A Comprehensive Model for Evaluation of Carbon Footprint and Greenhouse Gages Emission in Household Biogas Plants

Based on Life Cycle Assessment and other related methods, this paper introduced a comprehensive model for the evaluation of the carbon footprint and greenhouse gases emission in household biogas plants including nearly all the processes of the household biogas project, such as the collection of raw materials, fermentation processing, and fermentation residue processing and so on. The carbon footprint and greenhouse gas emission from three classical household biogas plants in China were analyzed. Considering the greenhouse gases emissions in life cycle of household biogas plants, the main emission processes were investigated to be the utilization of biogas, such as biogas combustion use and transportation of materials which both accounting for more than 98%. The greenhouse gases emissions in the stages of methane leakage and construction materials production were only estimated to be 1.1% and 0.5%, respectively. As comparing to the meandering fabric digester and the precast reinforced concrete panels fabricated digester, the in-situ concrete cylindrical water pressure digester showed the lowest carbon footprint and accordingly most potential for the reduction of greenhouse gases emission. It tried to analyze three household biogas plants´ carbon footprint and greenhouse gas emission during the stages. It can provide the basis for optimization low-carbon proposal and the analysis and built up a simple carbon footprint calculation model. About household digesters life cycle greenhouse gas emissions, the main emission process are biogas utilization period and transport phase , accounting for more than 98.38 percent , followed by methane leak stage and building materials production stage, about 1.11% and 0.51% .Compared to meandering fabric type digesters and precast reinforced concrete panels fabricated digesters, in-situ concrete cylinder shaped hydraulic digester´s carbon footprint is minimum so greenhouse gas emission reduction potential is great.