In the recent Nuclear Ammonia article post, ammonia was illustrated as a fuel that could propel vehicles in a zero carbon era. Despite our best efforts in developing new internal combustion engines and direct ammonia fuel cells, there will continue to be a role for carbonaceous fuels. Gasoline and jet fuel have double the volumetric energy capacity of liquid ammonia. A given fuel tank can only contain half as much ammonia combustion potential energy as gasoline combustion potential energy. Fuel tank size is very important in aircraft. Decades of engineering of airframes and turbine engines have optimized aircraft performance using diesel-like JP8 jet fuel.
CO2 emissions from burning liquid carbonaceous fuels continue to rise, exceeding even those from burning coal. Aside from the fact that CO2 emissions may cause a global warming catastrophe, and aside from the fact that the world is running out of economically recoverable oil, the US has an energy security problem.
The US produces just 35% of the 260 billion gallons used annually. We pay $400 billion per year for imported oil. The US spent $7 trillion through 2007 to maintain a US presence in the Persian Gulf.
We can and should reduce our use of liquid fuels derived from fossil petroleum, and we know we will always need some carbonaceous gasoline, diesel, and JP8 fuels. Yet there may be carbon neutral methods to recover or offset the CO2 released into the atmosphere by burning them.
Using nuclear heat and power, chemical engineers can design plants to synthesize CHx fuels from any carbon source. One source might be agriculture to harvest carbon from CO2 in the atmosphere. This is a different objective than growing corn to harvest its kernels’ sugar to be fermented into ethanol. This objective is to obtain the carbon from all the plant matter, not the potential energy from ethanol combustion. The energy source to make such synthetic fuels would really be the nuclear heat and power source.
How much agriculture might be needed? Very roughly, an acre of land can produce 3 dry weight tons of biomass per year. This is approximately the same for corn fields and forests. The mass of the carbon in biomass is about 50%, so the dry weight of carbon extracted from the atmosphere this way is about 1.5 tons per acre. The US has about one billion acres of farmland, capable in total of producing about 1.5 GT (giga tons) of carbonaceous fuels. US annual fuel consumption is about 1 GT per year. So making such fuel this way is barely conceivable, especially if we use less, perhaps substituting ammonia or battery power for most vehicles.
Project Green Freedom is conceived by Jeffrey Martin and William Kubic of Los Alamos National Laboratory. The idea is to use a nuclear power plant to provide the energy to synthesize fuel, and use the air flow of the cooling towers as a source for carbon from CO2 that makes up about 0.035% of the atmosphere. They observed that alkaline lakes absorb about 30 times the CO2 of similar size fields of switchgrass, and so conceived of trays of potassium carbonate exposed to the airflow within the nuclear plant cooling towers. The CO2 would be electrochemically removed from solution, combined with hydrogen from electrolysis of water to manufacture methanol, which is converted to gasoline. There is not yet a demonstration plant and there are some concerns about the efficacy of CO2 absorption and the number of cooling towers required. The whole fuel combustion/synthesis process would be carbon neutral, because just as much CO2 would be put into the atmosphere by burning as removed by Green Freedom.
There may be another way to implement a carbon neutral cycle for carbonaceous liquid fuels. Did you notice the “cement” line on the first illustration in this post?
The lime cycle has been used to make mortar for construction for millennia. Limestone is heated very hot to drive off CO2; it’s not really “burned”. Adding water makes calcium hydroxide used as the binding agent for mortar. Water is then given off and the setting mortar very slowly absorbs CO2 from the air to make a strong calcium carbonate cement. This idealized cycle is carbon neutral, but in the real world the process of heating the limestone is accomplished by burning large quantities of natural gas, which is why this process is the fourth largest contributor to atmospheric CO2 pollution, after natural gas, coal, and petroleum burning. In today’s construction industry, lime mortar is replaced by Portland cement, produced by a similar cycle, but with sand added to the limestone to add silicon to the chemistry, making a stronger cement. The CO2 cycle is the same.
This process is the conception of Darryl Siemer, a retired nuclear chemist from Idaho National Labs. Heat from a liquid fluoride thorium reactor (LFTR) would be transferred to the kilns to heat the sand and limestone. The molten salt might have a temperature of 800 C, so it just preheats the sand and limestone. The Portland cement process requires 1500 C, so that energy is supplied by a plasma arc powered by electricity from a LFTR. The exhaust gas contains CO2 and H2O, with the CO2 fed to a synfuel plant combining with H2 from electrolysis powered by LFTR. In this example Darryl proposed making 3 quads of carbonaceous fuel — about 8% of today’s US fuel consumption. Making that much fuel creates 300 MT (mega tonnes) of cement. The process would be carbon neutral, because the fuel synthesized and eventually burned would release CO2 into the atmosphere that would be absorbed by cement hardening as it is used in construction.
