Intrigued by this method of energy storage, I have been building an air compressor/wind turbine system.
My tower stands 30 feet tall, and has a rotor of 20 feet diameter.
The rotor operates at 60 to 90 RPM, and readily generates 2000 watts of power.
At the bottom of the tower, is a machine room that houses the compressor.
This comprises a 1300CC motor car engine, with its timing gear removed.
The engine is fitted with two sets of one way valves in the spark plug ports.
Modified spark plugs allow me to connect all manner of fittings to the compression chambers, so this makes for easy modifications.
The compression ratio of this engine is unknown, but I suspect that it is a little higher than I'd like. To lower this figure, I can use short lengths of tube between the spark plug ports and the one way valves.
That ought to make for a system that can't deliver dangerously high pressures?
At this time, I have yet to complete the compressor part of this project. My intention is to turn the engine at quite a low speed, approx 100RPM.
At this low speed, rotor torque requirements will be reduced, so it will have an easier time of turning the engine.
In addition to the engine, there is an electric clutch system. This slowly engages the engine to the turbine through a modified clutch plate. Control for this is to be managed by pressure sensors in the air storage tanks.
The electric clutch offers another useful advantage, it lets me isolate the engine from the turbine so I may still get electricity in low winds.
It remains to be seen if the engine will still be correctly lubricated, or if it will be inclined to heat up.
Once completed and working, my air tools will have plenty of power to enjoy .
Fingers crossed for good results.