Systems and methods of long-duration energy storage and regeneration of energy-bearing redox pairs

Patent metadata

Field	Value
Publication number	US-2018269515-A1
Application number	US-201815988192-A
Country	US
Kind code	A1
Filing date	May 24, 2018
Priority date	Jan 22, 2015
Publication date	Sep 20, 2018
Grant date	—

Abstract

Described herein are systems and methods of storing and delivering electrical using hydrogen at low-cost and for long-durations. The systems and methods use energy-bearing redox pairs that electrochemically bear energy through decoupled hydrogen and oxygen consumption and/or evolution reactions, which are typically associated with fuel cells. Each species of the energy-bearing redox pair is associated with a standard electrode potential within a water electrolysis voltage window for the electrolyte solution. Electrical energy delivery, hydrogen generation, electrolyte regeneration, or combinations thereof can be performed by logically or physically separated unit operations in a continuous manner, batch manner, or semi-batch manner facilitated by the energy-bearing redox pair.

First claim

What is claimed is:

1 . A system of energy storage comprising:
A first redox flow cell having a positive electrode side comprising an energy-bearing redox species dissolved in a liquid, energy-bearing, electrolyte solution, a negative electrode side comprising a H + /H 2 half-cell, and a proton permeable membrane separating the positive electrode and negative electrode sides, the first redox flow cell having a hydrogen generation mode and an electrical energy delivery mode; A first electrolyte regeneration cell comprising a reactor configured to react the liquid, energy-bearing, electrolyte solution comprising the energy-bearing redox species in a reduced state with an oxidizing agent to yield the energy-bearing redox species in an oxidized state; and wherein the energy-bearing redox species is associated with a reversible redox reaction having a standard electrode potential within a water electrolysis voltage window for the electrolyte solution.

2 . The system of claim 1 , further comprising:
A second electrolyte regeneration cell comprising a photoreduction cell having a photo-sensitive reducing agent, wherein the photoreduction cell is configured to receive solar radiation; and A circulation sub-system configured to transfer a first, liquid, energy-bearing, electrolyte solution comprising the energy-bearing redox species in the oxidized state from the first redox flow cell to the photoreduction cell, and configured to transfer a second, liquid, energy-bearing, electrolyte solution comprising the energy-bearing redox species in the reduced state from the photoreduction cell to the first redox flow cell.

3 . The system of claim 1 , further comprising:
A second electrolyte regeneration cell comprising a second redox flow cell having a negative electrode side comprising the energy-bearing redox species dissolved in the liquid, energy-bearing, electrolyte solution, a positive electrode side comprising a H 2 O/O 2 half-cell, and a proton permeable membrane separating the positive electrode and negative electrode sides, the second redox flow cell configured to reduce the energy-bearing redox species and yield O 2 ; and a circulation sub-system configured to transfer a first, liquid, energy-bearing, electrolyte solution comprising the energy-bearing redox species in the oxidized state from the first redox flow cell to the second, and configured to transfer a second, liquid, energy-bearing, electrolyte solution comprising the energy-bearing redox species in the reduced state from the second redox flow cell to the first.

4 . The system of claim 3 , wherein the circulation sub-system further comprises a first storage container configured to store a portion of the first liquid, energy-bearing, electrolyte solution and a second storage container configured to store a portion of the second liquid, energy-bearing, electrolyte solution.

5 . The system of claim 1 , further comprising a controller operably connected to the first redox flow cell and configured to select between the energy delivery mode and the hydrogen generation mode based on an energy-market condition.

6 . The system of claim 5 , wherein the energy-market condition comprises price of electrical energy supply, electrical energy demand, power grid health, H 2 price, H 2 demand, time of day, weather conditions, or a combination thereof.

7 . The system of claim 1 , wherein the energy-bearing redox species in the reduced and oxidized states comprise Fe 2+ and Fe 3+ , respectively.

8 . The system of claim 7 , wherein the oxidizing agent comprises oxygen.

9 . The system of claim 1 , wherein the reactor comprises a flow reactor.

