How to dispose of garbage

Biomass energy is solar energy fixed on the earth through photosynthesis of plants, and is most likely to become one of the major new energy sources in the 21st century. It is estimated that the energy stored by plants every year is about 10 times the world's main fuel consumption; and the amount used as energy is less than 1% of the total amount. In order to complete the carbon cycle of nature, most of these unused biomass are decomposed naturally to release energy and carbon and return to nature. In fact, biomass energy is the earliest, most abundant, and most direct energy source used by humans. To date, more than 1.5 billion people in the world still rely on biomass as their living energy source. Biomass combustion is a traditional utilization method, which not only has low thermal efficiency, but is also labor-intensive and causes serious pollution. Biomass energy conversion technology can efficiently utilize biomass energy to produce various clean fuels, replace coal, oil and natural gas and other fuels, and produce electricity. And reduce dependence on fossil energy, protect national energy resources, and reduce environmental pollution caused by energy consumption. Experts believe that biomass energy will become an important part of sustainable energy in the future. By 2015, 40% of total global energy consumption will come from biomass energy.

1.2 Energy and Environment

Human beings are facing the dual pressures of development and environment. The development of the economy and society relies on energy as an important driving force. The more the economy develops, the more energy is consumed, especially the increase in fossil fuel consumption. There are two outstanding problems before us: one is the increasingly serious environmental pollution, and the other is the existing of fossil fuels will one day be exhausted. Based on consumption projections, the world's oil resources will eventually be exhausted in the next 50 to 80 years. By 2059, the 200th anniversary of the drilling of the first oil well in the world, there will probably be very little oil resources left in the world. On the other hand, due to excessive consumption of fossil fuels, these limited resources are consumed too quickly and prematurely, releasing a large amount of excess energy and carbon, breaking the energy and carbon balance of nature, causing ozone layer destruction and global climate warming. , the direct factor of catastrophic consequences such as acid rain. This means that if new energy sources are not developed to replace the dominant position of fossil conventional energy sources in the energy structure, serious and catastrophic energy and environmental crises will inevitably occur in the 21st century. They are the three major problems that mankind will face in the next century. One of the most likely disasters.

1.3 National Security

Of course, developing biomass energy is not the only way to obtain new energy. Human beings can use high-tech means to obtain nuclear energy and even obtain energy from outer space. However, The harm is also obvious to all. First of all, the development of nuclear energy is likely to bring new instability factors to the already uneasy world, and even directly threaten the living environment of mankind; secondly, the limited outer space that countries or groups can reach under the technological level of mankind in the next century Energy development in the region will inevitably trigger new competition or disputes, and its consequences are self-evident. Biomass energy is not only the safest and most stable energy source, but also can produce different types of energy through a series of conversion technologies, such as solidification and carbonization to produce biomass fuel, gasification to produce gaseous fuel, liquefaction and vegetable oil. Liquid fuels can be obtained, electricity can be produced if needed, and more. At present, countries around the world, especially developed countries, are committed to developing efficient and pollution-free biomass energy utilization technologies to protect their own mineral energy resources and provide fundamental guarantees for the sustainable development of the national economy.

2. The development status of foreign biomass energy technology

The development and utilization of biomass energy has long attracted the attention of governments and scientists around the world. Many countries have formulated corresponding development and research plans, such as Japan's Sunshine Plan, India's Green Energy Project, the United States' Energy Farm and Brazil's Alcohol Energy Plan. Other countries such as Denmark, the Netherlands, Germany, France, Canada, and Finland have been conducting their own research and development for many years, and have formed unique biomass energy research and development systems with their own technical advantages.

