Juno gets most of the electricity from lakes that offer a clean hydropower resource. This means that the installation of electrified heating systems in the city is particularly environmentally friendly.
But to be fair, Juneau is on the warmer end of the state and doesn’t have the kind of scalding cold winter weather that can hit northern places like Anchorage or Fairbanks, where heat pumps can be less cost-effective.
In the village of Eklutna near Anchorage, electrician Derek Lampert found a heat pump that can handle extreme temperatures. He lives in a house he built with his father during the pandemic. The walls are 22 inches thick, he boasts. Lampert planned for the house to be as energy efficient as possible, so he invested in a SANCO2 heat pump that uses CO2 for coolant. The machine provides space heating and hot water supply.
“We had it as cold as -20 degrees Fahrenheit and it still worked,” Lampert says. “I got water at 135 degrees.”
High efficiency was clearly Lampert’s goal, and overall he is pleased with the results. At least financially, a well-insulated home and installing a heat pump proved to be profitable. “People in my area are spending more [than my entire electricity bill] on propane and fuel oil,” says Lampert.
However, due to the fact that the heat pump sucks heat from the outside into the room, sometimes for a long time, the outside of the machine can become especially cold and make the unit less energy efficient. Heat pumps are usually designed for periodic defrosting, but Lampert says his model could do a better job. He says he’s noticed a fair amount of frost and ice on the outside of his heat pump when it’s very cold. “Of course, the colder the worse. It just fights all the moisture,” he explains.
John Miles, spokesman for Eco2 Systems LLC, which makes the SANCO2 heat pump, says the current model operates down to -26 degrees Fahrenheit (-32 Celsius). He adds that he has various means of testing for frost formation, and that any ice that does form will eventually melt.
Terry Chapin, an environmental ecologist and professor emeritus at the University of Alaska Fairbanks, has a heat pump but notes that his model, which is designed to operate in temperatures as low as -13 degrees Fahrenheit (-25 Celsius), does not work well during the winter months. “It doubled our electricity consumption when I used it in very cold temperatures,” he says. When the temperature drops below 0 degrees Fahrenheit, he switches back to his oil heating system instead.
Vanessa Stevens, a building researcher at the National Renewable Energy Laboratory in Fairbanks, says the latest heat pumps are becoming more frost-resistant.
“We’re testing a heat pump this spring in our lab, where the cutoff temperature is -31 degrees Fahrenheit,” she says. “That was unheard of 10 years ago.”
Demand in Alaska appears to be growing strongly because heat pumps are becoming more efficient and cost-effective, she suggests, adding that there are now companies dedicated exclusively to heat pump installations, which is a relatively new development.
Heat pumps have great decarbonization potential, but it depends on the context, says Meredith Foley, an economist at the University of California at Berkeley. They will be most useful as a climate solution when they run on electricity generated predominantly from low-carbon sources and when manufacturers move away from least environmentally friendly refrigerants for heat pumps. New homes, or homes requiring a completely new heating system, should now choose a heat pump as the standard, Foley said. But as heat pumps continue to proliferate, there must be enough well-trained people to install them, as well as building codes to encourage more efficient systems, Foley says.
“There is a sense of urgency that needs to be balanced with some practical, pragmatic challenges that we need to overcome.”