Humankind has discovered several renewable energy sources that have vast applications. We use solar panels to harness the power of the sun, wind turbines to capture wind, and tidal lagoons to leverage the force of waves, but we have yet to fully utilize the heat of the Earth.
Instead of setting up endless fields of solar panels to capture the sun’s radiations we can simply use the heat that the Earth is already storing in its mantle (over 50% of solar radiation that hits the planet ends up in the ground) to produce energy. But the Earth’s heat also comes from its underground layers that harbor the life-giving warmth of a distant past. The geological layers between the core and the surface act as natural heat exchangers, transmitting high temperatures towards the surface.
The Earth’s heat is strong enough to melt rocks. The molten rocks, also called magma, are less dense than solid rocks and thus rise to the surface. While magma can escape through volcanoes as lava, it usually stays just below the surface and heats both the surrounding rocks and water. That heated water can form geysers or hot springs, but most of it stays in underground pools called geothermal reservoirs.
There are three ways to tap into geothermal energy. Direct geothermal energy is the oldest method; people use hot water at or near the surface to heat a building. They pump the hot water through a heat exchanger that transfers the water’s heat to the heating system in the building. They then send the used water down a well that returns it to the hot spring or underground pool.
Geothermal heat pumps are also used to heat single buildings. They take advantage of the fact that the temperature just a few feet below the Earth’s surface is a stable 50 to 60° F (10 to 15° C) all year.
A geothermal heat pump is a series of loops or pipes that is buried underground or beneath a small body of water. In cold weather, the loops send their heat through a heat exchanger and electric compressor to a duct system within the building. In hot weather, the loops draw heat from the building, where it is absorbed by the ground or water surrounding them.
There are three different types of geothermal plants, and they all use hot steam and/or water pulled from deep underground. All of them also use steam to generate electricity.
Main Uses Today
Geothermal energy is used mainly to produce heat for a variety of purposes. In addition to heating buildings, it can also be used to heat water at fish farms, pasteurize milk, and dry crops. Some spas still use hot springs.
Geothermal energy currently produces about 7000 megawatts (MW) of electricity, with 2700 of those coming from the United States. Those 2700 MW of geothermal power produce about the same amount of electricity as 60 million gallons of oil.
Geothermal heat pumps are currently the most common and viable means of producing energy. Since the temperature underground is the same everywhere, geothermal heat pumps can be installed almost anywhere. By contrast, geothermal plants can only be constructed in places where they can drill deep enough to reach a geothermal reservoir.
Frequently Asked Questions about Geothermal Energy
1) How long have people used geothermal energy?
Different cultures have used geothermal energy for thousands of years. The ancient Greeks and Romans, for example had spas heated by geothermal energy. Native Americans and the Maori of New Zealand used water from hot springs for both medicine and cooking for millennia.
The United States first built large-scale geothermal plants back in the 1960s. The town of Larderello, Italy, however, had built the first geothermal plant back in 1904!
2) Who uses geothermal energy?
Over twenty countries use geothermal energy. The United States is the largest producer and is home to the The Geysers, the world’s largest complex of geothermal plants. It is located in northern California and covers 45 square miles. A company called Calpine owns 13 of the power plants, and they produce 725 MW of energy – which is enough to power a city the size of San Francisco.
Iceland gets 85 percent of its electricity from indigenous renewable sources – more than any other country. About 65 percent of its power comes from geothermal energy, with hydropower making up another 20 percent. Geothermal energy heats about 85 percent of the houses in Iceland.
Geothermal Energy Pros and Cons
Despite the potential that geothermal energy displays, scientists are still wondering if it makes sense to invest in this unusual technology that can chill, warm or provide electricity for our every-day needs. We have briefly listed the most important geothermal energy pros and cons in our previous article, but today we would like to analyze all geothermal energy pros and cons in more detail to determine whether or not geothermal energy can become a reliable renewable energy source in the future or if it is worth implementing on a smaller scale (e.g. in homes).
