February 28, 2012

Technology Review

Battery to Take On Diesel and Natural Gas

Aquion Energy says its batteries could make the power grid unnecessary in some countries.

Aquion Energy, a company that's making low-cost batteries for large-scale electricity storage, has selected a site for its first factory and says it's lined up the financing it needs to build it.

The company hopes its novel battery technology could allow some of the world's 1.4 billion people without electricity to get power without having to hook up to the grid.

The site for Aquion's factory is a sprawling former Sony television factory near Pittsburgh. The initial production capacity will be "hundreds" of megawatt-hours of batteries per year—the company doesn't want to be specific yet. It also isn't saying how much funding it's raised or where the money comes from, except to mention that some of it comes from the state of Pennsylvania and none from the federal government.

The first applications are expected to be in countries like India, where hundreds of millions of people in communities outside major cities don't have a connection to the electrical grid or any other reliable source of electricity. Most of these communities use diesel generators for power, but high prices for oil and low prices for solar panels are making it cheaper to install solar in some cases.

To store power generated during the day for use at night, these communities need battery systems that can handle anything from tens of kilowatt-hours to a few megawatt-hours, says Scott Pearson, Aquion's CEO. Such a system could make long-distance transmission lines unnecessary, in much the same way that cell-phone towers have allowed such communities access to cellular service before they had land lines.

Eventually Aquion plans to sell stacks of batteries in countries that have electrical grids. They could provide power during times of peak demand and make up for fluctuations in power that big wind farms and solar power plants contribute to the grid. Those applications require tens to hundreds of gigawatt-hours' worth of storage, so to supply them, Aquion needs to increase its manufacturing capacity. Competing with natural-gas power plants—especially in the United States, where natural gas is so cheap—will mean waiting until economies of scale bring costs down.

The company has said that it initially hopes to make batteries for under $300 per kilowatt-hour, far cheaper than conventional lithium-ion batteries. Lead-acid batteries can be cheaper than Aquion's, but they last only two or three years. Aquion's batteries, which can be recharged 5,000 times, could last for over a decade in situations in which they're charged once a day (the company has tested the batteries for a couple of years so far).

Jay Whitacre, a Carnegie Mellon University professor of materials science and engineering who developed Aquion's technology and founded the company, says the cost will need to drop to less than $200 per kilowatt-hour for grid-connected applications. Reaching this price, and production capacity on the scale of gigawatt-hours, "will take a long time," he says. "But you have to start somewhere."

Whitacre developed the batteries with low cost and durability in mind from the start. In searching for potential electrode materials, he limited himself to cheap, abundant elements, settling on sodium and manganese. He also picked a water-based electrolyte that's safer and cheaper than the organic ones used in lithium-ion batteries. In turn, this allowed him to use cheap manufacturing equipment to make them. To keep costs down, the company is making the batteries with equipment that's normally used to make food or aspirin. Construction on the factory in Pennsylvania will begin immediately, and the first stage is expected to be finished next year.

"Some papers proposing new battery materials look great until you read the fine print about how they're made," Whitacre says. "We focused on manufacturing from the beginning."