What is Geothermal Power?

The term “geothermal” means “Earth heat” or “heat of the Earth.”. The heat flowing from the Earth’s interior is estimated to be equivalent to 44.2 terawatts-thermal (TWth) of power (Pollack et al.1993). This is more than twice the amount needed to supply total global primary energy consumption in 2015 (Energy Information Administration [EIA] 2017a).  So, why isn’t this renewable energy source more widely deployed?

Sustainable energy source

In times of climate change this type of sustainable energy source is vital for all humankind. Due to the location of Iceland in the Mid-Atlantic Ridge, a very active volcanic zone that powers the geothermal system we have extensive access to geothermal resources.  But this energy source certainly is also accessible in other countries. The other counties which already have deployed geothermal for long time is USA, New Zealand, Indonesia, Turkey, Italy and Kenya.

Geothermal energy originates as thermal energy within the Earth. To harness this power, we need to drill deep geothermal wells into underground reservoirs, tapping into steam and hot water. In basic terms, the geothermal gradient represents the temperature increase per 100 m of depth – around 2-3 degrees Celsius. For instance at the depth of 2000 meters, the temperature can reach around 60° C (140°F) rising to around 90° C (194° F) at 3000-meter. However these values vary globally.  In Iceland we have abundance of high temperature areas, meaning that the temperature gradient is many times the average value.

Electric generation using geothermal power

To access the energy source you need to drill deep wells usually down to 2-3000 meters in high temperature areas.  Steam from those wells usually exceeds 200° C (392°F) and is used to generate electricity. However lower temperature sources around 120° C (248° F) can also be employed using different technology.  The high-pressure steam flowing out of the deep wells, is used to drive turbines connected to electricity generators.

Direct use of geothermal power

Geothermal offers a wide range of advantages beyond just generating electricity. We label the utilization of temperature around 100° C (212° F) and below, as „Direct use“.  This includes heating homes through district heating systems and heating up swimming pools.  Aquaculture, horticulture, food processing and even the production of cosmetics utilize geothermal energy in Iceland. Interestingly, snow melting of sidewalks and car parking areas utilizes surplus geothermal water.

Geothermal energy is the most reliable form of renewable energy. It is the only renewable energy source that can provide baseload power to the grid 24/7, complementing the insecure supply of solar and wind energy.

Humans since ancient times have used the benefit of geothermal energy. Evidence have demonstrated activities like bathing, cooking in hot springs. In Iceland, historical record demonstrate that our ancestor utilized geothermal resources for bathing as early as the 13th Century.

We would be happy to take you on an educational tours in Iceland marked “geothermal” . Our Guide have decades of experience in the geothermal sector and will be able to give you excellent guidance in this field.

Watch a video for more geothermal information

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