Much Of The Grid Clean Enough To Electrify Home Heating

In some American cities the electric grid is already clean enough that carbon emissions would drop if homes converted to electric heating, according to a new study by the Rocky Mountain Institute.
The cost of electrification remains an obstacle for many homeowners, RMI concedes, but not all.
"Electrification already reduces carbon emissions with today’s technology and electric grid in all but the most coal-heavy regions," said Sherri Billimoria, an associate with RMI's electricity practice. "Among the cities we looked at, that’s Chicago."
Chicago gets its electricity from ComEd, a distribution subsidiary of Exelon, and 35 percent of the electricity it delivers still derives from coal, 26 percent from natural gas. Most of the remainder comes from nuclear power (35 percent), with only 2 percent from wind and a negligible amount from solar. Because of all that coal, electric heating in a Chicago home remains dirtier than burning natural gas.
The three other cities RMI examined have much cleaner grids—Oakland, Providence, and even oil-friendly Houston. In those cities, homes that convert to electric heating would immediately reduce carbon emissions.
"The Texas grid, like the California grid, is already clean enough to see immediate benefit from electrification," Billimoria said.
RMI chose the four cities based on the diversity of their fuel mix, electric rates, climate and other factors, suggesting the results may reflect a nationwide opportunity to eliminate the 9 percent of carbon emissions that derive from home heating.
"Just as there’s a lot of focus today on switching from gasoline to electric vehicles, there’s a comparable opportunity to switching from fossil fuels in buildings to electricity powered by renewable sources," said Mike Henchen, a manager with RMI's electricity practice.
The authors modeled one year of energy use for space heating, water heating and air conditioning in a single-family home. They did not examine multi-unit or commercial properties. For the single-family home, they determined the annual carbon impact and the 15-year cost of each scenario.
In Oakland, for example, an existing home that converts from natural gas heating with an existing air conditioner to an electric heat pump would drop from 7,500 pounds of carbon emissions annually to less than 5,500.
New homes perform even better because of the increased efficiency of new construction. If built all-electric, new homes in Oakland will emit about 2,500 pounds of CO2 annually on today's grid, compared to 3,500 if they burn natural gas.
"A takeaway we found across the board is that efficiency really does matter, as you would expect," Billimoria said. "The efficient buildings have less than half the emissions of older buildings."
But the cost remains prohibitive in most of the locations studied.
A homeowner in Oakland will spend about $16,100 over 15 years on natural-gas heating with an existing air conditioner, the study says, compared to more than $21,000 if they buy and install an electric heat pump.
"Incumbent natural gas in existing buildings is a challenge to electrify cost-effectively at this point," Billimoria said.
But there are some homes that could benefit from immediate conversion and save both money and carbon emissions. The authors found those homes in Providence, Rhode Island.
For electrification to happen, homeowners need more incentive, the authors conclude, including reduction in the cost of heat pumps and their installation, which is expected to occur as the market grows.
It could also require higher gas prices or carbon pricing in areas that do not currently have it.
Correction: An earlier version of this story mistakenly implied that ComEd's delivery mix is Exelon's generation mix. Exelon divested from its last coal assets in 2017.
Billimoria and Henchen detail their findings: