Windpower and compressing air

I'm curious about the efficiency of compessing and storing air with windpower. As compared to batteries, in the end still needs to be converted to electricity. Storage dosen't wear out. What about efficiency of air turbine driving generator vs. battery driving inverter? Mike

It takes batteries to store electricity. More conversion processes to store it as chemical change and back.
Air pressure is a storage method. Compare apples with apples.
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Never mind that compressed air will have to dump lots of heat on cooling back to ambient.
Lousy way to store energy.
J

amdxjunk wrote:

I'm curious about the efficiency of compessing and storing air with windpower. As compared to batteries, in the end still needs to be converted to electricity. Storage dosen't wear out. What about efficiency of air turbine driving generator vs. battery driving inverter? Mike

Converting windpower to compressed air to electricity just adds one more stage (at least) of conversion. Every stage, no matter how efficient, results in a net loss of energy. Best to go direct. Wind - electricity.
Harry K

I heard about someone using a waterpumping windmill driving an above ground water well cylinder to compress air. It supposedly worked very well. I don't think leathers would work long term though without oiling them frequently. I'm sure this would be a lot more efficient than using a wind generator.

amdxjunk wrote:

I'm curious about the efficiency of compessing and storing air with windpower. As compared to batteries, in the end still needs to be converted to electricity. Storage dosen't wear out. What about efficiency of air turbine driving generator vs. battery driving inverter? Mike

If you want compressed air, eg for powering tools, converting from wind to air would I expect minimise upfront costs. If OTOH you want electricity, putting air in the way adds more equipment and losses.
With refrigeration, coldth can be stored as ice, which is a lot cheaper than lead acid batteries.
But there are as always various ifs and buts. Eg you need variable gearing to get decent efficiency.
NT

This site list energy density of various fuels including gasoline, batteries, and compressed air. http://xtronics.com/reference/energy_density.htm

Never mind that compressed air will have to dump lots of heat on cooling back to ambient.
Lousy way to store energy.
J

In article , "amdxjunk" wrote:

I'm curious about the efficiency of compessing and storing air with windpower. As compared to batteries, in the end still needs to be converted to electricity. Storage dosen't wear out. What about efficiency of air turbine driving generator vs. battery driving inverter?

Sucks. For a quick, no mumbo-jumbo required evaluation of the inefficiency of compressed air, look at the air required to supply a 1 hp (.75KW) airmotor, and then look at the electric hp (KW) needed to run a compressor that will supply that airmotor. Should be educational...just take a quick gander at an industrial supply catalog.
If you want to engage in this type of "whacky scheme to avoid batteries", do what the big boys do and pump water uphill to store energy, then run it downhill to generate electricity.
Air power only makes sense if electricity is bad (religious issues, as for the Amish), or air offers a specific advantage (such as no sparks, or running cooler the more it's used, etc.) Air as intermediate storage is terrible. Directly compressing air would mostly make sense if you were using compressed air directly.
-- Cats, coffee, chocolate...vices to live by

"BobG" wrote:

This site list energy density of various fuels including gasoline, batteries, and compressed air. http://xtronics.com/reference/energy_density.htm

Energy density (using either J/m^3 or J/kg) is a useful measure primarily for mobile applications. For fixed applications it seems the measures of with the greatest consideration should be cost ($/J), loss rate (J/S), and safety. So very low energy density systems like water reservoirs are viable even though their J/m^3 and J/kg values pretty much suck. (Assuming you have the land!)
So compressing air, or springs (an idea not often proposed for some reason, though theoretically should give fair energy density), may be viable if the compressor and containment structure are low in cost and plenty of safety precautions have been taken.