SOFCs operate at high temperatures (600–1000 ˚C) and have immense potential for thermal energy storage (TES). Testing at NETL has shown that more thermal energy can be stored by increasing the thickness of the interconnect material—usually made of stainless steel. A significant amount of energy can then be recovered without damage to the fuel cell. In fact, initial testing has shown that when integrating TES, a fuel cell became more efficient, lasted longer, and in general, was more robust. This integration of TES into fuel cell systems can be used to overcome the problems associated with intermittent power production from renewable sources.