The resource limitation of fossil fuels and the problems arising from their combustion has led to widespread research on the accessibility of new and renewable energy resources. Solar, wind, thermal and hydro sources, and finally biogas are among these renewable energy resources. But what makes biogas distinct from other renewable energies is its importance in controlling and collecting organic waste material and at the same time producing fertilizer and water for use in agricultural irrigation. Unlike other forms of renewable energy, biogas neither has any geographical limitations and required technology for producing energy and nor is it complex or monopolistic. Considering the ever increasing amount of different types of organic waste materials (about 15 million tonnes) in Iran, working on the control of waste material and biogas production becomes inevitable. In this paper, biogas and the benefits from its production are discussed, as is the technical-economic analysis of the Saveh biogas power plant as a case study. (C) 2004 Elsevier Ltd. All rights reserved.