Geothermal energy also referred to as thermal energy is energy that is produced and stored in earth. It is generally derived from super heated rocks and water in the earth and can be used to produce electricity.

This is a reliable, enormous, clean and underused heat. Geothermal resources include things like hot dry rock, hydrothermal resources, geo- pressurized resources and magma. At the moment only hydrothermal resources are used to produce geothermal power for commercial purposes.

Deep wells are normally drilled to access the underground reservoirs so that they can tap very hot water and steam. This is finally brought to the surface to be used by a number of applications.

A Geothermal energy home system however, is not constrained by such definitions if it is only required to heat water for instance.

Seismic activity & Geothermal Power:

Places with the highest level of seismic activity provide the best grounds for harnessing such power as they have the hottest underground where hydrothermal reservoirs can be placed without too many challenges.

This is also known as the “Pacific Ring of Fire” as the seismic belt covers the edge of the Ocean and includes countries like Russia, Philippines, Japan, South America and the western seaboards found in the North. Geothermal reservoirs in the USA are found in Hawaii, Alaska and the western states.

Geothermal power plants are established close to the reservoirs making the process of producing electricity much easier. This is because there are turbines in place driven by the harnessed energy which are used to drive the electricity generators.

The process allows persons to use geo energy for cooling and heating.

Geo thermal heat pumps are made of pipes that are buried close to the building that needs to be heated on shallow ground. A duct and heat exchanger are used to transfer the energy to the building.

During winter, heat travels from the warmer ground to the house through the heat exchanger. The reverse happens during summer as cooler underground air is sucked up to cool down the house.

Methods of Geothermal extraction:

Dry steam power- this is the most common method of extracting geothermal energy. The process utilizes a dry steam reservoir. This is a collection of water vapour underground that holds a good amount of steam with very little water.

There are special pipes installed to harness the steam and transport it to the turbines on site. This helps to spin the turbines and the end result is the production of electricity. An example is the use of geysers.

Flash steam power: This method makes use of hot water reservoir that is found underground. Unlike the first method, this one holds more water than steam. The water has very high temperatures ranging from 150- 370 degrees Celsius.

A production well is used to pump the water and bring it on the surface. At this point it’s normally converted into steam, because of the deep pressure that is used for its release. This is then released to the turbines and works similar to the first method in the production of electricity.

Binary cycle power: This is the third method used for producing geothermal energy. Unlike the above method, this makes use of a cooler water reservoir with temperatures ranging from 120 – 180 degrees.

Water at this kind of temperature is usually not sufficient to produce steam needed for electricity production. For this reason, it is passed through a heat exchanger that is used to heat up a binary liquid.

This is a secondary liquid like isopentane which usually has a much lower boiling point than that of water. (BP of isopentane is 28 degrees). The liquid then produces the steam that is used for electricity production. However in this process, vapor from the secondary liquid is normally re-condensed so that it can be used later. This helps to curb emissions from getting into the air.

Small Scale Geothermal Energy Production:

The above methods are mostly used when producing electricity for large scale use. Geothermal energy can however also be harnessed for small scale use. This is mostly in terms of heating and cooling. The process works similar to large scale production only that this time pipes used are not installed too deep into the ground.

Also instead of pumping steam or water, the pipes usually have their own liquid that is sent underground. Most popular liquid used is antifreeze during winter. The liquid is heated up and sent back to the buildings foundation.

During summer, the reverse process happens where the building is cooled because air on the surface is usually warmer than the one found underground.

Advantages of geothermal energy:

There are a lot of benefits of using geo-thermal energy such as It is one of the cleanest and safest ways of producing energy. This means that is produces little or no pollution or greenhouse gases contributing to a safer environment for future generations.

The geothermal plants also do not take up a lot of space where there are set up as there is no need of building things like mine shafts, dams, open pits or tunnels. The plant runs round the clock without any interruptions. This is because the source of power is not affected by weather conditions.

Geothermal energy is also sustainable and renewable. Other than cost of maintaining and making sure pumps are in good working order, the energy is practically free. In addition to this, the energy does not have to be imported neither is it affected by fluctuating prices.

Disadvantages of Geothermal Systems:

While it might be considered as the best option for use of energy in the modern world it is marred by certain drawbacks including the fact that the plant cannot be planted anywhere in the world.

For a geothermal plant to flourish, it needs to be set in a place where there is a certain kind of rock that is usually not easy to drill through; unless a horizontal geothermal installation is required purely for central heating or domestic hot water systems. The ideal location also needs to be well endowed with steam or water.

There is also risk of dangerous minerals and gases surfacing on the earth as the water or steam are extracted. Recovering investment cost can also be quite slow.

Keen analysis indicate that geothermal energy is a safe bet as it possesses numerous advantages over the use of other fossil fuels despite the fact that there are certain restrictions; mainly due to land availability and the type of geothermal energy required.

For a simpler analysis of geothermal energy, check out our article on geothermal facts for kids.