“30 carbon peaks and 60 carbon neutrality"is a major strategic decision based on promoting the construction of a community of human destiny and achieving sustainable development.It is a phased carbon control goal that China solemnly promises to the world,and it will definitely affect the development of the entire economy and society.The ultimate goal of carbon control is carbon reduction,and all economic and social activities must anchor this carbon reduction goal;in this context,the utilization of biomass resources will usher in new opportunities and new challenges.

1.New opportunities

The key to carbon reduction lies in using the entire atmosphere as a control body,so that the total amount of carbon dioxide input to the atmosphere is less than the total amount of carbon dioxide output to the atmosphere,thereby reducing the content of carbon dioxide in the atmosphere.

Carbon reduction brings new opportunities for the utilization of biomass resources.We know that the fundamental way for carbon dioxide to be imported into the atmosphere is the combustion of carbon-containing fuels such as coal,petroleum,and natural gas outside the atmospheric control body;the most reliable way for carbon dioxide to be exported to the atmosphere is to convert carbon dioxide in the atmosphere into biomass through photosynthesis,and then carbon capture,utilization and storage.Carbon reduction requires reducing the combustion and utilization of coal,oil,and gas to reduce the total amount of carbon dioxide input into the atmosphere and strengthening photosynthesis and carbon capture,utilization,and storage to increase the total amount of carbon dioxide output to the atmosphere;this will enhance the status of biomass energy as an alternative energy source for coal,oil,and gas,and biomass as an alternative raw material for production and life,bringing two new opportunities for biomass energy utilization and material utilization.

According to the"Blue Book on the Development Potential of Zero-Carbon Biomass Energy in 3060(September 2021)",the annual output of China's main biomass will reach 3.494 billion tons in 2020,and it is expected to grow at an annual rate of 1.1%,reaching 3.795 billion tons in 2030 and 5.346 billion tons in 2060.Biomass is rich in resources.However,the resource utilization rate of biomass is very low.For example,the annual output of biomass in agroforestry and aquaculture in 2020 is as high as 3.047 billion tons,but its energy utilization rate is only 10.1%(total energy utilization is 309 million tons),and the material utilization rate data is unknown but it will not be high.The utilization of biomass resources,whether it is energy utilization or material utilization,has made a big difference.

2.New challenge

How to improve the carbon reduction effect of biomass resource utilization,how to broaden the way of biomass resource utilization and improve the efficiency of biomass resource utilization are new challenges encountered in the context of carbon reduction of biomass resource utilization.

1)Improve the level of comprehensive utilization of biomass

Biomass is the product of photosynthesis to absorb and transform carbon dioxide in the atmosphere;if biomass is used by matter,then this part of carbon dioxide becomes a net reduction in carbon dioxide in the atmosphere,and biomass material utilization has a“direct”carbon reduction effect(carbon sequestration effect);if biomass is directly burned and utilized,this part of carbon dioxide will return to the atmosphere,that is,the direct combustion and utilization of biomass has no“direct”carbon reduction effect.

However,it should be noted that the utilization of biomass materials will indirectly increase carbon,while the utilization of biomass energy will indirectly reduce carbon.In the actual process,the utilization of biomass materials requires additional energy(including water,electricity,gas,heat,etc.).The production of these energy may produce carbon dioxide and increase the carbon dioxide content in the atmosphere(carbon increase),that is,the utilization of biomass materials may indirectly increase carbon;the direct combustion and utilization of biomass can provide energy to production and life outside the direct combustion and utilization system,thereby playing an“indirect”carbon reduction effect,because if this part of the energy comes from the combustion and utilization of coal,oil,and gas,it will produce and discharge carbon dioxide into the atmosphere,which is the indirect carbon reduction effect of biomass as an alternative fuel for coal,oil,and gas.

It can be seen that the utilization of biomass materials has a direct carbon reduction effect and the possibility of indirect carbon increase,while the utilization of biomass energy has no direct carbon reduction effect but has an indirect carbon reduction effect.Generally speaking,to give full play to the carbon reduction effect of biomass,we should adhere to the biomass resource utilization route of“promoting the utilization of biomass resources”,“promoting the comprehensive utilization of biomass energy utilization and material utilization at the same time”and“improving the level of comprehensive utilization of biomass”;under specific circumstances,the ratio of biomass energy utilization to material utilization should be coordinated to improve the comprehensive carbon reduction effect of biomass;under current circumstances,the proportion of biomass material utilization should be increased,but not either.

2)Broaden the way of utilization of biomass resources

Is it possible to develop more biomass material utilization and energy utilization pathways,and even biomass energy utilization pathways with direct carbon reduction effects?I believe the answer is yes,but it is challenging.

