Much has been written on bio-gas plants as a solution to energy crisis and for overall benefits to the rural community. In the review of literature the strategy adopted by the government of India to encourage setting up small-sized individual farm-based units or large-sized community plants through subsidy has been examined. The social-cost benefit analysis of individual as well as community plants has been worked out. Many technical, operational and management difficulties are pointed out. However, there has been hardly any study investigating whether large sized bio-gas plants could be run on a commercial basis and whether rural entrepraneures could be attracted towards this entreprise. This paper attempts to study the strategy of setting up of bio-gas plants on a commercial basis by rural entrepreneures. The cost-benefits-analysis in the paper shows that bio-gas plants particularly of large size are commercially viable propositions. The working paper goes into the details of various senarios in which prices of important variables such as bio-gas, menure and cowdung are vaired considering the practical situations.