Even if we weren't going to be increasingly reliant on renewable power, which is prone to fluctuations, it would make a lot of sense to add energy storage to the electric grid. That was the message provided by Imre Gyuk, who heads the US Department of Energy's program for energy storage. On-grid storage is frequently pitched as a way to smooth over the swings in renewable power that accompany changing weather, like a drop in sunlight or increase in the wind. But Gyuk used his talk at last week's EmTech meeting to argue that grid storage provides a basic level of reliability to the grid that would be valuable under any circumstances; enabling renewable energy's just a bonus.

Gyuk started his talk by pointing out that the US, which only has storage capacity for a bit more than two percent of its generating capacity, badly lags Europe and Japan, where the figures are 10 percent and 15 percent respectively. It's no surprise, he said, that the systems overseas are far more stable than the one in the states, as a few missing cycles can blow the whole system.

Most of the power outages we face in the US don't actually last very long, meaning that most of us don't face any consequences that are more severe than having to reset a few clocks. Even a brief outage, however, can wreak havoc with an industrial process, where various things may sit still long enough to do things like solidify in the equipment. Gyuk said that, although the majority of outages last less than five minutes, the hours of downtime afterwards are estimated to cost the industry a total of nearly $80 billion dollars annually. Spending a small fraction of that on adding grid storage could radically reduce those expenses.

Gyuk used Texas, which has invested heavily in developing its wind capacity, as an example of why, if energy storage is good under normal circumstances, it's essential to enable greater reliance on renewable power. According to Gyuk, in 2008, a sudden plunge in wind caused the state to suffer a 1400MW drop in power in a mere 10 minutes; only fast action by the utilities' industrial customers, who cut their own usage quickly, bailed them out.

Events like that tend to drive up prices dramatically, but the converse also takes place when the turbines spin up. In a single month, Texas has apparently experienced 533 instances where the grid price for electricity was negative for short periods of time. Adding storage to the mix would not only smooth over the power disruptions, but it should significantly limit the price fluctuations, as well.

If on-grid storage is such a useful thing, why don't we have more of it? According to Gyuk, the US has deployed it only where it's absolutely needed or very convenient. In terms of convenience, we've primarily invested into pumped hydro storage, where water is pushed up to a reservoir when electricity is abundant, and used to drive turbines when more power is needed. There is room to increase our capacity for pumped hydro, but land and water use issues are likely to make that a challenge. Gyuk pointed to Fairbanks, Alaska, as a case where the potential for disruptions in the electricity supply, which comes in from Anchorage, has created an absolute need for backup. Earlier in the decade, a 40MW battery facility was installed there.

Thanks to the stimulus money, however, the DOE is planning on a wide variety of grid-level storage projects. Right now, for example, the US operates only a single compressed air storage facility; Gyuk now has enough money to ensure two more are built. He's also working with Beacon Power, which makes flywheels that help modulate spikes and dips in the energy supply, to get Megawatt-scale facilities online. A number of utilities are also planning on installing 2MW batteries (using sodium-sulfur technology) at substations in their distribution system.

So, the status of on-grid store is likely to be significantly different in just a few years, and Gyuk said it has the potential to be disruptive technology. But it was an audience member who may have best explained why. We tend to view renewable energy sources as intermittent and fossil fuels as constant supplies of power. But there's nothing that's inherently constant about fossil fuels—they only seem that way because we've built elaborate transport and storage systems that make them function as if they're constant. Grid scale storage has the potential to provide the equivalent infrastructure for renewable energy.