Last updated: 15 January 2018
Advantages and Disadvantages of Geothermal Energy - The Source of Renewable Heat
List of Pros & Cons of Geothermal Energy Production
Geothermal energy is currently believed to be one of the most advantageous sources of energy. Not only is it a renewable type of energy but is also present in most areas, outperforming even some conventional sources in many aspects.
The UK is even considering a construction of the world’s longest power connector between UK and Iceland, which would deliver more renewable energy to 1.6 million British homes that do not have geothermal heat pumps. Moreover, the first commercial geothermal power plant is planned to be built in Cornwall, UK if all the necessary funds are obtained.
That should come as no surprise since some countries profit from the presence of geothermal energy on a large scale. The most known case is Iceland whose electricity is 100% sustainable, making use of wind, hydro- and mostly geothermal energy.
Nevertheless, you don’t need a backyard the size of a football field in order to reduce your energy bills. In fact, more and more households all around the globe are investing in geothermal energy and heating systems to cut their costs.
What Are the Advantages of Geothermal Energy?
Geothermal energy has many advantages, especially when compared to conventional sources of energy:
1. Geothermal Energy Sourcing Is Good for the Environment
First and foremost, geothermal energy is extracted from the earth without burning fossil fuels, and geothermal fields produce practically no emissions. What’s more, geothermal energy can be very beneficial, as you can achieve savings of up to 80% over conventional energy usage.
2. Geothermal Is a Reliable Source of Renewable Energy
Geothermal energy also has many advantages when compared to other renewable sources like solar, wind or biomass. It is an exceptionally constant source of energy, meaning that it is not dependent on neither wind nor sun, and available all year long.
When looking at the availability factor, which shows how reliable and constant specific energy sources are, geothermal is ranking on the top (see the figure below), way above the other groups, which supports the argument of its independence on inconstant external circumstances when delivering energy.
3. High Efficiency of Geothermal Systems
Geothermal heat pump systems use 25% to 50% less electricity than conventional systems for heating or cooling, and with their flexible design they can be adjusted to different situations, requiring less space for hardware as opposed to conventional systems.
4. Little to No Geothermal System Maintenance
Due to the fact that geothermal systems only have few movable parts which are sheltered inside a building, the life span of geothermal heat pump systems is relatively high. Heat pump pipes even have warranties of between 25 and 50 years, while the pump can usually last for at least 20 years.
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Availability Factor of Geothermal Energy in Comparison to Other Renewables
What are the Disadvantages of Geothermal Energy?
However, there are always two sides of the coin so let’s have a look at the cons of geothermal energy:
1. Environmental Concerns about Greenhouse Emissions
Unfortunately, no matter its reputation of being an environmentally friendly alternative energy source, geothermal energy also causes some minor concerns in regards to the environment.
The extraction of geothermal energy from the grounds leads to a release of greenhouse gases like hydrogen sulfide, carbon dioxide, methane and ammonia. However, the amount of gas released is significantly lower than in the case of fossil fuels.
2. Possibility of Depletion of Geothermal Sources
Furthermore, despite being considered a sustainable and renewable energy, the chances are that specific locations might cool down after time, making it impossible to harvest more geothermal energy in future.
The only non-depletable option is sourcing geothermal energy right from magma but the technology for doing so is still in the process of development. This option is worth the investment mainly thanks to the fact that magma will be around for billions of years.
3. High Investment Costs for Geothermal System
Another disadvantage is the high initial cost for individual households. The need for drilling and installing quite a complex system into one’s home makes the price climb quite high. Nevertheless, the return on such investment is very promising, being able to earn the investment back within 2 to 10 years.
4. Land Requirements for Geothermal System to Be Installed
In case of geothermal systems, having a piece of land next to the house is required in order to be able to install one. That makes geothermal systems hard to be implemented for homeowners in big cities, unless a vertical ground source heat pump is used.
What Types of Geothermal Systems Are there?
There is a number of different geothermal systems available. Which system to choose depends on a variety of factors such as soil conditions, climate, local installation costs on site and available land. There are two basic ground loop systems which further divide into several subgroups:
Closed Geothermal Loop System
Open Geothermal Loop System
These systems differ mainly in the installation of the pipes, depending on the structure and size of the land available.
How Much Does a Geothermal Energy System Cost?
After all this information on the pros and cons of geothermal energy, the core question remains: how much do you actually have to invest in order to get your own geothermal system up and running in your own home?
