Heat-of-compression recycle system, and sub-systems thereof

A power recovery sub-system for a cryogenic energy storage system, the power recovery sub-system comprising:

• a primary thermal energy storage device;
• a secondary thermal energy storage device;
• a first primary heat exchanger;
• a second primary heat exchanger;
• a first primary expansion stage;
• a second primary expansion stage;
• a first secondary heat exchanger;
• a first secondary expansion stage;
• a first arrangement of conduits, having an upstream end and a downstream end, and configured to pass a working fluid through the first primary heat exchanger, the first primary expansion stage, the second primary heat exchanger, and the second primary expansion stage;
• a second arrangement of conduits configured to pass a first heat transfer fluid from the primary thermal energy storage device, through the first primary heat exchanger and the second primary heat exchanger;
• and
• a third arrangement of conduits configured to pass a second heat transfer fluid from the secondary thermal energy storage device, through the first secondary heat exchanger,
• wherein the second arrangement of conduits is further configured to pass a first portion of the first heat transfer fluid through the first primary heat exchanger and pass a second portion of the first heat transfer fluid through the second primary heat exchanger;
• and
• wherein the first arrangement of conduits is further configured to pass the working fluid through the first secondary heat exchanger and the first secondary expansion stage;
• wherein the secondary thermal energy storage device is configured to store thermal energy at a higher grade than that stored by the primary thermal energy storage device.