http://www.electrochem.org/dl/
As now accessible on the West Virginia Coal Association's web site, via:
West Virginia Coal Association | USDOE 2013 Solar CO2 + H2O = Methanol + Methane | Research & Development; concerning: "United States Patent Application 20130256147 - Solar Fuels Generator; Date: October 3, 2013; Inventors: Nathan S. Lewis and Joshua Spurgeon, CA; (California Institute of Technology); Abstract: The solar fuels generator (as described). Government Interests: This invention was made with government support under DE-SC000493/T-105066 awarded by the Department of Energy. The government has certain rights in the invention. Claims: A solar fuels generator, ...The supply stream .... can also include or consist of a reactant (in addition to water, and, in some embodiments) CO2 serves as the reactant that is delivered to the photocathodes. Examples of the fuels that can be produced using this reaction in combination with the disclosed solar fuels generator include ... methanol, methane, ethanol";
we recently made report of more "artificial photosynthesis" technology, wherein the energy of sunlight is harnessed to drive the conversion of Carbon Dioxide, in conjunction with Hydrogen concurrently extracted from Water, H2O, into hydrocarbon liquids and gases.
And, note that our US Government financed the development of that particular bit of Solar-powered Carbon Dioxide recycling technology.
Herein, we just wanted to provide you with a public presentation of the CO2 utilization technology behind "United States Patent Application 20130256147 - Solar Fuels Generator", which might help to better illustrate and explain it.
We caution that the presentation is rather "dense", delivered in an academic "techno-speak" that we, and we suspect the vast majority of our readers will as well, find too technically convoluted to be all that understandable or meaningful. Illustrations that are included might, though, be helpful.
What it represents, actually, is a technical justification for, and explanation of, the development processes entailed in formulating a technology like that disclosed in our above-cited report concerning "United States Patent Application 20130256147 - Solar Fuels Generator", wherein simple sunlight can power the conversion of Carbon Dioxide, perhaps collected via a process like that seen in our report of:
West Virginia Coal Association | WVU March 28, 2013, Economical Harvesting of Flue Gas CO2 | Research & Development; concerning: "United States Patent Application 20130078172 - Layered Solid Sorbents for Carbon Dioxide Capture; 2013; Inventors: Bingyun Li, et. al., West Virginia and Pennsylvania; Assignee: West Virginia University Research Corporation, Morgantown; Abstract: A solid sorbent for the capture and the transport of carbon dioxide gas is provided";
into such seemingly-desirable things as fuel alcohol Methanol and substitute, fracking-free natural gas Methane.
Comment follows excerpts from the initial link in this dispatch to:
"An Integrated, Systems Approach to the Development of Solar Fuel Generators
Nathan S. Lewis (lead named inventor of "US Patent Application 20130256147 - Solar Fuels Generator)
The Electrochemical Society Interface - Summer 2013
Two major technological challenges in the development of a sustainable, clean energy system are providing
massive grid-scale energy storage and an ample supply of carbon-neutral, high energy-density, transportation fuels. The development and deployment of massive, grid-scale energy storage is imperative for
reliably and robustly compensating for the intermittency involved with the utilization of very large amounts of wind energy and solar energy. Another challenge is that 40% of current global transportation fuel is
consumed in uses for which electrification is technically difficult, if not impossible, such as in heavy-duty trucks, ships, and aircraft.
Exhaustive use of advanced biofuels might possibly supply adequate carbon-neutral transportation fuel for these uses, but could not then also fulfill the requirement for long term, massive, grid-scale energy storage.
Chemical fuels are desirable for energy storage because fuels are the most energy-dense storage medium known to man (other than the atomic nucleus), and could (fulfil) the need for high energy-density, carbon neutral, sustainable, transportation fuels. Hence a clear rationale exists to develop technology options that involve the conversion of sunlight, by far the largest energy source, directly into chemical fuels.
One approach to address both of these technology development imperatives involves the development of artificial photosynthesis. In artificial photosynthesis, sunlight is directly converted, without the use of (or the limitations of) living systems, into a useful chemical fuel.
Natural photosynthesis provides a complex, but elegant, blueprint for the production of fuels from sunlight. With only water, carbon dioxide, and sunlight as the inputs, solar energy is stored in the form of chemical bonds as the output of photosynthesis. However, natural photosynthesis has significant performance
limitations at the systems level ... .
Production of fuels directly from sunlight is thus inspired by natural photosynthesis, but has the mandate to provide far superior performance than photosynthesis. In this respect, “performance” is measured by the net annually averaged energy conversion efficiency to produce a useful chemical fuel in a scalable, cost-effective fashion. A fully artificial photosynthetic system would also not require arable land, potable water, or involve tradeoffs of land to be used either for food or for fuel production.
