March 14, 2010
New Compressed Air Energy Storage Projects

Alexis Madrigal of Wired reports on compressed air energy storage (CAES) systems which will store compressed air deep underground. Electric power generated from wind blowing during times of low electric power demand gets used to compress air. Then the compressed air gets used to generate electric power when the demand is highest.

“CAES is the least cost, utility-scale, bulk-storage system available. If other factors such as its low environmental impact and high reliability are considered, CAES has an overwhelming advantage,” one Department of Homeland Security physicist concluded in a 2007 paper in the journal Energy (.pdf).

In the last four months, four projects have gotten new funding. In December, the rights to a long-awaited project in Norton, Ohio, were purchased by First Energy, a large utility in the area. The Norton project could store 2.7 gigawatts of power in an abandoned limestone mine.

Is that 2.7 gigawatts or 2.7 gigawatt-hours? I suspect the latter. That's equivalent to about 2 hours of electric power output from a nuclear power plant. Unfortunately no average expected cost per kilowatt-hour or efficiency numbers for these projects are provided in the article.

Can CAES make it more practical scaling up wind power to deliver a much higher percentage of total electric power? It is worth noting that electric power delivered during peak demand afternoons sells for more than electric power delivered late at night. So if the added cost of CAES isn't too great it can make wind much more competitive.

A cheap way to do electric power storage could help make some methods of generating electricity more competitive. For example, nuclear reactors running at night (when wholesale electric power rates are low) could power air compressors so that more nuclear electric power could be sold in the afternoon at higher prices.

Share |      Randall Parker, 2010 March 14 01:46 PM  Energy Electric Generators

Fat Man said at March 14, 2010 8:32 PM:

The CAES system that article describes uses the compressed air to replace the compressor stage of a gas turbine. Most of the energy comes from the natural gas.

Engineer-Poet said at March 14, 2010 9:21 PM:

Roughly 60% of the energy comes from the NG (because the heat of compression is not saved).  Even so, the efficiency of NG-to-electric hits about 80%.  This is about 20% better than the best combined-cycle NG powerplants.

Nuclear plants running at night, with the same nuclear plants supplying re-heat for compressed air during the day, could flip this equation even if NG is required to supply the balance (difference between nuclear output temp and CAES turbine input temp).  It's pity that the authors of the article are scientific illiterates, otherwise the interpretation would have almost no ambiguities.

Anonymous said at March 15, 2010 8:17 AM:

How are we supposed to take this seriously, when the word "efficiency" doesn't even show up in the article? I'll bet that this system isn't even 50% efficient.

Among the cows in Iowa said at March 15, 2010 1:55 PM:

I went through the figures for a system like this and calculated the efficiency at exactly 50% (5/8 natural gas input, 3/8 electric input). The output of electricity is 1/3 greater than the electric input.

JC said at May 15, 2010 5:04 PM:

When they are ready, and stop fiddling with there toys, I will have the answers to a totally new and renewable energy source that nobody can compare to!No pollutants from this unit it is totally self sufficent, it run off itself. let us invest in this unit.It would help the economy grow and expand in a number of diffrent markets and new future markets. Guess what else? We can sell this product to all other countries and put a percentage towards the deficeit and restructering the economy so it would never fail us again! WHEN THEY ARE READY CONTACT ME -JC-

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