Gas engine co-generation system:
Spark Ignition Gas Engine: These engines have shaft efficiency near about 35% but low capital cost/kW comparing to compression idnition engine. Temperature rangr of 70-80 C can be obtained at the engine cooling system which is possible to increase till 110C. Sizes of the engine may rangr upto 4 MW. Spark idnition engines are used to extract low pressure steam or medium or low temperature hot water on site.
Compression Ignition Engine: These are suitable for large co-generation plants. Shaft efficiency is in the range of 35- 40%. These are direct ibjection engines which may employ turbochargers, intercoolers on fittings. This system offfers flexibility to make use of an alternative fuel that is oil. Full output can be derived using the same which proves useful for curtailing the cost of gas tariff. Compression ignition engines require complex cooling system as compared to spark ignition gas engine.