Heat pumps: what they do and why they’re hot now

Heat pumps: what they do and why they’re hot now

The humble heat pump has finally found its moment in the spotlight. Proponents claim that the appliance could help you save money on energy, reduce Europe’s dependence on Russian gas and even fight climate change. One day, heat pumps might even replace air conditioning and heating systems across the world.

Although that may sound ambitious, lawmakers are working hard to get heat pumps installed wherever they are needed. President Joe Biden invoked the Defense Production Act earlier this year to boost domestic manufacturing of the technology, and Congress crafted major climate legislation that makes it easier for Americans to afford them. Across the pond in Europe, heat pumps are part of efforts to pivot away from Russian fuels.

With all that hype, you might want to get familiar with the technology suddenly making headlines. The verge has put together this primer on heat pumps, their uses, and the reasons they are so popular.

First off, what in the world is a heat pump?

There are different kinds of heat pump technologies, but for simplicity’s sake, we’ll focus on the appliances making the most waves right now. Electric heat pumps are the most talked about appliances. They heat and cool indoor air. Don’t be fooled by the name. Heat pumps can do the same job as furnaces and air conditioners.

How does the thing work?

This varies depending on the type of heat pump, but the defining feature is that they move heat around to where you want it. Specifically, the appliances use a refrigerant to draw in heat and redistribute it. A refrigerant is a substance with a low boiling point that can easily absorb heat. They’re also used in air conditioners and refrigerators. The most popular type of heat pump is the “air-source”, which transfers heat from your house to the air outside.

It has two components: an outdoor and indoor part. The indoor part is used to cool down a room by pushing warm air through coils that are filled with liquid refrigerant. Refrigerant is able to absorb heat, boil, and then evaporate into a gas. From there, the heated up refrigerant moves on to the outdoor component, where it releases the heat. Refrigerant then cools and turns into liquid again. The process reverses when heat pumps are used for heating up a space. The refrigerant absorbs heat from outside and moves that indoors. This works even in cold climates thanks to recent advances in heat pump technology. The refrigerant can absorb heat from any environment as long as the temperature is below freezing.

There are also “ground-source” or geothermal heat pumps that move heat between a home or building and either the ground outside or a nearby source of water.

That sounds surprisingly low-tech. Haven’t heat pumps been around for a while?

Yup. Austrian engineer Peter von Rittinger designed and installed the first documented heat pump system in the 1850s. The first electric ground-source heat pump is credited to American inventor Robert C. Webber, who was tinkering with a deep freezer in his cellar in the late 1940s when he realized it produced scalding water. He didn’t want to waste hot water and instead adapted it to his boiler to heat his entire home. Heat pumps are still a relatively new technology. In 2020, they only fulfilled 7 percent of global heating demand. Over the years, other technologies that many people have become more familiar with — i.e., air conditioning and furnaces — became more affordable to buy and install. It was cheaper to heat your house with gas than electric in many areas. Plus, heat pumps haven’t always worked as well in very cold places as they do in milder climates.

Why are we hearing so much about heat pumps now?

First off, the technology has improved. And that’s made heat pumps seemingly ideal for grappling with several crises the world faces today.

Both the COVID-19 pandemic and Russia’s war in Ukraine have contributed to a global gas crunch. Gas heating has become more costly, so you will need to rely on gas-fired power plants to maintain your lights.

That energy crisis is really stark in Europe, where the cost of gas has risen from around $5 per million British thermal units (MMBtu) to $55 per MMBtu over the past couple of years alone. A big part of the problem is that Europe has historically been very reliant on Russia for its supply of natural gas. Since Russia invaded Ukraine, the bloc has tried to quit that addiction — and electric heat pumps are a big part of that plan. Gas is currently the fuel Europe uses the most for its heating, and much of that gas has historically come from Russia. The European Commission wants to double the rate at which it’s deploying heat pumps, with a goal of deploying 10 million units over the next five years.

This is an acceleration of another transition that was already underway. One of the main strategies to slow climate change is to electrify everything — from cars to buildings. This allows them to run off clean and renewable energy such as wind or solar, once fossil fuels are eliminated from the grid. Some cities — like Berkeley, California — have even banned new gas hookups in homes and buildings.