Advantages of Geothermal Energy
To begin our list of geothermal energy pros and cons on a positive note, we will first list advantages and make our way towards disadvantages.
1. Geothermal Energy is Environmentally Friendly & Renewable
When we ask ourselves “What are the geothermal energy pros and cons?” the first thing that comes to mind is, without a doubt, the fact that geothermal energy is environmentally friendly and renewable. The knowledge that geothermal power is a renewable energy source means that it can never run out.
Because heat radiates from within the Earth’s core, it will be available for as long as the planet exists, and it will enable us to obtain renewable energy at a lower rate than non-renewable energy.
Geothermal energy will also produce significantly less pollution than fossil fuels or other non-renewable forms of energy. As a matter of fact, geothermal systems emit such a low amount of pollution that almost six million metric tons of CO2 have been saved.
“The general conclusion from all studies is that emissions and other impacts from geothermal plants are dramatically lower than other forms of electrical generation.”
Benefits of Geothermal Energy for the Environment:
- Geothermal power is almost 100% emission free (absolutely no carbon release).
- Geothermal energy has the smallest carbon footprint of all major energy sources.
- Geothermal energy is a predictable form of energy because it relies on the heating and cooling capabilities of the Earth, which never falters.
- E. use improves air quality and decreases greenhouse emissions.
- Geothermal energy does not require any type of fuel to run. It does not require manual excavation and it doesn’t require transportation. The fact that geothermal energy is produced locally is probably the key advantage for piping head from underneath your house.
Although geothermal power also has a series of negative environmental impacts that we will discuss below, they are minimal compared to other sources of energy. Hydrothermal methods deserve a solid round of applause for their holistic contribution to a cleaner, safer world.
2. Geothermal Energy is Reliable & Accessible
Number two on our list of geothermal energy pros and cons is reliability. Advocates of this renewable energy source say that it is one of the most reliable energy sources – geothermal supplies replenish naturally, and they are available across all seasons. Unlike wind and solar energy sources, which rely on fickle weather conditions, geothermal energy can provide a stable supply of electricity and heat for businesses and homes.
3. Geothermal Energy Technologies are Constantly Evolving
We are only beginning to explore the applications of geothermal energy. In time, new technologies that will enable power plants to extract energy with lower overall temperatures will appear. Furthermore, innovative solutions will eventually lower the costs of geothermal installations, making them more accessible to homeowners. In comparison, prices for fossil fuels are constantly increasing due to limited resources.
4. Geothermal Energy is worth the Investment
Number three on our list of geothermal pros and cons regards financial aspects. Because geothermal power is a relatively new concept for private homes, upfront costs for installing such a system are huge. But for homeowners who can stomach this initial investment, geothermal energy provides huge lifetime value through consistent energy savings. Testimony to this value are the approximately 100,000 geothermal heat pumps that are installed in the United States every year.
After pulling out around $30,000 from your pocket for the installation, you will see a huge decrease in monthly expenses. Over time, a geothermal heat pump will save you around 30-60% on heating, and 20-50% on cooling costs. Geothermal energy systems can be installed on new constructions as well as existing ones. Nevertheless, you should note that prices for retrofit situations will be significantly higher, because retrofits require major ductwork modifications.
Let’s break down the costs of using geothermal energy for private homes:
- Cost of powering the pump. These costs are extremely low because the heat pump will use the grounds energy to cool and heat your home. You will only have to pay for electricity power used to make the system work.
- Land consumption (for personal use). A geothermal energy system requires quite a bit of space because pipes must be laid out in a horizontal pattern (installing pipes in a vertical pattern is more expensive – so you have to consider if the investment is worth it).
Lastly, installing a geothermal system is worth it because it is extremely durable. Underground loops are protected from external elements like vandalism or fickle weather. They are also safe because they do not operate with flammable fuel or fossil fuel storage tanks.
