Microturbines

Size Range

25 KW to 500 KW

Technology

Microturbines are small high-speed generator plants. Microturbines evolved from automotive and truck turbochargers, auxiliary power units for airplanes and small jet engines. They consist of a single shaft connecting a turbine, compressor and generator. Air is drawn in through a compressor into a recuperation unit that has been heated by the exhaust gases. The air flows into a combustion chamber where it is mixed with the fuel and burned. The hot gas is expanded through the turbine creating mechanical energy. The exhaust gases pass out through the recuperation unit to capture some of the remaining heat.

Performance and Efficiency

Overall cogeneration efficiencies can reach 85%
High heat-to-power ratio, so electrical efficiencies are only 20% to 30%.

Fuel Types

Predominately fuelled by natural gas.
Diesel, petrol or biogas can also be used.

Applications

Commerical, Residential, Small Industry

The heat produced by a microturbine can be used to produce low-pressure steam or hot water for on-site requirements.
Microturbines are well suited to provide heat and electricity to small commercial applications such as restaurants, hotels and offices.

Hospitals, such as this one pictured here in Italy, are ideal applications of microturbines for use in combined heat and power mode.

Microturbines can be applied in remote oil extraction applications such as this off-shore oil rig off the coast of Mexico.

Advantages and Disadvantages

Advantages	Disadvantages
Microturbines can be used for back-up power for commercial applications and peak shaving; ‘Black start’ capability, enabling the system to operate with or without a grid interconnection; High overall efficiencies of up to 85% with heat recovery.	Relatively low electrical efficiencies of 20-30%; Efficiency is sensitive to changes in ambient conditions.

Economic Performance

Cost Range for Microturbines
Installed Capital Cost ($/kW)		1,300 – 2,500
Operating and Maintenance ($c/kWh)		0.5 – 1.6
Levelized Cost ($c/kWh)
8000hrs/year		5.0 – 7.0
4000hrs/year		7.0 – 11.0
Source: WADE, 2006

Mircoturbines costs remain relatively high, but manufacturers aim for significant mass production of standardized units relative to all other DE generation technologies, which could lower the cost and enhance competitiveness of these devices in cogeneration applications.