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Air source heat pumps provide energy relief in Southeast Alaska

Suzanna Caldwell
Wrangell risked maxing out its electrical load until air-source heat pumps like this one, on a city building, became popular. Clay Hammer/Wrangell Municipal Light and Power photo

For years, many communities in Southeast Alaska basked in the relative abundance of affordable, accessible hydropower.

But with supply, comes demand, and before long communities like Wrangell, Sitka and even Juneau found themselves turning to other renewable energy sources to make sure strained hydropower demands could be met.

One of the most popular sources to come along is the air source heat pump. With its fan-intake system and square box shape, it looks like an air conditioner -- which it can be -- but its primary function is to use a reverse refrigeration system that sucks heat from outside air and “steps” it up with electricity, providing an affordable alternative to heating homes with fuel oil.

The air need not be warm for the machines to work. Studies have shown that heat pumps are capable of working at temperatures as low as minus 15 degrees Fahrenheit.

That’s been a big change in the market, according to Colin Craven, building science research director at the Cold Climate Housing Research Center in Fairbanks. He said it was long thought that air source heat pumps couldn’t heat homes in the cold climates of Alaska.

“The rule of thumb was ‘this wasn’t going to work,’” he said.

But it has. In southeast Alaska, with its relatively mild climates, the use of the air source heat pumps has been win-win. It means less expensive heating for those who install the machines; while they run on some electricity, it is far cheaper than the fuel oil most people use to heat their homes. And although they use just a bit more electricity than conventional resistance space heaters, they're three to four times more efficient. The machines have gained ground in much of the Pacific Northwest and found practical applications in east Asia, especially in places like Japan and South Korea, where they were first developed.

There are a couple hundred scattered in homes and businesses across Southeast Alaska, due in part to utilities encouraging their installation.

Because of the increased interest, Cold Climate Housing Research Center is the early stages of conducting a study that will look at what the limits and uses of the heaters can be, with test sites in Southeast Alaska as well as in Kodiak and Dillingham.

“We want to be able to tell people were the boundaries are, so to speak,” Craven said.

Craven said the technology is fairly affordable, with smaller versions of the machine costing about $3,000 on average. They’re not as efficient as ground source heat pumps, which pull heat from water in the ground. But those pumps must be buried, significantly increasing the costs.

“That’s why air source is so attractive versus being coupled to the ground,” Craven said.

Success in Southeast

Sitka leads the charge; there are about 80 heat pumps in the community of about 9,000, according to numbers from Cold Climate Housing Research Center. There are about 30 air source heat pumps in Kodiak, another 20 to 25 in Ketchikan, and less than a dozen scattered in other Southeast Alaska communities.

They look and function much like an air conditioner. But instead of just cooling they take heat from the outside air -- even if that air is relatively cold -- and converting it to warm air.

Chris Brewton, utility director for the City and Borough of Sitka, said when he first installed his air source heat pump in December 2012, he had doubts about its efficiency. It was 22 degrees outside when it finally came time to turn on the machine. But within minutes, the air pump heat began pumping out 110-degree heat.

“The heat pump is incredible,” he said, noting that a since he’s had the heat pump, he’s never had to fill up the 250-gallon fuel tank that feeds a backup Toyo stove. He’s even gone on to install similar systems for his in-laws and friends.

He said for his relatives their electric bill went up slightly -- from $70 to $90 a month. But the real savings came on their heating oil bill, which dropped dramatically, from $400 a month to $100. They still use the oil heater for their domestic hot water.

In Wrangell, the small Southeast community of about 2,700 people, air source heat pumps have been a blessing. Clay Hammer said Wrangell has found itself in a unique position when it comes to electricity. Hammer said when fuel prices “went kind of crazy” in 2006, the city actively encouraged people to switch to electric resistance heating, which heats using an electrical coil to produce heat, like a space heater or a toaster.

Hammer said it was cheaper for people to heat their homes with electricity, since it cost about $2.80 for the equivalent amount of heat a $5 gallon of heating oil would produce.

In those days, Wrangell had excess hydropower -- so much so that they were selling the excess to nearby Ketchikan -- so it especially made sense to have people switch over.

However, Hammer said, they didn’t expect the program to be so popular, and within a few years Wrangell began to come to close to maxing out its electrical load, especially during the coldest times of year. The community was using so much electricity there was worry they’d have to look at either expensive diesel generation or building more infrastructure and instituting a rate increase.

So the community looked toward electrical conservation. Heat pumps have become a big part of that equation, he said. People have slowly been switching over to them, in turn flatlining electrical growth in the community.

Hammer even installed one in the Wrangell utility building and city hall, so visitors can see it right away when they walk in.

“I decided that in terms of saving the community money and getting the word out, we figured we’d get more bang for our buck if we have it right front and center,” Hammer said. “People can see it and see that it works.”

While there are some worries over how humidity might affect the heaters in soggy Southeast, for the most part those involved with the machines count them as a success. Brewton, in Sitka, said in the years he’s had his heat pump he’s had zero problems. But he joked that after being such a vocal advocate for the heat source, he might have to watch out if the maritime climate proves too harsh for them.

“In five years I might have to leave,” Brewton joked. “I might get run out of town.”