Geothermal power comes from heat deep within the ground, (geo meaning earth and thermal meaning heat). The greatest way geothermal power is used to make electricity is when we inject fluid deep into hot rocks so it will convert into steam, rise to the surface and spin turbines that then in turn generate electricity. Geothermal energy plants drill down anywhere between 100m - 7 500m, reaching temperatures over 375˚C. Studies show that geothermal power is a huge resource. Geoscience Australia estimates that one per cent of the geothermal energy shallower than five kilometres and hotter than 150°C could supply Australia's total energy requirements for 26,000 years. Another major advantage of geothermal energy, unlike many other renewables, is that geothermal is baseload—meaning geothermal plants could run continuously 24/7 and wouldn’t be disrupted by days without wind or direct sun.
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The heat for geothermal energy comes from deep inside the earth. But there are places where this heat is able to travel to the surface. This mainly occurs on the pacific ring of fire where the earth is particularly active. Most of the geothermal power plants that have been built so far are hydrothermal. They are powered by hot water that is close to the surface of the earth. They use hot water or steam from the ground to power turbines that make electricity. Today there are many hydrothermal power plants around the world, the biggest being north of san francisco at a hot spring called The Geysers. This kind of geothermal power, however, is only available where there is a natural source of water underground and underground rocks that are permeable.
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However, geothermal energy is not only limited to geothermal hotspots. Recently a new type of geothermal technology has been developed called enhanced geothermal systems or EGS. EGS works when we drill down into the earth's crust as far as 3.2 km. Next, they pump high pressure water down into the hot rock below the surface. This splits the rocks and creates a path for the water to flow. Once the system is in place engineers can pump water through the hot rocks. The water becomes superheated or turns into steam, before a second set of pipes is used to pump that hot water back up to the surface. There it's used to power a turbine and generate electricity. A major problem with ESG is that drilling deep into the earth can sometimes trigger an earthquake. This means that engineers have to be very careful when drilling around unstable areas. Special sensors have also been detected to warn if a drill is going to start a quake and shut down in time. Most EGS goes down only to 3 - 6 km deep but new technologies are being developed that could enable EGS to be able to go down over 9 km and capture more of the earth's heat. This makes EGS a potent and also growing renewable energy resource.
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The heat of the earth can also be used more directly to heat and cool houses instead of using energy consuming appliances to do the same thing. In winter, a cold liquid is sent down into the ground in pipes When the liquid goes through the earth it heats up. That hot liquid can then be pumped back up and used to heat houses and businesses. In the summer the opposite happens. Warm liquid is sent down, although not so deep where the soil is colder. As the warm liquid is cooled it is pumped back up and used to cool houses. This is a simple, efficient and renewable way to cool and heat our houses and buildings. The Philippines, El Salvador and Costa Rica have all recently achieved the production of more than 15% of their electricity from geothermal generation. Many countries also generate a lot of their energy needs from geothermal sources, especially around the pacific ring of fire. Geothermal power is a potent and important alternative energy source that we should be developing at top speed.
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