Electric water heaters could be a gold mine of grid flexibility -- with the right tools to control them. Think of thousands of household power loads that utilities could cycle on and off across neighborhoods or regions, to help smooth peak power demands, or to absorb the ups and downs of wind farms, solar panels and other intermittent sources of power.
All of this presumes, however, that there’s a cost-effective way to hook up all of those water heaters. This week, power and building control systems giant Emerson announced that it’s piloting just such a device, one of the first meant to solve the cost-effectiveness problem on a broad scale.
Emerson is testing its Electric Water Heater Control devices with Georgia electric cooperative utility Habersham EMC, in conjunction with a smart thermostat and home energy management pilot. In the next three to six months, Emerson intends to offer the controller for sale to utilities, demand response aggregators and hot-water-heater makers and installers, many of who are already Emerson partners, Geoff Godwin, vice president of marketing for Emerson subsidiary White-Rodgers, said Thursday.
The new heater controller is also built to conform to the CEA-2045 standard, developed by the Consumer Electronics Association and the Electric Power Research Institute (EPRI) to ease this kind of utility-to-appliance connectivity, Godwin said. That makes it among the first publicly announced set of products to meet the new standard, although EPRI project leader Brian Seal told us in February that several other unnamed utilities are trying out similar products.
Emerson was awarded a $1.6 million Department of Energy smart grid stimulus grant in 2010 to develop the technology, and the Habersham deployment is the first real-world test of its capabilities. First off, Emerson wants to make sure the remote-control switches actually work, he said. Second, it wants to prove the devices can be installed much more quickly, simply and cheaply than today’s utility-controlled water heater devices, he said.
Today’s installations typically involve bringing in an electrician to install a load control switch that’s operated by a one-way paging or radio network, he said. They’re not designed for water heaters specifically, and they require about an hour to install, at a cost that can reach several hundreds of dollars in equipment and labor, he said. That’s limited their appeal to a handful of demand response projects from the likes of Comverge, an Emerson partner, and Cooper Power Systems (now part of Eaton), he said.
Emerson’s device, on the other hand, takes minutes to install at the residential circuit breaker, a task that doesn’t require an electrician, and “that’s the big cost saver for the utilities and the installing companies,” he said. From there, the controlling utility can set it to turn off and on -- or stay off when it might want to turn on -- via schedules or commands, price signals or homeowner preferences, he said.
Electricity runs about half of the 150 million or so household water heaters in the United States, and in parts of the country (and the world), the percentage is much higher, he noted. In the United States, those include northern rural areas like Minnesota and New England, as well as regions where electric water heaters were installed as part of a broader electrification policy, such as in the territory served by the federal Tennessee Valley Authority, he said.
But even in warm climates, homeowners still dedicate roughly 15 percent of household energy use to water heating on average, he said. That’s a power load that can be tapped in virtually any home.
It may also be an easier household load to turn down than air conditioners, he noted. Because utilities can cycle their load-control signals from home to home and neighborhood to neighborhood over time, he said. Utilities use similar cycling techniques for air conditioning-based demand response, of course, but homeowners tend to be much more aware of their AC turning off, while turning off the water heater for ten to fifteen minutes at a time “is not really noticeable to the homeowner,” he said.
More advanced features are possible beyond simply shutting water heaters off to mitigate peak power demands, he noted. “There’s a lot of talk about using water heater tanks as thermalstorage” to essentially preheat water to higher temperatures when power is cheap to allow the switches to turn off for longer periods of time during high-power-price periods, he said. Future versions of the device could include learning algorithms to figure out how individual households tend to use hot water and adjust accordingly, he added.
Networked water heaters can also be turned on and off at faster intervals, which can offer an additional set of grid functionality. Projects in the U.S., Europe, Canada and Japan are exploring ways to use water heaters to absorb excess wind power, for example -- a task that requires a more fine-tuned, fast-reacting level of control than most of today’s residential demand response technologies offer.
Godwin said that Emerson is talking to other utilities interested in the capabilities of water heaters as grid resources, including big U.S. utility Duke Energy, Godwin said. In the meantime, keep an eye out for more companies launching products built to industry standards like CEA-2045, aimed at allowing more workhorse home appliances like water heaters to join the smart-grid-enabled future.