It is clearly possible to construct fuel-producing, man-made, solar energy conversion system that outperforms natural photosynthesis on an efficiency basis.
Once electrons ... with the required energetics are produced (via solar conversion), catalysts are generally needed to facilitate the efficient production of chemical fuels. The need for catalysis can be readily understood at the fundamental level because the sun is not a laser! Hence solar photons strike a device one at a time, but two or more electrons are needed at once to make and/or break chemical bonds (2 electrons to reduce water to H2 ... 6 electrons to reduce CO2 to CH3OH, etc.). The required electrocatalysts must be highly active, stable, and, for global scalability, must be either comprised of earth-abundant elements or must minimally utilize scarce metals such as Ruthenium or Iridium.Unfortunately, the most active catalysts for water splitting (in acidic environments) are Pt and IrO2,so a goal for the global solar fuels research and development community is to discover, develop, and exploit suitable
systems and architectures that can allow for the replacement of large quantities of these scarce transition metals with more abundant metals, such as Mo, W, Co, Ni, Fe, or Mn.
A suitable half-cell electrocatalyst alone does not of course suffice to provide an adequate blueprint for the construction of a fully operational solar fuels generator system. The oxidative and reductive electrocatalysts
need to work under mutually compatible conditions of pH, temperature, etc. The electrocatalysts also need to be interfaced with the light capture components, while retaining as an assembly the function of all of the individual pieces. The system must also be capable of operating safely with minimal, if any, co-evolution of H2 and O2 to produce an explosive gas mixture. Similarly if CO2 is reduced to form methanol, for example, the methanol must not diffuse to the oxidative region of the system, or it will be oxidized back to CO2 and the overall system efficiency will be unacceptably degraded.
Hence, a membrane, or some type of physical and chemical separation system, is needed to prevent deleterious product back diffusion ... . But production of O2 from water will produce protons, whereas the reductive formation of a fuel will consume protons. The system must therefore allow a facile, low-resistance,
path for ion (generally proton or hydroxide) conduction to neutralize the pH gradient, else the net reaction to form products will cease to occur.
For this reason, a key R&D opportunity in the development of a solar fuels generator system is the development of suitable membranes or alternative physical/chemical/mechanical product separation schemes for enabling a scalable, manufacturable solar fuels generator.
Optionality in fuels produced: A final emphasis of a balanced global R&D program on solar fuels generator systems should be to retain flexibility in the types of fuels that can be produced from sunlight.
In one embodiment, water is split into H2 and O2, but H2 is not necessarily the fuel that will be provided to the end-user.
The H2 could be ... combined with CO2 from flue gas or otherwise using the reverse water-gas shift reaction, in conjunction with Fischer-Tropsch reactions, to produce liquid fuels for use in transportation applications ... .
(We've discussed the "reverse water-gas shift", or, more simply, "reverse conversion", wherein CO2 reacts with Hydrogen to form Carbon Monoxide, and the "Fischer-Tropsch reactions", wherein a blend of Carbon Monoxide and Hydrogen, usually specified to be made by the gasification of Coal, is catalytically condensed into gaseous and liquid hydrocarbons, numerous times previously. Expositions of them, with additional reference links for even fuller explanation, can be accessed via:
West Virginia Coal Association | France Efficient CO2 to Carbon Monoxide Conversion | Research & Development; concerning: "United States Patent Application 20030113244 - Method for Producing Carbon Monoxide by Reverse Conversion with an Adapted Catalyst; 2003; Inventor: Rene Dupont, et. al., France; Assignee: Air Liquide; Abstract: The invention concerns a method for producing carbon monoxide by reverse conversion, in gas phase, of carbonic acid gas and gaseous hydrogen while minimising the production of methane. The invention is characterised in that the reaction is carried out at a temperature between 300 and 520 C and under pressure between 10 to 40 bars in the presence of an iron-free catalyst based on zinc oxide and chromium oxide. Said method is preferably carried out continuously and comprises preferably the following steps which consist in: a) preparing a gas mixture rich in carbon dioxide and in hydrogen (and) b) reacting said gas mixture, forming carbon monoxide and water vapour, by passing said mixture through a catalytic bed based on zinc oxide and chromium oxide"; and:
West Virginia Coal Association | USDOE Pays Kentucky to Improve Fischer-Tropsch Coal Conversion | Research & Development; concerning; "US Patent Application 20110294906 - Incorporation of Catalytic Dehydrogenation into Fischer-Tropsch Synthesis to Lower Carbon Dioxide Emissions; 2011; Inventor: Gerald P. Huffman; (University of Kentucky); Abstract: A method for producing liquid fuels includes the steps of gasifying a starting material selected from a group consisting of coal, biomass, carbon nanotubes and mixtures thereof to produce a syngas, subjecting that syngas to Fischer-Tropsch synthesis (FTS) to produce a hydrocarbon product stream". )
An alternative is to directly reduce CO2 to methanol or methane ... .
