An aerial view of the Hellisheidi power station, with steam rising above brown fields
Geothermal energy, harnessed through stations such as Hellisheidi, near Reykjavik, accounts for about a quarter of Iceland's power. Jemima Kelly/Reuters

From Austin to Atlanta, planned communities are tapping into geothermal power—and it has applications for denser urban neighborhoods, too.

Geothermal power is heating up around the world. It accounts for a quarter of Iceland’s total electricity production. On Long Island, National Grid and the New York State Energy Research and Development Authority kicked off a pilot program last month, using geothermal energy to power 10 homes. Cornell University has considered converting its HVAC system to it. Boise, Idaho, uses geothermal for 91 government and commercial buildings, totaling 5 million square feet of space. Supported by a geothermal fund, the city incentivizes developers to embrace geothermal power.

Even so, this energy type comprises a sliver of electricity in the U.S. In 2013, it provided just 0.4 percent of the total generation, according to the U.S. Energy Information Administration.

But that’s starting to change—especially in a handful of suburbs. Pinewood Forrest, an in-progress development of 700 single-family homes south of Atlanta, will host a commercial district, two hotels, and 250,000 square feet of office, retail, and restaurant space. Even in the Georgia summer, though, the homes in the master-planned subdivision won’t have air conditioning units. Instead, they’ll all rely on geothermal power.

The homes in the Pinewood Forrest development will all be heated and cooled via geothermal sources. (Pinewood Forrest)

Pinewood Forrest, whose first residents will arrive in November, follows in the steps of Whisper Valley, a development in Austin that will have 7,500 geothermal-powered homes and apartments upon completion. It first residents moved there in October. In Louisville, Kentucky, the 1,800 homes in the newest section of Norton Commons will be geothermal-powered.

“This is not new technology,” says Rob Parker, president of Pinewood Forrest, located in Fayetteville, about 24 miles from downtown Atlanta. “It has improved over the years. People have been using the Earth to heat and cool for a long time.”

Geothermal power taps into heat energy produced and stored below the Earth’s surface. Although the U.S. experiences seasonal temperature fluctuations, the layer a few feet below ground level stays at a relatively constant temperature, much like a cave. Heating, ventilation, and air conditioning (HVAC) systems can harness this power for heating and cooling buildings.

But geothermal sources could power homes beyond subdivisions. It works anywhere in the U.S., says Maria Richards, president of the Geothermal Resources Council board of directors. In the western U.S., hot water under the surface is especially prevalent. Prospective homeowners may not initially even realize that homes run on this energy, Richards says. Geothermal also works well in places with both extreme summers and winters, making the central U.S. perfect for geothermal heat pumps, she says.

One lesson from these planned communities is that installing geothermal pumps is easiest when building a new home. A geothermal heat pump requires the drilling of boreholes into the ground, typically up to 300 feet, says Richards, the geothermal lab coordinator at Southern Methodist University. It can also be a vertical well, like Pinewood Forrest has done.

“When there’s a new development or new homes, it’s easy to put [the system in] because then it’s part of the whole package and the upfront cost is just part of your mortgage, and the disturbance to your ground and things like that are all already happening,” she says.

For a home of 1,500 to 2,500 square feet, the materials and underground installation cost an average of $15,000 to $25,000, says Jay Egg, an HVAC consultant and designer who has co-authored two geothermal HVAC textbooks. Is that price tag worth it? Egg says that’s up for debate: “Each person has to determine for himself.” He says it typically takes five to 10 years for the system to save enough money on energy costs to pay for itself.

The potential for geothermal may already lie under your feet. Natural gas pipelines could be adapted to geothermal, Egg says. Richards says the infrastructure for a community geothermal system can tie in with other utilities: For example, Austin’s Whisper Valley used the same trenching for geothermal and Google Fiber. In dense apartment complexes, underground pumps could be sunk below outdoor green spaces, Richards says.

In the long-run, geothermal is an attractive financial case for community energy: It’s considerably more expensive to drill three boreholes for a single-family home than it is to drill 100 boreholes to power 30 homes, because the latter equalizes the cost. “But that means that the people who are building [multi-family buildings] have to think about that ahead of time, and then they also need to say, ‘I don’t want to make as much money right away,’” Richards says.

Pinewood Forrest finances the geothermal system for homebuyers, who then have a monthly geo-access fee, Parker says. When people are building a home and making decisions about countertops, surfaces, and amenities, “they’re oftentimes kind of either intimidated by or don’t know what a good, wise [geothermal] decision might be,” he says. By making geothermal the default, “we took that out of the equation with people.”

In order to get buy-in from housebuilders and governments, Richards says, people need to start talking about geothermal. “The average homeowner, somewhere in third or fourth grade, probably learned about geothermal and how it’s from the Earth, but by the time we get to high school and college, no one’s talking about it,” she says.

People also forget about geothermal energy because it’s silent and invisible, whereas wind and solar farms are hard to miss, Egg says. He calls solar panels “a green badge of honor” on a home’s roof. “Once [geothermal is] in, you’ll never hear about it again because there’s nothing to see,” he says. “It’s out of sight, out of mind.”

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