2.1 Biogas technology

It is mainly anaerobic treatment of livestock manure and high-concentration organic wastewater. It is an earlier-developed biomass energy utilization technology. Before the 1980s, developing countries mainly developed biogas digester technology, using crop straw and livestock manure as raw materials to produce biogas as domestic cooking fuel. Such as household biogas digesters in India and China; while developed countries mainly develop anaerobic technology to treat livestock manure and high-concentration organic wastewater. At present, developed countries such as Japan, Denmark, the Netherlands, Germany, France, and the United States generally adopt anaerobic methods to treat livestock manure, while developing countries such as India, the Philippines, and Thailand have also built large and medium-sized biogas projects to treat livestock manure. Application demonstration project. Using new self-circulating anaerobic technology. Dutch IC Company has achieved a gas production rate of 10m3/m3.d for the anaerobic treatment of beer wastewater, thus greatly saving investment, operating costs and floor space. Developed countries such as the United States, the United Kingdom, and Italy mainly use biogas technology to process garbage. The Staten Waste Treatment Station in New York, the United States, invested US$20 million to process garbage using wet methods. It produces 260,000 m3 of biogas per day and is used for power generation and fertilizer recycling. Benefits It is considerable and it is expected that the entire investment can be recovered within 10 years. The UK has achieved 18MW of biogas power generation using waste as raw material, and will invest 150 million pounds in the next 10 years to build more waste-to-biogas power plants.

2.2 Biomass thermal cracking and gasification

As early as the 1970s, some developed countries, such as the United States, Japan, Canada, and European countries, began to use biomass to produce biomass. Research and development of material pyrolysis and gasification technology. By the 1980s, there were 19 companies and research institutions in the United States engaged in research and development of biomass pyrolysis and gasification technology; 12 Canadian university laboratories were developing biomass pyrolysis and gasification technology. Research on chemical technology; in addition, developing countries such as the Philippines, Malaysia, India, and Indonesia have also carried out research in this area. Tampere Electric Power Company of Finland began to build a waste wood gasification power plant in Sweden with an installed capacity of 60MW and a heat production of 65MW. It was put into operation in 1996: The Swedish Energy Center obtained a World Bank loan and planned to build a waste wood gasification power plant in Brazil with an installed capacity of 20-3OMW. The power plant uses advanced technologies such as biomass gasification and combined cycle power generation to process the local abundant bagasse resources.

2.3 Biomass liquid fuel

Another concerning technology, because biomass liquid fuels, including ethanol, vegetable oil, etc., can be used as clean fuels to directly replace petroleum fuels such as gasoline. . Brazil is the most distinctive country in the development and application of ethanol fuel. In the mid-1970s, in order to get rid of over-reliance on imported oil, it implemented the world's largest ethanol development plan. By 1991, ethanol production reached 13 billion liters. Among the vehicles, nearly 4 million are pure ethanol vehicles, and most of the rest use 20% ethanol-gasoline mixed fuel, which means that ethanol fuel accounts for more than 50% of automobile fuel consumption. In 1996, the U.S. Renewable Resources Laboratory has researched and developed the technology to produce alcohol from cellulose waste. The U.S. Haskell Industrial Group established a 1MW rice husk power generation demonstration project: 12,000 tons of rice husk can be processed annually. The annual power generation is 8 million degrees and the annual output of alcohol is 2,500 tons, which has obvious economic benefits.

2.4 Other technologies

In addition, biomass compression technology can compress solid agricultural and forestry waste into briquette fuel that can replace coal. For example, the United States has developed biomass pellet pellet fuel; third world countries such as Thailand, Philippines and Malaysia have developed rod pellet fuel.

3. Biomass energy in my country

Our country is basically an agricultural country with more than 70% of the total population in rural areas. Biomass has always been one of the main energy sources in rural areas. It also plays an important role in the country's energy composition.

3.1 Biomass Energy Resources

my country’s existing forest, grassland and cultivated land area is 4.14 billion hectares, and theoretically the biomass resources can reach more than 65 billion tons/year (in But On a square kilometer of land area, the amount of organic carbon produced by plants through photosynthesis is approximately 158 tons per year). Calculated based on an average calorific value of 15,000 kJ/kg, the equivalent theoretical resource is 3.3 billion standard coal, which is equivalent to more than three times my country's current total annual energy consumption.

