This fall, about 150 households scattered around the Pacific Northwest will take part in a study to test whether specially wired appliances can help trim demand for electricity when the power grid is overtaxed.

The grid now has an extra 5 percent capacity built into it in case of a sudden drop in power supply, said Robert Pratt of the Pacific Northwest National Laboratory (PNNL). By monitoring the AC current’s frequency as it comes through the wires, PNNL’s test aims to tell when the power system is getting overworked.

Power plants generate electricity at 60 cycles per second, and all of the power plants in the western U.S. are in perfect synchronization. Pratt likens it to the engines in every car on the road running at exactly the same speed and all their pistons hitting top-dead-center at the same moment.

“When the power grid gets in trouble and doesn't have enough supply, the frequency starts to drop right away,” Pratt said. “A power plant dropping off-line is like your car not having enough power – the whole system slows down. What gives first is not the current, it’s the frequency.”

By tracking frequency and shutting down energy-intensive components when the grid is in trouble, “grid-friendly” appliances can conceivably lessen the demand on the power grid for a few minutes while the system rights itself.

“What you get with refrigerators and hot water heaters and dryers that can sense what is going on with the grid and can cycle down in response to grid conditions is all kinds of new capabilities to shave peaks and to respond to emergency conditions – also to provide reserve capacity,” said Patrick Mazza, consultant with Climate Solutions, a Seattle-based nonprofit.

“It's kind of a trendy thing in power right now - to make load a resource so you don't always respond to the needs of the grid with more power generation,” Mazza continued. “You use all these new capacities of communications, control, pervasive digital technology to control load. If you'd had a fleet of smart appliances in California and on the West Coast in 2000 and 2001, the owners of the reserve power system wouldn't have been able to hold up the power system for the huge megawatt rates because they would have had a competitor, in terms of the load response or demand response.”

Pratt said the test prepared for fall has two main objectives. The first is to prove to that at least some appliances can be shut down for brief periods for the benefit of the power grid - without the consumer knowing that it happened. “Number two,” said Pratt, “is that the technology really will work as advertised and that we don’t get false trips or trips that shouldn’t be happening for one reason or another. We want to make sure that our sensors and our algorithms don’t get fooled by something that we don’t know about at this point in time.”

He said PNNL has been running experiments in the lab for the past couple of years, but proving efficacy in the real world requires a demonstration involving dozens of households in different geographic areas.

“You need to be in a bunch of homes in a bunch of different places to make sure that all these things fire off at the same time,” he explained.

The initial demonstration will focus on two appliances: clothes dryers and water heaters. PNNL hopes to eventually expand the program to refrigerators, washers, air conditioners and space heaters.

Researchers have begun retrofitting water heaters with sensors and shut-off mechanisms. By September or October, Whirlpool (NYSE: WHR) plans to supply specially made dryers for test households to use during the year-long demonstration.

“Water heaters are easy,” Pratt said. “It’s like cheating. It’s so easy because nobody really notices the water heater if it turns off for a couple of minutes. Other appliances like fridges and washers and dryers and dishwashers and things of that sort - that’s tricky. There we have to work with manufacturers to turn off the high consumption parts of the appliance but leave the rest of the appliance functional. In the dryer we leave everything on except the heating element.”

Gale Horst, a lead engineer with the Whirlpool Advanced Concepts and Technology Center, said getting something as seemingly simple as a clothes dryer to function in a grid-friendly way without trouble for consumers is complicated. Turning off the heating element for a few minutes can mean clothes don’t get dry if the timer isn’t adjusted too.

“To be able to … appropriately extend the process to get the same amount of dryness that the customer selected on the control panel” requires that the dryer have an algorithm to add drying time automatically, Horst said.

Where the dryer is in its cycle also needs to be taken into account. “If it’s just starting to warm up or if it’s in a cool-down cycle, the effect is quite a bit different,” he said.

The ultimate goal is for the whole process to be invisible to the person using the appliance.

If the trial is successful and the new technology is adopted nationwide, Pratt said utilities could avoid building new power plants to make up the 5 percent buffer.