An innovative approach for waste heat utilization from municipal biogas plant

The efficiency of biogas powered Generator-set lies in the range of 30 to 35%. Remaining 65% to 70% energy goes waste at different stages of utilization. Out of these different ways of energy loss, heat rejection in the combustion and engine exhaust gases accounts for 55% - 60% of total fuel energy input to the engine. In this paper, an innovative approach from the view of combination of generation and consumption end for this waste heat utilization is presented. The generation of hot water to fulfill hot water requirements for domestic hot water use has been proposed. The data is collected from two biogas plants in Pune city of Maharashtra, India, having capacity of 5 tons per day (TPD) and genset capacity of 30 kW each. Energy analysis of two 30 kW biogas powered gensets has been done, which brings out potential for more than twenty thousand litres of water can be heated from 25 °C to 50 °C. This presented approach can result into overall efficiency of plant upto 60% - 65%. Also the techno-economical analysis of the proposed system has been done which shows payback period of approximately 10 months. Therefore, it is concluded that the approach is beneficial from both economical as well as environmental perspective.