10 . The system of claim 1 , wherein the energy-bearing redox species comprises iodine, vanadium, bromine, chlorine, or TEMPO.

11 . The system of claim 1 , further configured to operate in the energy delivery mode for a duration greater than or equal to 6 hours, 8 hours, 12 hours, 24 hours, or 48 hours.

12 . A method comprising the steps of:
In an electrical energy delivery mode:
generating electrical energy in a first redox flow cell comprising a H + /H 2 half-cell on a negative electrode side;
reducing an energy-bearing redox species on a positive electrode side of the first redox flow cell, wherein the energy-bearing redox species is dissolved in a liquid, energy-bearing, electrolyte solution and is associated with a reversible redox reaction having a standard electrode potential within a water electrolysis voltage window for the electrolyte solution; and
Regenerating the liquid, energy-bearing electrolyte solution by reacting the energy-bearing redox species in a reduced state with an oxidizing agent in a reactor of a first electrolyte regeneration cell, thereby yielding the energy-bearing redox species in an oxidized state; and
In a hydrogen generation mode:
Generating hydrogen on the negative-electrode side of the first redox flow cell and oxidizing the energy-bearing redox species on the positive-electrode side.

13 . The method of claim 12 , wherein the energy-bearing redox species in the oxidized and reduced states comprises Fe 3+ and Fe 2+ , respectively.

14 . The method of claim 12 , wherein said generating electrical energy further comprises generating electrical energy for a duration greater than or equal to 6 hours, 8 hours, 12 hours, 24 hours, or 48 hours.

15 . The method of claim 12 , further comprising selecting between the electrical energy delivery mode and the hydrogen generation mode based on an energy-market condition.

16 . The method of claim 15 , wherein the energy-market condition comprises price of energy supply, energy demand, power grid health, H 2 price, H 2 demand, time of day, weather conditions, or a combination thereof.

17 . The method of claim 12 , wherein the hydrogen generation mode further comprises the steps of:
Receiving solar radiation at a second electrolyte regeneration cell, which has a photoreduction cell comprising a photo-sensitive reducing agent; and Regenerating the liquid, energy-bearing electrolyte solution by reducing the energy-bearing redox species from the oxidized state to the reduced state in the photoreduction cell.

18 . The method of claim 12 , wherein said generating hydrogen further comprises:
Regenerating the liquid, energy-bearing electrolyte solution by reducing the energy-bearing redox species from the oxidized state to the reduced state on a negative-electrode side of a second redox flow cell and yielding O 2 on a positive electrode side comprising an H 2 O/O 2 half-cell, wherein the first and second redox flow cells are decoupled for independent operation one from another.

19 . The method of claim 18 , further comprising storing a portion of the liquid, energy-bearing, electrolyte solution comprising the energy-bearing redox species in the oxidized state and reduced state each in a separate storage container.

20 . A system comprising:
A first redox flow cell having a hydrogen production mode and an electrical energy delivery mode, the first redox flow cell comprising:
A negative electrode side comprising an H + /H 2 half-cell;
A positive electrode side comprising a Fe 2+ /Fe 3+ half-cell and a liquid, energy-bearing electrolyte solution comprising Fe 2+ , Fe 3+ , or both dissolved therein;
A first electrolyte-regeneration cell comprising a flow reactor with an oxygen port and configured to react oxygen with the liquid, energy-bearing electrolyte solution comprising Fe 2+ from the first redox flow cell in the ele

Assignees

• Battelle Memorial Institute

Inventors

• Wang Wei
• Lu Dongping
• Shao Yuyan
• Huang Qian
• Yan Litao

Classifications

• H01M2250/10

  Fuel cells in stationary systems, e.g. emergency power source in plant · CPC title

• H01M8/04925

  Power, energy, capacity or load · CPC title

• C25B1/10

  Chemistry & Metallurgy · mapped topic

• B01J2219/0877

  Liquid · CPC title

• B01J19/122

  Incoherent waves (gamma-radiation B01J19/082) · CPC title