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Most power plants need steam to generate electricity The steam rotates a turbine that activates a generator, which produces electricity Geothermal power plants use steam produced from geothermal reservoirs. There are three types of geothermal power plants D ry steam F lash steam
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Most power plants need steam to generate electricity • The steam rotates a turbine that activates a generator, which produces electricity • Geothermal power plantsuse steam produced from geothermal reservoirs PETE 450
There are three types of geothermal power plants Dry steam Flash steam Binary cycle PETE 450
Dry Steam Power Plant Dry steam power plants draw from underground resources of steam. The steam is piped directly from underground wells to the power plant, where it is directed into a turbine/generator unit. PETE 450
Dry Steam Power Plant • The dry steam power plant is suitable where the geothermal steam is not mixed with water. Production wells are drilled down to the aquifer and the superheated, pressurised steam (180 ° - 350 ° C) is brought to the surface at high speeds, and passed through a steam turbine to generate electricity. Schematic of a Dry Steam Power Plant PETE 450
Dry Steam Power Plant • The first geothermal power generation plant from dry steam was constructed in 1904 in Larderello, Italy. This had a capacity of 250kW. PETE 450
The Geysers The Santa Rosa Geysers Recharge Project is selected to transport 11 million gallons of treated reclaimed water per day to The Geysers through a 41-mile underground pipeline, 1998. Water is recycled back into the ground, heated, and used at steam to power the plants. PETE 450
Flash Steam Power Plant They use geothermal reservoirs of water with temperatures greater than 360°F (182°C). This very hot water flows up through wells in the ground under its own pressure. As it flows upward, the pressure decreases and some of the hot water boils into steam. The steam is then separated from the water and used to power a turbine/generator. Any leftover water and condensed steam are injected back into the reservoir, making this a sustainable resource. PETE 450
Flash Steam Power Plant • Single flash steam technology is used where the hydrothermal resource is in a liquid form. The fluid is sprayed into a flash tank, which is held at a much lower pressure than the fluid, causing it to vaporise (or flash) rapidly to steam. The steam is then passed through a turbine coupled to a generator as for dry steam plants. Single Flash Steam Power Plant PETE 450
Flash Steam Power Plant Hydrothermal plant in New Zealand PETE 450
Wairakei, New Zealand The first geothermal power station from flash steam was built in the 1950s at Wairakei, New Zealand. PETE 450
Kızıldere Power Plant • 20.4 MWe installed capacity • Uses steam at 4.5 bar (147 C) • Due to water disposal problems (B), it can produce 12-13 MWe PETE 450
Kızıldere Power Plant PETE 450