Windpower and compressing air

[amdxjunk]

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

 

[Ecnerwal]

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.

 

[Jim Logajan]

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.