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Voltage-reduction project may stave off blackouts

Posted at 10:09 p.m. PDT Thursday, June 7, 2001

BY PAUL ROGERS, Mercury News

In a move that could significantly reduce the risk of blackouts in California this summer, a group of scientists working with the state's three major utilities has begun testing a plan to conserve large amounts of electricity by slightly reducing the voltage on the power grid. The theory, known as ``conservation voltage regulation,'' is familiar to all motorists: Lift your foot from the accelerator and your car saves fuel.

If successful -- an early small-scale trial was encouraging -- the idea could save California's treasury millions and make the difference between keeping the lights on or off on some hot days. Yet state regulators must overcome fears about potential damage to appliances, and the loss of some profit to utilities, which would sell less electricity.

``It's a big deal. I think it's very promising,'' said Arthur Rosenfeld, a board member of the California Energy Commission and a physicist at Lawrence Berkeley National Laboratory in Berkeley.

Thursday, Rosenfeld held a conference call to plan tests with representatives of Pacific Gas & Electric, Southern California Edison, San Diego Gas & Electric, the governor's office and the Public Utilities Commission. Utility representatives agreed to spend the next two weeks testing their substations to measure the feasibility of the idea, he said.

Under the plan, California's major utilities would reduce the voltage delivered to homes and businesses from the present level of 120 volts, to perhaps 118 volts or 116 volts. Such a slight drop would cause almost no noticeable change on appliances and computers, but could dim some lights, supporters of the idea say.

Meanwhile, it also could save between 400 to 1,000 megawatts of electricity. Put in perspective, that is enough energy for 300,000 to 750,000 homes, or the equivalent of instantly creating one or two new power plants.

``We believe that even if customers have to suffer through some low voltages, it might be better than having the power out,'' with stuck elevators and darkened traffic lights, said Ron Ferree, director of grid operations for Southern California Edison.

Last Friday, Edison tested the idea by turning down the voltage 4 percent, to about 117 volts, at a substation in Riverside County, for 15 minutes. It received no consumer complaints and reduced power demand about 2 percent, he said. Edison can make the change by radio control. PG&E, which did not return calls Thursday, would have to manually adjust hundreds of substations.

Some experts are wary about potential pitfalls. Home appliances, computers and other equipment are normally rated to run best at about 115 volts. If voltage is dropped too low, say below 110 volts, it can damage appliances by overheating motors.

``If you permanently lower the voltage, you are subjecting your motors and compressors and appliances to greater stress and strain,'' said Ken Giles, a press officer for the U.S. Consumer Products Safety Commission. ``That will raise temperatures and can burn out motors.''

The key question: Can utilities turn down the voltage just a bit to prevent blackouts, while not going too far? ``So long as you don't bring anybody's voltage down enough to damage their equipment, it will work,'' said Julian Ajello, supervisor for gas and electric safety at the Public Utilities Commission. ``You should aim not to go below 114 volts, with 110 as rock bottom,'' he said.

In 1978, during a previous energy crisis, Ajello helped write the rule that set the operating range for California's grid at between 114 and 120 volts. Back then, the state saved energy by reducing the top range, which was 126 volts.

The change reduced energy consumption in California 3 to 5 percent, a savings of about 4 million barrels of oil a year, according to trade journals of the time. The latest plan grew out of experiments at PG&E's San Ramon testing center. PG&E scientists were working in April with Bill Wattenburg, a nuclear physicist and former professor of electrical engineering at UC-Berkeley.

Wattenburg, who also hosts a show on KGO radio, was testing an electric switch that could shut off partial power to homes and businesses during Stage 3 alerts. During the tests, the researchers began turning down the voltage to appliances, televisions, computers, pool pumps, microwave ovens and other equipment.

`We took them down from 120 volts,'' Wattenburg said, ``all the way to 90 volts before things shut down harmlessly. I was flabbergasted.'' Wattenburg said he realized that small changes in voltage, perhaps down to 117 or 115 volts, could result in big power savings statewide. ``Here's a way to give the governor the equivalent of a new power plant or two,'' he said. ``That way he could play poker better with these power suppliers.''

Wattenburg noted that engineers design appliances to run on a range of voltages so they can handle fluctuations in power from urban to rural areas, or in other countries, or in homes with spotty wiring. A generation ago, most U.S. power was delivered to homes at 110 or 115 volts, he said.

Experts from around the country had varying degrees of support for the idea.``You can do it. It's possible, but there is a difficult balancing act,'' said Ken Hall, manager of distribution issues at the Edision Electric Institute in Washington, D.C.

Electricity is moved throughout the state on a 32,000-mile network of transmission lines carrying current at up to 500,000 volts. It is ``stepped down'' in a series of substations and transformers for use in homes. In outlying areas, voltage can wane, so city residents might receive 120 volts while a rural area could get 115. Some fear that if the city level were cut too low, the corresponding drop might cause rural ``brownouts.''

``It is a good idea, certainly worth considering,'' said T.C. Cheng, professor of electrical engineering at the University of Southern California. ``But we have to raise it up to 120 afterward, because of the reliability of the system. But on a short-term basis, it's better than a blackout.''

Contact Paul Rogers at progers@sjmercury.com or (408) 920-5045.

-- Swissrose (cellier3@mindspring.com), June 08, 2001

Answers

<< In outlying areas, voltage can wane, so city residents might receive 120 volts while a rural area could get 115. Some fear that if the city level were cut too low, the corresponding drop might cause rural ``brownouts.'' >>

Yes, this is a problem. I have experienced this on my own home grid circuit, which as I've mentioned before is the literal "end of the line" in a rural area, with just a few residences atop a mountain. For example, some lights do dim: I have noticed that some fluorescent lights/ballasts are more sensitive than others to low grid voltage. I have also noticed that my whole house noticeably "browns out" for a few long seconds when the grid voltage is running a little low and then something big starts up too (my 700-foot-deep well pump, for example, or one of the woodworking tools in the basement-- AC motors with large surge demands at startup).

The radio talk show/engineer implies this effect is harmless. I have also heard repeatedly the claim from the CPSC spokesman, however, that lower voltage can cause problems to motors if it occurs over a long period of time. Who is correct??? And if this interesting power- saving measure is instituted *deliberately*, will it be occasional and temporary, or will it become "business as usual"? (and to us few rural consumers: "tough luck"?)

I highlight the word "deliberately" because around Rollover, some of us monitored the grid voltage at our homes and discussed the fact that it seemed to be wandering quite a bit. This is easy to measure, but be careful. You take a digital multimeter, set it per its instructions to measure appropriate AC voltage range, and stick the two probes into a regular wall socket. Exactly what you tell toddlers not to do. Be careful; put one hand behind your back, then insert one probe into one slot and then the other into the other slot with one hand only (so you don't somehow send 120 volts AC across your chest). And don't stand in a puddle, hold onto a grounded wire with your free hand, etc etc.

YMMV.

-- Andre Weltman (aweltman@state.pa.us), June 08, 2001.