Economic and environmental impacts of domestic bio-digesters: Evidence from Arusha, Tanzania

Despite substantial programmatic investment in domestic bio-digesters across sub-Saharan Africa in recent years, little empirical evidence has been published regarding the existence or magnitude of socioeconomic or environmental benefits accruing from bio-digester implementation. A cross-sectional study of 40 households in Arusha, Tanzania, suggests that bio-digester adoption has the potential to reduce fuel-wood use, energy-related expenditures, and time-costs of energy procurement; to lower CO2e emissions; and to increase farm incomes. No significant differences in synthetic fertilizer use were observed between households with and without bio-digesters. Domestic bio-digester investments were found to have a positive net present value across a wide range of discount rates. Further, we estimate that domestic bio-digester implementation at the country wide level in Tanzania could potentially access $80–$115 million annually in carbon emissions reduction (CER) financing through the Clean Development Mechanism.

► We compare 40 households with and without bio-digesters in Arusha, Tanzania. ► Bio-digester adoption may reduce fuelwood use and energy-related time and money costs. ► Time burden of energy procurement is more equitably distributed between genders. ► A net present value analysis indicates favorable returns for investment in bio-digesters. ► We calculate averted CO2-eq emissions and estimate potential carbon financing in Tanzania at US$80 to $115 million per year.