The oil crisis has led us to explore the alternative sources of nitrogen. One of the alternatives for nitrogen is cow dung (Gobar). Scientists have invented a gobar gas plant which gives methane gas for fuel and rich slurry with high content of nitrogen. Based on the data provided by the Khadi and Village Industries Commission, the cost-benefit analysis of the gobar gas plant shows that the investment in gas plant is economical both from the private and social points of view.