A common critique of the “electrify everything” movement is that it will be near impossible to produce enough clean electricity to replace the fossil fuels used in buildings and transportation and make sure the grid is strong enough to deliver it.
While this concern is valid, there is an important card humanity has in its back pocket to meet this challenge: Heat pumps, which are so efficient that their increased deployment will offset much of the electricity that’s currently used inefficiently. This saved electricity will allow new electrical loads (like cars) seamlessly onto the grid.
Let’s illustrate this point with two important electrification technologies: a heat pump water heater (HPWH) and an electric vehicle (EV). Both technologies are all electric and reduce carbon emissions and they complement one another in an important way. One will save nearly all the electricity that the other needs to operate. Two sets of numbers, and a couple drawings, explain how.
As Americans transition to EVs over the next decade, the average home will need around 2,363 kilowatt-hours (kWh) of electricity to power each of those vehicles, according to the Department of Energy’s 2020 RECS survey. This will be a new electrical load on the grid, as gasoline and diesel have powered our vehicles for the last century. 2,363 kWh is a lot of electricity, about a 22% increase in the annual consumption of the average home which currently uses 10,632 kWh per year.
But now for the second number. ENERGY STAR estimates that a three-person home (average US household is 2.5 people) will save 2,820 kWh annually with a heat pump water heater. Those savings more than offset the power needed to charge an EV! This is a testament to the efficiency of heat pumps and the amount of energy we currently waste in heating our water.
About half of the US has electric resistance water heaters, so as those homes switch to heat pump water heaters, we won’t have to worry about finding more electricity to power their electric vehicles. (The other half of homes heat water with fossil fuels so we will need to produce more clean energy for those homes and vehicles.) Plus, these homeowners won’t have to pay any more in utility bills when driving electric, and all the money they currently spend at the gas pump will go back into their pockets. Similar energy savings will also come from transitioning electric resistance space heaters and dryers to heat pumps.
While efficient electrification won’t save all the kWh we’ll need to completely electrify society, this one example shows how it will go a long way. So next time you hear that there won’t be enough clean electricity to power a clean energy world, ask the naysayer if they’ve ever heard of the mighty heat pump water heater.
If this article helps get you jazzed about heat pump water heaters, October 25 is Heat Pump Water Heater Day, a day to celebrate this amazing technology that no one has heard of.
This article is part of a series called Decarbonize Your Life. With modest steps and a middle-class income, our family has dramatically reduced emissions and is sequestering what remains through a small reforestation project. Our life is better for it. If we can do it, you can too.
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