Combined Heat and Power (CHP)

Typically this achieves a 35% reduction in energy use as well as ensuring a secure supply from having an independent source of power.

In a similar manner to most other means of generating electricity CHP plants use a prime mover to drive the electricity generator.

Types of Technology Available

CHP units can be based on a variety of prime mover technologies.

• Gas turbines drive a turbine generator and produce exhaust gases at between 400 and 550ºC. Gas turbines are typically available as 0.5 to 200MWe systems and produce high grade heat.
  
  
• Reciprocating engines are fuelled by gaseous fuels. Spark ignition engines are available up to 4MWe and compression ignition engines (diesel engines) up to 15MWe.
  • High-grade heat at about 400ºC is available from the exhaust gases from reciprocating engines.
  • Low-grade heat at about 80ºC is available from jacket cooling and lubricating/cooling systems.
  • Spark ignition engine based packaged CHP may be applicable to sites with a demand of less than 1MWe.
    
    
• Steam turbines use any fuel to generate steam and systems and are available from 0.5MWe upwards. Steam turbines:
  • Are often used in conjunction with waste heat boilers and produce medium grade heat.
  • Can incorporate several pressure stages.
  • May be fully condensing or pass out intermediate pressure or low-pressure steam for process use.
    
    
• Combined cycle systems involve passing exhaust gases to a steam raising boiler and then to a steam turbine. Such systems are available from 10MWe upwards and produce medium grade heat.