Why Is Geothermal Energy Considered a Renewable Resource?

Updated on November 23, 2022
Why Is Geothermal Energy Considered a Renewable Resource?

Is Geothermal renewable or non-renewable?

What is a renewable resource?

A renewable resource is any part of the Earth or its processes that can be used by mankind and can be renewed naturally faster than it can be used. Geothermal energy is considered to be a renewable resource – as long as the Earth exists geothermal energy will be generated deep underground.

What is a non renewable resource?

Non-renewable resources can be used up. 10 examples of non renewable resource are:

  1. Crude oil
  2. Coal
  3. Natural Gas
  4. Biomass
  5. Soil
  6. Building Sand
  7. Minerals
  8. Metal Ores
  9. Nuclear Power
  10. Drinking Water

Video – Is Geothermal Energy Renewable or Non Renewable Resource?


What is geothermal energy?

Geothermal energy is basically heat generated under the Earth’s mantle of rocks. This heat can be harvested and used in different ways, from generating electricity to home heating.

Normally, the temperature increases the deeper we go, but in some cases the geothermal heat comes up to the surface i.e. hot springs and volcanoes.

Many health spars have been built over hot springs, where the Earth’s heat naturally warms water which is then contained in hot baths and used as part of health cures.

Volcanoes can be a very destructive force and the high temperature of lava (molten rocks) gives some indication of the high temperatures existing deep underground.

Just one meter undergound the temperature fluctuates according to local insolation (the sun’s energy level) but at a depth of over two meters the temperature is generally constant.

Table – Temperature Increase vs Ground Depth – Thermal Gradient

Depth in Meters

Temperature in Centigrade

Temperature in Faranheit




























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As you might imagine, the temperature deep underground is very much higher. For example, the Earth’s crust is between 6 miles (oceanic crust) and 30 miles thick. Just below the crust the temperature is about 500 degrees Centigrade!

Geothermal Explained

What does it mean when we say that geothermal energy is sustainable?

What does sustainable mean?

Sustainability is basically the same as renewability and gives some indication of how much an energy resource can be used without depleting the supply. A resource is sustainable if mankind can use it and rely on the fact that it will always be there, because it is renewed by a natural process.

How is geothermal energy renewable?

Heat is generated deep inside the Earth by the tremendous pressure exerted on the core as gravity compacts the solid matter that forms our world.

Even if everything on the plant’s surface disappeared, this pressure would always exist and it is truly renewable and sustainable. As long as the Earth exists there will be geothermal energy.

What is geothermal heating?

What is geothermal heating?

The Earth’s natural heat can be used for domestic heating in any country, as the underground temperature variations between geographic locations are very small.

You might think that big temperature differences are needed to heat a home, and this would be true if we relied on the geothermal temperature gradient alone, but it’s not how it’s done.

Home heating uses a ground-source heat pump to amplify relatively small temperature differences. These devices act like a fridge in reverse, pulling heat from the ground and using the compressor principle to pump it into the home while expelling cold air into the atmosphere.

The advantage is that the heat energy recovered by a heat pump is 4 to 5 times more than the electrical energy use to recover it. The downside is that installations are expensive in the short term.

Why is geothermal energy considered a renewable resource? – Apex Learning

What is Apex?

Apex is a comprehesive digital learning platform aimed at US student grades 6-12. It’s aim is to accelerate learning with virtual access supporting in-class learning, including a hybrid approach to virtual learning.

The Apex platform has modules covering geothemal energy and other forms of renewable energy sources, if a more structure approach is needed for students following K6-12 curriculums. If you just need an overall and comprehensive explanation of geothermal energy, everything you need is in this post.

Why is geothermal energy a renewable resource?

What are the two advantages of geothermal energy?

  1. Advantage One – It is the most constant renewable energy and it is dependable. The sun is always shining but can be covered by clouds or obstructed by trees and other obstacles. Heat from inside the planet doesn’t vary much at all so can be relied on.
  2. Advantage Two – It represents a powerful way to replace fossil fuels and therefore save CO2 emmissions. Burning coal and oil produces a huge amount of pollutants. Apart from gases, particles of soot and toxic chemicals are emitted as non-renewable resources are converted into electricity or heat.

5 uses of geothermal energy – Infographic

5 uses of geothermal energy – Infographic

Download Infographic ‘Five Uses Of Geothermal Energy’ PDF.

