PETE 450 Introduction to Geothermal Reservoir Engineering Electricity Generation Dr. Mahmut...

PETE 450Introduction to Geothermal Reservoir

Engineering

Electricity Generation

Dr. Mahmut Parlaktuna

PETE 450 2ELECTRICITY GENERATION

Most power plants Most power plants need steam to need steam to generate electricitygenerate electricity

The steam rotates a The steam rotates a turbine that activates turbine that activates a generator, which a generator, which produces electricityproduces electricity

Geothermal power Geothermal power plantsplants use steam use steam produced from produced from geothermal geothermal reservoirsreservoirs


There are three types of geothermal power plantsThere are three types of geothermal power plants

DDry steamry steam

FFlash steamlash steam

BBinary cycleinary cycle


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.

Dry Steam Power PlantDry Steam Power Plant


Dry Steam Power PlantDry 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


The first geothermal power generation plant from dry steam was constructed in 1904 in Larderello, Italy. This had a capacity of 250kW.

Dry Steam Power PlantDry Steam Power Plant


LarderelloLarderello

The first modern geothermal power plants were also built in Larderello, Italy. They were destroyed in World War II and rebuilt. Today after 100 years, the Larderello field is still producing.



Larderello Landscape



Cooling Towers

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ELECTRICITY GENERATION


Steam vent

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The GeysersThe Geysers

Geysers Power Plant

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The GeysersThe GeysersFull-scale commercial development began by 1955, and the 11-megawatt (MW) Geysers Unit 1 power plant was commissioned in 1960. By 1989, installed generating capacity at The Geysers was 1,967 MW. Since 1987, The Geysers has experienced a decline in steam pressure and electricity production that has coincided with older power plants in the area reaching the end of their useful lives. Initial pressure in most Geysers production wells was above 500 psi, but by the mid-1990s many fell below 200 psi. And because pressure determines production rate, it is no longer practical in most areas of The Geysers to drill new wells to supplement steam supply.

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The Lake County-Southeast Geysers Effluent Pipeline Project begins operations in 1997. The pipeline project is the first wastewater-to-electricity project in the world. The 29-mile underground pipeline delivers eight million gallons of treated reclaimed water to The Geysers everyday to be recycled into the geothermal resource.

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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.

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The first geothermal power plants at The Geysers dry steam field were built in 1962.

It is still the largest producing geothermal field in the world.

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20 plants are still operating at The Geysers. Wastewater from nearby cities is injected into the field, providing environmentally safe disposal and increased steam

to power plants.

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They use geothermal reservoirs of water with They use geothermal reservoirs of water with temperatures greater than 360°F (182°C). This very hot temperatures greater than 360°F (182°C). This very hot water flows up through wells in the ground under its water flows up through wells in the ground under its own pressure. As it flows upward, the pressure own pressure. As it flows upward, the pressure decreases and some of the hot water boils into steam. decreases and some of the hot water boils into steam. The steam is then separated from the water and used The steam is then separated from the water and used to power a turbine/generator. Any leftover water and to power a turbine/generator. Any leftover water and condensed steam are injected back into the reservoir, condensed steam are injected back into the reservoir, making this a sustainable resource.making this a sustainable resource.

FlashFlash Steam Power Plant Steam Power Plant

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Flash Steam Power PlantFlash 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

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FlashFlash Steam Power Plant Steam Power Plant

Hydrothermal plant in New Zealand

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Wairakei, New ZealandWairakei, New ZealandThe first geothermal power station from flash steam was built in the 1950s at Wairakei, New Zealand.

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Kızıldere Kızıldere Power PlantPower 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

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Binary cycle power plants operate on water at lower Binary cycle power plants operate on water at lower temperatures of about 225°–360°F (107°–182°C). temperatures of about 225°–360°F (107°–182°C). These plants use the heat from the hot water to boil a These plants use the heat from the hot water to boil a working fluid, usually an organic compound with a low working fluid, usually an organic compound with a low boiling point. The working fluid is vaporized in a heat boiling point. The working fluid is vaporized in a heat exchanger and used to turn a turbine. The water is then exchanger and used to turn a turbine. The water is then injected back into the ground to be reheated. The water injected back into the ground to be reheated. The water and the working fluid are kept separated during the and the working fluid are kept separated during the whole process, so there are little or no air emissions. whole process, so there are little or no air emissions.

Binary CycleBinary Cycle Power Plant Power Plant

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Binary Cycle Power PlantBinary Cycle Power Plant Binary cycle power plants (Figure 9) are used where the geothermal resource is

insufficiently hot to efficiently produce steam, or where the resource contains too many chemical impurities to allow flashing.

Binary Cycle Power Plant

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Electricity GenerationElectricity Generation

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There is 8900 MW of installed geothermal electricity generation capacity worldwide. The United States is the largest producer of geothermal electricity (2544 MW), followed by the Philippines (1931 MW) (Bertani, 2005).

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High Temperature Geothermal SourcesHigh Temperature Geothermal Sources

Kızıldere-Denizli (242 °C) Germencik-Aydın (232 °C) Tuzla-Çanakkale (174 °C) Salavatlı-Aydın (171 °C) Simav-Kütahya (162 °C) Seferihisar-İzmir (153 °C) Caferbey-Manisa (150 °C) Yılmazköy-Aydın (142 °C) Dikili-İzmir (130 °C)

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Example-1Example-1

Husavik, Iceland Enery DevelopmentHusavik, Iceland Enery Development

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Example-2Example-2

Nesjavellir, Iceland Enery DevelopmentNesjavellir, Iceland Enery Development

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Example-3Example-3

Svartsengi, Iceland Enery DevelopmentSvartsengi, Iceland Enery Development

PETE 450 Introduction to Geothermal Reservoir Engineering Electricity Generation Dr. Mahmut...

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