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East Texas Getting Compressed Air Energy Storage Plant
First time accepted submitter transporter_ii writes "A compressed air energy storage (CAES) plant was first built in Germany in 1978, but East Texas will be the site of one of the world's first modern CAES plants. How does it work? A CAES power generation facility uses electric motor-driven compressors (generated by natural gas generators) to inject air into an underground storage cavern and later releases the compressed air to turn turbines and generate electricity back onto the grid, according to the plants owner. The location near Palestine, Texas was selected because of its large salt dome, which will be used to store the compressed air. The plant is estimated to cost $350 million-plus, and will create about 20 to 25 permanent jobs."
Anybody knows how efficient is that? As compared with storage in water reservoirs for example?
Rome taught me patience and assiduous application to detail. Virtues which temper the boldness of great, general views.
When your compress air it heats up, increasing the pressure and making it harder to compress more air.
After it's been in the ground for a while it cools back down to ambient temperatures.
Then when you're extracting it the air is expanding which makes it cool down and reduces the pressure, therefore reducing the practical energy you can get out of it.
This is basic stuff you learn in Chemistry I.
Likely not...earth is not a really good conductor of heat and the air temperature in caves tends to vary only slightly over the year.
CASE = CAES Acronym Spelling Error
I hope, at least, that using CAES is more efficient than just burning the natgas and twirling the turbines with that. (I doubt that but I'm no energy expert.)
It can be more efficient if wasted power generated is less, because power demand is highly variable. Burning straight up natgas may lead to waste, if not all the power generated is required. With CAES, all the output can be stored until needed, as long as there are no "leaks" in the underground cavern, and the rate of pressure loss isn't too high.
With CAES, the power generation output can possibly be more easily reduced, during off-peak hours, to match the demand, with less loss in efficiency, and without having to shutdown/fire up a certain number of natgas generators based on demand.
This isn't a government make-work program. It's a project intended to serve an actual purpose, with the creation of permanent jobs as a nice side effect. The 'goodness' and cost-effectiveness of the job will be whether it reduces the ratepayer's bills, and/or increases utility profits (not sure of the regulatory structure out there), and/or increases the reliability of the grid.
If it could do those things and employ zero people, it would still be a good expenditure.
Alcohol, Tobacco and Firearms should be the name of a store, not a government agency.
I just want to add something that might be escaping some people.
Most natural gas generators on the scale of a public utility use a turbine engine which means that it's efficiency concerning getting work from the fuel used is pretty much in a narrow spot close to peak production. If you wind it down to generate less electricity it becomes less efficient and degrades the engine components faster so it's avoided. If you keep it in it's peak range but turn the generation down, you are being almost as wasteful as if the machine was producing full bore all the time whether it was needed or not.
This is even true for traditional internal combustion engines like in your car or motorcycles where it is geared so that your cruising range is between a certain RPM in order to take advantage of it. Outside that range is a little less efficient but isn't as pronounced as it is when you are dealing with an engine producing thousands of horsepower to drive gigantic generators.
What this compressed air storage does is allow the generation to be controlled by something that can be turned up or down easily as demand increases or decreases (compresses air) and the natural gas portion of it operates in the peak efficiency range of converting fuel to useful work when it is running.
how much of this translates into savings or overall efficiency improvements is something I don't know, But it seems to be enough (on paper at least) to throw millions of dollars at.
Oh, uninformed twats all up in this thread; surprise, surprise.... (chiefly referring to submitter and GP)
First some links (as opposed to URLs as text -- this is 2012, learn HTML or GTFO):
EPA application you didn't link. A good read that should have been in TFS.
The company building it.
The gear to be used.
Okay, the submitter clearly got confused, but I think differently. Possibly from this sentence of the EPA application:
A natural gas fired reciprocating engine will power an emergency electric generator rated at 740 ekW, necessary to support starting the plant when power from the grid is unavailable (“black start”).
The other possibility is because it's a natgas-fueled hybrid CAES rig, which concept is apparently very difficult for a certain class of mushbrain to grasp.
This plant uses only electricity from the grid to compress air. Could well be from natgas (which is damn cheap these days, and less CO2 than oil or coal), but if so it'll probably be a modern combined-cycle plant with high efficiency. Could also be nuclear, hydro, wind, or coal.
It DOES, however, use natgas to run -- rather than simply blowing compressed air down to atmospheric in a turbine, they use the stored compressed air in a Brayton cycle. A conventional gas turbine exhibits low load range (typically can't run less than 50% of maximum power), because the compressor is designed for specific conditions; throttle it back, and you lose efficiency rapidly, and eventually it stops working completely.. With a hybrid CAES plant, though, the gas is pre-compressed, so you just add heat (burn natgas) and expand w/ reheat. This allows scaling to very low power output. (In this particular case, the very high storage pressure (1900~2830 psi) actually means they can put another turbine before combustion, blowing the air down to around 800 psi.)
Best i can tell is that they buy electricity during non-peak, and use that to compress the air so that it can be released against to drive the turbines during peak. Almost as if they are acting as electricity speculators (buy low, sell high).
More like cross-border arbitrage than speculation IMO; even though peak and off-peak pricing aren't set simultaneously, they both usually move slowly compared to the diurnal alternation of the two. So to me, rather than considering it a single market with wild periodic swings, it's useful to treat it as 2 (or many) concurrent markets, of which you can only trade in one at any given time.
Someone mod this up. You'd have to be retarded to use natural-gas-generated electricity to operate an electric compressed air storage plant. The submitter just made that up.
Texas has a relatively de-regulated electric grid with a lot of wind capacity. Prices fluctuate wildly. This facility will use renwable wind and solar energy to compress air at times when it is cheap. Then, at times when electricity is expensive, the air will be used to operate a natural gas turbine and generate electricity.
"I assumed blithely that there were no elves out there in the darkness"