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Remote Switch Plan For Air Conditioners

On-off cycles could save grid in summer

Carolyn Said, Chronicle Staff Writer Tuesday, February 27, 2001 2001 San Francisco Chronicle


It's the dog days of summer. The temperature is 110 in Concord, and California's power grid is ready to blow if one more kilowatt from one more air conditioner is added to the load.

Just as the power lines are about to melt, a technician at Pacific Gas & Electric flips a switch, temporarily shutting down thousands of air conditioners scattered throughout Northern California.

Blackouts are averted. Power flows normally. The grid is saved for one more day.

Sounds like science fiction, but energy regulators are considering just such a program for PG&E customers. Under a program called "air conditioner cycling," residential customers would volunteer to have their air conditioners equipped with a switch that is radio-controlled by the utility.

On a scorching day, when everyone cranks up the cooling, PG&E could selectively turn off groups of air conditioners for various times, such as 30 minutes out of every hour. That way the power drain would never get big enough to short out the beleaguered electricity grid. Customers in the program would get paid a modest stipend, ranging from $50 to $150 a year, depending on how often they agreed to be interrupted.

"That little step is almost worth a nuclear power plant (equivalent amount of energy) in PG&E's territory," said David Roe, a senior attorney with Environmental Defense in Oakland. "If you can guarantee that air conditioners will only get to 90 percent or less of their potential, you've done yourself an enormous electricity favor."

Curtailing electricity consumption this summer is going to be crucial.

If temperatures soar, California is expected to fall 5,000 megawatts short of the power it needs, leaving up to 5 million homes subject to rolling blackouts. (A megawatt is enough energy to power 1,000 homes.) To stave off problems, Gov. Gray Davis wants the state to cut electricity use by 10 percent,

which will require a wide range of conservation efforts. Air conditioning, which accounts for about 30 percent of the 52,000 megawatts consumed in California on hot days, is a prime target for reduction.

The idea of air conditioner cycling isn't new: Southern California Edison, Sacramento Municipal Utility District and the Modesto Irrigation District have had similar programs in place for years, as have utilities in the Southeast and East Coast.

Edison, for example, with 128,000 customers signed up, saved 193 megawatts during peak times last summer. Edison says it could add 56,000 customers, at an installation cost of $8.4 million, to get an additional 84 megawatts off the grid.

But Edison's costs of $150 per customer ($65 for the device and $85 to install it) are cheaper than PG&E's would be, because Edison already has an infrastructure in place.

Although consumer advocates and energy regulators back air conditioner cycling, PG&E says the plan would be too expensive and cumbersome to implement by this summer.

Although it does not have figures on cycling, PG&E says installing smart thermostats controlled by a satellite link -- a somewhat more expensive proposal -- would cost $29 million for 100,000 homes, yielding about a 200 megawatts savings.

While that sounds like a whopping sum, at $145,000 a megawatt it's a bargain compared with building a power plant. The 500-megawatt power plants coming online this summer cost about $300 million each to build, or $600,000 a megawatt.

But more important, PG&E says, is designing a program that would appeal to consumers enough to win their participation. "We should be out asking customers what they want before we say, 'This is the program for you,' " said Del Evans, principal project manager for load management programs at PG&E.

Programs that would allow customers to have their thermostat set back by a couple of degrees are more likely to find converts, he said.

And even if cycling is implemented, both PG&E and consumer advocates say it could be tweaked to be more appealing. Giving customers an override option so they could turn the air conditioning back on if they're home sick on a hot day,

and cycling air conditioners off for only 10 minutes out of every hour, might be more palatable than an all-or-nothing approach. Increasing the stipend for participation is another option.

"This program is much cheaper than building any kind of power plant," said Marcel Hawiger, an attorney with consumer advocate TURN, The Utility Reform Network. "The program would be more effective if the utilities gave greater incentives and operated the program so it's more customer-friendly."

The Public Utilities Commission has recommended that PG&E and San Diego Gas & Electric implement the program and that Edison expand its existing program. Next, an administrative law judge will issue a preliminary ruling on March 9, and the full commission will decide on March 27.

If PG&E is required to implement the program, it would focus on areas with high concentrations of residential air conditioners. That would leave out most of the Bay Area, with the exception of Contra Costa County and parts of Alameda County. The San Joaquin Valley and Central Valley, with booming populations and triple-digit thermometer readings, would be prime targets.

E-mail Carolyn Said at

-- Martin Thompson (, February 27, 2001

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