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| In future the geothermal will get a major role in the energy generation because they are exhaustless and many-sided useable. |
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The earth has many different mineral resources first of all heat. Every one of us knows the following daily situations: to pass frost-protected lines some meters under the earth, the swelter of miners with 40°C in a deep of 1000 meters under the earth, the wellness offer of 70°C thermal sole from 2000 meter deeps and finally the fascination of 1400°C hot lava. Earth scientist believe the earth’s core have nearly 5000°C. This heat quantity is a rest of the genesis billions years ago and a result of the radioactive process of disintegration. So come a constant heat flows out of the earth, that can be seen at special places in form of magma like in Island, Hawaii, New Zealand,…).
First readings of the earth temperature are done 200 years ago by Alexander von Humboldt on his expedition through South America. There he uses a travel thermometer to read the temperature in caves. The temperature grows up with the rushing deep.
Specific readings are done at the deepest hole of the world in the salt dome in Sperenberg, Brandenburg, in the years 1867 – 1871 to ascertaining the geothermic step of 32,5 m/K (or 3,1 K/100m ). |
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Geothermal the heat from the earth can be used for heat and energy production. Because in Germany are bad geothermic requirements so it is only used for heat supply. Normally the geothermal extraction is a process of changing the earth temperature. The cold water is conducted throw pipes in the deeps and come heated through one other pipe back. If there are no natural sources you can extract geothermal power by using the Hot-Dry-Rock process (HDR). At this process are used the temperature of rocks found some kilometres below ground. There is pumped high pressure water down in a heat zone and it come back with a temperature near 150°C. Geothermal compared to solar energy and wind energy it give a constant energy.
In central Europe the earth temperature is between 10 and 12°C in a deep of 10 – 20 meter. In near-surface straticulates the earth temperature is affected by the weather. On each square meter comes nearly 1100 kWh every year. In deeper layers the geothermal effects preponderate and every 33 meter the temperature grow about 1°C. The basic idea of near-surface geothermal is to use extract thermal heat about the fundament and use it with appropriate systems in the building.
This idea can be used in reversed use too to cool the building. So you give the excess heat to the ground. So if there is the right underground you have a seasonal storage of cooling and heating energy.
There are different ways to use the ground as energy source, for example vertical and horizontal loops, earth collectors, the rift collectors and in the strip footing integrated absorber. The last chooses are only much bordered energy sources and the loops are very expansive.
In Germany geothermal power exists in abound too. To use the stored power you must have a liquid - normally water. In the nature occurring liquids are called aquifer. Normally they are near-surface but there are some in a deep of 500 to 2000 meters. If there are no natural aquifers it can be used different methods to take the energy out with a fluid. |
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If the temperature of the source is higher then 150°C, the thermal power can profitable converted to electrical energy. If the geothermal fluid comes out with high compression and temperature, it is a mix of water and steam. The energy of the compressed are transformed to electrical energy via turbines and generators. The temperature of the fluid at the outlet of the turbine is still nearly 100°C. This rest temperature can directly used for the heating of buildings.
In future the geothermal will get a major position in the energy generation because it is exhaustless and many sided useable. |
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