Author: Phil  Mckenna        Published: 3/6//2023     Inside Climate News

Aaron Sinclair, of Dave's World, installs a heat pump at the home of Roland and Dale Bois on Sept. 25, 2018. Credit: Brianna Soukup/Portland Portland Press Herald via Getty Images
Using heat pumps to heat buildings would be a better use of limited clean energy resources, a new report concludes.

Efforts by natural gas utilities in Massachusetts to replace 20 percent of their fossil gas supply with “green hydrogen” derived from renewable electricity would consume more clean energy than would be produced by the state’s ambitious offshore wind energy buildout in the coming years while yielding few climate benefits, according to a report published on Monday.

Using heat pumps powered by renewable energy to heat residential and commercial spaces would be a more effective use of limited clean energy resources, the report, from Gas Transition Allies, a coalition of clean energy advocacy organizations in the Bay State, concluded.

“If you were to use green hydrogen for heating, you would be using roughly three and a half times as much electricity as if you were providing the same amount of heat to buildings with heat pumps,” said Gordon Richardson, a technology and business consultant and co-author of the report.

Hydrogen, a clean fuel that does not release carbon dioxide when burned, is produced by splitting water into hydrogen and oxygen, an energy-intensive process. If the electricity used for this process comes from renewable energy sources such as wind or solar, the hydrogen it produces is considered “green.”

If gas utilities in Massachusetts replace 20 percent of the volume of methane, the primary component of natural gas, with green hydrogen, they would need 3.9 gigawatts of renewable energy capacity to produce the hydrogen, according to the report. That is approximately 20 percent more clean energy than the state’s planned buildout of 3.2 gigawatts of offshore wind power capacity by 2030.

The climate benefit of a transition to a green hydrogen blend of fuel would be negligible as greenhouse gas emissions would decrease by just 6-7 percent, the report found.

If buildings relied on heat pumps for heat instead of burning a blend of methane and green hydrogen in a furnace or boiler, they would need 3.6 times less renewable energy, according to the report. The significant disparity in renewable energy requirements between the two heating systems is due to a fundamental difference between how furnaces and heat pumps provide heat.

For every unit of energy input in the form of fuel—whether natural gas or a blend of hydrogen and methane—furnaces or boilers can theoretically produce up to one unit of energy in the form of heat.

Unlike conventional heating systems which burn fuel to generate heat, heat pumps pull heat from outside into a building, like an air conditioner run in reverse.  Even on cold winter days there is still sufficient heat in outdoor air that can be drawn into a building through a heat pump’s series of fans, pumps and compressors.

Because heat pumps simply move heat from one location to another, their efficiency is far greater than conventional heating systems, allowing them to transfer upwards of three times the energy, in the form of heat, than the electricity that they consume.

The report doesn’t compare the cost of green hydrogen to heat pumps. Ben Butterworth, a director with the Acadia Center, a clean energy advocacy organization based in Rockport, Maine, said costs associated with the additional renewable energy needed for green hydrogen would be tremendous.

“It’s expensive to build this renewable energy capacity at scale already, and if we’re using or requiring 3.6 times as much electricity, that really underscores the cost difference between the two,” Butterworth said.

Butterworth, who reviewed an early draft of the Gas Transition Allies report, said he sees building electrification paired with energy efficiency measures as being the “lynchpin strategy” for decarbonizing buildings in Massachusetts.

“We know this, and we have to focus on that and not be distracted by putting green hydrogen into the gas distribution system because it’s just an inferior option all around,” he said.

National Grid, one of two large gas utilities operating in Massachusetts, pledged in 2022 to transition to 100 percent fossil free gas—including up to 20 percent green hydrogen as well as “renewable natural gas,” biogas sourced from landfills, dairies or food waste —by 2050.

Christine Milligan, a spokeswoman for National Grid, said electrification will play a “massive role” in the clean energy transition but added that green hydrogen is “being demonstrated around the world as a renewable carrier and a means for long-term storage of renewable power.”

By “carrier” Milligan is referring to hydrogen’s ability to effectively store the renewable electricity that goes into producing green hydrogen until the gas is needed as fuel.