In fact, currently, it can be used as energy Biomass mainly includes straw, firewood, livestock manure, domestic garbage and organic waste water. According to surveys, my country's straw resources currently exceed 720 million tons and about 360 million tons of standard coal. In addition to about 120 million tons used for feed, papermaking, textiles, and building materials, the remaining 600 million tons can be used as energy: Source of firewood Mainly forestry logging, silviculture and pruning, and firewood forests. A survey shows that my country's average annual firewood production is about 127 million tons, equivalent to 74 million tons of standard coal: the amount of livestock manure resources is about 130 million tons of standard coal; the amount of urban garbage The production volume is about 120 million tons, and is increasing at an annual rate of 8%-10%. It is estimated that the total amount of biomass energy resources that can be developed in my country is about 700 million tons of standard coal.

3.2 Biomass energy and utilization

Most of the energy utilization of biomass in my country is used for rural domestic energy, and a very small part is used for industrial production of township enterprises: and the utilization method has long-term Direct combustion has always been the main method in the past. Only in recent years have new technologies begun to be used to utilize biomass energy, but on a smaller scale. The popularity is low and it occupies a very small proportion in the energy structure of the country and even rural areas.

The direct combustion of biomass not only has low thermal efficiency, but also emits a large amount of smoke and ash, which worsens people's living environment and seriously damages the physical and mental health of women and children. In addition, it has extremely negative impacts on ecology, society and economy:

1. When biomass energy must be used but the utilization method is unreasonable, natural resources such as forests will inevitably be cut down unreasonably, destroying natural vegetation and ecological balance;

2. The insufficient utilization of resources such as organic garbage, organic wastewater, organic waste residues, livestock manure and some agricultural wastes not only results in a waste of resources, but also makes them a major source of organic pollution. In addition to causing serious air and water pollution, It also emits a large amount of greenhouse gases, exacerbating the global greenhouse effect;

3. At the same time, with the rapid development of the economy and the improvement of people's living standards, the energy shortage problem will surely become a major issue hindering the sustainable development of the national economy in the 21st century. Sufficient attention must be paid to it and effective measures must be taken to solve it.

In fact, vigorously developing and utilizing biomass energy is of great significance to alleviating energy, environmental and ecological problems in the 21st century and will generate many benefits;

4. Reduce pollution and improve people's living conditions. Whether it is organic sewage treatment, urban waste energy utilization or straw pyrolysis utilization, it is an important and important issue to solve the environmental pollution problem. This is also the primary goal of most biomass utilization.

5. Solve rural energy supply problems and improve farmers' living standards.

my country's rural energy supply is tight, but biomass sources are abundant, so the use of biomass energy can be carried out to improve the energy supply in rural areas. Improve their living standards.

6． Improve the energy structure and reduce pressure on the environment. Our country's exploitable biological resources amount to 700 million tons. If they can be fully developed, they can occupy an important place in our country's energy consumption. This will help improve our country's energy structure, reduce our country's dependence on fossil fuels, and thereby reduce our country's CO2 and SO2, etc. The emission of pollutants is of great significance in ultimately alleviating the pressure caused by energy consumption on the environment.

3.3 Market Demand

It can be expected that with the development of the national economy and the improvement of people's living standards, the market prospects of biomass energy utilization technologies and devices will become increasingly broad. Main basis:

1. At present, most crop straws are burned on the farmland because they cannot be effectively utilized, which not only wastes a lot of energy, but also causes serious environmental pollution and has a certain degree of negative impact on social life and economic development. Such as the smoke and dust incidents that occurred at Chengdu Shuangliu Airport and Capital Airport. With the improvement of living standards, farmers who are gradually getting rich are eager to change the original situation of directly burning straw and firewood for cooking and heating. Using biomass combustible gas as their living energy will improve their sanitary environment and improve their living standards. Improve the quality of life and reduce labor intensity.

2． Many grain, wood, tea, fruit and other processing plants produce a large amount of grain husk, sawdust, wood chips, fruit shells and other waste products every day. Biomass gasification technology is used to convert it into combustible gas to produce high-quality products. Energy, turning waste into treasure, can be said to kill two birds with one stone.

