AbstractThe Renewable-Energy-Source-Act (EEG) promotes German biogas production in order to substitute fossil fuels, protect the environment and prevent climate change. In this paper we quantitatively analyse the EEG-reform in 2008. Results imply that the reform contributes to an expansion of biogas electricity generation and thus to substitution of fossil fuels. However, subsidies, land and transport emissions per unit of electricity produced increase. An alternative analysis shows that an EEG with tariffs independent from plant-types would provide the highest subsidy-efficiency, lower land requirements and higher transport emissions compared to EEG before its reformation.