THERMAL ENERGY STORAGE

The present invention provides an energy storage apparatus. The energy storage apparatus comprises a storage tank (100, 220) for receiving thermal energy storage fluid (103, 203) therein, a first energy transfer component (107, 205) and a second energy transfer component (106, 206). The storage tank has a first portion and a second portion, each portion having a first end vertically spaced from a second end. The first portion is in fluid communication with the second portion at the respective first ends and at the respective second ends. The first energy transfer component is configured to transfer thermal energy into thermal energy storage fluid in the first portion of the storage tank. The second energy transfer component is configured to transfer thermal energy from thermal energy storage fluid in the second portion of the storage tank. The energy storage apparatus is configured such that operation of at least one of the first energy transfer component and the second energy transfer component causes convective fluid flow of the thermal energy storage fluid from the first energy transfer component towards the second energy transfer component and from the second energy transfer component towards the first energy transfer component.