3. Poultry and livestock manure is both a source of extremely harmful environmental pollution and an important biomass energy resource. With the continuous construction and development of large-scale livestock farms, the environmental pollution generated has become increasingly serious. The application of anaerobic technology to treat livestock manure has dual significance in terms of energy and environment.

4. With the rapid development of my country's social economy, the increase in urban population and the improvement of residents' lives, the problem of urban garbage disposal has become increasingly prominent. Taking Beijing as an example, in 1995, the annual garbage output exceeded 4 million tons, and in 1996, the amount of garbage in Beijing reached 4.85 million tons. Using anaerobic technology to treat organic waste can not only obtain energy, but also achieve the purpose of low-cost pollution control.

5. my country's remote areas are rich in biomass resources, and most of them are areas with little or no electricity. Biomass can be gasified to generate electricity, or heat can be produced for self-use.

6． In terms of business, the reason why biomass energy technology has broad market prospects is that the development and utilization of biomass energy can not only obtain inexhaustible energy, but also protect the environment and save resources.

3.4 Current status and problems of the development of biomass energy technology in my country

The Chinese government and relevant departments attach great importance to the utilization of biomass energy. Several major national leaders have given instructions and instructions to strengthen the Energy utilization of crop straws. The National Science and Technology Commission has listed the research and application of biomass energy technology as a key research project in three consecutive national five-year plans, and a large number of outstanding scientific research results and successful application examples have emerged, such as industrial biogas digesters, livestock Fecal biogas technology, biomass gasification power generation and centralized gas supply, bio-briquet fuel, etc. have achieved considerable social and economic benefits. At the same time, our country has formed a high-level scientific research team, including well-known domestic scientific research institutes and colleges and universities: it has a group of famous experts and scholars who are enthusiastic about the research and development of biomass pyrolysis and gasification technology.

a. Biogas technology is the earliest biomass energy utilization technology developed in my country and has been promoted in many factories. In the 1970s, in order to solve the problem of energy shortage in rural areas, my country vigorously developed and promoted household biogas field technology. 5.25 million household biogas pits have been built across the country. In the last three consecutive five-year plans, the country has listed the development of new biogas technology as a key scientific and technological project, and has planned and implemented a large number of research projects and demonstration projects on biogas and its utilization. So far, our country has built more than 30,000 large and medium-sized biogas digesters, with a total volume of more than 1.37 million m3 and an annual biogas output of 55 million m3. There are more than 630 biogas projects with a scale of more than 100 m3, including 583 centralized gas supply stations. There are 83,000 users, with an average annual gas consumption of 431m3. It is mainly used to treat livestock manure and organic wastewater. These projects have achieved a certain degree of environmental and social benefits, and have played a positive role in developing the local economy and my country's anaerobic technology. In the "Ninth Five-Year Plan", efficient anaerobic technology for treating high-concentration organic wastewater and urban garbage was listed as a key scientific and technological project. It was implemented by the Chengdu Institute of Biology, Chinese Academy of Sciences and the Hangzhou Institute of Energy and Environment respectively, and has now achieved expected progress.

The main problems existing in my country's anaerobic technology and engineering are: little research on related technologies, poor matching of auxiliary equipment, low degree of automation, rough processing of non-standard equipment, high engineering cost, and open secondary treatment before and after Serious pollution, etc.

b. my country's biomass gasification technology has made great progress in recent years. The forms of gasifiers range from traditional updraft and downdraft to the most advanced fluidized bed, rapid fluidized bed and twin-bed systems. In terms of applications, in addition to In addition to traditional heating, the most important breakthroughs are rural household gas supply and gasification power generation. During the "Eighth Five-Year Plan" period, the National Science and Technology Commission arranged a scientific and technological research topic on "Biomass Pyrolysis, Gasification and Heat Utilization Technology" and achieved considerable results: using oxygen gasification technology, a biomass medium calorific value gasification device was successfully developed; The following suction fluidized bed technology has successfully developed biomass gasification centralized air supply systems and devices for 100 households: The following suction fixed bed technology has successfully developed biomass gasification and drying systems and devices for food and economic crops; using fluidized beds Retorting process, and successfully developed biomass gasification centralized gas supply systems and devices for 1,000 households. During the "Ninth Five-Year Plan" period, the National Science and Technology Commission arranged a scientific and technological research topic on "Biomass Pyrolysis Gasification and Related Technologies", focusing on the research and development of 1MW large-scale biomass gasification power generation technology and rural straw gasification centralized gas supply technology. At present, nearly 200 rural gasification stations and more than 100 sets of rice husk gasification power generation have been built across the country. The influence of gasification utilization technology is gradually expanding.

