Summary of Combined Heat Power Technologies (nfm)

CHP system

Advantages

Disadvantages

Available sizes

Gas turbine

High reliability. Low emissions.

High grade heat available. No cooling required.

Require high pressure gas or inhouse gas compressor. Poor efficiency at low loading. Output falls as ambient temperature rises.

500 kW to 40 MW

Microturbine

Small number of moving parts. Compact size and light weight. Low emissions. No cooling required.

High costs. Relatively low mechanical efficiency. Limited to lower temperature cogeneration applications.

30 kW to 350 kW

Spark ignition (SI) reciprocating engine

High power efficiency with part load operational flexibility. Fast start-up. Relatively low investment cost. Can be used in island mode and have good load following capability. Can be overhauled on site with normal operators. Operate on low-pressure gas.

High maintenance costs. Limited to lower temperature cogeneration applications. Relatively high air emissions. Must be cooled even if recovered heat is not used. High levels of low frequency noise.

< 5 MW

High speed (1,200 RPM) = or< 4MW

Diesel/ compression ignition CI) reciprocating engine

Low speed (60-275 RPM) = or< 65MW

Steam turbine

High overall efficiency. Any type of fuel may be used. Ability to meet more than one site heat grade requirement. Long working life and high reliability. Power to heat ratio can be varied.

Slow start up. Low power to heat ratio.

50 kW to 250 MW

Fuel Cells

Low emissions and low noise. High efficiency over load range. Modular design.

High costs. Low durability and power density. Fuels requiring processing unless pure hydrogen is used.

200 kW to 250 kW