Westar, a Kansas utility serving 685,000 customers, installed the first of its planned 90,000 “watt-saver” thermostats last year. When Westar’s central generating plant sends its signal to the watt-saver, it “messages” the customer’s air-conditioning compressor to cycle on about half as many times during a peak-load period, which can be four hours. Instead of running continuously, the compressor will cycle on for 15 minutes and off for 15 minutes. When the compressor is off, the customer’s fan unit, which circulates cooled air in the house, will still be running.
During the first summer of its watts-saver program, Westar found that as long as its customers had air movement, “they didn’t notice any discomfort and only later learned that the cut-back was on,” said symposium presenter and Westar engineer Hal Jensen.
Westar’s watt-saver thermostat program does not operate on holidays and weekends.
Benefits for utilities
From the customers’ perspective, the peak-load control is the most obvious application of the smart grid, but it was not the prime motivation for developing it, said symposium presenter Andres Carvallo, who designed the nation’s first smart grid for Austin Energy.
The smart grid gives utilities control over other crucial aspects of their business. For a utility, the outside meter is like a cash register. The two-way communication allows it to collect billing information quickly, without having to deploy an army of meter readers and contend with biting dogs. The two-way communication allows utilities to pinpoint power outages quickly because the meter can send an “I am dying” signal before it stops. The method of detecting outages still used by most utilities is primitive by comparison. When the power goes out, the utility waits for unhappy customers to call in the news, and then their employees plot pins on a map of their service area. When enough pins are plotted, they know where to send their service trucks.
The smart grid also provides a much easier way for utilities to buy electricity from small producers at the “grid edge,” including homeowners with solar photovoltaic equipment on their roofs or wind turbines, Carvallo said.
A utility could also buy the electricity stored in the batteries of hybrid and electric vehicles, he said. It’s not being done, because of regulatory and business-model issues. No price has been established for “vehicle battery sourced” electricity, he said, and it’s impractical to buy small amounts of electricity from individual car owners. But in the future, as electric vehicles become more common and car-generated kilowatts are assigned a price, utilities could buy power from organizations with fleets of electric-powered vehicles, such as the U.S. Postal Service, Carvallo said.
Katherine Salant has an architecture degree from Harvard. A native Washingtonian, she grew up in Fairfax County and lives in Michigan. If you have questions or would like to suggest topics for coverage, contact her by e-mail or go to katherinesalant.com.