Microturbines are becoming wide spread for distributed power and combined heat and power applications. They range from handheld units producing less than a kilowatt to commercial sized systems that produce tens or hundreds of kilowatts.

Also known as:

• Turbo alternators
• Gensets
• MicroTurbine® (registered trademark of Capstone Turbine Corporation)
• Turbogenerator® (registered tradename of Honeywell Power Systems , Inc.)

Part of their success is due to advances in electronics, which allow unattended operation and interfacing with the commercial power grid. Electronic power switching technology eliminates the need for the generator to be synchronized with the power grid. This allows, for example, the generator to be integrated with the turbine shaft, and to double as the starter motor.

Microturbine systems have many advantages over piston engine generators, such as higher power density (with respect to footprint and weight), extremely low emissions and few, or just one, moving part. Those designed with foil bearings and air-cooling operate without oil, or other hazardous materials.

Microturbines accept most commercial fuels, such as natural gas, propane, diesel and kerosene. The are also able to produce renewable energy when fueled with biogas from landfills or sewage treatment plants.

Microturbine designs usually consist of a single stage radial compressor, a single stage radial turbine and a recuperator. Recuperators are difficult to design and manufacture because they operate under high pressure and temperature differentials. Exhaust heat can be used for water heating, drying processes or absorption chillers, which create cold for air conditioning from heat energy instead of electric energy.

Typical microturbine efficiencies range between 25 to 35 percent. When in a combined heat and power cogeneration system, efficiencies of greater than 80 percent are commonly achieved.