http://www.inl.gov/
We earlier presented you, some time ago now, with a number of reports concerning the development, by the United States Department of Energy's Idaho National Laboratory, of a technology known as "Syntrolysis", wherein Carbon Dioxide and Water vapor are co-electrolyzed, and broken down into Oxygen, which is scavenged from the system, and Carbon Monoxide and Hydrogen, that is, "synthesis gas", which can be catalytically and chemically combined, as via the long-known Fischer-Tropsch process, in the synthesis of both liquid and gaseous hydrocarbon fuels.
Examples of our reportage on Syntrolysis have included:
West Virginia Coal Association | Idaho Recycles CO2 | Research & Development; concerning: "'Syntrolysis: Simultaneously electrolyzing water and carbon-dioxide into Syngas'; Two global energy priorities today are finding environmentally friendly alternatives to fossil fuels, and reducing greenhouse gases like carbon dioxide. Idaho National Laboratory researchers have invented a technology that can do both. INL’s Syngas Generation from Co-Electrolysis uses high-temperature nuclear reactor technology and solid-oxide fuel cell technology to recycle carbon dioxide and water into Syngas, the feedstock for synthetic hydrocarbon fuel production. This breakthrough technology also is called Syntrolysis, which is a patent-pending process that leverages nuclear-powered high-temperature electrolysis at 750-950C in a solid-oxide electrolysis cell to convert water and carbon dioxide into synthesis gas. “Using the well-understood Fischer-Tropsch process, Syngas can subsequently be converted into synthetic hydrocarbon fuels,” said INL nuclear engineer Steve Herring. “Syntrolysis offers an affordable, domestic, long-term carbon recycling process that produces the feedstock for synthetic fuels'"; and:
West Virginia Coal Association | USDOE Idaho Lab Recycles More CO2 | Research & Development; concerning: "'Model of High Temperature H2O/CO2 Co-electrolysis'; 2007; By: G. Hawkes, J. O'Brien, C. Stoots, Stephen Herring, Joe Hartvigsen; Research Organization: Idaho National Laboratory (INL); Sponsoring Organization: USDOE; Abstract: A three-dimensional computational fluid dynamics (CFD) model has been created to model high temperature co-electrolysis of steam and carbon dioxide in a planar solid oxide electrolyzer (SOE) using solid oxide fuel cell technology. A research program is under way at the Idaho National Laboratory (INL) to simultaneously address the research and scale-up issues associated with the implementation of planar solid-oxide electrolysis cell technology for syngas production from CO2 and steam"; and:
West Virginia Coal Association | Utah 2011 CO2 + H2O = Hydrocarbon Syngas | Research & Development; concerning: "United States Patent 8,075,746 - Electrochemical Cell for Production of Synthesis Gas Using Atmospheric Air and Water; 2011; Inventors: Joseph Hartvigsen, et. al., Utah; Assignee: Ceramatec, Inc., Salt Lake City; Abstract: A method is provided for synthesizing synthesis gas from carbon dioxide obtained from atmospheric air or other available carbon dioxide source and water using a sodium-conducting electrochemical cell. Synthesis gas is also produced by the coelectrolysis of carbon dioxide and steam in a solid oxide fuel cell or solid oxide electrolytic cell. The synthesis gas produced may then be further processed and eventually converted into a liquid fuel suitable for transportation or other applications".
A close read of the documents concerning the Idaho Lab's development of Syntrolysis will reveal that the assignee of rights to the above "United States Patent 8,075,746", "Ceramatec, Inc.", was a corporate partner of the USDOE's during some of the development of Syntrolyis, and, that the lead named inventor, "Joseph Hartvigsen", was a key member of the core development team.
We deliberately restricted our reportage on the USDOE-developed versions of Syntrolysis for Carbon Dioxide recycling, at least the ones developed at the Idaho National Laboratory, there are other versions, since they almost invariably specify "nuclear reactor technology" as the preferred means to provide the needed energy to heat and electrolyze the CO2 and H2O.
And, we say "nuts" to more Three Mile Islands and Chernobyls. None of us needs glow-in-the-dark grandchildren ten feet tall with single eyes growing in the middle of their foreheads - or, elevated risks of leukemia and bone cancer. Rumor has it that dandelions growing in the vicinity of Three Mile Island, in Pennsylvania, now sprout leaves a yard long.
