http://prod.sandia.gov/techlib/access-control.cgi/2007/078012.pdf
Herein, a United States Department of Energy scientist urges us to "adopt revolutionary thinking about energy and fuels", asserting that, if we do, then, "it may be possible to the meet the future fuel challenges while maintaining our traditional hydrocarbon fuel framework".
Further, he says that we "must recognize that hydrocarbon fuels are energy carriers, not energy sources. The energy stored in a hydrocarbon is released for utilization by oxidation to form CO2 and H2O. Furthermore, just as H2O can be 'reenergized' by applying energy to split water back into H2 and O2, hydrocarbons can be recycled by capturing CO2 (and H2O) and 're-energizing' them back into hydrocarbon form".
And, he goes on to emphasize, that "there is a hydrocarbon analogy to the envisioned hydrogen economy that realizes the benefits of hydrogen while capitalizing on much of the existing liquid fuel infrastructure".
We have previously disparaged the utopian "hydrogen economy" aspirations of our ecologically-sensitive brethren, suggesting that, whether we know it now, or not, none of us really wants to be sailing down the Turnpike at 70mph in a mini-Hindenberg disguised as a minivan.
And, a hydrogen economy would, as we've previously pointed out, demand enormous investment in our fuel supply system; as the USDOE implies, by indicating that it would be better if we, instead, devoted ourselves to "capitalizing on" as "much of the existing liquid fuel infrastructure" as we can.
That can be accomplished, as the USDOE herein states, by using "thermochemical cycles to split CO2 into CO and O2 as a starting point for synthetic fuel production".
Comment follows more cohesive excerpts from the enclosed link to, and attached file of:
"Initial Case for Splitting Carbon Dioxide to Carbon Monoxide and Oxygen; 2007
James E. Miller; Sandia National Laboratories; Albuquerque, NM
Abstract: The United States presently imports ... more than 20 million barrels of petroleum that it consumes daily. The largest fraction of this consumption ... is for transportation.
Unfortunately, much of the non-domestic oil extraction, which we both directly and indirectly rely on, is from fields in unstable parts of the world. The national security and economic implications of our dependence upon foreign oil ... prompts a search for alternative sources of liquid fuels.
Independence from problematic oil producers can be achieved to a great degree by applying decades-old synfuel technologies to convert non-conventional resources such as coal ... into liquid fuels.
The 'hydrogen economy' is (an additional) alternative, but it poses significant infrastructure and technological challenges.
However, if we adopt revolutionary thinking about energy and fuels, it may be possible to the meet the future fuel challenges while maintaining our traditional hydrocarbon fuel framework. We must recognize that hydrocarbon fuels are energy carriers, not energy sources. The energy stored in a hydrocarbon is released for utilization by oxidation to form CO2 and H2O. Furthermore, just as H2O can be “reenergized” by applying energy to split water back into H2 and O2, hydrocarbons can be recycled by capturing CO2 (and H2O) and 're-energizing' them back into hydrocarbon form.
That is, there is a hydrocarbon analogy to the envisioned hydrogen economy that realizes the benefits of hydrogen while capitalizing on much of the existing liquid fuel infrastructure. Of course, the only credible pathway for implementing this vision is through the application of persistent energy sources (e.g. solar).
In this document, the concept of (using) thermochemical cycles to split CO2 into CO and O2 as a starting point for synthetic fuel production is introduced and potential advantages of this approach are discussed.
The most general way to convert CO2 and H2O into a fuel is through the intermediate production of synthesis gas or 'syngas'. Syngas is roughly a 1:2 mixture of CO and H2 whose exothermic conversion to fuel and other products is currently commercially practiced.
(The gasification of Coal, into "CO and H2" with subsequent "conversion to fuel and other products, is, as we have many times documented, already being "commercially practiced" by, for instance, SASOL, in South Africa; and, by Eastman Chemical, in Kingsport, Tennessee.)
Stated concisely, one key route to converting CO2 and H2O into fuel is the following 'reenergizing' reaction:
2CO2 + 4H2O → 2CO + 4H2 + 3O2
This reaction may of course be carried out either as written, or stepwise. For example, water splitting (WS) can be coupled with the reverse water gas shift reaction (RWGS) to produce syngas (as in the formulae):
6H2O → 6H2 + 3O2;
2CO2 + 2H2 → 2CO + 2H2O; (and, again, as above):
2CO2 + 4H2O → 2CO + 4H2 + 3O2
Recently, we proposed that it would be beneficial to split carbon dioxide and couple that reaction with the well known water gas shift reaction (WGS) to achieve the same result (as in the formulae):
6CO2 → 6CO + 3O2;
4CO + 4H2O → 4CO2 + 4H2; (and, then, again):
2CO2 + 4H2O → 2CO + 4H2 + 3O2
Herein, we begin to document and expand on the case for splitting carbon dioxide into CO and O2 as an attractive (option).
In making the case for carbon dioxide splitting (CDS), we necessarily begin with several assumptions. First, we assume that the hydrogen economy makes sense. That is, most of the assumptions that underlie the case for the hydrogen economy are necessarily incorporated here. These include assumptions regarding the desirability of increasing domestic sources of fuel and decreasing greenhouse emissions, as well as the assumption that the application of renewable/sustainable resources to fuel production, as opposed to
production of electricity, is appropriate.
Going further, for the purposes of this document, we assume that liquid fuels provide significant advantages over hydrogen such as compatibility with the current infrastructure.
(Thus,) the discussion herein is primarily limited to a comparison of water splitting and carbon dioxide splitting as the key steps in fuel production from CO2 and water.
Consider the example of methanol (CH3OH). Methanol can be selectively produced from syngas in high yields and ... has recently been touted as an alternate to hydrogen. (As illustrated, current synas conversion to methanol technologies) can theoretically result in per pass methanol yields in the range of 55-75%. Prior to World War II, less active catalysts were available and higher temperatures and pressures were required to achieve similar results.
Dimethyl ether (DME) has attracted interest as a clean-burning substitute for diesel. Similar to LPG, DME must be slightly pressurized for storage ..., but it has a higher cetane number than LPG, methanol, or diesel fuel, (and, the) energy density is higher ... than methanol.
(Further, at) low temperatures, CO is readily converted to H2 via the WS (Water Gas Shift) reaction. This suggests that CDS (Carbon Dioxide Splitting) should be considered as a route to hydrogen. Going further, if the goal is the utilization or recycle of CO2, then there are potential further advantages to CDS over WS.
Specifically, the thermodynamics of methanol and DME synthesis and possibly the kinetics of methanol synthesis are much more favorable for mixtures of CO and H2O than for CO2 and H2. That is, given the choice between “re-energizing” CO2 and H2O (to CO and H2 respectively), thermodynamic equilibria and kinetic models both strongly suggest that Carbon Dioxide Splitting is the better option."
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Allow us a question:
Did anyone, does anyone, in US Coal Country know that we have a "better" "Carbon Dioxide Splitting" "option", which would enable us to, as an end result, manufacture desirable liquid fuels such as Methanol and DME?
And, allow us to make another point:
The USDOE has some fancy ways in mind to effect the needed "CDS", and convert CO2 into Carbon Monoxide and Oxygen, so that they can then add some Water and make Methanol and DME.
But we remind you, that, as we several times, long ago, documented:
We can make all the Carbon Monoxide we might need - - for the USDOE to, as herein, combine with Water and thereby make, both an alcohol, Methanol, from which, as in ExxonMobil's "MTG"(r) process, we can synthesize Gasoline; and, the substitute Diesel fuel, DME -- by blowing Carbon Dioxide over red-hot Coal.