Our large-scale long duration hybrid energy storage systems, both the Optimized Liquid Air Energy Storage System and the Combined Gas and Electric Energy Storage (CEGS) System are based on the recently issued U.S. patent 11,598,261 “Re-Condensing Power Cycle for Fluid Regasification”. A European patent application has been filed. The primary use of the cycle is for producing power from stored liquid air or liquid methane (LNG).

In general terms the cycle works like this: The initial condensed liquid (liquid air or LNG) is pumped to a high pressure, vaporized, heated, then expanded in a turbine to produce power, re-condensed against the initially pumped stream (thus supplying the vaporizing heat) to form an intermediate pressure liquid stream, which in turn is pumped, vaporized, heated, and expanded again to produce more power. The cold available in the intermediate pressure condensed fluid released while being vaporized is usually used to produce additional power in an organic Rankine cycle, or this cold can be used in a district cooling system or for other refrigeration uses.

When the initial condensed liquid is liquid air the second expansion is down to atmospheric pressure. For the Combined Gas and Electric Storage System the initial condensed liquid is LNG and the second expansion is down to the receiving pipeline pressure. The LNG for the Combined Gas and Electric Storage System is taken from a natural gas pipeline at off-peak times and converted to LNG using excess renewable power, the electricity used to make the LNG is returned to the electric grid at peak times while concurrently returning the natural gas to the pipeline system, at a flow rate of about 3 to 4 times the off-peak flow rate into the LNG system, thus providing high deliverability gas at peak times.