This article is well-researched and contains every aspect a balanced geothermal energy pros and cons list should contain.
See more in-depth information further down the page. Here`s a short overview over the most important benefits and downsides:
Pros of Geothermal Energy
- Geothermal energy is generally considered environmentally friendly and does not cause significant amounts of pollution.
- Geothermal reservoirs are naturally replenished and therefore renewable (it is not possible to exhaust the resources).
- Massive potential – upper estimates show a worldwide potential of 2 terawatts (TW).
- Excellent for meeting the base load energy demand (as opposed to other renewables such as wind and solar).
- Great for heating and cooling – even small households can benefit.
- Harnessing geothermal energy does not involve any fuels, which means less cost fluctuations and stable electricity prices.
- Small footprint on land – can be built partially underground.
- Geothermal energy is available everywhere, although only some resources are profitably exploitable.
- Recent technological advancements (e.g. enhanced geothermal systems) have made more resources exploitable and lowered costs.
Cons of Geothermal Energy
- There are some minor environmental issues associated with geothermal power.
- Geothermal power plants can in extreme cases cause earthquakes.
- There are heavy upfront costs associated with both geothermal power plants and geothermal heating/cooling systems.
- Very location specific (most resources are simply not cost-competitive).
- Geothermal power is only sustainable (renewable) if the reservoirs are properly managed.
Advantages of Geothermal Energy
1. Environmentally Friendly
Geothermal energy is generally considered environmentally friendly. There are a few polluting aspects of harnessing geothermal energy (read more about them in the disadvantages section), but these are minor compared to the pollution associated with conventional fuel sources (e.g. coal, fossil fuels)
The carbon footprint of a geothermal power plant is minimal. Further development of our geothermal resources is considered helpful in the fight against global warming.
2. Renewable
Geothermal reservoirs come from natural resources and are naturally replenished. Geothermal energy is therefore a renewable energy source.
Sustainable is another label used for renewable sources of energy. In other words, geothermal energy is a resource that can sustain its own consumption rate – Unlike conventional energy sources such as coal and fossil fuels. According to scientists, the energy in our geothermal reservoirs will literally last billions of years.
3. Massive Potential
Worldwide energy consumption – about 15 terawatts (TW) – is not anywhere near the amount of energy stored in earth. However, most geothermal reservoirs are not profitable and we can only utilize a small portion of the total potential. Realistic estimates for the potential of geothermal power plants vary between 0.035 to 2 TW.
4. Stable
Geothermal energy is a reliable source of energy. We can predict the power output of a geothermal power plant with remarkable accuracy. This is not the case with solar and wind (where weather plays a huge part in power production). Geothermal power plants are therefore excellent for meeting the base load energy demand.
Geothermal power plants have a high capacity factor – actual power output is very close to total installed capacity.
5. Great for Heating and Cooling
We need water temperatures of more than 150°C (about 300°F) or greater in order to effectively turn turbines and generate electricity with geothermal energy.
Another approach is to use the (relatively small) temperature difference between the surface and a ground source. The earth is generally more resistant to seasonal temperature changes than air. Consequently, the ground only a couple of meters below the surface can act as a heat sink/source with a geothermal heat pump (much in the same way an electrical heat pump works).
We`ve seen a tremendous growth in the number of homeowners that utilize geothermal heating/cooling in the last couple of years.
Disadvantages of Geothermal Energy
1. Environmental Issues
There is an abundance of greenhouse gases below the surface of the earth, some of which mitigates towards the surface and into the atmosphere. These emissions tend to be higher near geothermal power plants.
Geothermal power plants are associated with sulfur dioxide and silica emissions, and the reservoirs can contain traces of toxic heavy metals including mercury, arsenic and boron.
Regardless of how we look at it, the pollution associated with geothermal power is nowhere near what we see with coal power and fossil fuels.
2. Surface Instability (Earthquakes)
Construction of geothermal power plants can affect the stability of land. In fact, geothermal power plants have lead to subsidence (motion of theearth’s surface) in both Germany and New Zealand.
Earthquakes can be triggered due to hydraulic fracturing, which is an intrinsic part of developing enhanced geothermal system (EGS) power plants.
3. Expensive
Commercial geothermal power projects are expensive. The exploration and drilling of new reservoirs come with a steep price tag (typically half the costs). Total costs usually end up somewhere between $2 – 7 million for a geothermal power plant with a capacity of 1 megawatt (MW).
