Benefit Analysis Of Large And Medium Scale Biogas Projects In Large-scale Farms

Since the 21^stcentury,with the continuous development of social economy and the acceleration of modernization,environmental problems and energy issues increasingly becomes a focus of social attention.As a clean and reproducible biomass energy,biogas has become one of the four major renewable energy projects in China.In recent years,with the vigorous supports of national policies and rapid development of large-scale breeding industry,the lager and medium biogas projects relying on large-scale breeding farms have sprung up.The promotion of biogas projects can not only sovle the environmental pollution resulted from livestock breeding,but also can substitute the fossil fuel for biogas,which is useful for optimizing the structure of rural energy consumption,improvr the rual ecological environment and reduce the greenhouse gas emission.With the increase of the construction quantity of biogas projects,the operation status and benefit of the projects have been paid more and more attention.At present,a lot of research has been done on the benefit analysis brought about by the biogas engineering at home and abroad,but quantitative analysis of the environmental,economic and greenhouse gas emission reduction benefits of large and medium-sized biogas projects is still scarce,the quantitative analysis of the environmental,economic and greenhouse gas emission reduction benefits brought by the biogas project is still less.Further more,the studyof large and medium scale methane projects in Jiangxi province is more less.In this paper,we conducted field research on large and medium-sized biogas engineering in eight large-scale farms in Jiangxi province,and obtained basic information of the farms and biogas projects to understand the operation status.The field research method,experimental analysis method,CDM methodology and cost-benefit method are used to carry out objective and quantitative analysis of the environment,greenhouse gas emission reduction and economic benefit of large and medium-sized biogas projects.The results are as follows:?1?The concentrations of NH₃ and H₂S in the 8 large-scale breeding farms in Jiangxi province is 0.078 and 0.011 mg/m³ respectly in summer,and is 0.104 and0.015mg/m³respectly in winter,which is significantly lower than the limits set out in the national standards for environmental quality of livestock and poultry.Due to the influence of air humidity and wind direction,the overall level of NH₃ and H₂S concentration in winter was slightly higher than that in summer,and the concentration NH₃ and H₂S in the lower wind direction was higher than that in the upper wind direction.?2?The physical and chemical properties of each treatment unit were significantly different in the 8 large-scale breeding farms in Jiangxi province.The rmoval rate of TS and VS in the feedstock from the feed pool to the oxidation pond was 86.9%and 88.4%respectly in summer,and is 95.5%and 95.6%respectly in winter.The rmoval rate of TN?NH₄-N and COD is 81.5%,83.5%and 89.3%respectly in summer,and is 76.9%,76.2%and 58.7%respectly in winter.The pH value which was between 7.2 and 7.4 have not changed obviously,and has no large seasonal variation.Although the contents of TN,NH₄-N and COD in raw materials were effectively reduced by biogas engineering and oxidation pond purification,they still failed to meet the emission conditions stipulated in the standards for pollutant discharge in livestock and poultry industry.Subsequent purification treatment shall be carried out until the standard can be discharged.?3?The emission of CH₄ and N₂O in the baseline scenario of the biogas project of Xinglong Livestock Development co.,ltd.in Suichuan County,in Jiangxi province were1607.345and146.25 tCO₂e respectively,and the total greenhouse gas emission was 1753.595 tCO₂e.In the event of project activities,CH₄ and N₂O emissions were847.3 and 131.63 tCO₂e,and total greenhouse gas emission was 980.74 tCO₂e.In terms of the net leakage of project activities,CH₄ and N₂O emissions were 63.82 and39.47 tCO₂e,and total greenhouse gas leakage was 103.29 tCO₂e.The greenhouse gas emission reduction of the biogas project is 669.565 tCO₂e,and the emission reduction rate is 38.2%,among which the CH₄ emission volume is 696.225 tCO₂e,the N₂O emission rate is-24.85 tCO₂e,and the emission reduction rate is 43.3%and-16.99%.The biogas projects CH₄ emission reduction benefits are obvious,while the N₂O emission reduction efficiency is negative.Overall,the project can effectively reduce greenhouse gas emissions,but the emission reduction rate is not high.?4?The economic benefit of biogas project is obvious.From the perspective of financial evaluation,the net present value?NPV?of the project is 376,000 yuan,the internal rate of return?IRR?is 29.44%,and the dynamic investment recovery period is2.07.The project presents the characteristics of obvious economic benefit,higher internal rate of return and quick recovery of funds.From the perspective of economic evaluation,the net present value?NPV?is 2166,000 yuan,the internal rate of return?IRR?7.92%,and the dynamic investment payback period is 9.99 years,which also has obvious economic benefits.Since the economic evaluation did not include financial supports such as state subsidies,government supports and bank grants,the internal rate of return of the project was reduced by 21.52%,and the recovery period of dynamic investment was extended by 7.92 years.Under the substantial supports of national polices,project can increase the net present value,improve internal rate of return and shorten the dynamic payback period,which has a powerful role in promoting the development of large and medium-sized biogas project.