An energy storage system converts variable renewable electricity (VRE) to continuous heat at over 1000 C. Intermittent electrical energy heats a solid medium. Heat from the solid medium is delivered continuously on demand. Heat delivery via flowing gas establishes a thermocline which maintains high outlet temperature throughout discharge. The delivered heat which may be used for processes including power generation and cogeneration. In one application, the energy storage system provides higher-temperature heat to a conventional lower-temperature heat source to boost the temperature of a thermal power cycle working fluid to a turbine, thereby increasing efficiency of the power cycle.

The disclosure provides a control method and apparatus for an energy storage heat exchange electric water heater. The energy storage heat exchange electric water heater includes a water tank, an energy storage electric heater, a heat exchanger, a flow-through electric heater and a thermostatic valve, the flow-through electric heater and the thermostatic valve are controlled to be in an activated operating state at the same time, thus the thermostatic valve is able to mix cold water with hot water outputted from the heat exchanger and then allow mixed water to flow through the flow-through electric heater for being heated. The flow-through electric heater is able to directly heat the mixed water outputted from the thermostatic valve, without heating cold water in the thermostatic valve. Therefore, the temperature of water outputted after the flow-through electric heater heats the mixed water is able to reach the second preset temperature value quickly.