A new report just busted another myth about heat pumps

Heat pumps move warmth from outdoor air into your home instead of burning fuel to make heat, and newer models keep working fine in cold climates. A common worry is that if millions of households switch to them, the electric grid would buckle. A new report from the energy research group RMI says that's not true. The grid has "headroom" in winter, since most places use far more electricity in summer for air conditioning than in winter for heat. That gap means roughly 109 million U.S. homes, about three-quarters of the country, could add a heat pump without straining the system. RMI says this shift could also cut electric bills by more than 20 percent in some states.

How much headroom exists varies by location, depending on local climate and how utilities generate power. Places with lots of solar, for instance, see less generation in winter when days are shorter, so utilities are turning to batteries and other storage to fill the gap.

The report also points to homes still using electric resistance heaters, like space heaters, especially common in the Pacific Northwest and Southeast. These are better than gas furnaces but far less efficient than heat pumps. RMI's earlier research found switching from resistance heating to a heat pump could save a household around $1,530 a year. Maine, despite its cold winters, already blew past its goal of 100,000 heat pump installations two years early, with help from state rebates. If you're due to replace an aging AC unit or furnace, this is the kind of upgrade decision where checking what rebates your state offers could pay off.