Greenhouse Gas Emission Reductions from Domestic Anaerobic Digesters Linked with Sustainable Sanitation in Rural China

Abstract

Anaerobic digesters provide clean, renewable energy (biogas) by converting organic waste to methane, and are a key part of China's comprehensive rural energy plan. Here, experimental and modeling results are used to quantify the net greenhouse gas (GHG) reduction from substituting a household anaerobic digester for traditional energy sources in Sichuan, China. Tunable diode laser absorption spectroscopy and radial plume mapping were used to estimate the mass flux of fugitive methane emissions from active digesters. Using household energy budgets, the net improvement in GHG emissions associated with biogas installation was estimated using global warming commitment (GWC) as a consolidated measure of the warming effects of GHG emissions from cooking. In all scenarios biogas households had lower GWC than non-biogas households, by as much as 54%. Even biogas households with methane leakage exhibited lower GWC than non-biogas households, by as much as 48%. Based only on the averted GHG emissions over 10 years, the monetary value of a biogas installation was conservatively estimated at US$28.30 ($16.07 ton−1 CO2-eq.), which is available to partly offset construction costs. The interaction of biogas installation programs with policies supporting improved stoves, renewable harvesting of biomass, and energy interventions with substantial health co-benefits, are discussed.

Greenhouse Gas Mitigation of Rural Household Biogas Systems in China: A Life Cycle Assessment

“…Our analyses reveal some important barriers for RHB adoption, confirming previous studies [14], such as the quality of digester construction [34] and biogas technology [15], ease of operation and maintenance [9] and socio-economic barriers such as level of education and household finances [19]. Based on our findings, we suggest that more efficient deployment of RHB systems requires careful evaluation of the local climate (biogas yield) and farm management practices (manure quantities and existing storage systems), and adequate local service support.…”

“…Bruun et al [9] estimated that the volume of biogas leakage in China overall represented 40% of biogas production, using literature data. Dhingra et al [34] proposed that Chinese RHB leakage amounted to only 4.5 m 3 biogas per household per year, based on path-integrated concentration measurements and VRPM technology. These rough estimations ignored artificial biogas discharge by farmers and did not clarify where the leakage occur.…”

Energy and GHG Analysis of Rural Household Biogas Systems in China

“…However, our primary survey of 150 household biogas projects in Guizhou Province shows that more than 42% of bio-digesters are abandoned within 2-3 years after their construction, which is consistent with previous investigations [42]. Among those that are still in use, about 32% encounter many obstacles such as unavailability of fermentation materials, leakage, and unstable biogas production.…”

Household Biogas Digesters—A Review

“…Even though, both methane and carbon dioxide are major contributors to the greenhouse effect, the global warming potential of methane is 21 times higher than that of carbon dioxide [195]. However, the comparison of the houses equipped with and without biogas systems, including the leakage of gases in the biogas systems revealed that the households with biogas plants have 48% less emissions compared to households without biogas systems [196]. It is worth mentioning that only 10% of households had methane leakage [194].…”