural and forestry waste, the annual fuel purchase payment to farmers is about 15 billion yuan, which has helped about 200,000 farmer families get rid of poverty and become rich. Taking Nangong Bio-Power Generation Co., Ltd. as an example, its annual power generation capacity is 200 million KWH, and it consumes about 300,000 tons of agricultural and forestry waste. The raw materials are mainly agricultural and forestry waste such as cotton straw, corn straw, corncob, wheat straw, bark, branches and wood segments collected by farmers within a radius of 150 kilometers around the power generation company. The purchase price of fuel heating value per ton of raw materials is between 280-430 yuan, which is converted to pay more than 80 million yuan to farmers every year, and can directly provide rural surplus labor employment of about 4,000 people. In some under-developed areas, the biomass power generation industry has fully docking targeted poverty alleviation, which has become a powerful move to win the battle against poverty.

Third, China's biomass power generation is of great significance to promote the recycling of resources and solve rural environmental pollution. The "Opinions of the Central Committee of the Communist Party of China and The State Council on Comprehensively Strengthening Ecological Environmental Protection and Resolutely Fighting the Battle of Pollution Prevention and Control" clearly requires that open burning of straw is strictly prohibited in accordance with the law, and comprehensive utilization is comprehensively promoted. According to the "Environmental Status Bulletin", in 2018, satellite remote sensing monitored a total of 7647 straw burning fire points in the country (excluding fire point information under cloud cover), mainly distributed in Heilongjiang, Jilin, Inner Mongolia, Shanxi, Hebei, Liaoning and other provinces. According to the estimation of the relevant departments in Heilongjiang, in 2018, The province's investment in banning crop straw open burning reached 6 billion yuan. Biomass power generation, as an effective way to deal with agricultural and forestry waste, not only has a great effect on clean heat supply and power generation, but also can effectively solve the open burning of straw, reduce rural environmental pollution, and the ash after combustion can also be used as an organic fertilizer, truly realizing the "waste to treasure" of agricultural and forestry and domestic waste. This is also the unique property of biomass energy power generation that is different from other renewable energy sources. Biomass power generation is also an effective environmental protection treatment project. Through biomass power generation, agricultural and forestry waste resources are utilized in high value, which can reduce a series of environmental problems such as soil and water pollution, space waste, fire safety hazards, and biological disease threats caused by agricultural and forestry waste to a certain extent. Effectively solve the impact of agricultural and forestry waste decay on village appearance and the environmental pollution and safety hazards caused by straw burning in the field, which is conducive to improving rural environmental health and residential living conditions.

Fourth, China's biomass power generation is of great significance to explore zero emission and even negative emission technologies of greenhouse gases. The results of the simulation studies related to the IPCC Special Report on Global Warming of 1.5 ° C released by the Intergovernmental Panel on Climate Change in 2018 show that the 1.5 ° C emission reduction path given by all models relies to some extent on carbon dioxide removal technology (CDR). Existing or potential CO2 removal measures include afforestation and reforestation, land restoration and soil carbon sequestration, biomass + carbon capture and storage (BECCS), direct air carbon capture and storage (DACCS), enhanced weathering and ocean alkalization. According to the analysis, by the end of this century, the scale of carbon dioxide removal technology in the 1.5 ° C path is about 100 to 100 billion tons, of which biomass energy + carbon capture and storage (BECCS) is more prominent, and the demand for BECCS to achieve the 1.5 ° C goal is about 15 billion tons of CO2/ year.

Biomass power generation comes from biomass, which effectively absorbs carbon dioxide in the atmosphere during the growth process, as a fuel or industrial raw materials process, although carbon dioxide is generally emitted into the atmosphere again, but from the perspective of the life cycle can achieve net zero emission of carbon dioxide, that is, the so-called "carbon neutral". If carbon capture and storage technology is used to capture carbon dioxide released during biomass energy use before it is released into the atmosphere and injected into deep underground reservoirs that meet specific geological conditions for permanent storage, negative emissions can be achieved. Biomass power generation + carbon capture and storage is a potential key technology to achieve medium - and long-term economy-wide "net zero emissions", and it is extremely necessary to make technical strategic reserves to promote the realization of medium - and long-term net zero greenhouse gas emissions.

The existing problems and challenges of biomass power generation

The sustainable and healthy development of biomass energy is not only an important task to promote the revolution of energy production and consumption, improve urban and rural environmental quality, and promote green, low-carbon and circular development, but also a major social issue affecting people's livelihood. The research found that biomass power generation enterprises currently have some problems and challenges in atmospheric pollutant emission standards, ultra-low emission transformation, nitrogen oxide treatment, material stacking and covering, tax incentives, carbon dioxide collaborative control, etc., which have a negative impact on the sustainable and healthy development of the industry to a certain extent.

One is the lack of clearly enforced flue gas emission standards for biomass power plants. The survey found that at present, there is no separate flue gas emission standard for biomass power generation, and most places refer to coal-fired power generation or natural gas power generation. In 2010, biomass power generation enterprises usually refer to the third period of the "thermal power plant emission standards for air pollutants" with coal gangue as the main fuel of the boiler flue gas discharge standards, its atmospheric particulate matter, sulfur dioxide, nitrogen oxides shall not exceed 50mg/Nm3, 200mg/Nm3, 400mg/Nm3; With the gradual improvement of environmental protection requirements, the flue gas emission standards in 2013 were adjusted to 30mg/Nm3, 200mg/Nm3, 200mg/Nm3; In order to fight the battle of pollution prevention and control, in 2018, the Ministry of Ecology and Environment issued the "Announcement on the Implementation of Special Emission Limits for Air Pollutants in Beijing-Tianjin-Hebei Air Pollution Transmission Channel Cities", and the flue gas emission standards were further adjusted to 20mg/Nm3, 50mg/Nm3, and 100mg/Nm3. The implementation of ultra-low flue gas emission standards for biomass generators has brought greater pressure on enterprises to control the emission of air pollutants.