As previously mentioned, most geothermal resources cannot be utilized in a cost-effective manner, at least not with current technology, level of subsidies and energy prices.
The upfront costs of geothermal heating and cooling systems are also steep. On the other hand, these systems are likely to save you money years down the line, and should therefore be regarded as long-term investments. Ground source heat pumps typically costs $3,000 – $10,000 and have a payback time of 10 – 20 years.
4. Location Specific
Good geothermal reservoirs are hard to come by. Some countries have been blessed with great resources – Iceland and Philippines meets nearly one third of their electricity demand with geothermal energy.
If geothermal energy is transported long distances by the means of hot water (not electricity), significant energy losses has to be taken into account.
5. Sustainability Issues
Rainwater seeps through the earth’s surface and into the geothermal reservoirs over thousands of years. Studies show that the reservoirs can be depleted if the fluid is removed faster than replaced. Efforts can be made to inject fluid back into the geothermal reservoir after the thermal energy has been utilized (the turbine has generated electricity).
Geothermal power is sustainable if reservoirs are properly managed. This is not an issue for residential geothermal heating and cooling, where geothermal energy is being used differently than in geothermal power plants.
The bottom line is this: Geothermal energy is generally regarded as environmentally friendly, sustainable and reliable. This makes geothermal energy a no-brainer in some places, but heavy upfront costs stops us from realizing the full potential.
How much influence geothermal power will have on our energy systems in the future depends on technological advancements, energy prices and politics (subsidies). No one really knows what the situation will look one or two decades down the line.
You might want to compare this article to the rest of the pros and cons series:
Author: Mathias Aarre Mæhlum
Last Update: 16 October 2012
Geothermal is always promoted as being very clean and green. This is not entirely true. While it is certainly clean, it is merely a heat transfer process. It brings heat from the inside the earth to the surface of the earth where is it converted to electricity. It does not contribute in any way to increasing greenhouse gasses but it does increase the warming of the surface of the planet. The heat being used would have remained under the earth’s surface but geothermal processes would bring this heat to the surface where it would remain and contribute to global warming. Of course this is inconsequential if it is implemented in small ways. But it should probably keep us from ever developing it on a large scale.
Vic,
Please understand what you are talking about before rendering opinions. First off there are two types of “geothermal” systems, true geothermal and heat pumps. True geothermal uses the earth’s inner heat that has been generated by radiation from the core. Think volcanoes and Old Faithful. True, this can and does bring more heat to the surface, but it statistically is inconsequential when referencing global warming. The direct and local affect on purge water in large power plants using geothermal can be a problem though.
The second type uses latent energy that has been stored in the soil directly from the sun. Using this heat will NOT affect global warming at all because it naturally conduct and transfer to the atmosphere anyhow. Now, greenhouse gasses… where do you think the electricity comes from to generate the energy to run the heat pump? Fossil fuels mostly, aka greenhouse gases. True it doesn’t burn anything locally, but that doesn’t mean that geo’s have a net zero carbon footprint. You are purchasing electricity that has been made from the burning of natural gas and coal.
refreshed my mind
Thank you for the interesting comment.
However, I don’t think this heat contribution is significant to global warming because global warming isn’t real. There is no science backed up to that theory and there never will be.
…Are you mentally challenged?…
global warming is real
Thanks for the comment, Vic.
However, I don’t think this heat contribution is significant to global warming. Here’s why:
-If we are talking about geothermal electricity generation, most of the heat is used to generate electricity (the rest being loss due to inefficiency).
-We may be worse off by not using geothermal energy, e.g. heating houses with electricity compared to waste water from geothermal power plants.
It is true that by harnessing geothermal energy, there is a net increase in surface temperature, as well as a net decrease in temperature under the surface. I’m curious whether there are any sources stating that this contributes in any significant way to global warming?
I’ve sold geothermal systems in Michigan long before working with dehumidification and indoor pools. In all honesty and I have asked the question numerous times; as energy efficient etc. as it is, States offering incentives and lower utility rates etc. to use it…. let’s also not forget just how much coal is burned to produce that electricity. I’m a strong believer in cycles and not global warming… what about the ice age? Global cooling? It’s all cyclical and yes we do need to pay attention, but when people start talking global warming, I say follow the money.
