Is there any efficient way of using a large volume but low pressure (<2 bar) stored compressed air, either to drive an engine or some other application?
To store a large volume of low pressure air requires a truly gigantic holding tank which would be completely uneconomical to build and operate. Consider the following: a wind turbine is the ultimate in extracting useful work from a high flow rate of low density working fluid (air) driven by an extremely small pressure difference. Assume a 100 foot diameter turbine feeding on air flowing at 22 feet per second, meaning that in one second, 173,000 cubic feet of air goes through it. In one minute, ten million cubic feet go through; in one hour, 620 million cubic feet and in 24 hours, 14.9 billion. That's a tenth of a cubic mile of air to run the turbine for one day and you want to store it all at a fraction of a PSI for the source pressure? From the standpoint of mechanical engineering, you'd never do it that way.
To make it economical dictates that you increase the energy density of the storage method which can easily be done by compressing the air to high pressure and releasing it at low flow rates instead of trying to do the same with low pressure and high flow rates.
welcome on this SE. Your question might be a little vague for Engineering SE, but here is a possibility:
You can use this volume of air as a refrigerant: You put it at ambient temperature, wait for the air volume to come to the ambient temperature, and then you put it close to a volume to cool down: the difference of pressure will cool down the volume of air, and heat transfer will do the rest.