A SYSTEM FOR HEAT STORAGE

摘要

Apparatus (200) for storing energy, comprising: a first stage comprising: a compressor (130a); and a first heat store (120a) for receiving and storing thermal energy from gas compressed by the compressor (130a); and a second stage comprising: an expander (140a) for receiving gas from the first heat store (120a); and a second heat store (110a) for transferring thermal energy to gas expanded by the expander (140a); wherein the apparatus further comprises pressure maintaining means (230) configured to substantially maintain gas pressure in at least a part of the apparatus within a predetermined pressure range.