The US only uses about 106 MT per year of cement, so the rest could be exported. China uses 1800 MT of cement annually — more than half the entire world production.
So here is another source for carbon neutral carbonaceous fuels — nuclear cement.
Does it save anybody any money to do it this way?
Terje, I’m not able to make any cost estimates for nuclear cement, sorry. Martin and Kubic estimated a consumer cost for gasoline produced by Green Freedom of $5 per gallon.
A particle physicist at CERN is studying an alternative theory for global warming that deals with fluctuations in solar winds, and how that indirectly affects cloud formation on earth, which in turn drives the earth’s climate. You can find an article about it below, and if your interested, the next link is for a lecture given by the lead scientist for the study.
http://www.nature.com/news/2011/110824/full/news.2011.504.html
http://www.youtube.com/watch?v=63AbaX1dE7I
Interesting idea.
I advocate LFTRs, Green Freedom, and several other technologies for producing fuel from CO2 in my ClimateColab entry here:
http://climatecolab.org/web/guest/plans/-/plans/contestId/5/planId/15204
If I get enough votes from the public, I’ll get to present these ideas to:
The U.N. Secretary General’s advisory team on climate change
Congressional staffers (and potentially a congressman or two)
I was a winner of this contest last year, but at the time I wasn’t aware of these technologies.
Maybe I’ m missing something but I don’ t understand which advantage is here over (for example) a biomass to liquid ordinary process, like a Fischer-Tropsch (or Bergius) one, aside from the need of large quantities of externally feed hydrogen and biomass. It’s even a more mature technology, at least if we consider the experience on coal liquefaction
to Alex P.
The advantage are:
1. That we are not using farmland to produce biomass. There will be 9 billion people in 2050 they will want to eat.
2. We are not adding CO2 to the atmosphere. Only an advantage is you into climate change.
3. We are not using fossil fuels which are likily tobe scarce (expensive) in the future.
4. We are not extracting the CO2 directly from the air.
Direct CO2 extraction, looks like not a great idea from a land use prospective. Consider the amount of air you have to move per mole of CO2, and the plants will have to be large, loud, and/or not produce very much with any possible tech I have seen. Though if we really need jet planes this might be a way to go. Though I haven’t seen the project green freedom number mentioned in the article maybe they are better. But concrete suggestion look like a much better idea.
Depending on you choice of alternatives one or more will of the above will apply.
Ok, so I’m a bit confused about something. . .
I’m all for the idea of using a LFTR to reduce CO2 emissions in the process of making cement (which we need and are making anyhow), but I want to double check something:
If I go down to the hardware, home depot, walmart, farm supply, etc, and buy a bag of portland cement. Then I mix it up with water and gravel to make concrete, pour it in place to make whatever it is I’m making, then let is “set”, during the next week or so as it sets, it’s absorbing CO2, which is part of the reaction that make the concrete so hard?
So, synthetic fuels made this way would ultimately be carbon neutral, because you extract CO2 from the limestone to make the cement and fuel, burn the fuel which releases the CO2, but then mix up the concrete which re-absorbs about the same amount of CO2?
Chris,
the points 2, 3 and 4 are the same with biomass to liquid fuels, with the indirect adv is a much more developed process (considering the not so different coal liquefaction)
The point 1 in my opinion is almost irrelevant, because we don’t need any specific food plant to grow rather to convert any “waste” biomass (maybe including used paper like journals, newpapers,etc…?) – and with a deep electrification of transportartion we don’ t need a big amount of liquid fuels, neither
There are right and wrong arguments in the whole concept. Using hot air from nuclear heat for preheating is a right idea. It saves on coal.
Using cement plant exhaust saves on collection of CO2.Conversion of CO2 to fuel is a net loss of energy. Photosynthesis or other methods of using atmospheric CO2 and sunlight are the best for carbon collection and converting it to biomass. With increasing CO2 concentrations and temperatures, the conversion of atmosphere to greenhouse may be seen as positive in this context. Specialized farming for biomass may also be a mitigating action regarding the GHGs.
Storage of nuclear energy in batteries for land transport and synthetic fuels for air may be the right answer, if it becomes necessary.
To Alex P.
