Load-shifting potential of warmth pump water heaters studied

A Pacific Northwest National Laboratory (PNNL) analysis crew has gained new insights about warmth pump water heaters (HPWHs), an energy-efficient know-how that extends the advantages of warmth pumps to the duty of warming home water.

In a three-year mission launched in 2017, the crew studied the operation of HPWHs in Pacific Northwest houses and explored the water heaters’ load-shifting potential—or the power to regulate operation to assist scale back electrical load on the ability grid. Researchers monitored a whole lot of water heaters, together with standard models that helped set up a baseline for the research.

One of the mission’s key aims was to look at the vitality use of the HPWHs over time and set up “electrical load shapes” that mirror the peaks, valleys, and patterns of day by day electrical energy use. Such information spotlights potential impacts to the ability grid, enhances electrical energy load forecasting, and informs nationwide efforts to decarbonize and create an environment friendly future vitality system.

The arrival of COVID-19 within the United States added a brand new wrinkle to the analysis effort.

“In March 2020, toward the end of our study, Oregon issued a COVID-19 stay-at-home order and that allowed us to explore water heater profiles when people spent increasing amounts of time at home,” says Walter Hunt, a senior analysis engineer within the PNNL Energy and Environment Directorate’s Electricity Infrastructure and Buildings Division.

HPWHs: Why a lot curiosity?

These superior water heaters supply massive effectivity beneficial properties over conventional electrical water heaters.

HPWHs are related in look to the usual scorching water heaters discovered in lots of U.S. houses, however function in another way. Rather than using electrical resistance heating parts that straight heat the water within the tank, HPWHs, very like warmth pumps used for space heating and cooling, extract warmth from the encircling air and switch it into the built-in storage tank holding a house’s home scorching water.

This method makes HPWHs considerably extra vitality environment friendly than conventional models. Considering that water heating accounts for about one-seventh of the electrical energy use in a house, improved effectivity interprets to important vitality and price financial savings, in addition to potential environmental advantages.

Researchers at PNNL are attempting to realize a greater understanding of how these water heaters—and ensuing load shapes—will have an effect on the vitality system.

The mission and its load-shape outcomes

The collaborative research included the Bonneville Power Administration (BPA) and Portland General Electric (PGE) and was funded by the U.S. Department of Energy’s Building Technologies Office. BPA and PGE recognized households throughout the Pacific Northwest geared up with appropriate HPWHs and offered utility views and analysis assist all through the research.

Researchers performed a website survey with the owners, figuring out the total variety of occupants, the times and occasions when occupants usually had been at residence, and the particular location and producer of every water heater. This data was essential to determine broader understanding of electrical energy consumption as a result of it allowed researchers to later develop particular person load shapes for every of the traits, in addition to a mixed baseline load form.

The outcomes of the load-shape evaluation offered perception into how website traits affected water heater load shapes and total electrical energy use. The variety of individuals occupying a house, in addition to the occasions they had been usually residence or away, proved to be important components within the load form. Occupant counts and seasonal impacts of air and water temperature had been the important thing drivers for total vitality utilization.

After Oregon’s COVID-19 stay-at-home order was issued, almost 50 houses within the state continued to take part within the research for a number of weeks. Under the stay-at-home state of affairs, researchers discovered that vitality consumption was extra constant over the course of a day, which provides a way of how a “work from home” posture would possibly have an effect on electrical energy use and energy grid operation.

“As end-use behavior evolves and as water heating technology advances, researchers need to re-examine the load shapes of water heaters to understand the impact on the energy system and how water heaters may be used as a grid resource,” Hunt says.

Hunt and his colleagues printed their findings, “Factors Influencing Electrical Load Shape of Heat Pump Water Heaters,” within the ASHRAE Journal.