Geothermal energy isn’t new. Most people accept that it was invented (or discovered, depending on how you look at it) by Piero Ginori Conti in Italy in 1904. Others maintain it’s been around for 10,000 years. In either case, the major pros and cons of geothermal energy haven’t changed much in at least 100 years.
This discussion is concerned with providing on objective outlook on geothermal energy, considering evidence from both large-scale (power plants) and small-scale (personal) geothermal options. If you want to use science to investigate green energy alternatives, check out this awesome course on how to model thermal energy systems based on realistic worldwide weather data.
A Brief Introduction To Geothermal Energy
Just in case you aren’t 100% sure how geothermal energy works, let’s do a quick review. It’s so ingenuous you can never really get tired of hearing about it.
Where The Energy Comes From: It works very much like a refrigerator, but instead of taking “heat” from inside the fridge and releasing it into the kitchen, geothermal energy takes “heat” from the ground and releases it into your house. This “heat” (I’ll explain the quotations momentarily) ultimately comes from the Earth’s molten core, although by the time the core’s heat reaches the Earth’s surface, it only clocks in at about 55F.
How It Works: You might not think 55F is very warm, but geothermal energy is brilliant in that it can heat or cool your home. Piping that carries water runs throughout the ground and returns to an energy pump in your home that extracts the energy from the water. In the summer, generating AC from 55F water is far more efficient than from 90F air. And in the winter, generating heat from 55F water is far more efficient than from 15F air. It’s a clever idea, but how does it all pan out?
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Pros Of Geothermal Energy
1. Renewable Energy, Finally
We’ve been hearing about fossil fuels and all their fatal flaws for so long that it’s hard to believe that renewable energy alternatives really exist. But geothermal energy comes from the Earth’s core, so as long as Earth is here (roughly another 4-5 billion years), geothermal energy will be a viable platform.
2. More Powerful Than You Think
The energy we could derive from geothermal technology is tremendous. There are problems, of course (more soon), but the point of the story is this: there is enough geothermal energy stored in the Earth to fulfill the entire energy needs of the human race. Even with current technology, which is not as efficient as it will be in another 25 years, we could power nearly 20% of the world with geothermal power plants.
3. Environmentally Friendly
This one’s obvious, but yes, it’s very environmentally friendly. It isn’t perfect, as we’ll discuss later on, but the carbon footprint is extremely small (1/8 of coal) and much of the operation is buried underground.
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4. Even Better Than Other Green Alternatives
Geothermal energy really outshines its competitors, whether they’re green or the bane of the environment. There are two main categories that give geothermal energy the advantage:
- Reliability: Geothermal is incredibly reliable. As long as you lay the pipes deep enough, the temperature of the ground will be almost perfectly consistent. This means that energy costs and levels of output will be reliable all year, every year. If you compare this to wind energy (no wind, no power) or solar energy (no sun, no power) or even fossil fuels (prices constantly fluctuating/foreign affairs supply issues), then you can see why it’s so desirable. Still, it’s worth looking into wind power and this post on the 5 key advantages of wind energy can give you the understanding you need.
- Output: Believe it or not, I think it’s safe to say that all power plants function below the installed capacity. But geothermal energy, if installed correctly, is almost perfectly efficient and powerful. This means production estimates are actually accurate.
5. Baby Steps (And Footprints)
Geothermal energy does require substantial piping to be laid in the ground; there’s no other way to collect heat from water. So you might think that to power a city you would need a ridiculous amount of pipe (and land). But as it turns out, thanks to clever ways to install piping, geothermal energy actually has the smallest land footprint of any major energy source in the world.
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6. Cost Effective
This actually ends up being a “Con,” as well, but once you get over the initial investment, the energy savings are immediate and significant. Conservative estimates say 30-60% savings on heating and 25-50% savings on cooling. Depending on location and circumstance, the savings can be as high or higher than 80%. Anyone who experiences the four seasons and has a reasonably sized home to heat or cool can save thousands of dollars year.
Cons Of Geothermal Energy
1. Upfront Expense
The upfront expense is really only an issue for the personal consumer, the home-owner who is thinking of installing geothermal energy in his or her front yard. I say this because there’s an upfront expense for every power plant every made, it’s just that personal coal plants aren’t exactly a thing. But for your average sized home with average drilling conditions, a geothermal energy system costs $10,000-$20,000. The upside is that it can pay itself off in an average of 5-10 years, so the investment is long, but not too long.
2. Environmentally Imperfect
Emissions: While nothing is as environmentally disastrous as a coal mine/plant, geothermal energy isn’t without its own imperfections. First of all, it tends to leak sulfur dioxide and silica into the atmosphere, but again, at much lower levels than other power plants.
Earthquakes: As hard as it might be to believe, building geothermal plants can cause earthquakes as a result of affecting the lay of the land. Yes, mining can cause similar things to happen, but geothermal energy has recently become infamous for “causing earthquakes.” The issue arises from the method in which geothermal plants are build. A process called hydraulic fracturing is essential for building large-scale, efficient geothermal plants. This would not trigger a deep, catastrophic earthquake, but it could disrupt the tension of the land near the surface of the earth and cause not inconsequential seismic activity.
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3. Large-Scale Problem
There is one huge problem that exists when building geothermal power plants. When you build a plant for your personal use, you basically create/build ideal conditions in your front yard. Sure, it doesn’t work out for some people, but if you’re willing to pay, then they can probably find a way to make geothermal energy work for you.
Location: But when you build a power plant, you need a natural environment of geothermal energy (basically, a geothermal reserve). A geothermal reservoir is a massive area of steam and/or hot water that is trapped in porous or semi-porous rock. While we still have to lay a healthy length of piping to withdraw energy from the reservoir, we simply cannot create such large scale geothermal plants on our own. That would add to the already high costs of production. This is quite unfortunate because not everywhere in the world sits on top of a geothermal reservoir (although to be fair, they are much more common than oil). But this hasn’t stopped certain countries, most notably Iceland, from using geothermal energy to power 1/3 of their energy needs.
Transport: You can always transport energy, of course, in a variety of ways, but again this adds to the cost. For example, if a city was a hundred miles away from an ideal geothermal reservoir, they could absolutely utilize it and transport the energy in the form of hot water or even electricity. The problem is that in both scenarios energy is lost. This is where coal and oil, which can be transported with the energy 100% intact, have an appealing advantage.
4. Finicky, At Times
Geothermal reservoirs can be finicky in the sense that while the actual heat from Earth’s core will never run out, the reservoirs themselves can slowly lose energy, can shift, can seep, etc. So after the huge cost of installing a geothermal plant, the energy could, over time, run away from it. Shifts in the ground could cause the reservoir to become unstable or to release its heat elsewhere. Rainwater (admittedly, over the course of hundreds and hundreds of years) can slowly deplete a reservoir’s reserves, although in the case of rainwater it can be replaced.
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5. Still Relies On Another Energy Source
For the private home owner who has geothermal energy, they still need a power source that can power the geothermal pump. The pump is, after all, what transfers the energy from the ground to the house. The pump uses minimal energy, but it still needs to be powered by electricity. Most people just use coal, but homes that are serious about being green can power their geothermal pumps with a few solar panels.
6. Best Technology Is Still New
This just means that the technology doesn’t have a 100 track record, which isn’t necessarily important. We still haven’t figured out how to make coal and oil perfect, for example. But this does mean that installation costs will stay high for at least a while longer. You won’t have ten companies in your town who specialize in geothermal energy. You’ll be lucky to have one, which means no competition and high prices.
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