c. During the "Eighth Five-Year Plan" period, my country began to explore and research the technology of using cellulosic waste to produce ethanol fuel. It mainly studied the dilute acid hydrolysis and fermentation technology of cellulose waste, and entered the intermediate experimental stage during the "Ninth Five-Year Plan" period. . my country has conducted preliminary research on alternative fuels such as vegetable oil and biomass pyrolysis oil: preliminary experimental research has been conducted on the physical and chemical properties of vegetable oil, esterification modification process and diesel engine combustion performance. During the "Ninth Five-Year Plan" period, a classification survey of wild oil plants and the construction of a breeding base were carried out. There is also some research on biomass liquefaction in my country, but the technology is relatively backward. Research on high-pressure liquefaction and pyrolysis liquefaction is mainly carried out.

d. In addition, during the "Eighth Five-Year Plan" period, our country also focused on scientific and technological research on biomass compression molding technology, introduced foreign advanced models, digested and absorbed them, and developed various types of biomass compression molding machines suitable for my country's national conditions. Used to produce rod-shaped, block-shaped or pellet biomass pellet fuel. The service life of the screw of my country's biomass spiral forming machine is more than 500 hours, which is at the internationally advanced level.

Although my country has made great achievements in the development of biomass energy, there is still a certain gap in technical level compared with developed countries, such as:

a. The development of new technologies is ineffective and the technology used is single. my country's early biomass utilization mainly focused on biogas utilization. In recent years, it has gradually paid attention to the development and application of pyrolysis and gasification technology, and has achieved certain breakthroughs. However, other technologies have been developed very slowly, including alcohol production, pyrolysis liquefaction, and direct combustion. There have been no breakthroughs in industrial technology and the cultivation of fast-growing forests.

b. Due to dispersed resources and backward collection methods, the scale of my country's biomass energy utilization projects is small; in order to reduce investment, most projects use simple processes and rudimentary equipment, resulting in low equipment utilization and low conversion efficiency. Therefore, the return on investment of biomass energy projects is low, the operating costs are high, it is difficult to form economies of scale, and it cannot play its due and important energy role.

c. Relative to the content of scientific research, the investment is too small, resulting in low technical content of the research, mostly low-level repetitive research, and ultimately failed to solve some key technologies, such as: low gas production rate of anaerobic digestion, and poor automation of equipment and management; The tar problem in gasification utilization has not been completely solved, causing serious problems for long-term application; the efficiency of biogas power generation and gasification power generation is low, and the corresponding secondary pollution problems have not been completely solved. As a result, many engineering systems are often in a state of repair or failure, thereby reducing system operating intensity and efficiency.

In addition, in my country's actual social and economic environment, there are still some negative factors that restrict or hinder the development, promotion and application of biomass energy utilization technology, mainly as follows:

a. Under the current energy price conditions, biomass energy products lack market competitiveness. The low return on investment dampens the enthusiasm of investors, while the high sales price dampens the enthusiasm of consumers.

b. Technical standards are not standardized and market management is chaotic. In the development of straw gasification gas supply and biogas projects, due to the lack of appropriate technical standards and strict technical supervision, many units and individuals without technical strength participated in the contracting of biogas projects and the production of straw gasification gas supply equipment. , causing the project technology to fail to meet the expected goals, and even causing safety problems, which will have a great negative impact on future biomass utilization work.

c. At present, policies to support the development of biomass energy are still lacking in operability. Governments at all levels should formulate relevant policies as soon as possible, such as price subsidies and special preferential policies for power generation and grid access.

d. The public lacks sufficient understanding of biomass energy, and the publicity and popularization of relevant common sense should be strengthened.

e. The government should pay sufficient attention to the strategic position of biomass energy. The development of biomass energy is a systematic project and should be regarded as a capital construction project to achieve sustainable development.