5. Small Land Footprint (for Industrial Use)
On number 5 of our geothermal energy pros and cons we have land footprint. In comparison to other forms of energy, renewable and non-renewable, geothermal energy has the smallest land footprint per kilowatt (KW). The approximate land usage of geothermal plants ranges between 53 and 367 acres. This value covers all activities, such as exploration, construction and drilling. It should be noted that much of the land is reclaimed after exploration, so the long-term land use decreases even more.
Disadvantages of Geothermal Energy
Now that we have covered the first section of geothermal energy pros and cons, more specifically, the advantages, let’s take a closer look at its disadvantages.
1. High Upfront Costs & Other Financial Issues
Money is the root of all evil. The reason why geothermal energy adoption is so slow is because the upfront costs are terrifying. While it is true that geothermal power usage will decrease costs over time, not many home-owners are ready to make such a big investment. Apart from huge initial costs, there are other financial considerations that you should understand before deciding if geothermal energy is good for you:
- Geothermal installations are not a DIY project. If you want to install a G.E. heating system in your home you will require pro expertise. The only problem to this is the fact that technology is still new, so there are a few experienced installers. Because there is also no competition prices remain high.
- Installation is disruptive to the landscape. In several situations, installation will not be possible at all. Installing underground pipes requires heavy drilling that will lead to negative impacts on the landscape and soil (more on this below).
2. Environmental Concerns
The negative environmental impacts of geothermal energy are almost insignificant compared to other forms of energy, but they exist. Here is a list of possible environmental dangers that you need to understand:
- High water usage. Geothermal processes require a lot of water. To balance underground reserves and facilitate production cycles, water from the exterior might be needed. In order to decrease environmental impacts, clean water is preferred, but waste water is also an option.
- Noise pollution is substantial.
- Surface Instability & Land Subsidence (= the gradual settling or sinking of the Earth’s surface due to movement of earth materials). Geothermic processes & installation (e.g. hydraulic fracturing) may result in surface instability and minor earthquakes.
- Production of water with high mineral content. Open-loop systems release minor amounts of unstable compounds into the air (e.g. sulfur dioxide, ammonia, boron and silica), which may harm the environment.
3. Sustainability Issues if Reservoirs aren’t Properly Managed
This problem only applies to geothermal power plants. Because the earth’s outer surface is porous, rainwater can seep through the soil and into geothermal reservoirs (over a period of several hundreds of years).
According to scientific studies, reservoirs can be depleted if water is removed faster than it is replaced. To ensure the sustainability of geothermal installations water must be periodically reinjected into the reservoir after the turbine generates electricity.
The good news is that, as long as geothermal energy is properly managed, sustainability should not be a problem. This problem will never appear for residential geothermal cooling and heating.
4. High Temperatures Required
At present, technology is not advanced enough to permit geothermal plants to work with water at low temperatures. The process of producing geothermal energy isn’t exactly easy to execute. For an area to be considered for geothermal processes the water in the ground must be at least 350 degrees Fahrenheit. Lower temperatures are only useful for the co-production of geothermal electricity in gas and oil wells.
“Low-temperature geothermal energy is derived from geothermal fluid found in the ground at temperatures of 150ºC (300ºF) or less. These resources are typically utilized in direct-use applications, such as heating buildings, but can also be used to produce electricity through binary cycle geothermal processes.” Source: UCSUSA
5. Widely-Spread but Suitable to Particular Regions
Despite the fact that geothermal energy hot-spots are widely-spread, there are certain particularities that an area must have in order to be considered for industrial use. Because geothermal activity may cause minor earthquakes and land subsidence, plants must be placed as far away from populated areas as possible.
This concludes our list of geothermal energy pros and cons. No energy source is perfect, and geothermal energy is no exception to the rule. Nevertheless, the pros of geothermal energy clearly outweigh the cons and demonstrate that this form of renewable energy source will play an important role in the future. If you found these geothermal energy pros and cons interesting, feel free to educate your friends and kids as well!