A power plant comprises a steam system, a first electrolyzer, a heat storage system, and a heat exchanger configured to exchange thermal energy between the steam system, the first electrolyzer and the heat storage system. A method of operating an electrolyzer in a combined cycle power plant comprises operating a steam system to convert water to steam, operating an electrolyzer in a standby mode, the electrolyzer configured to convert water and electricity to hydrogen and oxygen when the electrolyzer is in an operating mode, circulating water from the steam system through a heat exchanger, circulating a first heat transfer medium between the electrolyzer and the heat exchanger, and circulating a second heat transfer medium between the heat exchanger and a thermal storage container.