What is geothermal energy?


We all know that the burning of fossil fuels over the last 100 or so years since the Industrial Revolution has contributed to global warming. This is one of the biggest issues the world faces today, living with the consequences of generations past.

Though, there is a solution. The world is slowly moving away from fossil fuels and constantly looking at new ways to keep our lights on. Other renewable sources such as wind and solar energy can be inconsistent and unreliable ways to power the world, but again, there is a solution. It comes in the form geothermal energy. Geothermal energy refers to heat from the earth used in heat pumps and electricity production. To put it simply, below the surface of the earth lies a powerful furnace that never dies.

How does geothermal energy work?

If you think of the earth as a giant hot-rock, there are a number of ways to harness that energy. Using geothermal energy to create electricity is rather difficult and remains mostly ‘proof of concept’ in Australia; that is to say, it’s in its infancy and isn’t as well-developed. It requires the extracting of sub-surface hot water, or the injection of cold water deep into the ground to generate steam, which in turn spins a turbine, generating electricity.

A simpler and more common adaption of geothermal energy is through the use of heat pumps to cool and warm a building. Heat pumps are essentially energy-efficient versions of air conditioners. Most models simply shift warm air inside (and vice-versa on split-systems) however there are a few models which instead transfer heat from the earth into your home, making them ideal for very cold places.

What are the strengths of geothermal energy?

There are numerous benefits of using geothermal energy over traditional fossil fuels. The biggest and most obvious is that it’s a clean energy resource. Harnessing the energy can be done so without the use of fossil fuels such as coal or oil.

There has been much controversy surrounding coal seam gas and fracking recently. Geothermal energy can easily be mistaken for coal seam gas, but while they share similarities, they are in fact different. Geothermal fields emits one sixth of the carbon dioxide compared to natural gas fields. They also produce next to no nitrous oxides or gases with sulfur in them. These two elements have been the culprit in the controversy behind fracking – the fear that they could seep into water supplies. The fear is unfounded with geothermal energy.

There are numerous other benefits, but below are some of the main ones:

  • Potential sites can be found nearly anywhere in the world – great potential.
  • Water used is recyclable: In Santa Rosa, California for example, treated wastewater is pumped back into the plant and is used as reinjection fluid to continue power production.
  • The minimal sludge that is produced contains useful minerals such as zinc and silica, which can be resold for other applications.
  • Its power plants are small and there are no odors emitted: Visibility is little.
  • It is more sustainable: Some fields have been used for over 50 years with the aid of reinjection techniques. One field in Italy has been going since 1913!

There are numerous economic and environmental benefits to using geothermal energy, but as with most energy sources, there are a few downsides – read below:

What are the weaknesses of geothermal energy?

The biggest weakness with geothermal energy is that it’s not a widespread resource yet, and is not as well established with a clear direction such as solar and wind. Capitalisation of the resource is in its elementary stages, and the infrastructure does not exist in many countries to make it a viable contender against coal and oil.

Further, the infrastructure costs can be pricy. Ever noticed that computers back in the 1980s could cost as much as a car? The same deal is seen in geothermal energy due to it being in its infancy stage. While installation costs are likely to lower over the years, right now certified technicians are few and far between and they command a premium.

Several other disadvantages exist with geothermal energy:

  • If not treated properly, sites can run out of steam. A site’s lifetime can be extended with maintenance, but the fact is that they all have life cycles.
  • Research for ideal sites can be time and cost consuming. Some locations are superior and finding these locations can be like striking gold.
  • Once a site is set up, its transportation potential is limited being only able to power the surrounding area. Resources like oil and coal can be transported from region to region with ease.

There is a long way to go before geothermal energy becomes a viable resource of the future. However, with more investment hopefully this clean and powerful resource becomes viable, powering the cities of the future.

What countries use geothermal energy?

While on a global scale, geothermal energy is a relatively small operation compared to coal, oil – and other renewables – but there are a couple of countries that are leading the way.


Nearly every building in Iceland is heated with spring water. The country gets more than 50 per cent of its energy from geothermal and in its capital Reykjavik, geothermal water is piped in from 25 kilometres away. This is used for heating and hot tap water.

Iceland benefits from being a cold country with decent thermal activity from volcanoes. This is why geothermal energy is so prevalent – not to mention the country’s small geographic area makes it easier for the resource to be piped around.

United States

As expected, the list wouldn’t be complete until the US is mentioned. Particularly in the northwestern states, the US benefits from a colder climate and a relatively high rate of thermal activity. For more than a century, many homes in Idaho and Oregon have been heated using spring water. Those states on or near the Pacific Rim or ‘Ring of Fire’ benefit most from geothermic activity.

The largest geothermal plant in the world belongs to a site called the Geysers in Santa Rosa, north of San Francisco. This region lies directly on the San Andreas Fault, which makes it an ideal location for a geothermal plant. It has been operating since the early-mid 20th century and still operates at a strong pressure. Overall, as a share of total megawatt-hours, California possesses over 80 per cent of capacity in the US.

What’s the situation in Australia?

Geothermal energy is almost non-existent in Australia. While there is significant government-led exploration underway, no commercial projects yet exist. Until recently, it was believed our country’s lack of volcanic activity meant the ground was not hot enough to sustain geothermal generators on a large scale. This is due to Australia’s location on the tectonic plates, and geothermal energy is something that is much more prevalent in New Zealand. If you’ve been to Rotorua, you may have seen the natural geothermal baths the locals use. This is due to their location on the fault line. While Australia is safer from an earthquake or volcanic activity, this proves more difficult for producing geothermal energy.

Though this theory has recently been proven mostly incorrect, Australia has a much greater investment interest in alternative renewable generators such as solar, wind and hydro.

As for geothermal heat pumps, there are very few locations in Australia cold enough to warrant an expensive geothermal heat pump system.

What is the future of geothermal energy?

Geothermal energy is an exploration project that benefits from lessons from the past. With every site setup there is increased drilling efficiency, and increased strike rates of finding viable locations to setup a plant. Zero emission plants have also been devised and the capture of harmful byproducts has become an easier operation.

Geothermal energy is seen as the fourth most important renewable resources behind solar, wind and hydro. Its prevalence is sure to get a boost with increased funding for research and exploration. Experts predict that geothermal will eventually power one sixth of the world’s energy needs. Overall, while geothermal is in its infancy in 2016, there is a strong hope for the future as the world moves away from fossil fuels.

Compare electricity providers

Share this article