Energy and GHG Analysis of Rural Household Biogas Systems in China

Lixiao Zhang,Changbo Wang

doi:10.3390/en7020767

Abstract

The Chinese government has taken great efforts to popularize rural household scale biogas digesters, since they are regarded as an effective approach to address energy shortage issues in rural areas and as a potential way of reducing greenhouse gas (GHG) emissions. Focusing on a typical rural household biogas system, the aim of this study is to systematically quantify its total direct and indirect energy, concentrating on non-renewable energy and the associated GHG emission cost over the entire life cycle to understand its net dynamic benefits. The results show that the total energetic cost for biogas output is 2.19 J/J, of which 0.56 J is from non-renewable energy sources and the GHG emission cost is 4.54 × 10−5 g CO2-equivalent (CO2-eq), with respect to its design life cycle of 20 years. Correspondingly, a net non-renewable energy saving of 9.89 × 1010 J and GHG emission reduction of 50.45 t CO2-eq can be obtained considering the coal substitution and manure disposal. However, it must be run for at least 10 and 3 years, to obtain positive net non-renewable energy savings and GHG emission reduction benefits, respectively. These results have policy implications for development orientation, follow-up services, program management and even national financial subsidy methods.

Highlights

China was one of the first countries in the world to use biogas technology early in its history and it continues to play a leading role in the development and dissemination of household biogas technology.The first unofficial test to ferment biogas was undertaken in Guangdong Province back in the 1880s [1,2].it was not until the 1970s that the large-scale development of household biogas systems began in China, when the Chinese government introduced wide-scale biogas technology nationally to address energy shortages in rural areas [3]
This paper aims to systematically evaluate the cost and benefit of energy and greenhouse gas (GHG) emissions associated with a typical rural household biogas system with regard to different life cycle scenarios, in order to shed light on the more effective rural biogas use and to suggest appropriate rural biogas development policies
The energy cost (Ecost) for biogas is calculated as 2.19, while more importantly, the non-renewable energy cost (NEcost) is 0.56, indicating that 0.56 J of non-renewable energy is needed to produce a unit of biogas energy

Summary

Introduction

The first unofficial test to ferment biogas was undertaken in Guangdong Province back in the 1880s [1,2]. It was not until the 1970s that the large-scale development of household biogas systems began in China, when the Chinese government introduced wide-scale biogas technology nationally to address energy shortages in rural areas [3].

Objectives

Methods

Results

Conclusion