Geothermal is by no means a new form of energy. People have been using natural heat from within the earth since ancient times. Recently, though, the technologies for capturing geothermal energy have become much more advanced. Today, some countries, such as Iceland, get a large portion of their energy from geothermal resources. In the United States, it makes up about 0.4 percent of total utility-scale electricity generation. As technology improves and people seek ways to lower their carbon footprints and energy bills, residential homeowners and communities across the U.S. and elsewhere are starting to adopt more geothermal. Could it be the future of residential sustainability?

How Geothermal Works

Using geothermal energy means taking advantage of the natural heat below the Earth's surface. In the layer of magma beneath the Earth's crust, heat is continually produced mostly due to the decay of naturally radioactive materials. Underground temperatures are highest in areas with active or geologically young volcanoes.

We can capture this heat in three main ways.

A geothermal heat pump uses the constant temperature in the upper ten feet of the Earth's surface to heat or cool a building. A liquid gets pumped through the pipes, transferring heat from underground into the home in winter. In the summer, the liquid transfers heat from in the house into the ground.

We can also use pump the hot water from geothermal springs into buildings to heat them or to use directly. Some greenhouses use water from geothermal springs, and some cities pipe it underneath roadways to melt snow and ice.

Geothermal energy can also be harness to produce electricity. To do so, we drill wells into underground reservoirs and use the steam or hot water within them to drive turbines that generate electricity. The water then gets returned to the reservoir so that it can continue producing power. There are three main technologies geothermal plants use — dry steam, flash and binary.

Benefits of Geothermal Energy

Using geothermal resources for energy can be advantageous in numerous ways. They have the following beneficial attributes:

· Clean: Using geothermal energy is better for the environment than using fossil fuels. Geothermal fields produce about one-sixth the carbon dioxide emissions of many natural gas plants, and binary plants produce almost no emissions. Both technologies release very little nitrous oxide and sulfur-bearing gases

· Renewable: Geothermal energy is also a renewable resource because the Earth continually generates heat. Even if you take water or steam out of a reservoir, it will heat back up when reinjected and again become available for use.

· Reliable: It is also continually available, giving it an advantage over many other energy resources. Ground source heat pumps also have relatively few moving parts, increasing their reliability.

· Homegrown: Geothermal energy is a domestic energy source, meaning it helps to reduce dependence on foreign oil.

· Quiet: Geothermal heat pumps operate extremely quietly, making them more attractive to homeowners.

· Minimal Visual Impact: Geothermal heat pumps are mostly underground so they won't be an eyesore for homeowners. Geothermal power plants also require relatively little land.

· Economical: Switching to a geothermal heat pump can reduce your heating bill by 30 to 60 percent and shrink your cooling costs by 20 to 50 percent. For geothermal power plants, the initial capital costs are typically around $2,500 per kilowatt (kW) and $0.01 to $0.03 per kilowatt-hour for maintenance and operation costs.

Barriers to Adoption

The main barrier to the adoption of geothermal energy is the upfront costs, especially for homeowners. The national average for the cost to install a geothermal heating and cooling system is $7,797 — much more than the typical HVAC system.

It's important to keep in mind that, through energy savings, you can typically recoup your upfront investment in four to 15 years. While home geothermal systems are cost-effective, they are a long-term investment.

Taking advantage of financing options for local installers can help make the upfront cost more affordable. You may also be eligible for financial assistance and rebates from local, state and federal government as well as utilities. Residential geothermal heat pumps installed in 2019 are, for example, eligible for a 30 percent federal tax incentive.

Another way to reduce the cost of geothermal systems is to install them for entire communities rather than individual homes. Several communities across the U.S. are already doing this. In Whisper Valley, a community in Austin, Texas, using this approach reduced insulation costs by 40 percent as compared to installing a system house by house.

While installation costs for geothermal systems are still relatively high, there are ways to reduce them, and the resulting energy savings enable you to recoup your investment. As technologies continue to improve and more communities, homeowners, businesses and energy companies realize the value of geothermal energy, it may start to play a larger role in our energy system.

Bio: Emily is a green tech writer who covers topics in renewable energy and sustainable design. You can read more of her work on her blog, Conservation Folks.

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