Wikipedia: " In a thermal power station water is the working medium. High pressure steam requires strong, bulky components. High temperatures require expensive alloys made from nickel or cobalt, rather than inexpensive steel. These alloys limit practical steam temperatures to 655 °C while the lower temperature of a steam plant is fixed by the boiling point of water. With these limits, a steam plant has a fixed upper efficiency of 35 to 42%.
An open circuit gas turbine cycle has a compressor, a combustor and a turbine. For gas turbines the amount of metal that must withstand the high temperatures and pressures is small, and lower quantities of expensive materials can be used. In this type of cycle, the input temperature to the turbine (the firing temperature), is relatively high (900 to 1,400 °C). The output temperature of the flue gas is also high (450 to 650 °C). This is therefore high enough to provide heat for a second cycle which uses steam as the working fluid; (a Rankine cycle).
In a combined cycle power plant, the heat of the gas turbine's exhaust is used to generate steam by passing it through a heat recovery steam generator (HRSG) with a live steam temperature between 420 and 580 °C."
Europe is generally agreed to be the birthplace of western culture, including such legendary innovations as the democratic nation-state, football and tomato sauce.The word Europe comes from the Greek goddess Europa, who was kidnapped by Zeus and plunked down on the island of Crete. Europa gradually changed from referring to mainland Greece until it extended finally to include Norway and Russia.Don't be confused that Europe is called a continent without looking like an island, the way the other continents do. It's okay. The Ural mountains have steadily been there to divide Europe from Asia for the last 250 million years. Russia technically inhabits "Eurasia".Europe is presently uniting into one political and economic zone with a common currency called the Euro. The European Union originated in 1993 and is now composed of 27 member states. Its headquarters is in Brussels, Belgium.Do not confuse the EU with the Council of Europe, which has 47 member states and dates to 1949. These two bodies share the same flag, national anthem, and mission of integrating Europe. The headquarters of the Council are located in Strasbourg, France, and it is most famous for its European Court of Human Rights. In spite of these two bodies, there is still no single Constitution or set of laws applying to all the countries of Europe. Debate rages over the role of the EU in regards to national sovereignty. As of January 2009, the Lisbon Treaty is the closest thing to a European Constitution, yet it has not been approved by all the EU states. Text by Steve Smith.