When we think of energy, we think of generation: massive power plants that burn coal. But that’s only half the equation. The other is storage. And the more energy storage we build, the fewer power plants we need (and the more renewables we can add to the grid). That’s because many of our power plants sit idle except during periods of peak demand. This is incredibly inefficient and expensive--but then grid-scale energy storage has been too, until recently.
As costs have fallen, companies have built batteries that hook up to the grid. The utility AES just flipped the switch on the country’s largest hybrid energy systems. Its Laurel Mountain project in West Virginia combines a 98-MW wind farm, enough to power 20,000 homes for a year, with 1.3 million lithium-ion batteries capable of storing 32 MW. "It’s not a demonstration, it’s not a science project…it’s a commercial project with energy storage serving the largest energy grid in the world," says John Zahurancik, vice president of deployment and operations at AES Energy Storage. "You start looking at resources like this, so you don’t need to build as many plants, then at some point you ultimately get to the point when you are looking at the power stack of the future. You have most efficient baseload and renewable units in there, and you have something like [battery] storage providing flexible capacity."
AES is relying on advanced Li-ion batteries similar to technology you might find in laptops or hybrid vehicles. Energy is stored in huge battery banks during off-peak hours, and returned in short bursts for frequency regulation and ancillary energy services (The batteries are not yet big enough to supply long-term power needs). Utilities have done something similar for years, in effect, by using water towers that pump up water at night, then generate electricity by turning small turbines with falling water during the day.
And now, as more efficient technologies take the stage, ambitions to solving energy problems with storage rather than more capacity are growing. AES, now on its third grid battery project (the first two were in Chile and New York), is proposing a 400 MW project to the Long Island Power Authority and is prospecting in places such as Texas and New England, where the economics are right: Electricity is expensive or other grid limitations make quick, clean energy attractive.
Ultimately, one of energy storage’s greatest benefits will be cleaning up dirty grids by making inefficient or expensive plants obsolete, and making renewable-dominated grids even cleaner by storing up juice when natural sources of energy aren’t flowing, shining, or gusting.