Applicability of thermal energy storage recycled ceramics to high temperature and compressed air operating conditions

Recycled ceramics made of inertized asbestos containing wastes have been submitted to high pressure/temperature cycling tests in the operating range of ACAES and CSP applications. Ten successive cycles between room conditions and 610 °C/30 bars for a cumulated duration of 2500 h lead to a validation of the ability of the material to resist to those constrains. The Wollastonite/Augite initial structure is gradually transformed in a unique Augite containing material. While mechanical parameters and density are unchanged, thermal capacity is reduced by 5% and thermal conductivity increased by 30%. This last result offers an advantageous way to enhance the thermal conductivity of those recycled ceramics, a key parameter to control the charge/discharge power in TES systems.