Carbon Emission Accounting Analysis Of Large-scale Straw Biological Natural Gas Project Based On CDM Methodology

Large scale straw biogas project is an important way of new energy utilization of straw resources in China,and an important way to achieve the carbon peak in 2030 and the carbon neutralization goal in 2060.If the biogas industry wants to develop rapidly,whether it is policy support or obtaining additional income in the carbon trading system as a negative carbon industry,it is inseparable from the carbon emission reduction accounting of large-scale biogas projects.At present,there is a lack of reasonable and feasible carbon accounting methods.Based on the methodology of voluntary emission reduction projects and the methodology of clean development mechanism（CDM）,this study constructs a measurement method system of greenhouse gas emission reduction suitable for large-scale straw biogas projects;Taking an actual straw biogas project in the suburb of Harbin,Heilongjiang Province as a typical case,the emission reduction capacity of the project is quantitatively evaluated.Based on the data,the strategies to improve the emission reduction capacity of large-scale straw biogas project are put forward.（1）The measurement method of greenhouse gas emission reduction of large-scale straw biogas project mainly includes six parts:project boundary,baseline emission calculation,project emission calculation,leakage calculation,emission reduction calculation and project monitoring.The emission of biogas from the large-scale production line of straw and domestic fertilizer in rural areas refers to the situation where the emission of biogas from the production line of straw and domestic fertilizer does not exist.Project emissions refer to the emissions from project transportation activities,power consumption,fossil fuel consumption and excess biogas flare combustion.（2）In 2021,the actual baseline emission of straw biogas project is 65424.51t,the project emission is 10689.9t,the leakage emission is 316.4t,and the total carbon dioxide emission of the project is 54418.51t,which is equivalent to the CO₂emission of 21000t standard coal.The emission reduction of the project is equivalent to 4.9 times of the total project emission（the sum of project emission and leakage）.According to the requirements of NY/T 2142-2012 code for process design of straw biogas engineering,if the design service life of straw biogas engineering is not less than 25 years,the actual straw biogas centralized gas supply project can reduce CO₂by at least 1.36 million tons.In 2021,the actual straw biogas centralized gas supply project can reduce the net emission of 1.5 t co₂per 1t（dry weight）of straw and 15.77kgco2 per 1m3 of biogas.（3）The strategy of improving the greenhouse gas emission reduction capacity of large-scale straw biogas project was put forward.In terms of total project emissions（the sum of project emissions and leakage）,the order of emission contribution is:power consumption emission of project operation>carbon dioxide emission inside the project>leakage>biogas flare emission>project transportation activity emission>fossil fuel emission of project operation.The power consumption carbon emission of the project is 5990.29t,accounting for 41.29%of the total emission of the project,the carbon dioxide internal reaction carbon emission is 4036.5t,accounting for 27.82%of the total emission of the project,and the total leakage of the project is2709t,accounting for 18.67%of the total emission of the project.The project consumes the most carbon and emits the most greenhouse gases,and the carbon emissions generated internally and caused by leaked methane gas account for more than 88%of the total emissions.Reducing the total emission of straw biogas project mainly starts from two aspects.On the one hand,try to choose purification methods with low total emissions,such as membrane purification and cryogenic separation,which can reduce carbon emissions by more than 3000 per year.On the other hand,reduce the energy consumption in the operation of straw biogas project.