I agree with you. Though I have on more advantage. We are making Cement. So this is at least a good way to make a needed industrial product directly with out needing non-nuclear power. Given that you seem to be pro Fischer-Tropsch I think that you are mostly thinking of nuclear power in process heat too? I have just started looking into this process, does anyone know about the wast products left behind in reasonable modern processes. I am having nightmare about the old coal gas production methods…
To me this plan just doesn’t make sense. Different sources of energy are more valuable than others, but as I see it electricity is probably the most valuable. To use electricity to split water and then use the resulting hydrogen to synthesize liquid fuels is a step backwards. It makes more sense to electrify the transportation infrastructure, and then use nuclear power plants to create electricity.
Great article. How about nuclear iron and steel as an encore?
Chris, I think we should move this interesting discussion to the forum, anyway…
actually it’s not fully clear to me all the energy inputs in terms of heat (and the input temps), electricity and hydrogen to feed to a FT (or Bergius ?) process, maybe you or others can clear me this up. Anyway, I know that the most energy efficient (though not necessarily most economic and pratical) FT process version is that involving the fully burning of biomass, without the need of external hydrogen and heat – that means the yield is very modest, no more than 250 liters per dry tonn of biomass (or one barrel per tonn of coal in South African plants), while with a FT or Bergius process more than 60-70% of coal (slightly different with biomass) can be effectively converted to liquid fuels
Ned Speirs,
You’re absolutely right about electrification of transportation (both public and personal one), but we have to consider that : 1) we’ ll always need at least a bit of liquid fuels to power trucks, ships, or airplanes, or personal vehicles (including plugins) for longer trips; 2) the most (energy) efficient biomass to liquid (via Fischer-Tropsch) version needs to externally feed no hydrogen or heat (even if nuclear heat were readily available), if we really wanted it, at the cost to lower the liquid yield per tonn of input biomass to, say, 250 liter per tonn vs 5 or 6 barrel per tonn (coal mainly, but the point is the same for biomass) if electricity, hydrogen and heat were externally produced and only biomass is used as carbon feedstock
P.S.: extra hydrogen can be produced in situ using biomass (or coal) alone using the water/gas shift reaction, at the (huge, IMHO) cost to consume biomass (or coal) feedstock and decrease liquid fuel yield
The cement cycle could be made carbon negative. You have to capture the CO2, and make plastics out of them. Some plastics are durable, while other plastics eventually go into the landfill and becomes buried.
LTFR based nuclear power can drive these new processes.
Exporting stuff to China. Now there’s an idea whose time is long overdue.
Basically, this idea is making a Thorium Reactor a central part of a cement factory. The reactor provides all the energy needed for cement production, and the carbon released from the process used to make fuels.
I think we’ll need a prototype that works off of traditional power sources first to simply investigate the practical feasibility of capturing carbon this way, and then proceed to a LFTR based model once they are available–should the idea have practical merit.
I fully understand the argument for synthetic fuels, but has anyone investigated the feasibility for electrifying our transportation infrastructure?
We’ve had so much difficulty electrifying consumer vehicles, how are we supposed to store that much energy without a liquid fuel? With consumer vehicles, we can set up an infrastructure of recharging stations, much like today’s gas stations. That’s feasible with dispersed LFTRs around the nation. It’s not practical for commercial trucks, though. They get around 6-7 mpg on diesel fuel today, and typically carry around 100 gallons of fuel. That’s roughly 7 times the fuel capacity of consumer cars, with maybe 1/5 (guesstimate) the fuel economy (diesel gets somewhat better mpg than gasoline, but how much isn’t clear–there’s a reason trucks use diesel).
The issues only get worse with aircraft. The science fiction answer was a fusion power plant inside of aircraft. That makes me wonder if the airborne LFTR idea wasn’t completely ridiculous after all.
http://www.motherboard.tv/2011/11/9/motherboard-tv-the-thorium-dream
http://smithelectric.com/about-smith/overview/
electric trucks have been made since the 1920′s. They can be cheaper to run then diesel. When was the last time you tuned up your electric drill?
To make them useful in long haul options such as in the USA you would need to power them much like you would a train. either over head lines or inductively connected buried cable, either option is expensive. But after the lines are installed the return would be good. Picking up loads from diesel trucks at the interstate is another option.
Interesting concepts, except there is no way we could actually export concrete. It is way too heavy for shipment and is too cheap per ton to make it economical. It might be good for China to use this to make their cement but they will not buy ours.
Nick, you are confusing cement with concrete. Cement is well over $100 per tonne, roughly the same price as coal which is an export for many countries.
