How underground heat can heat and cool your home

Heat pumps are hot right now. It’s the technology that can take the energy-intensive, largely fossil fuel-driven business of keeping your home, office and business comfortable, and turn it into something that could potentially run on clean electricity.

But heat pumps are not all equal. There are air-water heat pumpswhich, at the risk of oversimplification, function in a kind of reversible way air conditioners. They are perfect for replacing a gas or oil-fired furnace with something powered by electricity, such as supplied by solar panels or a clean energy supplier.

Then there are geothermal heat pumps, which cost quite a bit more to install but can operate more efficiently. It is in this technology that the heat pump starts up Dandelion sees the future. Dandelion CEO Dan Yates compared it to the transition from gas-powered cars to electric vehicles.

“It’s the same transition for heat that we need to make,” Yates told CNET. “The solution is heat pumps, and there is no Tesla of heat pumps yet. Dandelion is leading the charge by saying a Tesla of heat pumps is going to be a geothermal company.”

Dandelion, a company that grew out of Google Project But it’s far from the only company offering this technology, which, while revolutionary, isn’t all that complicated.

A report from the Department of Energy’s Geothermal Technologies Office estimated a market potential for 28 million geothermal heat pumps nationally in 2050, and that does not yet include the more than 17,000 district heating systems, where one system can heat an entire neighborhood.

How exactly does this technology use underground heat to keep your home comfortable?

What makes a geothermal heat pump different?

The inherent technology behind a heat pump is quite simple: the machine circulates a type of coolant (sometimes water) in tubes where it absorbs thermal energy from one place and transfers it to another. If you want it to be warmer inside, it uses that energy to heat the inside. If you want it to be colder inside, the heat moves in the opposite direction. The same concept powers your refrigerator.

But geothermal heat pumps, instead of tapping into the volatile and inefficient air outside for that thermal energy, use the much more consistent temperature a few meters underground.

That gives geothermal heat pumps some advantages in terms of operation compared to air source units. Yates said Dandelion’s Geo Heat Pump can produce higher heat compared to an air source unit, meaning it can operate more efficiently and heat homes better at lower temperatures. It also doesn’t lose as much efficiency when the outside temperature drops.

Yates said the Dandelion Geo is twice as efficient as an air source heat pump under normal conditions, and up to four times as efficient on the hottest or coldest days. This allowed Dandelion to grow in the Northeast, where a heat pump that can handle winter is the only viable option.

Fortunately for people living in colder areas, many manufacturers are working on products, including air source heat pumps, that are more efficient and effective in colder temperatures. That has been boosted by a challenge from the U.S. Department of Energy to create more cold-climate heat pumps.

Geothermal heat pumps and the electricity grid

The energy efficiency of geothermal heat pumps makes them a powerful tool to tackle the problem of growing demand for electricity on the grid. Electrification, whether it’s your home or your car, is one of the biggest reasons why America’s energy demand is growing for the first time in decades. (AI, cryptocurrency, and other technologies that use massive server farms are also partly responsible.) But a technology that reduces energy demand while electrifying it could actually help shore up the electric grid.

If 70% of U.S. buildings used geothermal heat pumps, it would have the potential to save the energy system more than $300 billion in grid costs and reduce winter heating costs by $19 billion per year, according to a study. was published last year by the Ministry of Energy. found.

Like solar panels, home batteries and virtual power plants, the effect is to reduce the load on the centralized energy grid by using many small solutions.

“You can think of it as a distributed infrastructure,” Yates said.

The challenges of geothermal heat pumps

The benefits of geothermal heat pumps all stem from the fact that they pump a coolant underground to take advantage of the relatively stable temperatures of the ground. That is also where the biggest challenge comes from. Every geothermal heat pump requires digging or drilling, which is difficult and expensive.

Consider an example Dandelion gave of the cost of a heat pump for a hypothetical 2,500 square foot home in Maryland. The company said the equipment could cost $10,000, including the heat pump and other materials. But installation, including electrical work and drilling, can cost as much as $35,000. Much of that cost comes from drilling, which can be particularly difficult for an existing home, requiring digging deep holes in the basement or cutting large trenches in the yard.

The technology of the heat pump plays a major role in how much drilling needs to be done. Yates praised Dandelion’s ability to concentrate heat, meaning it can function well with less drilling. But that installation cost is still much higher than an air source heat pump, which may require the same level of electrical and plumbing as a geothermal pump, but without drilling.

The high cost of installing a geothermal heat pump compared to air source heat pumps is reflected in the fact that the federal government treats tax credits for them differently. Geothermal heat pumps fall under the Residential Clean Energy Creditjust like solar panels, which means that the credit covers 30% of the total installation costs. There is no limit: if it costs €50,000, you get a credit of €15,000. However, air source units are included Credit for energy-efficient home improvementswhich covers 30%, but only up to a total credit of $2,000.

Are geothermal heat pumps the next big thing?

Thanks to the federal tax credit, we have a good idea of ​​how many Americans took advantage of that incentive to purchase a geothermal heat pump in 2023.

Data from the Tax Authorities shows that 80,730 tax returns include a credit for geothermal heat pumps, totaling more than $975 million. That pales in comparison to the number of credits for solar panels (752,300), but more Americans took advantage of the credit for geothermal heat pumps than for home batteries (48,840).

The biggest obstacle when switching to a geothermal heat pump is the high drilling costs. However, these heat pumps may have a bright future in new construction rather than in existing homes, as their installation in new construction homes could be much easier. “It’s a lot easier to install the system in your home because you don’t have to modify or redesign it,” says Yates.