However, recent developments in Syntrolysis-type CO2-recycling technology, by the USDOE and others, have reduced, through catalysis and other adaptations, the energy required to operate the component processes, and have made it feasible to utilize environmental, non-nuclear, and not fossil fuel-based, energy to drive them.
So, herein, we wanted to reintroduce the USDOE's version of Carbon Dioxide conversion into hydrocarbon synthesis gas via the process of Syntrolysis; with follow-up reports of later, quite recent, developments and improvements to follow.
Comment follows and is inserted within excerpts from the initial link in this dispatch to:
"'High-Temperature Co-Electrolysis of H2O and CO2 for Syngas Production'
2006 Fuel Cell Seminar; Carl M. Stoots; November 2006
Idaho National Laboratory; United States Department of Energy
Abstract: Worldwide, the demand for light hydrocarbon fuels like gasoline and diesel oil is increasing. To
satisfy this demand, oil companies have begun to utilize oil deposits of lower hydrogen content (e.g., Athabasca Oil Sands). Additionally, the higher contents of sulfur and nitrogen of these resources requires processes such as hydrotreating to meet environmental requirements. In the mean time, with the price of oil currently over $70 / barrel, synthetically-derived hydrocarbon fuels (synfuels) have become economical.
Synfuels are typically produced from syngas - - hydrogen (H2) and carbon monoxide (CO) - - using the Fischer-Tropsch process, discovered by Germany before World War II.
South Africa has used synfuels to power a significant number of their buses, trucks, and taxicabs.
(In South Africa, of course, the "synfuels" are made from Coal. And, their use isn't restricted to "buses, trucks, and taxicabs". They are conventional fuels that anyone in South Africa can buy at their local filling station; and, Coal-derived liquid fuels supply a significant percentage of South Africa's needs. See, for example, our report of:
West Virginia Coal Association | South Africa Improves Coal to Gasoline Conversion Efficiencies | Research & Development; which concerns, among other things: "United States Patent 4,318,797 - Process for Converting Coal into Liquid Products; 1982; Assignee: Sasol One Proprietary, Sasolburg (South Africa); Abstract: The invention provides a process and an apparatus for hydrogenative liquefaction of coal to produce high yields of gasoline fraction and optional yields of diesel"; but which also contains additional reference links indicating the importance of Coal liquefaction to South Africa's economy.)
The Idaho National Laboratory (INL), in conjunction with Ceramatec Inc. (Salt Lake City, USA) has been researching the use of solid-oxide fuel cell technology to electrolyze steam for large-scale nuclear-powered hydrogen production. Now, an experimental research project is underway at the INL to investigate the feasibility of producing syngas by simultaneously electrolyzing steam and carbon dioxide (CO2) at high-temperature using solid oxide fuel cell technology.
H2O + CO2 = H2 + CO + O2
The syngas can then be used for synthetic fuel production.
This program includes a combination of experimental and computational activities. Since the solid oxide electrolyte material is a conductor of oxygen ions, CO can be produced by electrolyzing CO2 sequestered from some greenhouse gas emitting process. Under certain conditions, however, CO can be further electrolysed to produce carbon, which can then deposit on cell surfaces and reduce cell performance. Furthermore, the understanding of the co-electrolysis of steam and CO2 is complicated by the competing water-gas shift reaction.
Results of experiments and calculations to date of CO2 and CO2/H2O electrolysis will be presented and discussed. These will include electrolysis performance at various temperatures, gas mixtures, and electrical settings. Product gas compositions, as measured via a gas analyser and their relationship to conversion efficiencies will be presented. These measurements will be compared to predictions obtained from a chemical equilibrium/electrolysis model. Better understanding of the feasibility of producing syngas using high-temperature electrolysis will initiate the systematic investigation of nuclear-powered synfuel production as a bridge to the future hydrogen economy and ultimate independence from foreign energy resources.
(In the above, we see reference to things, the "hydrogen economy" and "nuclear-powered synfuel production", we here, based on our instincts for safety and sanity, think should be discounted and discarded as both unrealistically utopian and downright dangerous. But, the "ultimate independence from foreign energy resources" is something, via Coal conversion and CO2 recycling, we can realistically aspire to.)
