It took nearly 170 years, but geothermal heat pumps are finally ready to have a moment. The poorly named appliance—they heat and cool buildings—could be the key to ensuring our homes are more comfortable and climate pollution-free.
The world is in a zero-sum race to electrify everything and prepare our homes, apartments, and offices for the climate crisis. Using the ground as a natural source of heating and cooling and electricity to move that warmth or chill into homes would be a huge step to do just that, allowing us to kick fossil fuels and climate-damaging chemicals. And with the federal and more state governments catching onto their benefits and offering incentives to install them, it’s heat pumps’ time to shine.
When Lord Kelvin—yes, the guy for which Kelvin temperature is named after—conceived of the general idea of a heat pump in an 1852 journal article, climate change was not on his mind. In fact, his concept for the heat pump arose in part from figuring out how to use coal more efficiently to heat homes in the UK winter and cool them in the tropics. In the article, published in the London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, he called for something with the “properties of a ‘perfect thermo-dynamic engine,’” which makes a heat pump sound absolutely incredible.
Kelvin envisioned a steam engine or another machine that evaporated or condensed liquid to generate heat or cooling. The air would be circulated to other locations through a cylinder while another cylinder pulled air from that location. His concept was never built, but it became the foundation for what was to come in the 20th century, including heat pumps that relied not on steam engines or coal but another source of near constant temperature: the ground.
It’s those geothermal heat pumps, the first of which as patented in 1912, that could now be key to ensuring no-carbon homes of the future. (Yes, there are air and even water heat pumps, but we’re focusing largely on geothermal here.) The upper 300 feet (91 meters) or so of the Earth’s crust is a fairly constant temperature in the 50s. That makes it an ideal place to pump or dump heat depending on the season. A heat pump does this by running either a loop or a long, straight run of pipe filled with anti-freeze into the ground and connecting to a building where a pump inside that blows over the coils and disperses the air. In the winter, it essentially pulls heat out of the air coming from the ground and blows it into your home. In the summer, the opposite happens. If you want to go wild, This Old House can tell you some of the specifics.
The reason why heat pumps are essential for the homes of 2030 has to do with what they don’t require: fossil fuels. There’s no propane, oil, gas, or coal, all fuels used to heat buildings. They not only produce carbon dioxide but also a host of other dangerous air pollutants.
“We burn stuff in the house and blow air across it and it could possibly kill us,” Joanne Huang, a special projects lead at Otherlab and co-founder and CEO of heat pump startup Sensible Storage, said, describing how furnaces work in terms that made me slightly nervous. “Ultimately, our grandkids are going to be like, ‘you did what, you piped flammable gas into your homes and blew air across the in the early 2000s?’ And we’ll be like, ‘yes, and we had carbon monoxide detectors to make sure we didn’t die.’”
Geothermal heat pumps lowering the chance of death by explosion seems like reason enough to consider them for more widescale use (they currently only comprise about 1% of all home heating and cooling systems). But it’s the carbon benefits that makes them so invaluable as we consider what to do with our homes, offices, and other buildings in the face of the climate crisis. A United Nations report published late last year found that buildings account for 38% of the world’s greenhouse gas emissions, a percentage that’s rising. Among the factors for the uptick is wasteful energy use tied to heating and cooling.
Heat pumps are wildly efficient compared to fossil fuel sources of heating and cooling, and they run solely on electricity. While it’s true that much of the grid is still powered by coal and natural gas, thus meaning your clean-in-the-home heat pump might be powered by a dirty power plant, that is changing. It’s also markedly easier to regulate emissions at the 3,300 or so fossil fuel power plants in the U.S. than what’s sitting in the basements of the country’s nearly 140 million homes. Heat pumps also lightly sip on electricity, making them much more efficient than fossil-fueled furnaces and air conditioners.
A growing number of companies like Huang’s see a chance for heat pumps to be synched up with rooftop solar, creating an all-in-one clean energy, heating, and cooling system. (Sensible’s system, as well as other heat pump setups, can also be used to provide hot water, adding even more value for owners.)
The main thing keeping heat pumps from going mainstream—aside from their horrible name that fails to properly highlight their wonders—is the upfront cost. A heat pump can run anywhere from $5,000 to $10,000 more than the average gas furnace. While they’re more efficient and will pay off over time, that’s a huge chunk of change to pony up. Innovations like vertically integrating the installation process could help bring costs down. But relying on the free market alone isn’t the answer, and governments will have a crucial role to play to speed up adoption.
“Geothermal is always viewed as an expensive technology, and it’s been segregated or pushed over to the custom home,” said Tim Wright, the vice president of sales for geothermal manufacturer Enertech. “People have the idea that if I’m not building a mansion or building a custom home, this really isn’t for me.
