Device and method for converting and storing electrical energy in the form of compressed air

An energy conversion device for converting electrical energy into aeraulic energy and vice versa, and for storing this in the form of compressed air, the device comprising:

• dynamo-electric machines which have an electrical power link to a grid;
• dynamo-hydraulic machines mechanically linked to the dynamo-electric machines;
• at least one conversion chamber capable on the one hand of containing liquid pumped by the dynamo-hydraulic machines operating as pumps or receiving liquid intended to supply power to the dynamo-hydraulic machines operating as expanders, and on the other hand of containing air, such that the liquid present in the chamber forms a liquid piston for compression or expansion of air;
• a reservoir for storing compressed air at a storage pressure;
• sealable means for bidirectional aeraulic communication between the conversion chambers and the storage reservoir;
• and
• each dynamo-hydraulic machine is provided in order to operate within a respective pressure range at its high-pressure opening in order to carry out the pumping or the hydraulic expansion in stages inside each conversion chamber successively with several said dynamo-hydraulic machines up to or, respectively, from the desired storage pressure, the pressure range being narrower than the difference between the low pressure and the storage pressure, and in that distribution means are provided to connect each conversion chamber successively to at least two dynamo-hydraulic machines provided in order to operate within different pressure ranges.