Second, the ultra-low emission transformation cost of biomass power generation enterprises is relatively high. The "Action Plan for the Comprehensive Control of Air Pollution in the Autumn and Winter of 2018-2019 in Beijing, Tianjin, Hebei and surrounding Areas" issued in 2018 clearly requires: "Biomass boilers should use special boilers, and it is prohibited to mix coal and other fuels, supporting cloth bags and other efficient dust removal facilities; Actively promote the ultra-low emission transformation of biomass cookers in urban built-up areas; Accelerate the low-nitrogen transformation of gas boilers, and in principle, the nitrogen oxide emission concentration after the transformation shall not be higher than 50 mg/cubic meter." The survey found that in order to achieve the ultra-low emission requirements of atmospheric pollutants in biomass direct combustion boilers, the National Energy Company invested a lot of money to carry out desulfurization and denitrification transformation of its power generation projects, and in 2018, the company only invested about 283 million yuan in flue gas treatment. According to the economic analysis of the existing construction projects, the investment of a 30 MW unit desulfurization, denitrification and dust removal integrated technical transformation project is about 17 million yuan, the investment of sewage treatment is about 3 million yuan, the investment of dust screen construction is about 1 million yuan, and the annual operation and maintenance cost of environmental protection facilities is about 10 million yuan. The increase in costs has made it difficult for the biomass power generation industry, which is already at the break-even point.

Third, the treatment of nitrogen oxides in biomass power generation is still facing technical problems. Considering that the raw materials used by biomass power generation enterprises are agricultural and forestry straw, etc., the calorific value, water content, sulfur content and alkali metal content of the fuel are very different from the fuel characteristics of coal power plants, and the ultra-low emission transformation standards of the standard coal power industry are analyzed from the technical level, and there is no obstacle to achieve ultra-low emission of particulate matter and sulfur dioxide. But in the reduction of nitrogen oxides exposed a series of problems, mainly as the current technology is not mature, there are also ozone escape and power consumption and liquid oxygen production and storage security risks and other problems, this is due to the biomass fuel containing chlorine elements and alkali metals, while the fuel ash and water content is high, the furnace temperature can only reach 800 degrees. Far less than coal-burning boilers. At present, non-selective catalytic reduction (SNCR) technology is usually used, because the furnace temperature can not reach the best reaction temperature of SNCR technology, resulting in incomplete reaction, a large amount of ammonia escapes and forms crystallization on the tail heating surface tube row, the bag dust collector box and the induced draft fan impeller, resulting in a decrease in denitrification efficiency and boiler efficiency. At present, Nangong Biopower Co., Ltd. is further implementing the ozone denitrification transformation, but the enterprise reflected in the survey that the operating cost is large, 1 kg of ozone consumes about 8 degrees of electricity, a 30MW biomass generator unit needs an additional power consumption of 1.72 million to 4.6 million degrees per year (according to 300 days of operation time), and there are problems such as liquid oxygen safety risks and ozone escape.

Fourth, the material stacking and covering requirements of biomass power plants should not be simply applied. The investigation found that Nangong Bio-Power Generation Co., Ltd. was repeatedly required to implement the provisions that "the open-air stacking of materials in the material yard should be covered by dustproof nets, and the covered area should be greater than 85%" in the strengthened inspection of air pollution prevention and control. However, enterprises and the government safety production authorities believe that covering the biomass fuel storage field is easy to bring fuel spontaneous combustion and other hidden dangers. This is because the biomass material used by enterprises has a large water content and the size is more than 5 cm. Although it is not easy to generate dust, the black dust filter is easy to absorb heat and the fuel is easy to spontaneous combustion, and there are great hidden dangers in high temperature weather. In addition, in order to avoid dust generation of materials, irregular fog gun dust removal is required according to relevant regulations, but this will correspondingly increase the water content of materials, which is not conducive to full combustion, but will cause more pollutant emissions and other problems.

Fifth, the preferential tax policy of biomass power generation industry is greatly restricted by environmental protection. Biomass enterprises enjoy the preferential policy of VAT collection and refund, but they will lose concessions at the same time when enterprises face environmental penalties. According to the spirit of the Notice of the State Administration of Taxation of the Ministry of Finance on Issuing the Preferential Catalogue of Value-added Tax for Products and Services of Comprehensive Utilization of Resources in 2015, "Taxpayers who have enjoyed the policy of VAT collection and refund as stipulated in this notice are punished for violating laws and regulations of tax and environmental protection (except for warnings or fines of less than 10,000 yuan for a single time). Within 36 months from the month after the punishment decision is issued, they shall not enjoy the VAT collection and refund policy stipulated in this notice." Biomass fuel because of its own characteristics, low ignition point, high humidity, easy spontaneous combustion, can not be closed to the material field, but the investigation of the enterprise reflected that the local environmental law enforcement departments to the material field is not closed, according to the provisions of the "People's Republic of China Air pollution Prevention Law" article 48, issued a penalty of more than 10,000 yuan environmental fine notice, At the same time, it will also cause the problem that the enterprise will no longer enjoy the VAT refund after 36 months, which has a significant impact on the survival and efficiency of the enterprise.

Sixth, the understanding of the importance of carbon dioxide control of biomass power generation enterprises has not been in place. Combined with the problem of air pollutant reduction and greenhouse gas collaborative control of two biomass power plants in Heze, which was the focus of the 22nd round of air strengthening supervision, the survey also found that there is a large gap in the understanding of the importance and urgency of carbon dioxide emission control.