“This is so untrue,” he added in an email. “Everyone can benefit from this technology and will realize a monthly positive cash flow and have the most advanced, carbon reducing system available in the marketplace today.”
Installing a geothermal heat pump also involves some serious machinery. Drilling dozens or even hundreds of feet into the Earth’s surface requires large drilling rigs that are fine in new developments where houses are being built, but really challenging to maneuver into existing neighborhoods. Beyond a specialized drilling rig and operator, homeowners also need to hire various contractors to do the rest of the installation. It’s a hassle and a costly one at that.
Companies like Dandelion Energy, a startup that spun out of Google’s X lab, are working to bring some of those costs down by being a one-stop shop. Kathy Hannun, the co-founder of Dandelion, said she and her partners spun the company out of X because it wasn’t about creating a moonshot breakthrough technology but how to figure out scaling up something already in existence and desperately needed on the market.
“We spend a lot of time thinking about how we make this customer experience better,” she said. How do we make it simpler to install these things? How do we bring the cost down? It’s more engineering and product work versus fundamental research. And it didn’t require us to spend a decade doing research in order to come up with something. It’s actually the type of sound problem where it’s much better to launch and iterate quickly and learn from customers.”
The company is currently up and running in New York, a state that could use a lot of upgrades. It’s the top state in the country for using home heating oil. (I grew up in Massachusetts, number three on the list and where my grandfather ran a home heating oil business, and didn’t realize until well into my adult life how weird it is to use oil to heat homes.) The state also offers incentives that Hannun said have improved as Dandelion and other companies drove an uptick in heat pump installations, creating a type of virtuous cycle.
“We’ve just shown that people do want to get off of fossil fuels,” she said. “People want to move to heat pumps provided the price is acceptable, and they’re convinced it will heat and cool effectively. So, I think that’s a huge step forward.”
Getting costs down is of utmost importance to ensure that poorer households aren’t left behind. Those households already spend a disproportionate amount of their income on utilities, and if incentives aren’t aligned to help ensure they’re among the first adopters instead of the last, it will widen the inequality gap further. Another startup, BlocPower, is focused on doing just that by installing heat pumps and other energy-saving measures in 1,100 low-income buildings in New York City and the vicinity. But more incentives and regulations could help bring clean heating and cooling even more within reach. As clean energy group Rewiring America put it in an exhaustive 2020 report, “We simply won’t solve climate change if we don’t figure out how to help everyone afford the future.”
There are political forces to overcome for heat pumps to meet the moment and be in a growing number of homes by 2030. The U.S. lags well behind countries like Japan, Sweden, and Germany in heat pump installation, in part because those countries lack the U.S.’s seemingly endless supply of natural gas. The rise of natural gas in the U.S. threatens to derail the climate, but it also has some powerful backers in the form of oil majors, Republicans, and even some Democrats like President Joe Biden’s international climate advisor John Kerry. Utilities heavily invested in gas are also deadset against any regulations that would curtail its use like local gas bans or rolling back gimmes like a rule in New York that lets utilities provide a hookup for gas to any home within 100 feet (31 meters) of a gas line.
“They could give that home a free geothermal system more often for less than the cost of connecting to the gas line,” Hannun said. “There’s a lot of built-in policy structure like that that makes it so that the playing field isn’t quite even yet between an electrification technology and a fossil fuel technology. As we see more states trying to encourage electrification, I think it’s we’re getting closer.”
Those types of rules have to go, though, or we risk locking in more and more homes to the heating source of the past rather than the future for years to come. Letting that happen is an impediment to the good life for millions of people.
Wright said seeking longer term incentives at the federal level for geothermal heating and cooling could also further speed up the development and market adoption. And more importantly, he noted that government and state and local utilities should ensure those incentives don’t disappear to level the playing field with fossil fuel systems and giving “homeowners, builders, developers, architects, engineers, everybody that long runway” to plan. An analysis from Rewiring America and the Center for American Progress put out in early June shows that a program that offers low-to-moderate income households $6,500 and everyone else $5,000 in rebates on heat pumps could spur fairly rapid adoption and climate benefits. The cost would be $77.4 billion but would save 112.5 million tons of carbon pollution, or a roughly 47% dip from the start of the decade. A report by the Sierra Club published last year mirrors those findings, and shows the emissions reductions are equivalent to half the country giving up driving.
More incentives for developers could also lead to even bigger gains in district geothermal heat pump systems that heat and cool entire neighborhoods, which Wright said is already becoming the next frontier. But waiting for the frontier to come rather than running to meet it is the name of the game for heat pumps and home electrification.
“The time is now. You cannot wait,” Huang said. “To build it smart from the beginning, to drive that low cost, and then stick it into the market in a place where it’s really going to make an impact sooner rather than later. We just don’t have the time to wait.”