An electrolyzer operates within an energy system, for example to provide grid services, energy storage or fuel, or to produce hydrogen from electricity produced from renewable resources. The electrolyzer may be configured to operate at frequently or quickly varying rates of electricity consumption or to operate at a specified power consumption. In one process of operating an electrolyzer, a series of dispatches is received indicating a specified power consumption for a period of time. The dispatches may occur at least once every 30 minutes. The electrolyzer is operated according to the dispatches. Hydrogen produced by the electrolyzer is discharged to a natural gas system.