Underground 'Wind Mines' Could Keep Datacenters Powered 109
Nerval's Lobster writes "Major IT vendors have been including custom-built wind- and solar-power farms in their datacenter construction plans. But while wind and solar power may be clean, they're often unreliable, especially by the standards of datacenters that need a way to keep operating through any unexpected surges or drops in power. How about saving the wind that generates the power? That might work, according to researchers at the federal Bonneville Power Administration (BPA), and U.S. Department of Energy's Pacific Northwest National Laboratory. A study published in February (PDF) outlined the potential benefit of pumping pressurized air into caverns deep underground as a way to store wind energy, then letting it out whenever demand spikes, or the wind drops, and the above-ground facilities need help spinning enough turbines to keep power levels steady. The technique, called Compressed Air Energy Storage (CAES) isn't new: existing CAES plants in Alabama and Huntorf, Germany (built in 1991 and 1978, respectively) store compressed air in underground salt caverns hollowed out by solution mining (pumping salt-saturated water out of concentrations of salt buried far underground and replacing it with fresh water). But implementing such a technique for datacenters might take a little work. The BPA and the Pacific Northwest National Laboratory have already identified, and are evaluating, sites in the Pacific Northwest that would be suitable for CAES underground reservoirs; the first, which could be located in Washington's Columbia Hills could—via existing CAES technology—store enough compressed air to generate a steady 207MW for 40 days of continuous usage, ultimately delivering 400 additional hours without adding any compressed air."
Re:A bit confused. (Score:4, Insightful)
Wouldn't it take a buttload more power to move the air down, and then back up, than it would generate?
I think it presumes excess power during some periods. High winds, excess hydro power, what ever.
They do this at Grand Coulee Dam [wikipedia.org] already by pumping water up-hill to an additional reservoir in periods of excess runoff when they would otherwise have to open the spillways just to get rid of the excess.
Pumping water uphill is probably far more efficient than compressing air.
Re:A bit confused. (Score:4, Insightful)
Wouldn't it take a buttload more power to move the air down, and then back up, than it would generate?
Any flavor of energy storage is going to introduce some sort of conversion losses: battery banks aren't 100% efficient to charge or discharge, flywheels suffer from friction losses, pumped-water hydro suffers from inefficiency in the pumping uphill and the conversion to electricity downhill backup generators suffer from the fact that small heat engines generally get lousy efficiency compared to big ones(and need to be kept supplied with diesel, which doesn't help you 'green' cred).
The advantage to pressurised air is that(in geologically suitable locations) you can build in fairly large amounts of storage without anything obtrusive on the surface, and at comparatively low cost(compared to buying and keeping fresh huge banks of batteries, say).
Re:A bit confused. (Score:4, Insightful)
sure. not to mention the atrocious efficiency of wind power. Just pump water to a reservoir instead and let it out when you need it.
I think that the article is trying to be clever, but missing an important point in doing so. Energy is generated from the compressed air using a more conventional turbine/generator setup... not a wind farm. This system is just an ENORMOUS UPS.