Thermal energy storage system for simple and combined cycle power generation

Patent metadata

Field	Value
Publication number	US-12480719-B2
Application number	US-202519189085-A
Country	US
Kind code	B2
Filing date	Apr 24, 2025
Priority date	Apr 24, 2024
Publication date	Nov 25, 2025
Grant date	Nov 25, 2025

Abstract

A thermal energy storage (TES) system converts variable renewable electricity (VRE) to continuous heat at over 900° 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. Configurations of simple cycle systems and combined cycle power plants using thermal energy storage units can provide even greater efficiency and responsiveness.

First claim

What is claimed is:

1 . A method of enhancing responsiveness of a combined cycle power generation system including at least one gas turbine, at least one heat recovery steam generator (HRSG), a steam turbine, and a thermal energy storage (TES) system, the method including:
charging the TES system using heat energy generated from electricity from a renewable energy source and/or an electrical grid; using heat output from the TES system to generate steam; using a portion of the TES-generated steam to maintain a preselected temperature condition in one or more portions of the HRSG while the gas turbine is in an offline condition; using a second portion of the TES-generated steam to operate the steam turbine in a spinning state while the gas turbine is in an offline condition; and selectively placing the gas turbine in an online condition in response to detection of a predefined system condition including at least one of: an energy drop from the renewable energy source below an availability threshold, a TES system drop below a heat output threshold level, a real-time or forecast electricity market price increase above a predetermined price threshold level, a command from a system operator, and/or a power demand increase above a demand threshold level.

2 . The method of claim 1 , further including the steps of maintaining the steam turbine in a reduced-output state and keeping the HRSG warm by the TES system.

3 . The method of claim 1 , further including the step of selectively operating the TES system to drive the steam turbine within a predetermined power level range in response to detection of the predefined system condition.

4 . The method of claim 1 , wherein the step of initiating the gas turbine includes operating the gas turbine at or near a design efficiency point in response to detection of the predefined system condition.

5 . The method of claim 1 , further including the step of selectively delivering steam from the TES system while the at least one gas turbine is in an online condition, thereby producing a higher combined steam flow to the steam turbine, in response to detection of the predefined system condition.

6 . The method of claim 1 , further including:
operating a set of control valves to selectively isolate steam sources, including the HRSG and the TES system; and routing steam to the steam turbine based on predetermined economic, environmental, and/or operational considerations.

7 . The method of claim 6 , further including the steps of sparging steam into one or more steam drums of the HRSG to maintain drum temperature, and supplying auxiliary steam to maintain condenser vacuum during periods when the gas turbine is inactive.

8 . The method of claim 1 , further including the step of maintaining synchronization of the steam turbine to the grid.

9 . The method of claim 1 , further including the steps of routing intermediate steam from the steam turbine to the TES system, reheating the intermediate steam, and providing the reheated steam to the steam turbine.

10 . A power generation system for enhancing responsiveness of a combined cycle power plant, including:
a gas turbine; a heat recovery steam generator (HRSG) thermally coupled to the gas turbine; a steam turbine coupled downstream of the HRSG; a thermal energy storage (TES) system configured to be charged using heat derived from electricity supplied by a renewable energy source and/or an electrical grid; a steam generation subsystem configured to receive thermal energy output from the TES system and generate steam therefrom; a first steam delivery pathway configured to route a portion of the steam generated from the TES system to one or more regions of the HRSG; a second steam delivery pathway configured to supply another portion of the TES-generated steam to the steam turbine; a control system configured to selectively initiate operation of the gas turbine in response to detection of at least one predefined system condition, the system condition including one or more of: 1) a reduction in energy output from the renewable energy source below an availability threshold, 2) a drop in heat output from the TES system below a predetermined threshold level, 3) an increase in real-time or forecast electricity market prices above a defined price threshold, 4) a command received from a system operator, or 5) an increase in power demand above a defined demand threshold; wherein the control system is configured to modulate the first steam delivery pathway to maintain a predetermined temperature condition in the HRSG while the gas turbine is in an offline condition; wherein the control system is configured to regulate the second steam delivery pathway to maintain the turbine in a spinning state while the gas turbine is in an offline condition.

11 . The system of claim 10 , further including:
the control system configured to operate the steam turbine in a reduced-output state; and the control system configured to operate the TES system to supply thermal energy to maintain the HRSG in a warm condition during offline periods of the gas turbine.

12 . The system of claim 10 , wherein the TES system is configured to drive the steam turbine within a predetermined power level range in response to a predefined system condition selected from at least one of: an energy drop from the renewable energy source below an availability threshold, a TES system drop below a heat output threshold level, a real-time or forecast electricity market price increase above a predetermined price threshold level, a command from a system operator, and/or a power demand increase above a demand threshold level.

13 . The system of claim 12 , wherein the gas turbine is configured to be operated at or near a design efficiency point upon detection of the predefined system condition.

14 . The system of claim 10 , further including:
a steam routing system configured to deliver steam from the TES system while at least one gas turbine is in an online condition, wherein the TES-generated steam supplements HRSG steam to produce a higher combined steam flow to the steam turbine in response to the predefined system condition.

15 . The system of claim 10 , further including:
one or more control valves configured to selectively isolate steam sources including the HRSG and the TES system; and a steam distribution system configured to route steam to the steam turbine based on one or more of economic, environmental, and operational parameters.

16 . The system of claim 15 , further including:
a sparging subsystem configured to inject steam into one or more steam drums of the HRSG to maintain drum temperature.

17 . The system of claim 10 , wherein the control system is configured to maintain the steam turbine synchronized with an electrical grid.

18 . The system of claim 10 , further including:
a reinjection pathway configured to deliver intermediate steam from the steam turbine to the TES system.

19 . A method for clean-energy operation of a microgrid power generation system including at least one gas turbine, at least one heat recovery steam generator (HRSG), a steam turbine, and a thermal energy storage (TES) system with a steam generation subsystem, the method including:
charging the TES system using heat energy generated from electricity from a renewable electricity source and/or an electrical grid; selectively operating the steam turbine using steam generated from the steam generation subsystem of the TES system to maintain the steam turbine in an operationa

Assignees

• Rondo Energy Inc

Inventors

• O'Donnell John Setel
• Terdalkar Rahul
• Ferhani Yusef Desjardins
• Riley Colin

Classifications

• Y02E60/14

  Thermal energy storage · CPC title

• Y02E20/16

  Combined cycle power plant [CCPP], or combined cycle gas turbine [CCGT] · CPC title

• F28D2020/0078

  Heat exchanger arrangements · CPC title

• F02C6/14

  Gas-turbine plants having means for storing energy, e.g. for meeting peak loads · CPC title

• F01K23/18

  characterised by adaptation for specific use · CPC title