The present invention relates to a reversible solid oxide electrochemical cell that may operate in two modes: a discharge mode (power generation) and a charge mode (electrolytic fuel production). A thermal system that utilizes a SOFB and is inclusive of selection of operating conditions that may enable roundtrip efficiencies exceeding about 80% to be realized is disclosed. Based on leverage of existing solid oxide fuel cell technology, the system concept is applicable to energy storage applications on the kW to MW scale.