In “Dumping Natural Gas: Not as Simple as it Seems,” (CDN, April 27) Abe Jacobson writes that we should hesitate before replacing gas furnaces with heat pumps to heat our homes and buildings. On cold days, he says, heat pumps emit more greenhouse gases than efficient gas furnaces, because fossil fuels still generate 80% of the electricity on the Western Grid. Since the Climate Action Plans recently approved by both Bellingham and Whatcom County vigorously promote electrifying our buildings, we need to examine Dr. Jacobson’s claims more carefully. In fact, his arguments are misleading.
Heat pumps use less energy, even on cold days
While it is true that air-source heat pumps are less efficient at cold temperatures, modern heat pumps are still far more efficient than the “wasteful electric baseboard heaters” that Dr. Jacobson compares them to. Even at below-zero temperatures, heat pumps can be twice as efficient as resistive heating. And at temperatures more typical of our heating season in western Washington, air-source heat pumps can be 400% efficient, or 4 times better than resistance heaters.
Western Washington does connect with the larger Western Grid. However, within that grid, individual areas are largely responsible for balancing their supply and demand. Moreover, state mandates govern the minimum percentage of renewables in the electricity mix. Thus, less than 40% of the electricity in the Northwest Power Pool (which includes Washington, Oregon, Idaho, Montana, Utah and Nevada), comes from fossil sources — far less than Dr. Jacobson’s 80% claim. According to the EPA, the average emission rate in the grid is 600 lbs of CO2 emitted per MWh of electricity produced. That is about as clean as if all of the electricity came from natural gas power plants running at 66% efficiency.
Now, we can either burn natural gas directly or use the gas (and other fuels, including renewables) to generate electricity to drive a heat pump. Because a heat pump extracts heat from its surroundings, like a refrigerator working in reverse, it can be 200% efficient (on a cold day) or 400% efficient (on average) in converting electricity into heat. So it will be as efficient as a furnace that is 132% efficient on a cold day or 264% efficient on average. Since the best gas furnaces are about 95% efficient, the heat pump wins. Even with fossil fuels producing 40% of our regional electricity, the heat pump emits less greenhouse gases.
We need not wait “until the entire Western grid is substantially carbon-free” to reduce emissions by electrifying heating, as Dr. Jacobson claims. Choosing a heat pump today will reduce your emissions immediately and even more so in the future as renewables replace fossil fuels to generate electricity. But choosing a natural gas furnace locks you into higher emissions for the next 15-20 years. For this reason we also need to make heat pumps more affordable for those who can’t afford an expensive initial investment.
People naturally worry about electric heating during power outages. But during an outage, gas furnaces will not work either, since they move air with electric fans. If you have not worried about power outages with your gas furnace, you need not worry with a heat pump either. But if you live where outages are common, many backup options exist.
Moreover, during those summer heat spikes that may come more often with climate change, rather than buy and install an air conditioner, you can simply run your heat pump in reverse.
Personal experience proves the point
To show how heat pumps compare to gas furnaces, we can compare both energy usage and energy bills for one of our houses in November through March 2020-21, when we heated with gas, against the same season in 2021-22, after we changed out the gas furnace for a heat pump. Even though December 2021 through January 2022 was one of the coldest times in Bellingham’s history, and the heat pump had to rely partly on backup resistance heating, we still used only 60 percent as much energy over the season as in the previous winter. Also, our combined electric and gas bills were about 10% less with the heat pump. And we saved over a ton of greenhouse gas emissions.
As we all unite to fight climate change and its disastrous effects, we must realize that natural gas is the fuel of the past, while renewable electricity is the fuel of the future. One important way we can make the future real is to electrify our homes and other buildings. Replacing gas furnaces with efficient electric heat pumps makes sense right now, when fossil fuels still generate much of our electricity, and will make even more sense when renewables replace fossil fuels.
Imran Sheikh (PhD, Energy and Resources) is an Assistant Professor in the Institute for Energy Studies and Department of Environmental Sciences at Western Washington University.
Stevan Harrell is a retired professor of environmental and forest sciences and of anthropology at the University of Washington. He lives in Bellingham.
Ray Kamada (Ph.D. in Atmospheric Sciences), is a retired Department of Defense and RISOE National Labs consultant and former director of the Environmental Physics Group, Monterey Naval Postgraduate School.
Drs. Sheikh, Harrell and Kamada all serve on the Whatcom County Climate Impact Advisory Committee. The views expressed here are their own.
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