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Georgia is really hot for much of the year and is expected to get hotter as climate change worsens.
That means air conditioners are fighting an uphill battle here, trying to get stuffy 80s, 90s, or even 100+ degree air down to something livable.
Traditional air conditioning systems push heat outside while cooling the air inside. But a Macon-based engineering company has pioneered technology at two Georgian military bases that instead uses land to store cold or hot water. This basic idea for a more energy efficient heat pump system isn’t new, but adding a storage element is, at least in the US.
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The systems save energy, which helps fight climate change – and also saves money for the military.
With a traditional air conditioner, “you’re pumping heat from the inside out,” explained Chuck Hammock, a Macon engineer who specializes in heating, ventilation, and air conditioning (or HVAC) systems. “But the outside is hot, he doesn’t want that heat.”
Thus, the air conditioner uses an enormous amount of energy to expel heat into the already hot summer air. This, of course, drives up electricity bills. And in Georgia, much of that electricity comes from burning natural gas, which contributes to climate change.
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But what if the air conditioner could send that extra heat somewhere cooler, more ready to absorb it? Like underground, where the temperature remains fairly stable, in the 60s?
“It takes a lot less energy to move that heat up. The hill is much smaller,” Hammock said.
This is the basic idea of a geothermal heat pump: by using the constant temperature underground, it is possible to heat and cool a building with much less energy. Hammock’s firm, AH&P Consulting Engineers, has found a way to make it even more efficient: storage.
A ground source heat pump requires a system of holes drilled deep into the ground with plastic pipes inside, circulating water from the building to the ground and back. At Marine Corps Logistics Base Albany, Hammock’s company hit the nail on the head, so there’s a well-insulated core. In winter, the cold air cools the water, which moves first towards this core, then moves outwards.
“We put our cold in the middle where we can keep it or we can use it,” Hammock said.
When summer comes, and the brutal heat of Georgia, this stored cold water returns to the building.
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“And the AC unit says hello, I love that, that’s awesome. I thought it was 95 degrees outside, but you’re sending me water at 70 degrees,” he said .
Thus, the air conditioner of this installation has much less work to do.
“We saved 50% on electricity in this building just because of this system,” said Hubert Smigelski, who oversaw this project as deputy director of installation and environment at the Corps Logistics Base. Albany Marines. He retired from that position last year.
“It’s something that every base, whether it’s a Marine Corps, Navy, Army, anybody could look into, and we tried to get them to do that,” Smigelski said. “Because it can be used anywhere.”
Hammock’s company installed a similar system at Fort Benning near Columbus, using an underground aquifer to preserve the winter cold rather than insulating the ground itself.
The pair of geothermal systems is a demonstration project under the Department of Defense’s Environmental Security Technology Certification Program, and it was deemed a success, halving energy consumption at both sites. The systems were named ESTCP Project of the Year in 2017, and MCLB Albany funded three more geothermal systems serving 10 additional buildings.
Heat pumps are part of a larger effort to make military installations more environmentally friendly. Last year, President Joe Biden issued an order calling on federal operations to achieve net zero emissions by 2050.
The command pointed out that MCLB Albany hit net zero earlier this year, meaning all of its power is generated on the base rather than relying on the broader power grid. In addition to improving efficiency, the base achieved this goal with the help of a nearby biomass plant and landfill generator.
Although these energy sources do not exist near all military bases, geothermal heat pump systems will work just about anywhere because the underground temperature remains fairly constant, regardless of weather conditions.
But there’s a caveat, according to Marilyn Brown, who studies sustainable energy at the Georgia Tech School of Public Policy: In many places, it’s difficult to add a heat pump to an existing building.
“Usually if you have a facility that’s already occupied, you don’t have the luxury of tearing down the infrastructure to install the necessary pipes,” she said.
Still, with enough space, Brown said geothermal heat pumps are a great solution. And adding the storage component developed at MCLB Albany and Fort Benning is a “valuable incremental improvement” in efficiency, according to Brown. That’s key, because when it comes to efficiency, every little bit counts.
“Energy efficiency is the cleanest and most affordable source of energy on all levels,” she said, explaining that it is cheaper to use less energy than to generate electricity. new energy and deliver it where it is needed.
Brown said that although these systems save energy, and therefore money, they have a high initial cost, so they are often better suited to an institution such as the military, a college or a large corporation, than to the average owner.
But, she says, with funding or incentives, heat pumps could also benefit rural Georgians, who often have higher energy costs.