Abstract: In this paper, we present a mathematical model for integrating renewable energy sources in order to meet an energetic demand in Nagapattinam district with a lowest cost. It would be beneficial to switch over to renewable energy sources like solar, wind, tide and biomass etc. This study focuses on making use renewable sources as an alternative source of energy. The study area is Nagapattinam district a south coastal region of Tamilnadu in India, and a generalized findings and suggestions have been given based on the secondary data obtained. The problem is formulated as an integer linear program where the objective function is to be minimizing the initial capital investment.