Heat pumps could offer major efficiency benefits compared to traditional fossil-fueled or electric building heating. A new pilot project in Ireland indicates they could also help balance an increasingly renewable-powered grid.
By pulling heat from the air, water or earth, then compressing it and storing it, heat pumps can beat the energy efficiency of traditional home heating and cooling by about 50 percent, according to the Department of Energy. Deployed widely, that could bring about meaningful reductions in carbon emissions.
Though heat pumps currently account for only about 5 percent of global heating demand, per the International Energy Agency, their efficiency has compelled countries such as China, Italy and Norway to encourage their wider deployment with installation subsidies and incentives. In the U.S., replacing gas furnaces with heat pumps would lead to carbon-emission reductions in 46 out of the 48 states studied last year by nonprofit think tank RMI.
“In order to meet our climate goals, we need…efficiency, grid-interactivity and all-electric,” said Stephanie Greene, a senior principal in RMI’s Carbon-Free Buildings program.* “That means heat pumps.”
Ireland’s national government plans to install 600,000 residential and 25,000 commercial heat pumps in the next decade, part of a larger climate roadmap unveiled in 2019.
This switch could yield significant savings for customers as well as emissions reductions, according to newly released study results from ESB, a partly state-owned utility that’s one of the country’s largest energy providers, and GreenCom Networks, an internet-of-things provider with experience linking distributed home devices for energy management across Europe.
From January 2020 to March 2021, the partners monitored a small group of electric Mitsubishi heat pumps installed across Ireland, measuring demand flexibility along with changes in carbon-intensity for heating homes and water. Networking heat pumps and shifting use to times that correlated with high renewable electricity generation offered demand-response capacity to ESB while lowering the amount of energy consumed for heat production in homes.
The two companies also experimented with shifting usage to times when electricity costs are low, which allowed pilot customers to slash heating costs by more than 15 percent (although it should be noted that the installation of a heat pump incurs upfront equipment costs).
The pilot also measured an estimated 8 to 10 percent reduction in carbon emissions. According to GreenCom, it can be challenging to precisely quantify emissions reductions in studies like this that are optimized for both emissions impact and energy prices.
RMI’s Greene, who was not involved in the pilot, said, “In general, having a grid-interactive device is always better from a CO2 emissions standpoint” than traditional devices because they can be used at times of day when electricity production is cleanest. As renewables come to account for a larger portion of electricity production, the emissions impact of shifting load to cleaner times of day is expected to grow.
Shifting usage in this way shouldn't disrupt customer consumption patterns because heat pumps can store hot water for later use.
Using heat pumps to balance the grid is a relatively new concept. In 2019, distributed energy platform EnergyHub and United Illuminating, a Connecticut utility, presented the results of a New England pilot that demonstrated how heat-pump water heaters could provide demand-response capabilities much like traditional electric water heaters.
Also in 2019, the U.S. Pacific Northwest National Laboratory unveiled the results of a study undertaken in partnership with a dozen utilities in the region; it showed that 90 percent of peak electricity load in the evening could be reduced by switching customers from traditional electric water heaters to heat-pump water heaters.
*RMI is a Canary Media sponsor.
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