The biogas CHP units are applicable for utilization of Biogas from Anaerobic Digestion and allow the simultaneous production of electricity and heat. The electricity can be used to power the surrounding equipment or exported to the national grid. For biogas plants that are using a CHP unit, there are two key types of heat: Low-grade heat and high-grade heat.
Low-grade heat from the cooling circuits of the gas engine, typically available as hot water on a 70/90°C flow/return basis. The low-grade heat is typically used to heat the digester tanks to the optimum temperature for the biological system. Mesophilic anaerobic digesters typically operate at 35-40°C. Thermophilic anaerobic digesters typically operate at a higher temperature between 49-60°C.
High-grade heat from the engine exhaust gas (typically ~450°C) The high-grade heat can either be used directly into a drier or waste heat boiler. Alternatively, it can be converted into hot water using a shell and tube exhaust gas heat exchanger to supplement the heat from the engine cooling systems. Biogas CHP unit electrical output 50 – 580 kWe and can be supplied as stand-alone units or in pre-plumbed and wired containers.