Geothermal Energy: Pros and Cons

The world’s environmentalists and engineers are on a mission to replace our dirty and wasteful energy infrastructure with something cleaner, longer-lasting, and more efficient. As states and nations seek to bolster their renewable energy portfolios, many are looking to geothermal energy as a way to remove fossil fuels from the mix.

So what’s worth knowing about it? And what are geothermal energy’s pros and cons compared to other sources of energy – renewable or otherwise?

How Does Geothermal Energy Work?

The Earth features a crust made up primarily of water and minerals. Below this is a layer of molten rock known as magma. This magma is an intense source of heat and energy. Geothermal power plants and heat pumps are currently the best technology available to harness this energy.

Geothermal power plants are installed by drilling a shaft into the Earth’s surface to release steam from these high-temperature reservoirs. This steam is used to spin a turbine connected to a generator, which turns the mechanical energy into usable electricity.

On a smaller scale, geothermal heat pumps transfer heat from beneath the Earth’s surface into livable spaces in wintertime and reverses this process in the summer. This provides a reliable, low-cost source of climate control for dwellings and buildings.

What Are the Advantages of Geothermal Energy?

As you can imagine, tapping into this wealth of heat and energy could help us heat, cool, and power the built environment extremely efficiently if it’s done properly. Geothermal power plants and heat pumps hold a lot of promise to help us keep our world powered.

There are several geothermal energy pros and cons associated with this clean energy technology. Let’s take a look at them, beginning with the good news.

1. Geothermal Is Environmentally Friendly

The first advantage of geothermal energy is the same as any other renewable energy source – it’s far more environmentally friendly than conventional energy systems. Harnessing energy from Earth’s subsurface releases an extremely limited amount of greenhouse gases – geothermal’s carbon dioxide (CO₂) output is about 10 times less than petroleum or coal.

2. Geothermal Is Supremely Reliable

The major advantage of geothermal energy is its reliability. Although you can store the energy generated by solar and wind in batteries, such systems are still ultimately at the mercy of the elements, which may not shine or blow 24 hours a day.

Geothermal systems rely on reservoirs of thermal energy beneath the ground, which is extremely sustainable over the long term. Geothermal reservoirs are very slow to deplete and measures can be taken to maintain their pressure and effectiveness over time. A geothermal power plant could last for 50 years if it’s maintained well.

3. Geothermal Energy Uses Land Effectively

It’s no secret that generating energy of any kind requires an investment of land. Geothermal has an edge over hydroelectric, wind, and solar power installations because of its very small terrestrial footprint. Here’s an estimate from National Geographic to put it into perspective:

• A geothermal plant would need 404 square miles to generate 1 gigawatt-hour (GWh) of electricity.
• To produce the same amount of power, a wind farm would require 1,335 square miles and a solar panel array would need 2,340 square miles.

That’s up to an 88% savings in land utilized to generate usable power – and it’s a win at a time when resource management is more important globally than ever.

4. Geothermal Can Be Deployed at Small or Large Scales

As we’ll discuss in more detail momentarily, geothermal power plants are location-dependent if you’re hoping to scale this technology to power entire towns and communities. The race is on to make our cities as green and clean as they can be, and geothermal power may factor into that mission.

However, geothermal power plants are only one piece of the puzzle. Geothermal heat pumps are a smaller-scale solution tailored to individual homes and buildings. These mechanisms, instead of the high-temperature reservoirs required by larger power plants, require lower-temperature reservoirs that are much more common beneath the earth.

What Are the Disadvantages of Geothermal Energy?

It might seem like an ideal solution to Earth’s energy crisis, but geothermal energy technology isn’t perfect. Let’s look at some of its current shortcomings.

1. Not Every Location Is Suitable

The biggest disadvantage of geothermal energy systems is that they’re location-dependent. It’ll require a professional survey to determine whether your parcel of land is suitable.

Most larger geothermal energy installations require placement near the boundaries between tectonic plates and other hot spots. A geothermal reservoir of 100°C is usually sufficient, but not every area has these.

California and the American West is a famously active region in the U.S. for geothermal energy installations because it’s situated close to an active Pacific fault zone. Other regions may have the landscape features required, but it’s not a given.

2. Initial Costs Can Be High

Another disadvantage of geothermal power is its high upfront cost. This comes with some relief, though: There are no ongoing costs to fuel the system, and no real expenses other than general maintenance.

In 2018, the estimated cost of a geothermal energy system was up to $6,000 per kWh (kilowatt-hour). The high cost is mainly attributable to the labor required to drill into the ground and install the system. Geothermal is presently the most expensive of the available renewable energy options, including solar and wind.

3. Installation May Lead to Surface Instability

In addition to the high costs, installing a geothermal energy plant requires considerable know-how to get right. Even then, the presence of the energy plant may cause difficulties in the surrounding environment.

Due to the drilling required and the release of water and steam trapped within the earth, geothermal plants are known to cause surface instability and even earthquakes. Even if they don’t, the underground apparatus may cause the surface land to slowly subside as it depletes the subsurface geothermal reservoir.

Geothermal Energy: Pros and Cons

Now you know a little more about what makes geothermal an attractive replacement for fossil fuels, as well as some of its limiting factors. Geothermal energy pros and cons are an interesting topic of conversation, and it’s a discussion that’ll continue as the technology improves.

There’s a lot more work to do, of course. The United States is the global leader in harnessing geothermal energy – it has more geothermal capacity than any other country right now. Yet, these power plants and heat pumps represent just 0.4% of the United States’ energy portfolio.

It makes good sense to deploy geothermal technologies everywhere they’re feasible. Whether a large-scale power plant near shifting tectonic plates or a residential heat pump, Earth has tons of energy to offer in the form of magma and steam. Whether we choose to harness this effectively free energy is up to us.
And remember – even if geothermal technology is out of your price range right now, there’s plenty even the average citizen can do to alleviate some of the burden we’ve placed on the natural environment.