What is Geothermal Electricity?

Brendan McGuigan
Brendan McGuigan
Iceland gets much of its energy from geothermal sources.
Iceland gets much of its energy from geothermal sources.

Geothermal electricity is electrical energy generated by harnessing the power contained in the earth’s internal heat. Geothermal power is widely used in the world, and geothermal electricity is looked at by many as one of the most sustainable, environmentally-friendly forms of electricity available to us. Although not currently feasible for all locations, many people believe that in places where geothermal electricity can be generated, it could replace the bulk of energy currently created by fossil fuels, and offer an alternative to other alternative energy sources.

There are a handful of renewable energy sources currently receiving a great deal of attention as the world tries to find a replacement for the fossil fuels that it has depended on to drive the Industrial Revolution and the growth of the modern age. Solar power, hydro power, bio fuels, wind power, and tidal power are some of the most popular. All have their share of problems; however, solar panels are quite toxic to make and can only be used where there is ample sun energy, hydro power can cause serious problems with rivers, bio fuels may rob the world of needed food supplies, wind power can disrupt the pathways of migratory birds, and tidal power may damage aquatic ecosystems. While geothermal electricity is not ideal either, many people believe that it offers the greatest benefits with the least negative impact.

The earth contains a functionally-limitless reservoir of heat coming up from the core, and geothermal electricity taps into that source. Geothermal wells are created to tap into that source, and while these wells may temporarily need to recover their heat, they can do so indefinitely so long as our power use remains within a few orders of magnitude of what it is currently at. A number of fields have been sustainably running generating geothermal electricity since the early- and mid-20th century, giving real-world evidence that the energy source does seem to last for some time.

In addition to its sustainability, geothermal electricity also requires relatively little land use for the power generated. While a coal power plant requires around 20 acres to generate a single Megawatt of energy, and a nuclear power plant requires between 5 and 10 acres for a Megawatt, a geothermal power plant requires only between 1 and 8 acres for a Megawatt. Geothermal power plants are also incredibly scalable, so that a tiny remote site can get geothermal electricity through a very small generator, while a metropolis can get all of their geothermal electricity through a massive plant.

Worldwide, total energy consumption is around 16 Terawatts, and about 85% of that is generated by fossil fuels. Around 10 Gigawatts of electricity are currently generated by geothermal power, but this is distributed quite differently throughout the world. Many countries are just beginning to use geothermal energy to create electricity or supply heat, but those that have been doing it for some time often meet a great deal of their energy needs exclusively through geothermal sources. Iceland, for example, meets more than one-quarter of its total electricity demands with geothermal electricity, and there are plans to increase this number greatly in the coming years, with the ultimate goal of eliminating the use of fossil fuels in that country entirely.

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Discussion Comments


@Georgesplane- I agree with you completely. I am studying energy and I believe that the biggest impact in reducing fossil fuel use will happen at the building and neighborhood level. I am a big fan of things like geothermal heating and cooling and passive energy systems. Smarter design and integration into the built environment will be the most important area to increase efficiency and reduce waste simply for the fact that the built environment accounts for almost forty percent of energy use. Unlike industry, which responds to economic pressures to become more efficient, residential and commercial buildings mostly become more efficient due to regulation.


Geothermal energy is a great alternative to fossil fuels, but much like hydroelectric, geothermal lacks the versatility of solar and wind energy. You can only locate geothermal plants in areas that have abundant water and are near the borders of tectonic plates. This presents the problem of transporting electricity over long distances, thus resulting in line losses. Many of the easy targets for geothermal energy have been exploited, and they can cause many of the same problems as drilling an oil well.

Geothermal drilling can cause earthquakes and possibly even mud volcanoes. Additionally geothermal plants can only be located in places where the earth’s crust is thin. Geothermal is one answer, but the truth is it will be a number of substitutes for oil and coal, not just one. There are no other sources of concentrated solar energy that are as easy to transport as fossil fuels. Energy solutions will need to be regional. Ultimately, the easiest solution is to reduce consumption and increase efficiency. People will simply need to face the fact that energy is scarce and precious.


I watched a special on Iceland and the country's use of geothermal energy resources. I think that geothermal electricity generation is great. I was surprised to find that small farms and residences were able to harness geothermal energy. I always thought that geothermal plants electricity plants were the only way to harness the earth's energy. One farm used a small geothermal system to generate all of its electricity. The only downside was the volcano erupted and covered the farm in ash that would take years to work into the soil. I wonder if we could extract all of our energy from the earth through geothermal electricity generation.

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    • Iceland gets much of its energy from geothermal sources.
      By: Ben Burger
      Iceland gets much of its energy from geothermal sources.