American Electric Power, a coal-burning utility company that is looking for ways to connect more wind power to its grid, plans to announce on Tuesday that it will install huge banks of high-technology batteries.
The batteries are costly and their use at such a big scale has not been demonstrated, but they may be an essential complement to renewable power, experts say.
“We’re looking at what we believe the grid of the future is going to be,” said Carl L. English, president of A.E.P. “We’re going to need a significant amount of storage if for no other reason than to take greatest advantage of alternative energy sources like wind power.”
The investment would position the company well if any of the 11 states in its service territory establish a minimum quota for renewable energy, or if Congress sets a national standard, company executives said; it would also help if carbon controls were instituted and wind power were to gain a financial advantage over coal.
An expert not involved in the program, Edgar DeMeo of Renewable Energy Consulting Services, said, “They must think there’s enough potential there so they want get a better handle on how it works.” But Mr. DeMeo and others said that wind energy had substantial room to grow before storage became necessary.
American Electric Power’s batteries will be used to smooth the power delivery from wind turbines. They can charge at night, when the wind is strong but prices are low, and give the electricity back the next afternoon, when there is hardly any wind but power prices are many times higher, company officials said. That strategy would reduce the amount of power generated from inefficient peak-demand units.
The batteries can also insert energy into the grid during brief voltage drops, reducing the chance of a blackout and stabilizing the grid for all users. They may also delay or eliminate the need for transmission upgrades in some areas, the company said.
At least at this stage, saving money by storing a windmill’s production for peak-price hours will be difficult. The cost is very high, $27 million for six megawatts of capacity, or about $4,500 a kilowatt, including the price of substation improvements. Building a gas turbine of that size to meet peak needs would cost substantially less. But the battery system would be able to store power made from wind, a form of generation that does not produce any carbon dioxide.
The batteries can each deliver one megawatt of power – enough to run a medium-size shopping center – for a little more than seven hours. Replenished nightly, they give back about 80 percent of the electricity put into them. Each is the size of a double-decker bus, and installation is not permanent; they can be moved to another site as the need arises.
The batteries will be built by NGK Insulators Ltd. of Japan. They use a sodium sulfur chemistry and operate at temperatures of more than 800 degrees Fahrenheit.
And while the batteries are large by the standards of previous installations, they are small relative to wind production; one battery would hold about as much energy as a single large wind machine could produce in a day, Mr. DeMeo pointed out. And they are small relative to total energy demand.
But, he said, “If we ever really do get cheap storage, and that’s a possibility, that’s a game changer.”
A.E.P. intends to have 1,000 megawatts of energy storage on its system in the next decade, according to the company, and at least 25 megawatts from batteries of this type.
A range of options is available for the remainder of the storage, including the use of plug-in hybrid cars, Mr. English said. The idea behind plug-in hybrids is that the owner of a car would charge the batteries every night when demand and cost of electricity were low. The next day, under a contract between the utility company and the driver, the car would be left plugged when not in use, and the power company could reverse the flow of electricity and draw power out of its batteries during times of peak demand. Enough power would be left in the batteries to start the engine, so that a driver returning to a drained car could still run it on gasoline until the batteries could be charged again at night. It would take more than 1,000 such vehicles to equal one of the sodium-sulfur batteries, however.
By Matthew L. Wald
11 September 2007
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