(Note, that, as seen for two examples in our reports of:
West Virginia Coal Association | USDOE Finances September, 2012, CO2 to Methanol | Research & Development; concerning; "United States Patent Application 20120225956 - Catalysts for the Reduction of Carbon Dioxide to Methanol; 2012; Inventor: Felix Studt, et. al., California, Denmark and Germany; Assignee: Trustees of the Leland Stanford Junior University, California; Abstract: A catalytic composition is provided for methanol production. The composition (as specified) is configured to catalyze a reduction of CO2 to methanol. Government Interests: This invention was made with Government support under Grant No. DE-AC02-76SF00515, awarded by the Department of Energy. The Government has certain rights in this invention"; and:.
West Virginia Coal Association | Japan Converts CO2 into Lower-Cost Methane | Research & Development; concerning: "United States Patent Application 20120018311 - Carbon Dioxide Reduction Method; 2012;
Inventors: Satoshi Yotsuhashi, et. al., Japan; Assignee: Panasonic Corporation, Osaka; Abstract: The carbon dioxide reduction method of the present invention is a method (and catalyst as described.) The present invention relates to a carbon dioxide reduction method, and a carbon dioxide reduction catalyst and a carbon dioxide reduction device used for the method. ... (The) method and the device of the present invention achieve reduction of carbon dioxide to carbon monoxide, formic acid, methane, etc. and provide these substances with less energy and at lower cost. ... The present embodiment can also be applied to more environmentally-friendly methods and devices. For example, it can be applied to the use of a solar cell as an external power supply, and to a catalyst for solar energy reduction by combination with a photocatalyst";
the process disclosed in the USDOE-financed "United States Patent Application 20130256147 - Solar Fuels Generator", which arose from the project and concept being described in the subject report of this dispatch, is not the only way "to directly reduce CO2 to methanol or methane".)
R&D should also therefore be devoted to developing, discovering, and studying catalysts that can promote the six-electron and eight-electron reduction of CO2 to methanol or methane, respectively.
This process is envisioned as one in which the prototypes will have the optionality to produce either gaseous or liquid fuels, so that when the catalyst development program matures, the prototypes will already be
developed and will be ready to receive this enhancement in functionality.
Summary: The development of a complex system, such as a solar fuels generator, requires much more than just the discovery of a catalyst, or of a photocatalyst, or even of a water splitting nanoscale construct. It requires a full macroscale object that is embedded in, and forms the basis for, an article of manufacture that can be made at scale, and that can operate safely, cost-effectively, and efficiently over all length and time
scales of interest. A highly integrated effort, involving individual research groups, teams of research groups, centralized, focused R&D efforts, and global cooperation is therefore important to realize this goal in a cost-effective, time-effective, and effort-effective fashion. This realization is the most compelling, and in fact the overriding, justification for a systems level approach to the successful development of a technology that enables the direct production, in a globally scalable fashion, of fuels from sunlight by artificial photosynthesis, to provide an important technology option in the pursuit of a globally scalable sustainable
energy system."
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Again, as in our introductory comments, our excerpts are as concise and as meaningful as we could make them. The bulk of the full dissertation is devoted to the reporting of technical minutiae that are, in and of themselves, difficult to relate directly to the core truths being expressed, which are:
Environmental energy of one sort or another can be harnessed to "pry", as it were, elemental Hydrogen out of Water, H2O.
The Hydrogen can then be, in reactions that need only proper catalysts to drive them, without additional energy input, reacted with Carbon Dioxide and made to form thereby useful products, like Carbon Monoxide, and which products can also include fuel alcohol Methanol and substitute natural gas Methane.
We wanted to make certain you had this background available to you, since we will be referring back to it as we go along, making further report of the fact that we can, if we elect to do so, begin treating Carbon Dioxide as a valuable raw material byproduct that arises from our essential use of Coal in the generation of truly abundant and truly affordable electric power.
The implications that should bring home to all of us, concerning the potentials for greatly increased Coal Country employment and vastly enhanced national security, all aside from any potential environmental benefits, should be obvious.