The state most heavily dependent on home heating oil is making significant strides in its campaign to get electric heat pumps in more homes.

Maine Gov. Janet Mills (D) said Friday that 104,000 of the systems have been installed with help from a series of initiatives begun after she took office in 2019.

The goal had been 100,000 by 2025, so she set a new goal: 175,000 additional heat pumps by 2027. Success would mean a significant portion of the state’s 750,000 housing units had at least partially decarbonized.

Maine is a state that would seem at once ideally suited and highly challenging for heat pumps. Few areas have natural gas distribution infrastructure and only 1 in 13 households use it as the primary heating fuel, according to the U.S. Energy Information Administration. As a result, about 60% of Mainers heat with oil as of September 2022, more than any other state.

Air-source heat pumps are less expensive to operate than oil furnaces and can have a lesser impact on the environment. But there is some lingering skepticism in the public mind about their efficacy during cold snaps, and Maine is one of the coldest states in the nation.

The Maine Energy Marketers Association, whose members sell all manner of fuels, is trying to ensure the public is aware of the potential shortcomings of heat pump technology.

However, state residents seem to be voting with their pocketbooks: The number of heat pumps installed statewide has climbed from about 40,000 in 2019 to roughly 145,000 now.

Mills’ office said Friday that heat pump rebates through Efficiency Maine and a low-income heat pump program at MaineHousing have been instrumental in getting the technology installed in the state’s residential and commercial structures.

Efficiency Maine pitches federal tax credits to accompany the state rebates for installation. Together with savings on operating costs, a homeowner can recoup the purchase cost in as little four to six years, the program’s website says, depending on whether they qualify for a low- and moderate-income adder.

Efficiency Maine does, however, warn that a fuel-burning backup system is needed in temperatures below minus 15 degrees.

Legislation Mills signed in 2019 to encourage and subsidize property owner adoption of heat pumps was accompanied by another important effort: development of a workforce to install all those heat pumps.

The state’s community college system expanded its heat pump training courses and has trained 558 technicians to date.

The heat pump campaign is part of a larger effort by Maine to fight climate change. Mills last year signed a law setting the goal for carbon neutrality as 2045 and this year proposed moving the 100% clean energy target date from 2050 to 2040.

Clean energy is important to the climate impact of heat pumps. As the Maine Energy Marketers Association points out, heat pumps are not as green as they seem if the electricity that powers them comes from burning carbon.

White House National Climate Adviser Ali Zaidi joined Mills for her announcement Friday.

“Maine is paving the way for states across the country seeking to build a clean energy future that protects our climate and creates good-paying jobs for all Americans,” he said in a news release.

Mills added: “Our transition to heat pumps is creating good-paying jobs, curbing our reliance on fossil fuels and cutting costs for Maine families, all while making them more comfortable in their homes — a hat trick for our state.”