As we have determined in one of our previous posts ‘Ground source heat pump prices,’ a geothermal ground source heat pump can cost from £13,000 to £20,000, whereas an air source heat pump hovers around £7,000-£11,000.
See approximate informative numbers on geothermal installation for a 100m² house:
|Average Lifetime||18-23 years|
|Payback Time||2-10 years|
|Average Installation Cost||£15,000-£30,000|
|Energy Bill Reduction||40%-60%|
|Government Incentives||Up to 30% of total cost|
Even though geothermal systems are more costly compared to other heating or cooling systems, they have much lower operating costs and deliver more energy per unit.
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Governmental Geothermal Grants
Incentives from the UK government or the community typically hover around 30% of the total price, making the implementation of geothermal systems highly competitive to conventional systems. It is believed that costs for the implementation are likely to be reduced further in the future.
The Domestic/Non-Domestic Renewable Heat Incentive (RHI) is a UK governmental financial incentive promoting the use of renewable heat. However, the amount of such aid depends on many factors, like the house size, location, roof type, current heating system, etc., and can be calculated online.
How and Where to Install a Geothermal System?
As the shallow ground temperatures from which geothermal energy is taken are relatively constant, geothermal heating systems can be used almost everywhere. However, the characteristics of the land decide which systems might be more favorable, and needs to be determined by your supplier and installer.
Aspects that influence the type of geothermal system to install:
Composition and properties of soil and rock can affect heat transfer rates and therefore need to be taken into consideration for designing geothermal systems.
Ground and surface water influence the type of ground loop, as well as groundwater can be used as a source for open-loop system, if the water quality is sufficient.
The size and layout of the land, landscaping, location of sprinkler systems, etc., determine the design of the geothermal system as well.
If you are interested in implementing a geothermal system, we can provide you with quotes and offers from up to four different suppliers of geothermal systems that will match your requirements. The only thing you have to do is fill in the form on top of the page, and you will be contacted with tailored offers. This service is completely free and without any obligation!
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To understand geothermal energy, imagine having a fireplace nearby, one which never goes out. The fire we speak of exists at the core of our planet. But let’s look at geothermal energy advantages and disadvantages and more geothermal energy basics for a deeper dive.
Earth’s Geothermal Energy Basics
The temperature at Earth’s core measures close to 7200 degrees Fahrenheit. As you might imagine, such a high temperature can produce extraordinary amounts of sustainable energy and untold gigawatts of electricity. Technically speaking, geothermal energy is regarded as a renewable source of energy which can produce energy for as long as our planet exists.
According to the Geothermal Energy Association (GEA), the geothermal power industry reached about 3,442 MW at the end of 2013. Add to this about 1,000 MW of planned capacity additions under development and about 3,100 MW of geothermal energy resources under development. The industry’s US additions in 2013 added about 85 MW of new capacity at new and refurbished power plants in Utah, Nevada, California, and New Mexico.
The GEA’s 2014 Annual U.S. & Global Geothermal Power Production Report states, “The international geothermal power market is booming, growing at a sustained rate of 4% to 5%. Almost 700 geothermal projects are under development in 76 countries. Many countries anticipating the threats caused by climate change realize the values of geothermal power as a baseload and sometimes flexible source of renewable energy.”
Upper estimates show a remarkable worldwide geothermal energy potential of 2 terawatts (TW), though — much more than we are on track to tap.Then why aren’t we producing such energy? Let’s take a closer look at some of the advantages and disadvantages when it comes to producing geothermal energy for home, business, or city.
Geothermal plant near Viti crater in Krafla, North Iceland
Using geothermal energy is not a new practice. Writing for Kids Discover, Robin Koontz describes how our ancient ancestors knew about the earth’s heat and used it to heat dwellings, cook food, and bathe.
Today, there are two ways in which geothermal energy can be used.
First, heat from the Earth’s surface can be used with geothermal heat pump systems. An air delivery system using ducts, along with a heat exchanger buried in the ground, can pump heat into a home or building. The heat pump can also work in the summer, removing heat from inside the building into the heat exchanger. That hot air can also be used to provide hot water.
Secondly, there is the option of electricity, writes Koontz.
“Electricity-generating power plants convert hydrothermal fluids to electricity, depending on the state of the fluid and its temperature, in three ways – dry steam, flash steam, or binary cycle. Dry steam systems extract steam out of fractures in the ground, harvesting hot water and steam that can drive turbines on electricity generators.”
