PETE 450 Introduction to Geothermal Reservoir Engineering Electricity

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

l Most power plants need steam to generate electricity l The steam rotates a turbine that activates a generator, which produces electricity l Geothermal power plants use steam produced from geothermal reservoirs PETE 450 ELECTRICITY GENERATION 2

There are three types of geothermal power plants Dry steam Flash steam Binary cycle PETE 450 ELECTRICITY GENERATION 3

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 ELECTRICITY GENERATION 4

Dry Steam Power Plant l 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 ELECTRICITY GENERATION 5

Dry Steam Power Plant l The first geothermal power generation plant from dry steam was constructed in 1904 in Larderello, Italy. This had a capacity of 250 k. W. PETE 450 ELECTRICITY GENERATION 6

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. PETE 450 ELECTRICITY GENERATION 7

Larderello Landscape PETE 450 ELECTRICITY GENERATION 8

Larderello Cooling Towers PETE 450 ELECTRICITY GENERATION 9

Larderello Steam vent PETE 450 ELECTRICITY GENERATION 10

The Geysers Power Plant PETE 450 ELECTRICITY GENERATION 11

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-1990 s 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. PETE 450 ELECTRICITY GENERATION 12

The Geysers 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. PETE 450 ELECTRICITY GENERATION 13

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 ELECTRICITY GENERATION 14

The Geysers PETE 450 ELECTRICITY GENERATION 15

The Geysers PETE 450 ELECTRICITY GENERATION 16

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. PETE 450 ELECTRICITY GENERATION 17

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. PETE 450 ELECTRICITY GENERATION 18

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 ELECTRICITY GENERATION 19

Flash Steam Power Plant l 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 ELECTRICITY GENERATION 20

Flash Steam Power Plant Hydrothermal plant in New Zealand PETE 450 ELECTRICITY GENERATION 21

Wairakei, New Zealand The first geothermal power station from flash steam was built in the 1950 s at Wairakei, New Zealand. PETE 450 ELECTRICITY GENERATION 22

Kızıldere Power Plant l 20. 4 MWe installed capacity l Uses steam at 4. 5 bar (147 C) l Due to water disposal problems (B), it can produce 12 -13 MWe PETE 450 ELECTRICITY GENERATION 23

Kızıldere Power Plant PETE 450 ELECTRICITY GENERATION 24

Kızıldere Power Plant PETE 450 ELECTRICITY GENERATION 25

Kızıldere Power Plant PETE 450 ELECTRICITY GENERATION 26

Binary Cycle Power Plant Binary cycle power plants operate on water at lower temperatures of about 225°– 360°F (107°– 182°C). 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. PETE 450 ELECTRICITY GENERATION 27

Binary Cycle Power Plant l 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 PETE 450 ELECTRICITY GENERATION 28

Electricity Generation PETE 450 ELECTRICITY GENERATION 29

Electricity Generation l 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). PETE 450 ELECTRICITY GENERATION 30

Electricity Generation PETE 450 ELECTRICITY GENERATION 31

High Temperature Geothermal Sources ü Kızıldere-Denizli (242 °C) ü Germencik-Aydın (232 °C) ü Tuzla-Çanakkale (174 °C) ü Salavatlı-Aydın (171 °C) ü Simav-Kütahya (162 °C) ü Seferihisar-İzmir (153 °C) ü Caferbey-Manisa (150 °C) ü Yılmazköy-Aydın (142 °C) ü Dikili-İzmir (130 °C) PETE 450 ELECTRICITY GENERATION 32

Example-1 Husavik, Iceland Enery Development PETE 450 ELECTRICITY GENERATION 33

Example-2 Nesjavellir, Iceland Enery Development PETE 450 ELECTRICITY GENERATION 34

Example-3 Svartsengi, Iceland Enery Development PETE 450 ELECTRICITY GENERATION 35