Published in the Colorado Sun on August 27th, 2023
Climate change disasters are making headlines on a daily basis. One of the key solutions is to replace polluting natural gas furnaces with clean, high-performance electric heat pumps. Across the country cities and towns like Crested Butte have banned gas in new buildings.
Building electrification is a serious threat to the business models of utilities that distribute natural gas. Xcel Energy has responded by:
1) Casting doubt about the ability of heat pumps to heat Colorado homes, and
2) Promoting a Clean Heat Plan that continues to rely heavily on natural gas.
Xcel paid the National Renewable Energy Laboratory to measure the performance of heat pumps at Colorado’s higher elevation. Engineers already understood that heat pump performance is moderately less at elevation than at sea level, just as it is for gas furnaces. The laboratory’s preliminary results confirmed this, but Xcel caused a controversy when it reported the results in a way that implied that heat pumps do not provide adequate heating in the winter. For example, in a July 24 newspaper interview, an Xcel representative made this misleading statement: “We do think heat pumps can deliver a significant amount of heating and emissions reduction in a reliable and affordable way when it’s relatively mild outside —the spring and the fall“[emphasis added].
In fact, the renewable energy laboratory has shown that heat pumps can perform well in the laboratory at cold temperatures. Out in the real world, today’s cold-climate heat pumps consistently demonstrate they provide excellent heating even in the coldest locations such as Maine, northern Minnesota, and even the “Icebox of the Rockies:” Fraser, Colorado. I can personally attest that our heat pump kept our all-electric home in Jefferson County warm this past winter as outdoor temperatures dropped to -15°F — without requiring auxiliary electric resistance heating.
Xcel’s Clean Heat Plan
Xcel’s heat-pump comments were made during the lead-up to the Aug. 3 release of their Clean Heat Plan. While that plan includes efficiency and electrification (it’s not clear how much of that will happen anyway), its stated emissions reductions rely to a great extent on a number of questionable carbon accounting measures:
- Carbon offsets. These are credits purchased from others who claim to make carbon reductions that will offset the purchaser’s carbon emissions. But it is difficult to prove that these reductions would not have happened in any case, and it is no substitute for a company reducing its own carbon emissions.
- Certified natural gas. This is a dubious green marketing effort by the gas industry to certify its natural gas as meeting certain requirements, but with an emphasis on reductions of methane leaks in supplier wells and pipes before the gas reaches the utility. The gas supply industry should have addressed these leaks long ago. Claims that upstream leaks will finally be reduced is a poor justification for Xcel’s continued burning of natural gas. And the bottom line is that “certified natural gas” is just natural gas.
- Recovered methane. Xcel is referring here to the limited amount of natural gas that can be economically captured at some Colorado locations, such as coal beds and landfills, to prevent its loss to the atmosphere. The one source Xcel specifically cites is the Southern Ute Coal Bed, which could provide less than two-tenths of one percent of Xcel’s retail gas sales.
- Hydrogen. Despite all the hype, hydrogen is not an energy source. It is an expensive, highly energy-intensive energy carrier. To really address carbon dioxide emissions, renewable electricity must be consumed to produce, compress, and distribute carbon-free “green hydrogen.” Because it is the smallest molecule, hydrogen is extremely leak-prone, and a recent study showed that leaked hydrogen has a global warming impact that is significantly higher than that of carbon dioxide. Hydrogen is highly explosive, and when it burns it releases not just water vapor but nitrogen oxide air pollutants as well. Most importantly, heating a home with green hydrogen would consume more than 3 times as much electricity as heating it with a cold-climate heat pump.
While heating with hydrogen is extremely inefficient, Xcel’s plan to simply mix some hydrogen with natural gas to reduce emissions is just plain ineffective. To avoid damage to existing pipes and furnaces, Xcel can only mix in small amounts of hydrogen. In a subdivision in Adams County, Xcel intends to use only a 10% mix, which translates to a mere 3% reduction in greenhouse gas emissions — and even less if we account for the effects of hydrogen leakage. Because green hydrogen is so expensive to produce, Xcel may wind up buying commercial gray hydrogen (which is produced from natural gas), in which case the project will actually increase total carbon dioxide emissions!
Xcel argues that a plan that focuses on electrifying buildings is too expensive. While installing a heat pump currently costs more than installing a gas furnace, the heat pump provides both heating and cooling, and excellent heat pump tax incentives are available. In addition, a study by the New Buildings Institute showed that a new all-electric building saves on construction costs because the cost of the entire gas infrastructure is avoided. And as more homes are electrified, prices will drop.
Building electrification is a key step in addressing climate change, and it provides the added benefit of giving us healthy air to breathe both inside and outside our homes. Don’t be misled by Xcel’s statements about heat pumps and by a Clean Heat Plan that could more accurately be called the “Keep Burning Natural Gas Plan.”
Chuck Kutscher, of Jefferson County, is a mechanical engineer and college instructor who worked as a researcher and center director at NREL before his retirement. He is the lead author of the 3rd edition of the college textbook, Principles of Sustainable Energy Systems.