Geothermal Energy Ismail Yilmaz Murat Yakut

WHAT DOES THE WORD "GEOTHERMAL" MEAN? Geo = Earth Thermal = Heat Heat flows outward from Earth's interior. The crust insulates us from Earth's interior heat. The mantle is semi- molten, the outer core is liquid and the inner core is solid.

When hot water and steam reach the surface, they can form fumaroles, hot springs, mud pots and other interesting phenomena.

HOW DOES GEOTHERMAL HEAT GET UP TO EARTH'S SURFACE? Conduction When the rising hot water and steam is trapped in permeable and porous rocks under a layer of impermeable rock, it can form a geothermal reservoir. When the rising hot water and steam is trapped in permeable and porous rocks under a layer of impermeable rock, it can form a geothermal reservoir. Convection In some regions, the mantle beneath the crust may be hot enough to partly melt and create magma. Magma rising upward out of the mantle can bring intense shallow into the crust. Rainwater seeping downward through pores and crevices in the crust to depths of a mile or more is heated. The heated water may be stored at depth in geothermal reservoirs, or the hot water may flow upward out the reservoirs to the surface as hot springs, or boil near the surface to create geysers, fumeroles, and mudpots.

Geothermal Regions Many areas have accessible geothermal resources, especially countries along the circum- Pacific "Ring of Fire," spreading centers, continental rift zones and other hot spots. Many areas have accessible geothermal resources, especially countries along the circum- Pacific "Ring of Fire," spreading centers, continental rift zones and other hot spots.

HOW HAVE PEOPLE USED GEOTHERMAL ENERGY IN THE PAST? Bathing: Ancient civilizations used hot springs for bathing

Medical Therapy Early Romans used geothermal water to treat eye and skin disease

Cooking Native Americans and others used geothermal water for cooking

Heating Early Romans used geothermal water to heat their homes in Pompeii

HOW DO WE USE GEOTHERMAL ENERGY TODAY? Space Heating/Cooling Water Heating / Spas Aquaculture : Fish, Shrimp, Abalone, Alligators Drying of fruits / vegetables / lumber Industrial Uses: Dying of cloth, washing wool, piping under sidewalks to keep from freezing, manufacturing paper Greenhouses: Vegetables, flowers and other crops Electricity Generation

Some pictures for Geothermal energy

HOW IS ELECTRICITY GENERATED USING GEOTHERMAL ENERGY? Natural steam from the production wells power the turbine generator. The steam is condensed by evaporation in the cooling tower and pumped down an injection well to sustain production. Natural steam from the production wells power the turbine generator. The steam is condensed by evaporation in the cooling tower and pumped down an injection well to sustain production.

EASY ON THE ENVIRONMENT Geothermal power plants have been built In the middle of corps In the middle of corps In the forested recreation areas In the forested recreation areas In fragile deserts In fragile deserts In tropical forests In tropical forests

HOW IS ELECTRICITY GENERATED USING GEOTHERMAL ENERGY? Flash Steam Power Plants Flash Steam Power Plants Binary Cycle Power Plants Binary Cycle Power Plants Dry Steam Power Plants Dry Steam Power Plants Hot Dry Rock Technology Hot Dry Rock Technology

Dry Steam Power Plants “Dry” steam extracted from natural reservoir “Dry” steam extracted from natural reservoir Steam is used to drive a turbo-generator Steam is used to drive a turbo-generator Steam is condensed and pumped back into the ground Steam is condensed and pumped back into the ground Can achieve 1 kWh per 6.5 kg of steam Can achieve 1 kWh per 6.5 kg of steam –A 55 MW plant requires 100 kg/s of steam

Prince Piero Ginori Conti invented the first geothermal power plant in 1904, at the Larderello dry steam field in Italy.

Flash Steam Power Plants Steam with water extracted from ground Steam with water extracted from ground Pressure of mixture drops at surface and more water “flashes” to steam Pressure of mixture drops at surface and more water “flashes” to steam Steam separated from water Steam separated from water Steam drives a turbine Steam drives a turbine Turbine drives an electric generator Turbine drives an electric generator Generate between 5 and 100 MW Generate between 5 and 100 MW Use 6 to 9 tonnes of steam per hour Use 6 to 9 tonnes of steam per hour

This flash plant is in Japan. In flash plants, both the unused geothermal water and condensed steam are injected back into the periphery of the reservoir to sustain the life of the reservoir.

Binary Cycle Power Plants Low temps – 100 o and 150 o C Low temps – 100 o and 150 o C Use heat to vaporize organic liquid Use heat to vaporize organic liquid Use vapor to drive turbine Use vapor to drive turbine –Causes vapor to condense –Recycle continuously Typically 7 to 12 % efficient Typically 7 to 12 % efficient 0.1 – 40 MW units common 0.1 – 40 MW units common

In the heat exchanger, heat is transferred from the geothermal water to a second liquid. The geothermal water is never exposed to the air and is injected back into the periphery of the reservoir.

Binary technology allows the use of lower temperature reservoirs, thus increasing the number of reservoirs that can be used. This binary plant is at Soda Lake, Nevada.

Hot Dry Rock Technology Wells drilled 3-6 km into crust Wells drilled 3-6 km into crust –Hot crystalline rock formations Water pumped into formations Water pumped into formations Water flows through natural fissures picking up heat Water flows through natural fissures picking up heat Hot water/steam returns to surface Hot water/steam returns to surface Steam used to generate power Steam used to generate power

Benefits of Geothermal Power Provides clean and safe energy using little land Provides clean and safe energy using little land Is renewable and sustainable Is renewable and sustainable Generates continuous, reliable power Generates continuous, reliable power Avoids importing and benefits local economies Avoids importing and benefits local economies Offers modular, incremental development and village power to remote sites. Offers modular, incremental development and village power to remote sites.

Worldwide Electricity Generation Geothermal power plants are producing over 8,200 megawatts of electricity in 21 countries, supplying about 60 million people, mostly in developing countries. Geothermal power plants are producing over 8,200 megawatts of electricity in 21 countries, supplying about 60 million people, mostly in developing countries.

Disadvantages of Geothermal Energy Extracting large amounts of water can cause land subsidence, and this can lead to an increase in seismic activity. To prevented this the cooled water must be injected back into the reserve in order to keep the water pressure constant underground. Extracting large amounts of water can cause land subsidence, and this can lead to an increase in seismic activity. To prevented this the cooled water must be injected back into the reserve in order to keep the water pressure constant underground. Some high mineral / metal wastewater and solid waste is produced Some high mineral / metal wastewater and solid waste is produced Smelly gasses – H 2 S, Ammonia, Boron Smelly gasses – H 2 S, Ammonia, Boron Release of steam and hot water can be noisy Release of steam and hot water can be noisy

Countries Generating Electricity with Geothermal Resources Australia Australia China China Costa Rica Costa Rica El Salvador El Salvador Ethiopia Ethiopia France France Guatemala Guatemala Iceland Iceland Italy Italy Japan Japan Mexico Mexico United States United States Turkey Turkey Russia Russia