Potential of the engine-driven cogeneration system in a palm oil mill in Thailand

Biogas engine based power plants in Thai palm oil mills (POMs) plays a crucial role in the renewable energy policy of the country. Thermal efficiencies of the engine power plants range from 25–44%, while more 60% of the feeding energy is converted to waste heats, which mainly are engine cooling and exhaust. Recovering and utilizing such waste heat improves the energy efficiency. The objective of this study was to investigate the potential and feasibility of a cogeneration driven by the waste heat of the engine power plant in Thai POMs. A case study approach was conducted, and secondary data of the mill were collected and used as baselines for the calculation. The cogeneration model and techno-economic feasibility were presented. It shows that the thermal efficiency of the cogeneration has increased from 37.34% to 75.60% compared with the conventional approach. Steam and hot water production from the waste heat of 1 MW engine are 659 kg/hour and 8.54 m3/hour respectively. Thus, saving the boiler biomass-fuelled of the mill about 2,748 tons a year with a simple payback is 1.3 years. These data demonstrate the engine-driven cogeneration system is a co-benefits way for the energy efficiency improvement of Thai POMs, and it should be implemented nationwide.