4. Development direction and countermeasures

4.1 Development direction

my country’s biomass energy resources are rich and cheap, but the economic environment and development level have a negative impact on biomass The development of technology is at a relatively favorable stage. Based on these characteristics, the development of biomass in my country must not only learn from foreign advanced experience, but also emphasize its own characteristics. Therefore, the future development direction should be in the following aspects:

a. Further give full play to the role of biomass energy as supplementary energy in rural areas, provide clean energy for rural areas, improve the rural living environment and improve people's living conditions. This includes practical technologies such as biogas utilization, straw gas supply and small gasification power generation.

b. Strengthen the industrial application of biomass, increase the proportion of biomass energy utilization, and improve the status of biomass energy in the energy field. Only in this way can the impact of biomass energy be fundamentally expanded and conditions created for the large-scale application of biomass energy in the future. This is also the key to whether biomass energy can become an important alternative energy source in the future.

c. Research technologies for converting biomass into high-grade energy products to improve the utilization value of biomass energy. This is an important technical reserve, the basis for utilizing biomass in multiple ways in the future, and the key to improving the role and status of biomass energy in the future.

d. At the same time, use mountains, wastelands and deserts to develop new biomass energy resources, research, cultivate and develop fast-growing, high-yield plant varieties, develop energy farms and forest farms in areas where current conditions permit, establish biomass energy bases, and provide large-scale energy resources such as wood or vegetable oil.

4.2 Countermeasures

According to the above main development directions, whether my country's biomass utilization technology can develop rapidly in the future mainly depends on the following aspects:

a. In terms of industrialization: strengthen the commercialization of biomass utilization technology, formulate strict technical standards, strengthen technical supervision and market management, standardize market activities, and create a good market environment for the promotion of biomass technology.

b. In terms of industrial production and large-scale application: strengthen the connection between biomass technology and industrial production, and solve key technologies in demonstration applications. In terms of technical research: focus on solving technical problems that arise in promotion and application, and improve and test them in production practice The reliability and economy of biomass energy technology create conditions for large-scale use of biomass.

c. In terms of technical research: we should not only focus on solving technical problems that arise in promotion and application, such as tar treatment, biogas technology in cold areas, etc., but also explore new technologies for biomass utilization, such as biomass oil production, biomass oxygen production, etc. Research on advanced technologies.

d. Formulate a national development plan for biomass energy, introduce new technologies and new processes, conduct demonstration, development and promotion, and fully and rationally utilize biomass energy resources. In the 21st century, some fossil fuels will be gradually replaced by high-quality biomass energy products (solid fuel, liquid fuel, combustible gas, fuel, etc.) to solve my country's energy shortage and environmental pollution problems.

4.3 Priority areas

． Straw energy utilization

． Organic waste treatment and energy conversion

. Industrial organic waste residue and wastewater treatment and energy conversion

. Biomass liquid fuel

4.4 Major key technologies

. High-efficiency biomass gasification power generation technology

． Organic waste IGCC power generation technology

. Efficient anaerobic treatment and biogas recovery technology

. Cellulose alcohol production technology

. Biomass pyrolysis and liquefaction technology

. Energy plant cultivation and utilization technology

5. Conclusion

Biomass energy will become an important part of sustainable energy in the next century. Our country has a vast territory, but limited fossil energy resources and rich biomass resources. The development of biomass energy has important strategic and practical significance. Using high and new technologies to convert biomass such as straw, livestock manure and organic wastewater into high-grade energy, the development of biomass energy will involve many interests such as rural development, energy development, environmental protection, resource protection, national security and ecological balance. We hope to receive widespread attention and support from all walks of life, governments at all levels, experts and scholars, and create a beneficial development environment for my country's biomass energy industry.