Abstract:

In order to explore regional characteristics of the greenhouse gas emission reducing effects of the rural household biogas project, Sichuan Province was cited as a case for study. Based on farmer household surveys in five major agricultural zones of the province, carbon emission reducing effect of the household biogas project in each of the five agricultural zones was figured out. Results show that a household biogas digester could reduce 2.21-3.21 t·a^-1 of carbon emission and 2.69 t·a^-1 on average over the province. The effect varied sharply with the agricultural zone and the five zones followed an order of the mountainous areas around the Sichuan Basin(3.21 t·a^-1) > the high mountains and the plateau in Northwest Sichuan(2.94 t·a^-1) > the mountainous area of Southwest Sichuan(2.65 t·a^-1) > the hilly area of the Sichuan Basin(2.42 t·a^-1) > the Chengdu Plain(2.21 t·a^-1). According to contribution of the biogas digesters to carbon emission reduction, the household biogas digesters in the study area can be sorted into two categories, namely, forest protection digesters and energy structure alteration digesters, of which the former was much higher in carbon emission reducing effect. In 2013, the use of biogas digesters changing the way of domestic waste treatment reduced carbon emission directly by 4.164 million tons, and indirectly by 14.936 million tons through protecting forests and altering energy structure, while increasing carbon emission by 3.307 million tons via leakage and combustion of methane, thus, making the total reduction of carbon emission up to 15.793 million tons. Aiming at the new problems and phenomena confronted in extension of the household biogas project, it is suggested that the emphasis of the extension should lean towards the mountainous areas around the Sichuan Basin and the high mountains and plateau area of Northwest Sichuan, and as for the hilly area and the Chengdu Plain of the Sichuan Basin, more attention should be paid to construction of the maintenance support system for household biogas digesters, and extrapolation of the moderate- and small-sized biogas digester project to new small-scaled animal-rearing farmers.

Key words: household biogas digester, carbon emission reduction, regional characteristics, development strategy