Another ARPA-E Winner: General Compression’s Renewable Energy Storage Ramps Up in 30 Seconds

March 6th, 2011 by Susan Kraemer



[Updated correction: Per GC, this can ramp-up in under 6 seconds!]

One of the success stories at the recent Department of Energy ARPA-E summit held to highlight innovators funded under the $400 million to find renewable energy innovations in the Recovery Act, is General Compression (GC). The start-up is developing an innovative compressed air energy storage system that will help get more renewable energy on the grid.

Just in time, too. At the end of last year, California made storage mandatory. And last week, FERC just proposed that fast storage be paid better than slower storage, because we will need it more.

And this start-up makes fast storage: it can unload in as little as 6 seconds! (It sure pays to have a Nobel Prizewinner running the DOE! Remember when an oil man ran it?)

Energy storage is becoming more critical because it helps utilities quickly ramp up or down grid supplies to balance more renewable power. (FERC Wants Smaller, Faster, Distributed Storage to Speed Renewables)

General Compression is developing a variation on compressed air energy storage (CAES). Once the air is compressed, it is pumped underground for storage, and then when needed, can be expanded again to make electricity.

Like traditional CAES, their system stores the compressed air in salt caverns (constructed in geologic salt formations), saline aquifers, or depleted gas fields. Unlike conventional gas-turbine based CAES systems, the General Compression system can be started or stopped at a moment’s notice.

The GCAES system can switch from idle to operation in under 6 seconds, and during operation has a control response time of less than 1 second, including reversal between compression and expansion.

Each of the units is 2 MW each, and power plants can use any number of these independent units to achieve a preferred power level. Because they are completely independent they can be deployed to achieve absolute power levels, or to achieve preferred levels of redundancy, or for maintenance scheduling convenience.

The hours of energy storage a power plant achieves (measured in MW-hours), is entirely a combined function of the plant’s power capacity (measured in MW) and the volume of air storage constructed (measured in cubic meters).

GCAES power plants may be configured to supply tens of hours of storage, to many hundreds of hours of storage; at any power that is a multiple of 2 MW.

1,000 MW of storage is the size Cal-ISO says California will need when it gets 33% renewable power on its grid in 2020.

And by not being reliant on nearby natural gas, it can be sited near existing wind farms, and near existing transmission. This is key, as we seem to be moving in a regulatory direction where wind farms are being required to supply their own storage.

It is modular, so it can scale up or down. It can be built in arrays of modular units, from 2 MW to 1,000s of MWs. And because it is fuel-free, it is cheaper to run over time.

The company also naively assumes that, because it is uses no fossil fuels, it will be easier to permit, too. Green, climate safe, fuel-free and all that. Well, yes, in a sane world. Maybe in Europe. But at Cleantechnica, we see the opposite. Clean solar or wind takes years to permit.

But filthy fossil power has tantrums when asked to wait two months – McConnel and Inhofe’s Mining Jobs Protection Act gives the EPA just 60 days to approve or veto coal mining permit applications: if no decision, permit is therefor automatically “granted”!

[Update: since writing this story Tyler Infelise of General Compression has clarified some technical errors I made, in confusing the current technology, and added this point in response to the renewable permitting discrimination that I see:

“While there is nothing technically wrong with this statement, we are certainly aware that the permitting process is no trivial matter.

Our longterm view is that while there certainly are difficulties in permitting wind and solar, these will be nothing compared to trying to permit new coal.

And as the costs of renewable technologies decline, particularly when coupled with large-scale, low-cost storage such as ours, permitting will become increasingly less of an issue. But we are fully aware that permitting anything is a non-trivial challenge.”]

Susan Kraemer@Twitter

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