GEOTHERMAL+ENERGY+-+Maggi

**Back to 11.3 PRESENTATIONS**
= = =__**GEOTHERMAL ENERGY**__=

**HOW IT WORKS:**
====Geothermal power plants drill into the ground to extract hot steam which is used to turn the turbines. This can be done in 2 different ways, by just drilling into the ground and letting steam escape into the turbine (dry steam method), or extracting hot water from the ground and lowering the pressure of it to flash it into steam, which is then used to turn the turbine (flash steam method). The steam used to turn the turbine is then condensed back into water, and then either used for different purposes around the power plant, or returned to the Earth, making geothermal energy sustainable.====

====Another system that geothermal power plants use is called the binary cycle. This allows cooler geothermal reservoirs to be used than with the normal steam powered plants. With the binary cycle, hot water is pumped from a geothermal well, and when it goes through a heat exchanger, the cooled water is then returned to a reservoir. Another fluid with a low boiling point is pumped at a high pressure through the heat exchanger, and the fluid is vaporized from the heat that came from the geothermal water, and then it is directed through a turbine. After passing through the turbine, the fluid is condensed back into a liquid form with cold water, and then it is reused and cycled back again.====

AN EXAMPLE:
====The world's first geothermal power station was built in 1911 in Larderello, which is in Southern Tuscany, Italy. Some parts of Italy are volcanically active, and it has a history of using steam and hot water springs for bathing and hot water, which dates back as far as the Roman times.====

Geothermal energy was first used in 1904, when emerging steam was used to turn a turbine that powered five light bulbs. Geothermal energy was then proved to work, and the Larderello power station was built in the //Valle del Diavolo// (Devil's valley) in 1913, and it was the only geothermal power station for almost half a century. The 250kW power station provided power for the Italian electric railway system.

====The Larderello power station is still running, and currently powers about one million homes, which is almost five thousand GWh per year, and it's 10% of the world's total geothermal electricity production.==== ====Geothermal energy is a renewable energy source, but eventually the rocks that heat the steam below the surface would cool. Since the 1950's, the steam pressure from the Valle del Diavolo site has fallen around 30%.====



====The most used method of using geothermal energy is the flash steam method. Now, the biggest producers of geothermal energy is China. The use of geothermal energy in China started around the 1970's, and the electricity producing plants are all located in Tibet.====

FACTS AND FIGURES:
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 * ====Geothermal energy plants are generally found near the plate boundaries, on the Ring of Fire, where volcanoes are created, and where earthquakes generally happen, due to the shifting plates. The Ring of Fire surrounds the Pacific Ocean.====
 * ====The molten rock in the volcanoes and underground heats ground water which is trapped in porous rock.====
 * ====Geothermal energy is a renewable energy source, and fully sustainable, as the the steam used to turn the turbine can be condensed back into water and released into small reservoirs, or back into the ground. Some CO2 and methane trapped in rocks and underground may be released as wells are drilled to reach the hot rocks, but the amount releases is small compared to what fossil fuel burning stations release.====
 * ====The word "geothermal" is derived from the greek roots geo, meaning earth, and thermos, meaning heat. So geothermal literally means "earth-heat".====
 * ====Geothermal energy is generated in over 20 countries now, including Iceland, Italy, United States, and China.====
 * ====The government has calculated that the entire world resource of geothermal energy is larger than the resources of coal, oil, gas and uranium combined. This makes it a very good alternative energy source.====
 * ====Because it's situated where there are a high concentration of volcanoes, Iceland is an ideal location for generating geothermal energy. Over 26% of Iceland's electrical energy is from geothermal sources, and geothermal heating is used in 87% of the homes in Iceland.====

ENVIRONMENTAL EFFECTS:
====The environmental effects of building and maintaining a geothermal power plant can affect land stability in the surrounding regions. This mostly is a concern with flash steam power plants, where the plant injects water into hot rock where water wasn't there before. Dry steam and flash steam power plants also emit low levels of greenhouse gases, although it's only about 5% of the total gases released by fossil fuel power plants. Also, water collected from geothermal sources will contain tiny amounts of dangerous substances like mercury, arsenic, and antimony. This water has to be treated properly,====

otherwise, if dumped into rivers directly, it can make the water unsafe to drink, and potentially endangering species of aquatic life.
====To solve some of these problems, geothermal plants can be built with emissions controlling systems that can contain the gases and inject them back into the earth, reducing the total emissions to less than 0.1% of the emissions given out by fossil fuel power plants. Water collected from geothermal sources can be run through a filter before using, reducing if not eliminating the risk of dangerous substances in the water, making it safe to let the water into reservoirs or rivers after it has been used in the power plant.====


 * ====Geothermal power stations don't create any pollution. Some gases may be released from deep inside the earth, but it could be easily contained.====
 * ====They cost less to build than to construct an oil, gas, coal or nuclear power plant.====
 * ====Geothermal power plants take up very little space.====
 * ====Running costs for the plant is very low, as there are no fuels used to generate the power, which means cutting the costs of purchasing, transporting or cleaning up of the fuels that are used to generate power.====



DISADVANTAGES:

 * ====Finding a suitable location could take a long time, because the land has to be tested for the heat first, and usually, most of the suitable areas for a geothermal power plant are deemed unable to support an energy plant, or near the poles, high up in the mountains or near a volcano.====
 * ====In many cases, a lot of power plants that have been extracting steam for many years could suddenly stop producing steam. Sometimes, it takes around 10 years for the steam to come back. So the energy isn't that reliable.====
 * When developing a piece of land for use as a geothermal power plant, developers have to be careful and know that harmful gases can escape from deep in the earth, through holes drilled by builders, contain any leaked gases, and dispose of them safely.