How does geothermal energy help the environment?

Geothermal helps the environment because it replaces, or partly replaces, non-renewable energy sources such as coal, oil and gas (fossil fuels). These resources are heavily used and at latest estimates have between 40 to 75 years left before they run out.

Unfortunately, renewable resources such as solar energy and wind are not being utilised fast enough to replace fossil fuels. Part of the problems is that we need fossil fuels to create the machines and tools that convert renewable energy into electricity and heat.

The more geothermal energy is used then the less fossil fuels we use up. The goal is to keep fossil fuels in the ground so that the percentage of carbon dioxide in the atmosphere doesn’t reach dangerous levels.

How effective is geothermal energy?

Home heating makes use of the increased temperature just a few meters below the Earth’s surface where the temperature difference is quite low. Using heat pump technology, the difference is enough to amplify 4 or 5 times for heating an indoor space.

Domestic heat pumps are said to be 400% efficient, because they push out 4 times more heat energy than the elctrical energy needed operate the machine. Heat pumps are an effective way to heat a house.

It gets much hotter the deeper we drill into the Earth. Below several hundred meters there are found resevoirs of water under pressure that are being heated to high temperature by geothermal forces.

Once tapped, the pressurised water can escape to the surface as steam and be used to drive turbines for electricity production. Plants designed to convert underground hot water resevoirs are very effective and can have an efficiency of up to 97%.

Geothermal FAQs | Department of Energy

Which energy source is renewable?

There are many energy sources on the planet. Unfortunately, most of them are not sustainable, which means they are not easily renewed.

Before we decide if a resource is renewable or not, we need to specify ‘in our life-time’. After all, even coal and oil will eventually replace itself over millions of years, but this is no help to our civilization.

We need resources that can be replenished during several years, or at least during our lifetimes. The table below gives a quick look at the most common resources and indicates their renewability:

Table – What are renewable and nonrenewable energy resources?



Natural gas


Crude oil


















Wave-power (oceans)







YES – but how use?


YES – if well-managed

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What is the best renewable energy source?

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Sunshine is by far the best renewable energy resource available. While geothermal is more constant, it is not as easy to harvest and convert, requiring complex and expensive machinery.

Photovoltaic cells have been refined and improved over the past 10 to 15 years to the point where they are relatively cheap and are becoming competitive with power generators using fossil fuels.

The great benefit of solar power is that once the solar panels are installed they are almost maintenance and trouble free, simply requiring a clean twice a year.

One downside is that solar panels are not very efficient, only converting up to 20% of the sun’s energy into electrical energy. That said, as the price of panels goes down, bigger installations easily compensate for this.

Geothermal Energy News

Other questions relating to Renewable Resources:

What is the fastest growing renewable energy source?

On the domestic home front, solar energy is by far the fastest growing renewable energy resource, mostly due to the fact that the costs of solar panels have fallen tenfold during the past 10 years or so.

There has also been a healthy increase in  heat pump installations for home heating, but not nearly as much as solar. If we extend the question to large-scale electricity production, then it’s probably wind power that has had the fastest growth overall.

Biomass has also grown, both in bigger plants designed to heat community homes and buildings, but also in the form of pellet stoves for home heating.

Although tidal (wave power)has huge potential on the larger scale, the expense and difficulties associated with installation at sea make this technology slow to grow.

Are biofuels renewable?

Biomass or biofuels are often cited as the latest renewable energy source, but this is nowhere near true!

Most people are under the misconception that most biomass is simply waste wood or vegetation left over from other processes, such as construction or farming.

However, biomass is often grown specifically for burning, which contradicts the idea of renewables not adding to the carbon footprint i.e. emitting CO2 into the planet’s atmosphere.

Pellet stoves are becoming popular for individual home heating and these bring their own problems. It isn’t just waste wood that it turned into wood pellets. If trees are classified as unsuitable for construction, they can be chopped down for biomass.

This is bad in two ways:

  1. More CO2 is destined to be added to the atmosphere, and
  2. A living resource has been destroyed, a resource which absorbs carbon dioxide and emits oxygen.

Resources relating to geothermal energy as a renewable resource:

Is Geothermal Energy Renewable or Nonrenewable?

Is Geothermal renewable or nonrenewable – Tech-addict


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