Heat pump technology has been a viable alternative to oil and gas heating. There are many climate policies that attempt to encourage heat pump adoption. The giant climate bill Democrats are working to pass, called the Inflation Reduction Act, for instance, includes up to an $8,000 rebate for income-eligible Americans who install a new heat pump in their home. Anyone who doesn’t qualify for the rebate can still get a tax credit of up to $2,000 for installing a heat pump.

So you’re saying heat pumps are good for the environment?

For the most part, yes. They’re electric appliances, so they can run on clean energy like we mentioned above. However, the environment benefits depend on the quality of the network they are connected to. If you have a grid that is still dominated by coal and gas — which many still are — then that electricity isn’t very clean. At least not yet. The climate case for heat pumps is forward-looking. The thought is that if people switch from gas over to heat pumps while the grid is getting cleaned up, then countries can get to their climate goals much faster. More than 30 countries and the European Union have entrenched a goal in law or policy of reaching net zero carbon dioxide emissions. And more than 100 countries have made similar proposals but are still working to adopt policies to reach those goals.

The other climate benefit that comes with heat pumps is that they are generally pretty energy-efficient. After all, they’re not generating heat — they’re simply moving it around. Air-source heat pumps are 2. 2 to 4. 5 times more efficient than Energy Star gas furnaces, according to a US-focused analysis published in 2020 by the nonprofit clean energy research organization RMI. Ground-source heat pumps can cut energy use by 30 to 60 percent, according to the Department of Energy. Efficiency gains vary, though, because heat pumps essentially have to work harder to gather enough heat from the ambient environment in colder climates.

All said, 70 percent of houses in the US would reduce emissions today by installing a heat pump, according to one study published last year in the journal Environmental Research Letters. That study took both greenhouse gas emissions and air pollutants like particulate matter into consideration. Looking at just planet-heating carbon dioxide, the US would shrink residential CO2 emissions by a hefty 32 percent if every single-family home started using a heat pump.

Is a heat pump going to save me money?

Once again, it depends. For now, just 32 percent of households would “benefit economically” by installing a heat pump, according to the same study in Environmental Research Letters.

While the appliance can save you money in the long run through lower utility bills, heat pumps typically still come with higher upfront costs than traditional heating or cooling systems. People paid a median of $7,791 to buy and install a ducted air-source heat pump compared to $6,870 for a gas furnace, according to a Consumer Reports survey of its members. A heat pump system, however, can become more cost-competitive if it’s replacing both a gas furnace and an air conditioning unit or if it’s being built into a new structure. In the short-term, heat pump subsidies will be crucial to make them more attractive to customers.

Thanks to their energy efficiency, heat pumps might offer the cheapest clean energy alternative to heating and cooling a home for most US households in the coming decades, according to an analysis by the American Council for an Energy-Efficient Economy.

Will a heat pump work for anybody, anywhere?

Technically, heat pumps can work just about everywhere. Thanks to technological breakthroughs over the past decade, heat pumps can now heat homes even when outdoor temperatures reach subzero. For now the appliances don’t perform as well in colder temperatures than they do in warmer climates.

People who don’t have their own homes will find it harder to get a heat pump as they usually need to have them installed by professionals. The next big advancement in newfangled heat pump technologies is easy-to-install window units, comparable to window AC units. These new units are much more convenient than traditional heat pumps and can be installed right in the window sill. New York state recently said it would shell out $70 million to two companies — Gradient and Midea America — to produce 30,000 window heat pump units for New York City public housing.

Gradient says its product will become commercially available sometime this year. It’s not cheap. While a window AC unit might cost a couple hundred bucks or less, Gradient’s new window heat pump (which can both heat and cool a home) costs way more: $1,999.

This is a big problem with energy-efficient appliances and clean energy technologies in general. So far, many of these technologies have been out of reach for many people — often, renters and folks without thousands of extra dollars to spend on a new appliance, especially when their old one still works just fine. This will have to change if we are to see a true heat pump revolution.

The post Heat pumps: what they do and why they’re hot now appeared first on The Verge.

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