1. Any of various machines having a rotor, usually with vanes or blades, driven by the pressure, momentum, or reactive thrust of a moving fluid: A turbine can be operated by steam, water, hot gases, or air, either occurring in the form of free jets or as a fluid passing through and entirely filling a housing around the rotor.
2. A general term for any machine capable of generating rotary mechanical power by converting the kinetic energy of a stream of fluid, such as water steam or hot gas: Turbines operate through the principle of impulse or reaction, or a combination of the two.

Turbines have been around for hundreds of years

• Primitive hydraulic turbines made of wooden discs carrying straight blades were believed to exist in Egypt and Mesopotamia in the 5th century B.C.
• Turbines were also in existence in ancient India and China in about the same time period.
• These early machines were used for milling corn and other cereals.
• Until the end of the Middle Ages, hydraulic and wind turbines were the only non-animal source of mechanical power.
• The modern development of the hydraulic turbine began towards the end of the 18th century where it powered sawmills, textile, and manufacturing industries.
• The first steam turbines in commercial service were installed in the norther United States by W. Avery, in 1831, to power some sawmills.
• Modern development of steam turbines began in the 1920s when large industrial groups like General Electric, Allis-Chalmers, Westinghouse, and Brown-Boveri applied these machines to generate electricity.
• The significant advances for the gas turbine came from its aeronautic applications.
• The majority of fossil fuel thermo-electrical conversion locations use steam turbines, and gas turbines as mechanical converters.

A common type of turbine with axial flow through the runner blades axially to the turbine shaft: An axial-flow turbine normally has 1-3 rotating stages and the flow of gas is essentially axial.

A steam turbine in which the exhaust steam is condensed and the water formed from this process is then used to supply the feedwater for the generator: Condensing turbines were built in the USSR at the Leningrad Metal Works in 1924.

A steam turbine in which a portion of the working fluid is tapped between stages of an expansion process and used for purposes other than generating mechanical power: The extraction turbine has provided many rooms with heating because of the devices that allow the hot vapor to be utilized.

A pistonless rotary engine having a four faces articulated rotor with a free and accessible center, rotating without vibration or dead time, and producing a strong torque at low RPM under a variety of modes and fuels; Qurbine: The Quasiturbine can be used as an air motor, steam engine, Stirling engine, compressor and pump. The Quasiturbine is also an optimization theory for extremely compact and efficient engine concepts.

The Quasiturbine is at the crossroad of three modern engines. Inspired by the turbine, it perfects the piston, and improves upon the Wankel.

The Quasiturbine is universal in relation to energy sources: Liquid and gaseous fuel, hydrogen, steam, pneumatic, and hydraulic. The Quasiturbine engine was invented by the Saint-Hilaire family and first patented in 1996. The engine makes use of a complex computer calculated oval shape stator housing, creating regions of increasing and decreasing volumes as the rotor turns. It is capable of burning fuel using detonation, the optimal combustion mode of the future which the piston cannot stand.

Ocean-power technology splits into two broad categories, tidal and wave power.

1. Wave power involves the use of the up and down motions of the waves to produce electricity.
2. Tidal power consists of harnessing the action of the tides with underwater turbines, which twirl like wind machines.
3. A third type of power generation, called ocean thermal, has the objective of exploiting temperature differences between the surface and the deep ocean, and is primarily applicable to tropical areas.
4. Some experts claim that ocean electrical power has more advantages than wind power because water is about 850 times denser than air, and so it consists of far more energy.
5. The ocean's waves, tides, and currents are also considered to be more predictable than the wind.
6. The negative aspect is that seawater can batter and corrode machinery, and costly undersea cables may be needed to bring the electrical power to shore and the machines are considerably more expensive to build.
7. General Electric, which builds wind turbines, solar panels, and other equipment for virtually every other type of energy, has so far stayed clear of ocean energy because of the much greater costs.

Viewed from the United States or Asia, Denmark is an environmental role model.

About one-fifth of the Denmark's electricity comes from wind, which wind experts say is the highest proportion of any country.

A closer look shows that Denmark is a far cry from a clean-energy paradise.

The building of wind turbines has virtually ground to a halt since subsidies were cut back.

Meanwhile, compared with others in the European Union, Danes remain above-average emitters of the greenhouse gas carbon dioxide.

For all of its wind turbines, a large proportion of the rest of Denmark's power is generated by plants that burn imported coal.

Danish experience shows how difficult it can be for countries grown rich on fossil fuels to switch to renewable energy sources like wind power.

Among the hurdles are fluctuating political priorities, the high cost of putting new turbines offshore, concern about public acceptance of large wind turbines, and the destructive volatility of the wind itself.

Some parts of western Denmark derive 100 percent of their peak needs from wind if the breeze is up.

Germany and Spain generate more power in absolute terms, but in those countries wind still accounts for a far smaller proportion of the electricity generated. The average for all 27 European Union countries is three percent.

The Germans and the Spanish are catching up as Denmark slows down.