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Seawater Flow Battery as Technology Platform P. J. Schubert*and Y. Fu* *Indiana University-Purdue University Indianapolis (IUPUI), Richard G. Lugar Center for Renewable Energy, 799 W. Michigan St., Indianapolis, IN 46202, pjschube@iupui.edu ABSTRACT Grid-level storage of renewable energy using electrolytes from seawater is a platform technology with multiple byproducts and use-case scenarios. The core application is to provide load-leveling for intermittent sources such as wind and solar. Membranes which conduct sodium to a cathode for energy storage yields chlorine gas, which can be sold. Discharging stored sodium produces electric power, and also sodium hydroxide and hydrogen gas. Hydrogen can be sold, or combined with stored chlorine gas in a H2-Cl2 fuel cell to boost the round-trip energy efficiency of the seawater flow battery system. Sodium hydroxide can be used in alkaline exchange membrane fuel cells. The brine from conventional desalination can be processed to produce sodium metal plus fresh water which can be released into the marine environment. Sodium metal extracted from the cathode can be used as an energy vector which, when combined with water, produces hydrogen on-demand for use in variable load applications such as fuel cell vehicles. Keywords: sodium, flow, battery, seawater, low-cost, multi- purpose, hydrogen. 1 INTRODUCTION Water is critical to the sustainability of our society and economy. With the global population increasing, the demand for desalinated water for irrigation and human consumption is on the rise. Current technologies include vacuum distillation and reverse osmosis, which have shortcomings such as high energy consumption and low flow rate, respectively. Superior technologies which can address these disadvantages and have a favorable economic model are needed. In addition, utilization of renewable energy sources such as solar and wind in desalination is desired to help mitigate the negative environmental impact, however, energy generation from these sources is intermittent in nature. Introducing energy storage, such as batteries, to the desalination system can overcome this issue. An integration system of desalination and batteries using renewable energies is a promising model with significant economic potential. One potential byproduct of desalination is salt. Brine discharged from desalination systems stresses the environment. Damage to marine ecosystems is an externality not always included in project finance. If the sodium from salt could be harvested as a pure metal and used for a hydrogen-on-demand system like fuel cells, it has higher probability of improved economics and is likely more commercially viable. Fuel cells are promising technologies for mobile and stationary backup power supplies. A highly integrated system to simultaneously: (i) store renewable energy such as solar and wind; (ii) produce desalinated water; and (iii) create portable, salable energy storage as an additional byproduct is highly desirable. A system meeting these multi-faceted needs would be of considerable value. What is proposed herein builds upon this first-ever capability, and provides even more benefits besides. 2 TECHNICAL APPROACH Energy storage and water desalination are accomplished simultaneously with a novel, patent pending device called the Seawater Flow Battery (SWFB), as shown in Fig. 1 (see page 4). The system consists of two cells (electrolysis cell on the left and discharge cell on the right) which have a common sodium metal electrode immersing in nonaqueous liquid electrolyte working as cathode for the electrolysis cell and anode for the battery cell on the right, respectively. The nonaqueous chamber is separated by two sodium ion- conducting solid-state electrolytes from the seawater. The working principle is: seawater is supplied to the charge cell with the electrical energy generated from solar or wind to produce a valuable byproduct of chlorine gas and sodium metal which is deposited on the cathode as a form of energy storage. At the same time, seawater is desalinated and discharged from the electrolysis cell. As energy is demanded, the discharge cell starts to consume sodium metal anode and seawater to produce electricity and a byproduct of hydrogen for fuel cells. At the same time, sodium hydroxide as a valuable product is formed and discharged from the discharge cell. The chlorine and hydrogen gases produced can also be used as fuels in H2- Cl2 fuel cells, providing extra energy as demanded. In conventional electrolysis of seawater or concentrated sodium chloride solution (brine), chlorine gas can be easily generated on the anode, while sodium metal cannot be produced on the cathode because water is more easily reduced. The advance of the SWFB technology is to separate the anode in aqueous electrolyte and cathode in nonaqueous electrolyte by the solid sodium ion conductor in the electrolysis cell, so that metallic sodium can be produced on the cathode. Similarly, the anode (Na) and cathode in the discharge cell are separated by the solid sodium ion conductor which allows on-demand generation of electricity energy and production of hydrogen gas. The key component in this system is the sodium ion conductor. 446 NSTI-Nanotech 2014, www.nsti.org, ISBN 978-1-4822-5830-1 Vol. 3, 2014PDF Image | Seawater Flow Battery as Technology Platform
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Product and Development Focus for Salgenx
Redox Flow Battery Technology: With the advent of the new USA tax credits for producing and selling batteries ($35/kW) we are focussing on a simple flow battery using shipping containers as the modular electrolyte storage units with tax credits up to $140,000 per system. Our main focus is on the salt battery. This battery can be used for both thermal and electrical storage applications. We call it the Cogeneration Battery or Cogen Battery. One project is converting salt (brine) based water conditioners to simultaneously produce power. In addition, there are many opportunities to extract Lithium from brine (salt lakes, groundwater, and producer water).Salt water or brine are huge sources for lithium. Most of the worlds lithium is acquired from a brine source. It's even in seawater in a low concentration. Brine is also a byproduct of huge powerplants, which can now use that as an electrolyte and a huge flow battery (which allows storage at the source).We welcome any business and equipment inquiries, as well as licensing our flow battery manufacturing.CONTACT TEL: 608-238-6001 Email: greg@salgenx.com (Standard Web Page)