They sell cement clinker all over the world.
Darryl Siemer asked me to post this comment for him:
I’d like to add some background about “nuclear cement”.
I dreamed up the concept while preparing slides for a talk about “nuclear ammonia” presented at the 8th annual NH3FUEL conference two months ago: while liquid ammonia (LNH3) could indeed serve as a practical synfuel for most large engine applications (e.g., farm tractors and automobiles), it would not be practical for most light engine applications (e.g., chainsaws, lawnmowers, and airplanes). For these, my energy scenario’s assumptions suggested that our descendants would need about 3 quads worth of “CHx”-based synfuels (vs about 15 quads worth of LNH3). Getting the approximately 140 million tonnes of carbon necessary to make that CHx from close-coupled (to LFTRs) cement plants seemed to make good sense because:
1) our descendants will be needing much more cement that we do (the asphalt that we make roads out of comes out of the same barrels of “cheap” crude oil that our fuels do);
2) it would be uniquely simple/cheap to recover CO2 from the concentrated off gas generated by an electrically heated cement/lime kiln because it would consist almost entirely of CO2 and water vapor – essentially no elemental nitrogen, NOx, or SOx;
3) extracting that much of CO2 from air would be extremely expensive/difficult (in particular, conventional nuclear reactor cooling towers would not work);
4) “biomass” isn’t dirt cheap now and is apt to become much more expensive in the future; and
5) this scenario would be greenhouse gas neutral because all concretes made with lime-based binders (which includes Portland cement) eventually carbonate by absorbing CO2 from air and/or from the bicarbonate in water. In other words the binder matrix eventually changes from amorphous “CSH” to silica embedded in limestone – a process which increases the strength of the concrete.
The downside of carbonation is that also reduces the concrete’s pH to a level which no longer inhibits the corrosion of any steel embedded in it. Rebar corrosion is the root cause of much of the USA’s decaying public infrastructure. The solution to this would be simple – site another LFTR near a high-iron basalt rock outcropping, and use it to manufacture basalt fiber rebar – it’s stronger than steel and far more durable (this is another US invention which never got much traction here but is now being made/sold in China).
I am as much a supporter of the LFTR tech as I can be, but, in my opinion, this idea of Nuclear Cement is a non-starter.
First, as of about 15 years ago (and I don’t believe it has changed)almost all cement used within 200 miles of any US coast was imported, either as finish or clinker to be ground here. Further, about 50% of the population lives within that 200 miles, so about 50% of the cement would be used in the zone. While I can understand that LFTR should reduce the energy cost, I have grave doubts that it will be enough to get the costs low enough to export any of it.
Second, I don’t believe that the jacketing of the cyclone train will work, especially if it is anticipated that the waste heat of the electric generation side will be used. The ‘quality of heat’ is not there and you can’t get the approach dT high enough. A quick perusal of the Wikipedia entries for ‘Portland Cement’ and ‘Cement Kiln’ would help
get a handle on what temps are required where. Also, keep in mind the need for an ‘Alkali Bypass’. Maybe a second blown arc at the calciner discharge would do it with the main kiln discharge to atmosphere at that point. Also, I don’t know what color the arc is, but be aware that the main mode of heat transfer in the kiln proper is via infra-red.
I’ m too very skeptical about this nuclear cement option
On the other hand, *waste* biomass to liquids (via Fischer-Tropsch diesel fuel synthesis) is quite simple, relatively mature and pratically available today. If you are concerned about biomass consumption/availability and liquids yield, well, then externally introduce heat, electricity and hydrogen to the system multypling the liquid yield by a factor of 3 (from about 15-20% to 50-55% in mass)
http://www.wcce8.org/doc/090803_CH_Technico_economy_of_ScBtL.pdf
I do note in the most efficient versions it takes ~ 10 kWh of electricity per final liter of diesel fuel for a yield of 3 or 4 barrels of diesel fuels per tonn of dry biomass
The other serious option I see is to produce methanol and/or DME from biomass (again waste biomass), I don’t really know yet if this route can be easier in term of hydrogen/heat/electricity and other energy inputs than FT biomass to liquids
Alex, Gerry, et al
I do admit that nuclear cement is at the outer limits of practicality for obtaining carbon for synthesizing carbonaceous fuels. But stimulating thinking gets results, like the paper Alex referenced — well worth reading.
http://www.wcce8.org/doc/090803_CH_Technico_economy_of_ScBtL.pdf
I note that the technology that produces the most diesel from biomass uses external heat, hydrogen, and plasma heating (as does the cement kiln concept) — available from LFTR sourced energy.
