What the Heck Are Heat Pumps?

What the heck is a heat pump? Many of us try to stay up to speed on the latest and greatest clean energy technology.  We’ve replaced our old incandescent light bulbs with CFLs and LEDs, we know electric busses and trucks are an excellent alternative to polluting diesel and gas vehicles, and we understand how important energy storage will be to reaching 100 percent clean electricity.  But, a heat pump? What is that, and why are people so psyched up about them?

People are psyched about heat pumps because they are vital to helping us efficiently heat our homes and buildings with wind and solar, instead of gas and other fossil fuels. As I describe in another column, using gas to heat homes and buildings in California is a major source of climate pollution, roughly equivalent to the greenhouse gas emissions of all the state’s power plants.  It shouldn’t come as a surprise that in order for California to achieve our needed climate and air quality goals we need to drastically cut gas consumption.  But, since around 75 percent of our homes rely on gas furnaces and water heaters everyday, significantly cutting gas use has historically been pretty daunting.  

Here’s where a heat pump comes in.

Heat pumps are super efficient

A heat pump is a pretty simple technology that can cut the energy for heating water or your home by a factor of 3 or 4, which can lower your utility bills especially if you have rooftop solar or time of use rates.

Unlike a conventional water heater that uses a gas-flame or electric resistance to create heat, a heat pump water heater uses far less energy because it transfers existing heat instead of creating heat.  Here’s how: a heat pump water heater pulls warmth from the surrounding air (even if the air is cool), compresses the warm air to increase its temperature, and then pumps this heat through condenser coils that transfer heat to the water in a storage tank.  

Heat pumps can be powered by clean electricity instead of gas

Electric heat pumps are especially exciting because they are a clean alternative to heating your home with fossil fuels like gas.  

With an electric heat pump water heater, you can heat your water with wind and solar -- i.e. when there are ample renewables on the grid-- and then use the tank store that hot water, ready for use throughout the day and night. Heat pumps can be both programmable by the homeowner or renter, or potentially interact with the grid to provide demand response and other load flexibility services, helping integrate more renewable energy on the grid. Grid-interactive means your utility or third party aggregator can power your water heater up or down depending on the needs of the grid.  If this option is available to you, you’d be compensated and will have the same reliable level of hot water available in your home. Grid-interactive water heaters represent a potentially large and low cost thermal storage capacity that can help integrate renewables while reducing costly infrastructure upgrades. It’s a great two for one where you can help reduce gas use at home, and help your utility reduce its dependence on gas power plants.

Here are some common questions folks ask about heat pumps:

1.  Can a “heat pump” replace all of your gas heating appliances?  Almost.

You can replace your gas water heater, furnace, and clothes dryer with a super efficient electric heat pump. You can’t get a heat pump stove, but you can get an electric induction stove to replace your gas range. It’s the new in thing for top chefs and restaurants. They’re a whole lot better for indoor air quality and your health than gas stoves, they heat more quickly than gas, but they are also a bit more expensive too.

2.  Are rebates available to help lower the upfront costs of buying and installing a heat pump? Sort of.

Most utilities in California offer rebates for energy efficient products, including electric heat pump water heaters and space heaters. The catch is that you are only eligible to get this rebate if you already use an electric heater. Since approximately 75 percent of homes in California use gas furnaces and gas water heaters, most people are not eligible for a rebate for an advanced electric heat pump. Dozens of environmental advocates, green builders, and even some utilities are currently pushing the California Public Utilities Commission to update and revise this outdated rule that is hindering California's progress toward its climate goals.  Here is our latest Motion on the topic.

3.  Are heat pumps just for people who live in a warm climate? Nope!

Many people, with good reason, wonder if heat pumps are only appropriate for warm climates, since the warmth used for heating originates in the ambient air.  The good news is that this is not the case. Heat pumps perform well across most climate zones, even in very cold areas.  In fact, heat pumps work in the coldest climates in the country, from Alaska to North Dakota and the Northeast.  Many heat pumps are “hybrids” meaning they also have an electric resistance element for supplemental heating needs on very cold days.

4.  If heat pumps are so great, why isn’t everyone getting them?

Although adoption is increasing, heat pump water heaters are only one percent of all water heater sales. Lack of consumer awareness is a major reason. Over 80 percent of water heater sales are for emergency replacements. When your water heater breaks, you’ll likely want a replacement fast, typically within 1-3 days max. This is not the time to begin researching all the advanced models and options. Moreover, most installers don’t have heat pumps in stock yet because there isn't enough demand - a typical chicken and egg problem. And even if you are motivated to get a heat pump (and pay the higher upfront cost), this will entail an appointment with not just a plumber but also an electrician to run conduit.  Most opt for the quickest and easiest solution-- a simple replacement that uses gas.  The problem with this is that it locks you into continued fossil fuel heating for at least another decade.

As we all take steps to cut climate and air pollution to achieve California’s needed climate and air quality goals, the appliances and equipment we choose for our homes, especially those that last a decade or more, have consequences. There are lots of things we're doing to make heat pumps more accessible. If you've made it this far into a blog about something called a heat pump - well, that was our goal and hope! Most of us will have one or two opportunities between now and 2030 to cut our home’s gas consumption. Next time you or a family member needs a new appliance, check out a heat pump. If your water heater or furnace is more than 10 years old, don't wait until it fails and you have to scramble for a replacement. Do your research and plan to replace it with a clean energy alternative: You'll not only slash your carbon footprint, but you'll also avoid emergency replacement costs.

 

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