As for geo, I use it.. however, I am well aware that coal is being burned in many areas to provide electricity. There is no free lunch!
Hi Chris, I’m with you on the Global Warming garbage, yes let’s follow the money. I don’t believe it either, and no I’m not mentally challenged, I feel that the earth has cycles like you say, the Ice age is a good example, now we are going to be the hot planet; I know we can help the earth by keeping it clean, our water clean, and other stuff we can do to help the earth. I don’t know who started the Global Warming but I wish it would stop, but people do believe in global warming, this is only my opoin.
not really i have implemented a geothermal emergy in belize and the country it self are happy
Okay first of all you are NOT completely right. Greenhouse Gases is what warms up the atmosphere including Carbon Dioxide.
wow .
I know right Sam.
Aaron , why are you yelling at Vic when he is completely right ? I’ve done research and he is smart !
I really hope that’s sarcasm, Sam.
Thank you, well done, well synthesized, perfect for my homework.
Great article. Quick question. Can solar (PV) (and a backup battery array) be used to power the heat pump and any other powered devices that work in conjunction with a Geothermal system? Thanks, -J
You can use the electricity that is generated by photovoltaics to power anything you want. In fact, you can become completely energy self-sufficient if you use some of these technologies together.
You’ll have to ask the producers whether a specific heat pump would fit together your battery backup array.
No , Aaron . I’m serious . : )
And you’re welcome Vic !
Your comments in cons for geothermal say that the intitial cost is steep and will be a long term payback while your solar cons say initial cost is somewhat or fairly steep and will take a few years to pay back.
Geothermal heat pumps are much more economical (quicker payback) than solar due to its reliability for base load and working 24/7/365. Your comments seem to have a solar bias as many people do. The geothermal uses stored solar energy from the ground to heat your home. It is just a solution for the solar/thermal storage challenge. Don’t down play a more reliable solution just because it is not as visable as solar or wind.
You are absolutely right and I edited the cons list to include this.
Thank you for contributing!
I agree with all the 14 people
I am working on making a small powerpoint presentation on geothermal energy. This will certainly help me a bit. Thanks!
wow geothermal energy is cool this info will really help with my project
I have to debate the topic and unfortunatly, I have to take the con side. This has helped a bit, but I heard something about companies trying to dig where the heat source is too deep causing the ground to heave making buildings fall and destroying towns. Is that true?
The article says the following about the issue:
“A couple of years ago (January 1997), a geothermal power plant in Switzerland triggered an earthquake with magnitude of 3.4 on the Richter scale.”
Can you tell me if their are any ill health effets living close (2 to 3 miles) to a geothermal plant? Thank you, anyadvice would be greatly appreciated.Sincerely, B.C.
I think it depends on the situation. Svartsengi Geothermal Power Station in Iceland is located right next to a big bathing Resort (Blue Lagoon) without any adverse effects.
Geothermal power plants do release carbon dioxide (CO2) and hydrogen sulfide (H2S), which both can be dangerous for people. Arsenic, mercury, lithium and boron can contaminate drinking water.
There are safety features around geothermal power plants that should minimize these issues. Contacting the company behind the geothermal power plant directly would be the best thing to do to learn more about this.
How do I ask you a question?
I enjoyed your article, Mathias. One comment I have is that I believe you meant to say in the first sentence in #4 “This is closely tied together with the fact…’ rather than tide.
You’re right!
Thanks for the feedback Kay:)
how you guys were able to keep the pros and cons discussion/debate, in particular for geothermal,along non-party-political partisan ilnes was a treat in itself; you see. we in little Dominica, 289 sq miles, aka known as The Nature Isle of the Caribbean are currently exploring energy independence via geothermal.
Geothermal is a really great way to go! I’m using it for an engineering project.
essay due tomorrow and this website helped me finish it. AWESOME website!!!!!!! thanks guys
There are criticisms of geothermal energy tapping which prevent its being implemented on the large scale which it should be. Critics say that study and research to find a resourceful area is too costly and takes up too much time. Then there is more great expense needed to build a geothermal power plant, and there is no promise of the plant turning a profit. Some geothermal sites, once tapped, might be found to not produce a large enough amount of steam for the power plant to be viable or reliable. And we hear from the environmentalists who worry that bringing up magma can bring up potentially harmful materials along with it.