There are roughly three directions for broadening the utilization of biomass resources:first,the direct use of biomass,such as the production of biomass into breeding raw materials and building materials;second,the first conversion of biomass(by animals,microorganisms,physical chemistry)into intermediates and then direct or modified utilization,such as the conversion of agroforestry breeding waste and food waste into biogas,and then the direct combustion of biogas for power generation,or the decarbonization of biogas(methane cracking to hydrogen)after combustion for power generation,or biogas as a chemical raw material;It is worth emphasizing that feeding animals is not only an important way of biomass,but also an important way for biomass to be reused after animal transformation.;The third is the use of secondary waste for the resource utilization of biomass,such as the use of biogas residue composting,breeding,and the resource utilization of flue gas that has attracted more attention recently.

It is attractive to convert carbon dioxide from the flue gas of direct combustion of biomass into methane.There are currently two ideas,one is the photocatalytic reaction of carbon dioxide and water to generate methane,and the other is the catalytic reaction of carbon dioxide hydrogenation(Sabatier reaction)to generate methane.Companies have tried to convert carbon dioxide and water into resources such as methane.A technology of Japan's Showa Shell Petroleum Company uses sunlight to convert carbon dioxide and water into methane and other resources at room temperature and pressure.According to reports,the company uses the gas diffusion electrode used in the fuel cell and the newly developed catalyst to directly convert water and carbon dioxide into methane and ethylene using only sunlight at room temperature and pressure.The company believes that this technology is an important progress in the field of reducing carbon dioxide emissions and new energy synthesis.The Japanese government tried to use the Sabatier reaction to catalyze the hydrogenation and methanation of carbon dioxide.The Ministry of Economy,Trade and Industry of Japan will consult with 19 companies such as Nippon Steel and Mitsubishi Corporation to study how to strengthen the research and development of carbon dioxide methanation technology.The phase proposed by the Ministry of Industry,Trade and Economy of Japan is to replace more than 1%of civil gas with synthetic methane by 2030,and to expand to 90%in one fell swoop by 2050.Calculations by the Japan Gas Association show that 1%of the replacement volume can reduce 800,000 tons of carbon dioxide,while 90%of the replacement volume can reduce 80 million tons of carbon dioxide,which is equivalent to 0.07%and 7%of Japan's total emissions,respectively.The success of Japan's plan depends on whether the cost of hydrogen production from solar power can be controlled.

Broadening the ways of biomass material utilization and energy utilization is related to the development prospects of biomass resource utilization,and it is necessary to increase research and development of comprehensive biomass utilization methods,technologies,processes,equipment and products.

3)Improve the efficiency of biomass resource utilization

How to improve the direct carbon reduction effect(carbon sequestration effect)of biomass material utilization and reduce its indirect carbon increase effect,and how to improve the indirect carbon reduction effect of biomass energy utilization?This requires improving the resource recovery and utilization rate and reducing the self-consuming energy of the resource utilization system.In other words,it is necessary to improve the efficiency of the biomass resource utilization system.

Different biomass resource utilization methods,technologies,processes and equipment have different efficiency.When building and upgrading and expanding biomass resource utilization projects,more efficient methods,technologies,processes and equipment(selection)should be selected to improve the resource recovery and utilization rate,and energy-saving programs should be optimized and information,intelligent,and intelligent management programs should be improved to reduce the self-consumption of the resource utilization system and ensure that the biomass resource utilization system achieves high efficiency.There is a lot of room for efficiency and carbon reduction in the selection,energy saving and management of biomass resource utilization.

Take the utilization of biomass energy as an example.The direct biomass combustion/steam turbine power generation system only has a power generation efficiency of about 22%,but the biomass is converted into biogas/internal combustion biogas power generation system.Due to the lower moisture content of biogas and the higher energy conversion efficiency of internal combustion biogas generator sets than steam turbine generator sets,it will have a power generation efficiency of more than 28%(assuming that the conversion rate of biomass solid materials into biogas is 60%);the higher the power generation efficiency,the greater the power generation capacity per unit of carbon dioxide production,therefore,the greater the indirect carbon reduction effect of the biomass energy recovery power generation system;in terms of expansion,biomass energy utilization The higher the energy recovery and utilization efficiency of the system,the greater the indirect carbon reduction effect.The“carbon dioxide output per unit of recovered energy”index can be introduced instead of the energy recovery and utilization efficiency index to measure the indirect carbon reduction effect of the biomass energy utilization system.In addition to power generation efficiency or energy recovery and utilization rate,the system's energy-saving plan and management level will affect the level of self-consumption of the system,which will also affect the indirect carbon reduction effect of the system;at present,the proportion of self-consumption of biomass direct incineration power generation systems mostly varies in the range of 10%to 15%.In addition to the selection factors,this difference is the factor of energy saving and management level.