⭐️Geothermal Energy comes from the Greek words geo (earth) and therme (heat). Geothermal energy is heat inside the Earth. The inside of the Earth is very hot. Sometimes this heat comes near the surface. We can use this heat to warm our houses. We can make electricity with it.
👉The Earth is made of layers or parts, like a hard boiled egg. It has three layers core, mantle, and crust. At the center is a solid core of iron. Around that is the outer core, made of iron and rock so hot the rock is melted. This liquid rock is called magma. The middle layer is a mixture of rock and magma called the mantle. The shell of the Earth with the oceans and mountains is called the crust. In some places, magma comes close to the Earth’s surface. It heats the water underground.
👉We can use this heated water. We dig wells and pump the hot water and steam out of the ground. The hot water we use will be replaced by rain. The heat inside the Earth will always be there. More heat is made every day in the Earth’s core. We won’t run out of geothermal energy. It is renewable energy.
👉Geothermal Energy is everywhere under the ground, but sometimes it is hard to reach. In most places, the crust is miles thick. Magma is near the surface in only a few places. Earthquakes and volcanoes are signs that magma is near the surface. The lava from volcanoes is magma that has reached the surface of the Earth.
👉Many ancient peoples, including the Romans, Chinese, and Native Americans, used hot mineral springs for bathing, cooking, and heating. Water from hot springs is now used worldwide in spas, for heating buildings, and for agricultural and industrial uses.
👉Power plants use steam from geothermal wells to make electricity. The steam is used to spin turbines. The turbines spin magnets in coils of copper wire to make electricity. The power plants are built close to the wells. The steam is pumped straight from the wells to the power plants.
👉 2019, worldwide geothermal power capacity amounts to #16 Gigawatts), of which #24 percent are installed in the United States.
👉Geothermal energy is clean energy. No fuel is burned, so there is no air pollution. The steam is turned into water and put back into the Earth. And geothermal energy is cheap—once a new power plant is built, it can make electricity for less cost than a coal or natural gas plant.
👉Types of Geothermal Resource
1.Convective hydrothermal
2.Vapour dominated
3.Water dominated
4. Hot dry rock
5.High temperature fields
6.Low temperature fields
How Does Geothermal Energy Work ?
Geothermal power plants come in three different designs;
- Dry Steam plant
- The oldest type is dry steam, which takes steam directly from fractures in the ground to drive a turbine.
2. Flash Steam plant
- Flash plants pull high pressure hot water from underground and mix it with cooler low pressure water. This, in turn, creates steam that is used to drive a turbine.
3. Binary Steam plant
- Binary plants use hot water passed through a secondary fluid that has a lower boiling point than water. The secondary fluid is turned into vapour which drives a turbine. Most future geothermal power plants are expected to be binary plants.
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The United States is the world’s largest producer. They also have the largest geothermal development in the world, situated at The Geysers north of San Francisco, California. Despite the name, there are no geysers there and the energy used is all steam rather than hot water.
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The first power generation well was sunk in 1924, with more wells drilled in the 1950s and further development taking place from the 1970s on.
Other nations, such as Iceland, are well placed to exploit geothermal resources, which they have done since 1907. With 25 active volcanoes and 600 hot springs, 25% of Iceland’s energy comes from five geothermal power plants.
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Advantages of Using Geothermal ?
1. Environmentally Friendly: Geothermal energy is more environmentally friendly than conventional fuel sources such as coal and other fossil fuels. In addition, the carbon footprint of a geothermal power plant is low. While there is some pollution associated with geothermal energy, this is relatively minimal when compared to fossil fuels.
2. Renewable: Geothermal energy is a source of renewable energy that will last until the Earth is destroyed by the sun in around 5 billion years. The hot reservoirs within the Earth are naturally replenished, making it both renewable and sustainable.
3. Huge Potential: Worldwide energy consumption is currently around 15 terawatts, which is far from the total potential energy available from geothermal sources. While we can’t currently use most reservoirs there is a hope that the number of exploitable geothermal resources will increase with ongoing research and development in the industry. It is currently estimated that geothermal power plants could provide between 0.0035 and 2 terawatts of power.
4. Sustainable / Stable: Geothermal provides a reliable source of energy as compared to other renewable resources such as wind and solar power. This is because the resource is always available to be tapped into, unlike with wind or solar energy.
5. Heating and Cooling: Effective use of geothermal for electricity generation requires water temperatures of over 150°C to drive turbines. Alternatively, the temperature difference between the surface and a ground source can be used. Due to the ground being more resistant to seasonal heat changes than the air, it can act as a heat sink/ source with a geothermal heat pump just two metres below the surface.
6. Reliable: Energy generated from this resource is easy to calculate since it does not fluctuate in the same way as other energy sources, such as solar and wind. This means we can predict the power output from a geothermal plant with a high degree of accuracy.
7. No Fuel Required: Since geothermal energy is a naturally occurring resource there is no fuel required, such as with fossil fuels that are a finite resource which needs mining or otherwise extracting from the earth.
8. Rapid Evolution: There is a great deal of exploration into geothermal energy at the moment, meaning that new technologies are being created to improve the energy process. There are an increasing number of projects to improve and grow this area of industry. With this rapid evolution many of the current cons of geothermal energy will be mitigated against.
Disadvantages of Geothermal Energy ?
1. Location Restricted: The largest single disadvantage of geothermal energy is that it is location specific. Geothermal plants need to be built in places where the energy is accessible, which means that some areas are not able to exploit this resource. Of course, this is not a problem if you live in a place where geothermal energy is readily accessible, such as Iceland.
2. Environmental Side Effects: Although geothermal energy does not typically release greenhouse gases, there are many of these gases stored under the Earth’s surface which are released into the atmosphere during digging. While these gases are also released into the atmosphere naturally, the rate increases near geothermal plants. However, these gas emissions are still far lower than those associated with fossil fuels.
3. Earthquakes: Geothermal energy also runs the risk of triggering earthquakes. This is due to alterations in the Earth’s structure as a result of digging. This problem is more prevalent with enhanced geothermal power plants, which force water into the Earth’s crust to open up fissures to greater exploitation of the resource. However, since most geothermal plants are away from population centres, the implications of these earthquakes are relatively minor.
4. High Costs: Geothermal energy is an expensive resource to tap into, with price tags ranging from around $2-$7 million for a plant with a 1 megawatt capacity. However, where the upfront costs are high, the outlay can be recouped as part of a long-term investment.
5. Sustainability: In order to maintain the sustainability of geothermal energy fluid needs to be pumped back into the underground reservoirs faster than it is depleted. This means that geothermal energy needs to be properly managed to maintain its sustainability.
It is important for industry to assess the geothermal energy pros and cons in order to take account of the advantages while mitigating against any potential problems.
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