Compressed Air Storage

Taking example calculation at https://en.wikipedia.org/wiki/Compressed_air_energy_storage -

a 250 gallon propane tank stores 1 kWhr of energy when compressed to 200 PSI. Pressure rating of propane tanks is 215 PSI - [1]. Taking efficiency of an air engine - generator to be 50% - we have .5 kWhr. So a 500 gallon tank would get us 1kW hr of usable energy.

See comments below:

Calculations

For volume of 500 gallons (propane tank) -

E=Pressure x Volume.

=200 PSI x 1.9 cu meters
=1,400,000 Pascals x 1.9 cu meters
=2.7 million Joules
=.75 kW hr

With 60% efficient air engines - this makes it slightly under 1/2 kWhr of energy storage.

For comparison, one motorcycle battery at $20provides a comparable amount of electrical energy storage, making a weak case for compressed air storage on cost considerations.

For comparison - if one could generate an average of 50W via wind power, that appears to be an easier route of power generation.

Links

• EPRI head states that air will be cheaper per watt hr store than batteries. - [2]
• Cost Comparison of Energy Storage - [3]