Comprehensive evaluation of environ-economic benefits of anaerobic digestion technology in an integrated food waste-based methane plant using a fuzzy mathematical model

In this study, a quantitative and comprehensive evaluation of environ-economic benefits of anaerobic digestion (AD) of food waste was conducted on an operational project in China. Fuzzy evaluation method based on life cycle assessment and cost-benefit analysis was employed. Single-factor evaluation of environmental impacts and energy consumption indicated that AD was a green and clean energy producing technology. The study indicated that the total environmental impact was not significant at 6.65 E-03, and the net energy output (186.01 MJ) was slightly higher than the net energy input (167.47 MJ), when only methane production was considered. However, economic benefits were not ideal, recording loss of 64.99 RMB for each ton of food waste. Additionally, results of comprehensive evaluation conducted using fuzzy mathematical model were consistent with above results. Environmental benefits, energy consumption, and economic benefits of AD technology were 4.75, 3.58, and 1.36, corresponding to grades I, Ⅱ, and IV, respectively. Single benefits decreased in the order of environmental impact > energy consumption > economic benefit, indicating that economic benefit is the restrictive factor in integrated environ-economic benefits of AD technology in practice. Thus, increasing economic benefit should be the focus of research and management processes. Additionally, overall environ-economic benefit of AD rated good (Grade II), with a value of 3.39. Further sensitivity analysis results confirmed the stability of the comprehensive evaluation model. The established fuzzy mathematical evaluation model can realize comprehensive and quantitative evaluation of environ-economic benefits of AD technology; serve as valuable reference for perfecting evaluation systems, and assist in rational choice of renewable energy recovery technology from food waste.