I wrote that synthesizing all US carbonaceous fuel consumption would require 1 GT of carbon per year, possible from using 2/3 of our cropland. In the presentation I proposed reducing carbon requirements by an order of magnitude via vehicle efficiency, electrification of autos and trains, and substitution of ammonia for most fuels. Also, there is three times as much forestland and grassland as cropland, so we really could satisfy carbon requirements from bio-sources.
Dear Jerry
Re your first comment: “Nuclear cement” assumes that LFTRs will make clean energy cheap which renders arguments based upon the cement/concrete industry’s current cost drivers/customs irrelevant. In other words it assumes that “change” happens.
Second, it also assumes that this country could profitably utilize 3-4 times as much cement as it currently does. (e.g., for housing which is now primarily made of wood & roads now primarily glued together with asphalt) & therefore that it’s not necessary to assume that most of the “new” cement would have to be exported. For example, if concrete were significantly cheaper than it is today, I’d pave a ~250’ driveway out in front of my house.
I agree that putting molten salt jackets on the cyclones is probably not worth the trouble. I also agree that a LFTR’s “waste heat” is too cool to be of much use. Putting 100% of the required energy into the system as electricity would certainly be simpler & probably cheaper.
Re alkali bypass: I suspect that the clinker would retain more alkali because much of the alkali blown out of today’s cement kilns comes out in the form of sulphates originating from the sulfur in the “dirty” fuels usedby today’s kilns. More alkali retention isn’t necessarily bad because the cure to problems engendered by it is to simply add a cheap pozzolan (e.g., calcined clay). In any case, the degree of akali bypass needed by an arc-heated kiln can’t be determined until somebody screws up enough resolve to build & use a pilot plant. The same comment applies to optimizing everything else in such a radically different process.
Wouldn’t it be fun to actually do those tests?
Wouldn’t what ever carbon is store as methanol in tanks effectively be sequestered?
The larger the use and capacity stored the more is sequestered?
Alex – Please be aware that the ag community is progressing to ‘no till’ and the removal of stover represents a removal of fertilizer. Diesel can be produced from CO2, sunlight and LFTR waste heat. The production rate being bandied about was 10k gals per acre per year. I would say that anything over 2k would be great. The leftovers, sugar and protein, would have other uses.
Robert – I would suggest that crops are being grown where it is economically viable to do so. Forest and pasture are generally less productive. Vehicle eff is increasing with, of course, fleet eff lagging. Electrification of vehicles is necessary, but must be in form of PHEV. Many people, like myself, do not live in SFH. Electrification of trains is a $1mil+/mile deal and there are a lot of miles. Milwaukee Road had 1 or 2 divisions that way many years ago.
Darryl – I understand that “change’ happens, but chemistry does not and the temperatures are what they are. I agree that the sulphates are from the pulv coal fuel.
If I had a 250′ driveway it would be pea gravel, but, hey, that’s just me.
It will be a long time before SFH are built of concrete w/ insulation on outside where it belongs.
Low quality waste heat is useable w/ the marriage of the right processes.
If injection of calcined clay would cure the alkali problem, they should be doing it. Seems simple enough.
I’m strongly in favor of using biomass as a carbon source, and not an energy source. I’m equally in favor of using the concentrated CO2 from sources like cement production to make synfuels. But one small point of correction: the type of cement that is overwhelmingly dominant in construction does not absorb a significant amount of CO2 over its lifetime. Absorbtion of CO2 is not what causes it to harden. Rather, it’s a hydration reaction, with CaO + H2O -> Ca(OH)2. Crystals of hydrated material grow and interlock.
There *is* a type of cement in which absorbtion of CO2 plays a key role in hardening. I believe it’s based on MgO, rather than CaO. Fuzzy about the details, but I know that some green technology folks have advocated for using that type of cement more. As I recall, however, it starts out very weak, and takes decades to achieve full strength.
The primary hardening mechanism in Portland (or lime pozzolan)-type cements does indeed involve the formation of interlocking hydrated calcium silicate (CSH)fibers. However, in the presence of carbon dioxide, CSH is thermodynamically unstable with respect to silica and limestone which combined with the fact that concretes are porous means that they will eventually become fully carbonated. Since carbonation is a non expansive reaction, it doesn’t weaken concrete which explains why Rome’s Parthenon etc. are still standing. On the other hand modern concrete structures possess a fatal weakness (steel rebar) which does undergo an expansive reaction (corrosion) which will destroy those structures in far less time.
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