Combined Heat and Power (CHP) or Cogeneration is the simultaneous production of useful heat and electricity in the same plant. Conventional electricity generation is via large power stations releasing low-grade heat into the atmosphere as a wasted by-product. By retrieving some of this rejected heat via heat exchangers and being situated near where it can be used, CHP plants can greatly increase their overall efficiency and provide heat to commercial, industrial or public sectors at the same time as producing electricity.
The main components of a typical system are:
- the engine or prime mover which drives the generator.
- the generator which produces electricity.
- the heat recovery system that recovers the waste heat from both the engine water cooling jacket and exhaust gases.
- the exhaust system to take away the products of combustion.
- the control panel to monitor the operation.
| ||Spark Ignitiion Engine||Compression Ignition Engine||Gas Turbine||Combined Cycle||Back Pressure Steam Turbine||Pass Out Steam Turbine|
|Fuel Type||Natural gas, Biogas...||Natural gas, Biogas, Gas oil, Heavy oils||Natural Gas, Biogas, Gas Oil||Natural Gas, Biogas, Gas Oil||All types||All types|
|Capacity Range||30 kWe to 2 MWe||100 kWe to 20 MWe||> 1 MWe||> 3 MWe||> 500 kWe||> 1MWe|
|Heat: Power Ratio||1: 1 to 3: 1||0.5: 1 to 1.5: 1 (3: 1 with boost firing)||1.5: 1 to 2.5: 1 (5: 1 with supplementary firing)||1: 1 (3: 1 with supplementary firing)||3: 1 to 10: 1||3: 1 to 8: 1|
|Heat Output Quality||LPHW, Steam (rare)||LPHW, Steam||High Grade Steam||Medium Grade Steam||Medium Grade Steam||Steam at 2 pressures|
|Electrical generating Efficiency %||25-33||35-42||25-40||35-50||7-20||10-20|
|Overall Efficiency %||70-78||65-75 (75-82 with boost firing)||65-80 (75-82 with suppl. firing)||73-80 (80-85 with suppl. firing)||75-84||75-84|