Hot water heaters have long posed an obstacle to energy efficiency and transitioning homes and commercial buildings off of fossil fuels, which means they've also long been targets for innovation.
Pacific Gas & Electric, California's largest utility, is preparing to roll out its latest attempt at hot water heater innovation. Its WatterSaver program will install at least 5,000 and up to 9,000 electric water heaters over the next few years with technology that will allow for centralized load shifting. The fitted water heaters will feed usage data back to the utility, and the utility will have the ability to shift water heater use to off-peak hours, shedding load and shedding, slowly, the need for dirty peaker power plants.
Studies have shown that heat pump water heaters are perfect candidates for limiting use to off-peak. Heat pump water heaters can act somewhat as batteries—water can be heated during the daytime hours when renewable energy is at its most abundant, and then can remain hot throughout the evening peak hours. According to the Natural Resources Defense Council, the water heaters can still deliver steaming hot showers during the night time when heated during the day, which, practically speaking, might otherwise be the largest obstacle for public adoption. One study from the NRDC showed these water heaters could shift roughly 70 percent of their electricity use into off-peak hours.
PG&E embarking on this project is significant, as it is the largest utility in the U.S.'s most populous state. However, other utilities in the southeastern U.S. are already attempting to tackle the water heater dilemma with similar load-switching technology.
These efforts also reflect the acceleration toward smart grid and smart appliance technology as two of the answers to reducing carbon emissions and creating more energy efficiency. A lot of smart grid and load-shifting technology remains nascent but appears positioned to be the future.
Customer convenience will always remain an axiom determining the likely success of a smart appliance or load shifting technology—throughout the short history of home electricity, paying customers have gotten too used to being able to get what we want it, despite the environmental costs. As long as customers aren't forced to take hot showers at night, it's hard to see why this heat pump water heater technology won't be widely adopted.