Comments on: In Iowa, Compressed Air to Be Source of Electricity

By: Just Guess

Just Guess — Thu, 06 Nov 2008 08:03:35 +0000

This is just a guess, but from the article they are talking about running these air compressors at night when energy is being generated but not used. This process would allow at least a portion of that energy to be stored and then released during peak times.

By: Compressed-Air Startup to Inflate Utility Power Generation « Earth2Tech

Compressed-Air Startup to Inflate Utility Power Generation « Earth2Tech — Tue, 26 Aug 2008 20:01:22 +0000

[...] Department of Energy, Sandia National Labs, and several Midwestern utilities are already at work designing a compressed air storage system for a plant in Iowa scheduled for completion by [...]

By: Flex Your Power Energy News - Power Plug » Compressed Air Poised to Store Surplus Wind Electricity in Iowa and California

Thu, 31 Jul 2008 20:03:25 +0000

[...] to accounts by Sandia National Laboratory and Greentech Media, Sandia along with DOE and over 100 municipal utilities in the Midwest are collaborating on a CAES [...]

By: Steve Pluvia

Steve Pluvia — Thu, 03 Jul 2008 15:02:18 +0000

Criag,

A power plant needs to run at a set capacity to produce power efficiently. Power demand ALMOST NEVER meets optimal operating capacity — the excess capacity in existing power plants is simply wasted. Storing excess capacity allows you to use it on demand, and the cost is very low because it was previously waste.

Steve Pluvia

By: Michael Kanellos

Michael Kanellos — Wed, 02 Jul 2008 17:33:59 +0000

But you’re not generating power directly in a natural gas plant. You’re using the gas to crank a turbine to produce electricity. If you flared the gas directly, that would be different. in any event, I’ve got more calls into the lab and we will see what they say.

By: Craig

Craig — Wed, 02 Jul 2008 17:03:39 +0000

I’ll have to agree to disagree on this one… Seems to me it’s simple conservation of energy. You have to generate electricity to pump the air underground. Unless you are extracting energy from the earth (which you aren’t in this case), you are going to get less energy out than you put in.

So, it’s always going to be more efficient to use the electricity directly, versus using it to pump air into the ground, and release it to generate electricity. That’s true wether or not the electricity is generated via natural gas, coal, wind, or solar. You lose in the storage.

Compressed air is only storage - it’s not generation. Unlike geothermal, which does extract energy from the earth…

By: mike kanellos

mike kanellos — Wed, 02 Jul 2008 15:30:48 +0000

A lot of it comes down to efficiencies. Sandia is basically saying they can extract more power out of this system than you would a standard natural gas plant for the same input. In other words, you use half the gas for this for the same amount of power. The pump puts the air underground but the earth maintains the pressure on it. You have losses in gas plants too. It’s equivalent to having a better wind turbine. Storage is a key issue, but they also claim better performance. Of course, it also doesn’t exist yet so who knows if the mathematical models will bear out in reality.

By: Craig

Craig — Tue, 01 Jul 2008 22:25:53 +0000

Michael - still doesn’t make sense. To produce 1W of electricity from the compressed air system requires more than 1 W input. And that input is coming from a natural gas generator! How can that be better than using the 1W from the natural gas generator directly?

The benefit of this system is the storage, and the ability to shift energy use from peak to off-peak times (saving money, but not reducing emissions). Or being able to better integrate wind (which would have a net emissions reduction).

Maybe I’m still missing the point…

By: Michael Kanellos

Michael Kanellos — Tue, 01 Jul 2008 20:02:25 +0000

It uses 50 percent of the energy that a natural gas plant would use to produce the same amount of power, in theory. in other words, if you had them side by side in a John Henry contest, natural gas generators combined with compressors would use have the fossil fuels a natural gas power plant would to produce the same amount of power.

Tanks? too small and costly. You need massive underground capacity. A similar issue comes up with carbon sequestration. Some like the idea of turning it into baking soda, but the volumes of co2 coming out would result in a lot of powder, say critics. Imagine the amount of steel that would be required for air tanks. Then again, it’s in its infancy so who knows what will happen.

By: greensolutions

greensolutions — Tue, 01 Jul 2008 19:52:21 +0000

ditto on the 50% natural gas thing…

Why do we need to use geological formations? Is it too expensive to build tanks? What is the input and output efficiency of compressed air storage?

By: Craig

Craig — Tue, 01 Jul 2008 19:26:47 +0000

How does use 50% of the natural gas of a power plant? It’s storage, which inherently has some inefficiencies. So, you get less energy out than you put in. And the energy you are putting in is electricity - presumably generated by a natural gas plant. Something doesn’t add up. Is the 50% emissions cut when you use wind to power it?

Craig