Pete 552

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

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• There are three types of geothermal power plants
• Dry steam
• Flash steam
• Binary cycle

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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.

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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
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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.

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Larderello
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.
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Larderello
Larderello Landscape
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Larderello
Cooling Towers
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Larderello
Steam vent
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The Geysers
Geysers Power Plant
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The Geysers

• Full-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 Geysers

• The Lake County-Southeast Geysers Effluent
  Pipeline Project begins operations in 1997. The
  pipeline project is the first wastewater-to-electr
  icity 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 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.

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The Geysers
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The Geysers
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The Geysers
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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The Geysers
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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Flash Steam Power Plant

• They use geothermal reservoirs of water with
  temperatures greater than 360F (182C). 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.

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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
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Flash Steam Power Plant
Hydrothermal plant in New Zealand
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Wairakei, New Zealand

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

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Kizildere 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

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Kizildere Power Plant
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Kizildere Power Plant
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Kizildere Power Plant
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Binary Cycle Power Plant

• Binary cycle power plants operate on water at
  lower temperatures of about 225360F
  (107182C). These plants use the heat from the
  hot water to boil a working fluid, usually an
  organic compound with a low boiling point. The
  working fluid is vaporized in a heat exchanger
  and used to turn a turbine. The water is then
  injected back into the ground to be reheated. The
  water and the working fluid are kept separated
  during the whole process, so there are little or
  no air emissions.

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Binary 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 Generation
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Electricity Generation

• 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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Electricity Generation
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High Temperature Geothermal Sources

• Kizildere-Denizli (242 C)
• Germencik-Aydin (232 C)
• Tuzla-Çanakkale (174 C)
• Salavatli-Aydin (171 C)
• Simav-Kütahya (162 C)
• Seferihisar-Izmir (153 C)
• Caferbey-Manisa (150 C)
• Yilmazköy-Aydin (142 C)
• Dikili-Izmir (130 C)

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Example-1
Husavik, Iceland Enery Development
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Example-2
Nesjavellir, Iceland Enery Development
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Example-3
Svartsengi, Iceland Enery Development