Emergy Analysis Of Comprehensive Benefits Of Biogas Cogeneration System For Livestock Farming Based On Life Cycle Assessment Within The Operating Period

At present,the comprehensive benefit evaluation of the CHP project for livestock and poultry farming mostly focuses on the internal energy flow or conversion efficiency of the system.The emergy analysis and life cycle assessment adopted in the livestock breeding system are applied to get the ecological,environmental,economical and energy efficiency of the system is of great significance.In order to study the comprehensive benefits of biogas projects for livestock breeding,the life cycle assessment framework and the emergy analysis methods are applied to evaluated the comprehensive benefits of the biogas cogeneration system for livestock manure from the aspects of economy,energy efficiency,environmental impact and sustainability.The comparative analysis of the benefits of biogas projects under different technologies and different operating strategies was conducted.The main research contents and results are as follows:(1)Taking a large-scale livestock farm biogas power generation project in Lanzhou,Gansu as the research objective,a detailed survey was conducted on the basic conditions,process flow,and process parameters of the farm.Based on the LCA and EMA method,the economic,energy efficiency and environmental impacts of the biogas project were evaluated.(2)In terms of economy,the situation ?(adding solid-liquid separation equipment)is obviously better than that of situation ?(full load);compared with situation?,with an energy input increase,1.8 times its unit production capacity can be obtained in situation?;the comprehensive environmental impact potential shows that the comprehensive environmental impact of situation ? is less than situation?.Therefore,considering the three factors of economy,energy efficiency and environmental impact,the situation?(adding solid-liquid separation equipment)is an economic,energy-saving and environment-friendly biogas project operation mode.(3)The emergy analysis results show that the annual emergy consumption value of the biogas project is 5.09E+16sej/ a,the system output emergy value is 3.82E+17sej/a,and the system self-consumption power accounts for 13.3% of the output emergy value.The results of the indicator analysis show that compared with situation ?(full load),the energy value output rate EYR a nd the sustainable development index ESI increase in the situation ?(adding solid-liquid separation equipment).The rate of EIR has also increased slightly;the rest of the indicators have been reduced by between 3% and 9%,which is the price paid for impro ving the energy yield rate.The overall energy value indicators that,regardless of the situation? and the situation ? both indicate that the project has a good ecological and economic benefits,sustainability and emission reduction benefits.(4)Divide the actually operation years of the livestock manure biogas cogeneration system into three phases.The three-phase energy efficiency output ratio is 4.36,3.22,and 3.74,respectively,which is far less than 7.75 under full-load operation.In the actual three-phase operation,the dynamic investment payback period of all investment or self-raised funds is more than 20 years,which means that investment can not be recovered during use.(5)The input emergy structure is not significantly different from the full load,but in the calculation of the emergy index,in addition to the value of the self-sufficiency rate of the emergy in the actual operation stage being higher than the full-load condition,the remaining indicators have been reduced to different degrees,and both point to the system's eco-economic capacity and emergy output capacity have been greatly reduced,and the impact on the environment has increased.Therefore,maintaining full-load and high-load operation of the system is of great significance for obtaining good overall benefits.(6)Categorize the problems in the actual operation of the biogas project.The main problems are poor system economics,poor system operation stability,and potential environmental pollution.According to the problems arising from the actual operation of the project,four suggestions are proposed for the future development of biogas projects.The policy can be improved through policy support,increasing organic-organic separation by solid-liquid separation,adding auxiliary temperature-increasing equipment,and learning from scientific research results.The innovations in this article are listed as follow:Using the life cycle emergy value analysis,a comprehensive evaluation of the biogas plant of livestock and poultry biogas production about economy,energy efficiency and environmental impacts are conducted.Comparing the comprehensive benefit between the full-load operation and the add the separator situation.the actual operation years is divided into three phases.The problems encountered in the actual operation of the project are obtained,and several suggestions are made.