Experimental: A schematic of the apparatus used for co-electrolysis testing at the INL is shown in (an accompanying illustration). (An included photograph shows the primary) components (which) include
gas supply cylinders, nitrogen gas generator, mass-flow controllers, a humidifier, dewpoint measurement stations, temperature and pressure measurement, high temperature furnace, and a solid oxide electrolysis cell. Nitrogen is used as an inert carrier gas. The use of a carrier gas allows for independent variation of both the partial pressures and the flow rates of the steam and hydrogen gases while continuing to operate near atmospheric pressure. The flow rates of nitrogen, hydrogen and air are established by means of precision mass-flow controllers. Air flow to the stack is supplied by the shop air system, after passing through a two-stage extractor / dryer unit.
(The inclusion of Nitrogen, as above, mimics the use of atmospheric air in actual operation, which pertains to cost reductions. But, it also entails inefficiencies in the process, and we're not so certain the trade-offs are worth it. There are technologies available which could, with seeming economy, separate the gases and make the inclusion of Nitrogen unnecessary.)
The inlet gas mixture is then directed to the high temperature furnace. The electrolyzer is heated and maintained at an appropriate operating temperature (800 to 830 C) via computer-based feedback control. The furnace also serves to preheat the inlet gas mixture and the air sweep gas. Oxygen produced by electrolysis is captured by the sweep gas stream and expelled into the laboratory.
The syngas product stream is directed towards a second dewpoint sensor and CO2 sensor upon exiting the furnace and then to a condenser through a heat-traced line. The condenser removes most of the residual steam from the exhaust. The final exhaust stream is vented outside the laboratory through the roof.
The rates of steam and CO2 electrolysis are monitored by the measured change in inlet and outlet steam and CO2 concentration as measured by the on-line sensors. In addition, a Gas Chromatograph has been incorporated into the facility to quantify the dry constituents in the electrolysis product stream (including any CH4 that may be produced).
(The above is an interesting sidelight. This type of process is also capable, if wanted, of producing Methane, "CH4", from Carbon Dioxide and H2O. As indicated in the full document, and in supporting and related literature which we might in the future report, changes in catalysis and some of the operating conditions can allow Methane to be selected for. Thus, this sort of process is capable of being directed to the production of either synthesis gas, for the production of liquid hyrocarbons, or Methane.)
The chemistry involved in the co-electrolysis of steam and CO2 is significantly more complicated than steam electrolysis. There are three main competing processes occurring simultaneously. These are (in order of increasing kinetic rate) the electrolysis of CO2 to CO, electrolysis of steam to H2, and the reverse gas shift reaction: CO2 + H2 = CO + H2O.
In spite of the greater complexity of co-electrolysis versus electrolysing steam and CO2 separately, there are inherent advantages to co-electrolysis for syngas production.
In co-electrolysis, the reverse gas shift reaction is relied upon for most of the CO production and therefore the overall electrical requirement is less. (And,) in coelectrolysis the likelihood of producing carbon by electrolysis of CO is reduced."
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Again, our primary purpose in submitting this report is to reintroduce the technology of "Syntrolysis".
Should you examine the full report and study the experimental results, the CO2 reduction and Syngas production rates might seem disappointing. Note, however, the low electrical currents used, and the discussion of linear increases in conversion rates relative to power increases.
The study presented herein was done primarily to assess the potentials for inhibiting the "competing water gas shift reaction", as opposed to the "reverse water gas shift reaction", which is to a certain extent desired; and, for using relatively unpurified, and relatively dilute, gases burdened with high levels of Nitrogen, as might represent the mix of gases present in exhaust streams or even in atmospheric air with minimal pretreatment.
Other options exist and have been subsequently developed, as we will see in reports to follow, to economically enable higher concentrations of CO2 and H2O in the starting gas mix; to inhibit the water gas shift reaction; and, to reduce the amount of energy required to effect the chemical recombinations; all of which lead to higher production rates and greater efficiencies - - so much so that a collection of United States Patents and Patent Applications have been published, which provide a complete and practical technology for the reduction to practice of the basic processes studied herein, i.e.:
The production, as our United States Department of Energy herein states it, of "syngas by simultaneously electrolyzing steam and carbon dioxide (CO2)", with the understanding that synthetic liquid hydrocarbon fuels "are typically produced from syngas - - using the Fischer-Tropsch process, discovered by Germany before World War II".