A power plant can comprise a gas turbine productive of an exhaust gas, a steam turbine, a heat recovery steam generator that extracts heat from gas turbine exhaust gas and supplies fluid to the steam turbine, a thermal storage unit storing a thermal storage working medium that is configured to discharge thermal energy into the fluid supplied from the heat recovery steam generator to supplement power generation by the steam turbine, a first heat exchanger disposed within the heat recovery steam generator to transfer thermal energy from the exhaust gas to the thermal storage working medium, and a second heat exchanger in flow communication with the heat recovery steam generator and the thermal storage unit, the second heat exchanger facilitating a direct heat transfer of thermal energy from the thermal storage working medium in the thermal storage unit to the fluid supplied from the heat recovery steam generator.