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Analysis of Solid Oxide Membrane (SOM) Electrolyzer with Liquid Metal Anode

2010
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Release : 2010
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Book Synopsis Analysis of Solid Oxide Membrane (SOM) Electrolyzer with Liquid Metal Anode by : Soobhankar Pati

Download or read book Analysis of Solid Oxide Membrane (SOM) Electrolyzer with Liquid Metal Anode written by Soobhankar Pati. This book was released on 2010. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Concerns about the depletion of fossil fuel reserves and increase in atmospheric carbon dioxide and temperature make hydrogen based energy systems an attractive alternative energy source. However, a cleaner, reliable, and cheaper hydrogen production route, which is independent of fossil fuel, is necessary for hydrogen to be used extensively as a fuel. In this work, the performance of a novel, energy-efficient, solid oxide membrane (SOM) electrolyzer for production of high purity hydrogen from steam and various reductants including hydrocarbon waste is analyzed and modeled to assist in scaling up of this technology. The SOM electrolyzer consists of an oxygen-ion-conducting yttria-stabilized zirconia (YSZ) electrolyte with a dip coated Ni-YSZ cermet cathode on one side and liquid metal anode on the other side. The SOM electrolyzer is operated at 800-1100°C by feeding a steam-rich gas to the Ni-YSZ cermet cathode and a reductt (coal, natural gas, hydrocarbon waste) into the liquid metal anode. Along with electrolytic production of hydrogen, AC impedance spectroscopy and potentiodynamic scans are performed to characterize the various polarization losses (ohmic and non-ohmic) in the electrolyzer and understand the fundamental nature of the electrode reactions. The long term performance of the SOM electrolyzer is evaluated using chronoamperometric measurements. Further, the durability of the liquid metal anode and Ni-YSZ cathode are evaluated employing symmetrical half cells. Based on the results obtained from the experimental study and theoretical modeling, the design of a cathode-supported commercial SOM electrolyzer producing 25 kg/day of hydrogen is proposed. Energy analysis of the proposed electrolyzer shows that hydrogen can be generated at an efficiency of nearly 75% employing carbon as reductant. Finally, future research is proposed for successful implementation of the SOM electrolyzer technology utilizing different types of wastes.

Solid Oxide Membrane (SOM) Stability in Molten Ionic Flux for the Direct Electrolysis of Magnesium Oxide

2013
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Release : 2013
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Book Synopsis Solid Oxide Membrane (SOM) Stability in Molten Ionic Flux for the Direct Electrolysis of Magnesium Oxide by : Eric Gratz

Download or read book Solid Oxide Membrane (SOM) Stability in Molten Ionic Flux for the Direct Electrolysis of Magnesium Oxide written by Eric Gratz. This book was released on 2013. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Direct electrolysis of magnesium from its oxide is less expensive and more environmentally friendly than current methods of magnesium production. The solid oxide membrane (SOM) process is a viable method for production of magnesium via direct electrolysis. In the SOM process magnesium oxide is dissolved in a molten flux, which acts as a supporting electrolyte. A yttria stabilized zirconia (YSZ) membrane is immersed in the flux and separates the anode from the cathode. When an electrical potential is applied between electrodes, magnesium cations travel through the flux to a steel cathode where they are reduced. Simultaneously, oxygen anions travel through the YSZ to a liquid metal anode where they are oxidized. However, in order for the SOM process to be commercially successful it must run for thousands of hours at high current efficiencies. It is believed the degradation of the YSZ membrane determines the lifetime and operating costs of the SOM process. This study investigates the mechanisms of YSZ membrane degradation. There are two main pathways of YSZ degradation: 1) yttria (yttrium oxide) diffusion out of the membrane, and 2) electronic conductivity in the flux providing a pathway for the applied potential to reduce the YSZ membrane. It is shown through diffusion experiments that the loss of yttria from the membrane into the oxy-fluoride flux can be prevented by adding yttrium fluoride to the flux, so that the activity of yttria in the flux is equal to the activity of yttria in the membrane. The electronic conductivity then becomes the primary source of membrane degradation in the SOM process. Electronic conductivity lowers the current efficiency of the SOM process. It is shown through measurements that the electronic conductivity is reduced by lowering the magnesium solubility in the flux. This is accomplished by performing SOM electrolysis at a reduced pressure (0.1 atm). When SOM electrolysis of magnesium oxide is carried out at reduced pressure, the membrane is not degraded and the current efficiency is high (70%). Thus this process provides a basis for a successful commercial operation for the direct electrolysis of magnesium oxide.

Hydrogen Production, Transport, and Storage 3

2009-10 Science
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Release : 2009-10
Genre : Science
Kind : eBook
Book Rating : 526/5 ( reviews)

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Book Synopsis Hydrogen Production, Transport, and Storage 3 by : M. C. Williams

Download or read book Hydrogen Production, Transport, and Storage 3 written by M. C. Williams. This book was released on 2009-10. Available in PDF, EPUB and Kindle. Book excerpt: The research articles included in this issue of ECS Transactions were originally presented during the 215th meeting of The Electrochemical Society, in San Francisco, CA from May 24 to 29, 2009 and are key to furthering the movement to the hydrogen economy enabled by fuel cells.

Issues in Metal Research: 2011 Edition

2012-01-09 Technology & Engineering
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Release : 2012-01-09
Genre : Technology & Engineering
Kind : eBook
Book Rating : 451/5 ( reviews)

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Book Synopsis Issues in Metal Research: 2011 Edition by :

Download or read book Issues in Metal Research: 2011 Edition written by . This book was released on 2012-01-09. Available in PDF, EPUB and Kindle. Book excerpt: Issues in Metal Research / 2011 Edition is a ScholarlyEditions™ eBook that delivers timely, authoritative, and comprehensive information about Metal Research. The editors have built Issues in Metal Research: 2011 Edition on the vast information databases of ScholarlyNews.™ You can expect the information about Metal Research in this eBook to be deeper than what you can access anywhere else, as well as consistently reliable, authoritative, informed, and relevant. The content of Issues in Metal Research / 2011 Edition has been produced by the world’s leading scientists, engineers, analysts, research institutions, and companies. All of the content is from peer-reviewed sources, and all of it is written, assembled, and edited by the editors at ScholarlyEditions™ and available exclusively from us. You now have a source you can cite with authority, confidence, and credibility. More information is available at http://www.ScholarlyEditions.com/.

Design of Optimum Solid Oxide Membrane Electrolysis Cells for Metals Production

2015
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Release : 2015
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Book Synopsis Design of Optimum Solid Oxide Membrane Electrolysis Cells for Metals Production by :

Download or read book Design of Optimum Solid Oxide Membrane Electrolysis Cells for Metals Production written by . This book was released on 2015. Available in PDF, EPUB and Kindle. Book excerpt: Oxide to metal conversion is one of the most energy-intensive steps in the value chain for metals production. Solid oxide membrane (SOM) electrolysis process provides a general route for directly reducing various metal oxides to their respective metals, alloys, or intermetallics. Because of its lower energy use and ability to use inert anode resulting in zero carbon emission, SOM electrolysis process emerges as a promising technology that can replace the state-of-the-art metals production processes. In this paper, a careful study of the SOM electrolysis process using equivalent DC circuit modeling is performed and correlated to the experimental results. Finally, a discussion on relative importance of each resistive element in the circuit and on possible ways of lowering the rate-limiting resistive elements provides a generic guideline for designing optimum SOM electrolysis cells.

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