Geothermal Energy: When the Earth becomes our Green-Energy Supplier

Geothermal energy is the energy obtained by the extraction and use of internal heat of the Earth. This type of heat represents therefore a highly available and renewable energy resource produced in the depths of our planet and transmitted to the surface by thermal conduction. As any type of energy resource, geothermal energy has both its advantages and its drawbacks, which we will discuss in the following lines.

But before we take a look at pros and cons of geothermal energy we should know more details about this resource. How does heat exactly appear? What happens in geothermal power plants? How can we use this type of green energy?

How does Geothermal energy work?

Geothermal energy originates in the different temperatures existing between the surface and the interior of the Earth. This difference is called a thermal gradient. Usually the temperature increases with 2-4 degrees Celsius per 100 meters if you are heading to the center of the Earth.

The heat accumulated in the subsoil is used in geothermal heat pumps for heating in the winter, cooling in the summer and providing hot water supply to households. The whole process of “extraction” of the heat takes place in a series of collectors (or panels) buried underground in which it is circulating a solution of water and glycol.


Although there are still many unknown factors, there are countries who work with this geothermal green energy. Sweden was the first country in Europe to use geothermal energy in 1979 (when they suffered an oil crisis). Also, there are countries such as Finland, the USA, Japan, Germany, Holland, Italy and France with such power plants implanted.

Types of geothermal energy

There are different types of geothermal areas:

  • Hydrothermal areas containing water at high pressure and temperature, stored under the crust of the Earth in a permeable rock near a heat source;
  • Hot rock systems formed by layers of impermeable rock covering a heat source;
  • Magma resources offering high geothermal energy and also has natural and highly observable manifestations such as hot springs and geysers.

The hydrothermal energy is the most used in producing green electricity and hot water for direct use.


Advantages of geothermal energy

  • It implies a relatively low cost and no risks;
  • Being highly available in any country makes it sustainable enough to provide energetic independence;
  • The waste is minimum and it produces less environmental impact than the use of fossil fuels;
  • Although it needs more studies and technology development, geothermal energy is totally functional (as demonstrated by various countries) and it should be an option for those people who want to produce green energy.

Drawbacks of the geothermal energy

  • Emission of CO2 and hydrogen sulfide;
  • It is possible to appear a contamination of the nearby waters with substances such as arsenic, ammonia etc.
  • Another significant drawback could be the fact that geothermal energy cannot be transported.
  • It could produce some kind of thermal pollution (but that wouldn’t be a problem if you liked heat).


Only a small fraction of our geothermal resources are being exploited today, but they could be used a lot more, if the available technology would improve more and the governments would look more into it. The hot dry rock, magma and the geysers have immense potential that remains untapped and that could produce cheap and easy-to-get power.

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