No matter how good all of this might sound, a number of advantages and disadvantages come into play when considering the development of geothermal energy plants. I have provided the following ‘advantages/disadvantages’ compilation, using information from energyinformative, TriplePundit, and ConserveEnergyFuture. There are plenty of pro/con lists to choose from, but I chose these.
→ Also recommended: Geothermal Energy: What It is & How It Works
→ Also recommended: Geothermal Energy Facts
Geothermal Energy Advantages
- Environmentally friendly – There are a few polluting aspects to harnessing geothermal energy, and the carbon footprint of a geothermal power plant is seen as minimal. An average geothermal power plant releases the equivalent of 122 kg CO2 for every megawatt-hour (MWh) of electricity it generates – one-eighth of the CO2 emissions associated with typical coal power plants.
- A renewable resource – Geothermal reservoirs are naturally replenished. According to some scientists, the energy in our geothermal reservoirs will last billions of years. While fossil fuels have an expiry date, renewable sources like geothermal energy is not going to expire anytime soon.
- Potential capacity – Estimates for the potential of geothermal power plants vary between 0.035 to 2 TW.
- A stable resource – The power output of a geothermal plant can be accurately predicted. Not subject to the same low-energy fluctuations as with solar or wind.
- Great for Heating/Cooling – There is significant growth in the number of homeowners utilizing geothermal heating/cooling over the last couple of years.
- No fuel required – After installation, no mining or transportation activity is necessary.
- Small land footprint – Smallest land footprint of any major power source.
- Stable resource – Can provide base load or peak power.
- Economic factors – Cost-competitive in some areas.
- Accessibility – Some level of geothermal energy available most places.
- Renewable – Geothermal energy is extracted from earth’s core and will be available as long as earth exists. It is therefore renewable and can be used for roughly another 4-5 billion years.
- Abundant Supply – With geothermal energy, there are no shortages or other sorts of problems which sometimes occur with other types of power.
- Significant Savings for Home Owners – There has been a tremendous increase in the number of homeowners who want to utilize geothermal energy for heating and cooling purposes. The result is that less energy is used for heating homes and offices which results in significant savings for home owners. After the initial expense, a 30-60% savings on heating and 25-50% savings on cooling can cover that cost within few years.
Matsukawa Geothermal Power Plant
Geothermal Energy Disadvantages
- Potential emissions – Greenhouse gas below Earth’s surface can potentially migrate to the surface and into the atmosphere. Such emissions tend to be higher near geothermal power plants, which are associated with sulfur dioxide and silica emissions. Also, and the reservoirs can contain traces of toxic heavy metals including mercury, arsenic and boron.
- Surface Instability – Construction of geothermal power plants can affect the stability of land. In January 1997, the construction of a geothermal power plant in Switzerland triggered an earthquake with a magnitude of 3.4 on the Richter scale.
- High cost for electricity – Total costs usually end up somewhere between $2 – 7 million for a 1 MW geothermal power plant.
- High up-front costs for heating and cooling systems – While there is a predictable ROI, it will not happen quickly.For an average sized home, installation of geothermal heat pumps costs between $10,000 – $20,000 which can pay off itself in another 5-10 years down the line
- Location Specific – Good geothermal reservoirs are hard to come by. Iceland and Philippines meet nearly one-third of their electricity demand with geothermal energy. Prime sites are often far from population centers.
- Distribution costs – If geothermal energy is transported long distances, cost can become prohibitive.
- Sustainability questions – Some studies show that reservoirs can be depleted if the fluid is removed faster than replaced. This is not an issue for residential geothermal heating and cooling, where geothermal energy is being used differently than in geothermal power plants.
- Cost of Powering the Pump – Geothermal heat pumps need a power source.
- May Run Out of Steam: You have to be incredibly careful when you are trying to check everything that is related to geothermal energy. Mind must be taken to watch the heat and not to abuse it, because if the heat is not taken care of properly, it can cause a meltdown or other issues where the energy is not properly distributed or used.
Whether geothermal energy is going to be used for heating a house or generating electricity at a power plant, there is much to be looked at and considered. Although the footprint for this form of energy is considerably smaller than one than that of fossil fuels, it still has possible negative impacts. Then there is the issue of cost. Geothermal power plants are expensive to create and not always that easy to find. And the initial cost for buildings or houses using a geothermal heating and cooling system is expensive and without a fast payback.
Coming next, I will provide more details about geothermal energy systems and how they work.
Images: Geothermal plant near Viti crater in Krafla, North Iceland via Shutterstock; Matsukawa Geothermal Power Plant via Shutterstock