and how does it compare to carbon emissions?
In: Technology
The principle behind geothermal energy is that the Earths core is hot, so if you drill far enough down into the ground it is going to get pretty toasty. And that can be used as a heat source. There are two primary use cases for this heat. Fairly simple plants is able to get water hot enough to be delivered to peoples homes and to their radiators to heat up their homes. This reduces the need for electrical heating and gas heating to almost nothing.
It is also possible to use the heat to generate electricity itself. This requires considerably hotter water under much higher pressures. The basic principle of turning hot things into electricity is the same as with coal, gas, biofuel and nuclear power plants and is basically a steam engine.
The places that have a geothermal plant currently is restricted to places where it is easy to extract heat from the ground. Typically areas near volcanoes as these may already have thermal springs already. The most famous and most efficient geothermal power plant is in Iceland but the US is one of the biggest sources of geothermal power. Geothermal is completely free of carbon emissions. There are some slight exceptions in the plants used for heating as there may be some electrically operated pumps and compressors involved. But compared to any of the alternatives it is very clean with little environmental impacts and almost no emissions.
The disadvantage to geothermal is that it can be quite expensive to build and maintain. And this often depends on what area you are in. Some places we need to drill very far down to get any usable temperatures and other places we get usable temperatures at the surface. And it is often very expensive to build them near the cities where we want them, assuming we even have the technology to build them there. Most places it is much cheaper to build solar and wind power. Another issue which also applies to nuclear power plants is that even though geothermal might give a nice return on investment in the long run it will take a long time to pay down the debt from initial construction. We are talking 10-20 years before a geothermal power plant will pay for itself. And that is a long time for modern investments to mature.
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