Study: Synthetic Fuels from Nuclear Hydrogen and Captured CO2 Viable
30 September 2006
A study published earlier this year by researchers at MIT’s Center for Advanced Nuclear Energy Systems (CANES) concluded that producing synthetic transportation fuels from nuclear hydrogen and captured carbon dioxide would be technically viable.
Based on a reference year 2025 case, the report found that 43.1% of the CO2 projected to be emitted from coal plants could serve to produce the 6.6 billion barrels of ethanol required to displace gasoline use in the US. For the production of that much ethanol, there would need to be between 700 and 900 GWth (gigawatts thermal) of nuclear power to produce the needed hydrogen and energy for the synthesis of the fuel.
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| Nuclear power requirements for transportation hydrogen. Click to enlarge. Source: General Atomics |
Estimates for the amount of nuclear power required to generate sufficient hydrogen to fuel a hydrogen fleet vary based on the efficiency of the vehicle fleet. General Atomics earlier this year estimated a required range of between 1,000 to 2,000 GWth to produce hydrogen for half of the current US fleet.
The study also concludes that replacing the entire world’s projected consumption of gasoline with 16.87 billion barrels of ethanol in 2025 would required the capture of 29.5% of the total emitted CO2 and a nuclear power requirement of between 1,800 and 2,300 GWth.
These numbers show that there is a very wide market for using nuclear power to aid in the production of alternative fuels to aid in the transition to the hydrogen economy. The large fraction of emitted CO2 that need to be captured shows that a benefit of this process would be to significantly decrease the total greenhouse gas emissions. A total cycle analysis reveals that the total reduction in CO2 emissions will be slightly more than 12%...A second benefit would be to decrease a nation’s dependence on imported petroleum.
The study also explored the production of methanol as a substitute.
Tne study incorporated a review of the literature on the use of nuclear power to produce hydrogen, as well as a review of possible nuclear reactor concepts. The researchers also concluded that nuclear power could be utilized in the production of oil from sand and shale.
Several nuclear cycles have potential application for the production of hydrogen, including High Temperature Steam Electrolysis, the Sulfur Iodine Cycle and UT-3. The report focuses on the High Temperature Steam Electrolysis option.
A number of possible new nuclear reactor concepts show potential in producing hydrogen, although many have drawbacks, according to the study.
Ultimately the report focuses on the High-Temperature Gas Cooled Reactor (HTGR), which uses helium coolant, and a modified version of the Advanced Gas Reactor (AGR) using supercritical CO2 as the coolant (S-AGR).
The reactor concepts selected for aiding production of oil from tar sands are the Advanced Candu Reactor (ACR-700), the Pebble Bed Modular Reactor (PBMR), and the Advanced Passive pressurized water reactor (AP600).
Separately, last week the Department of Energy announced that the Idaho National Laboratory (INL) will make awards valued at about $8 million to three companies to perform engineering studies and develop a pre-conceptual design to guide research on the Next Generation Nuclear Plant (NGNP).
The INL will issue a contract to Westinghouse Electric Company for the pre-conceptual design of the NGNP, and will later issue contracts to AREVA NP and General Atomics to perform complimentary engineering studies in the areas of technology and design tradeoffs, initial cost estimates and selected plant arrangements.
NGNP is a very high-temperature reactor concept capable of producing high temperature process heat suitable for the economical production of hydrogen, electricity and other energy sources. The NGNP research and development program is part of DOE’s Generation IV nuclear energy systems initiative aimed at developing next generation reactor technologies and is authorized by Congress in the Energy Policy Act of 2005.
Resources:
“An Alternative to Gasoline: Synthetic Fuels from Nuclear Hydrogen and Captured CO2”; Middleton, B.D. and M.S. Kazimi; MIT-NES-TR-006, July 2006.
Nuclear Fission and Fusion (General Atomics)
Anything to keep coal viable. I like the idea of no oil imports, that's a good thing. Reduced GHG emissions is great too, though we need to do better than 12%. How would the price of this stuff compare to business as usual? That's what it would really come down to. Of course, we need to decommision as many coal fired plants as possible, so with more efficient vehicles we'd need a lot less fuel. Bin the coal plants and keep the nuclear ones until we can come up with a better base load solution.
Posted by: Tripp | 30 September 2006 at 10:05 AM
Since coal is cheap and plenty of it is available domestically in the US, it's not going to go away. The immediate costs of global warming are not clear or high enough and, few decision makers in industry or government actually give a damn about future generations.
Ergo, there is some value in figuring out how to mitigate the GHG emissions of coal-fired power plants. Converting the CO2 to transportation fuels would not amount to sequestration, but it would reduce aggregate emissions from electricity generation + transportation.
However, the notion of building a gargantuan number of new nuclear power plants to achieve this strikes me as total lunacy. Global warming is a serious issue, but so is nuclear waste. Out of the fire, into the frying pan hardly amounts to a solution - in either direction, btw.
A more sensible approach might be to use that CO2 exhaust gas for the intensive aquaculture of oil or starch algae in non-stagnant pools located at an appropriate distance from the power plants. By controlling the extent to which the scrubbed flue gases are cooled prior to contact with the algae, the temperature of the water in the pools can be be kept high enough even at night and in winter. This would increase yields by raising the metabolic rate of the algae in the morning hours. (Part of) the enthalpy from the cooling process would be used to kill off and dry previously harvested algae prior to transport.
Posted by: Rafael Seidl | 30 September 2006 at 10:43 AM
The difficulty with petrolistic arguments against greatly increased nuclear waste production is that the fossil fuel wastes CO2, carbon dioxide, and CO, carbon monoxide, have a terrible record of numerous fatal accidents -- especially the monoxide.
Ashes from non-nuclear fuels routinely kill; nuclear ashes seem never to. They obviously could, but they just don't.
Moreover, the minerals from which non-nuclear fuels are made are ~100 times more expensive on a per-joule basis than uranium; and special taxes are levied on them.
Thus, the lives that are saved when nuclear fuel replaces them are saved at some cost to the tax-funded. This, it must be suspected, is what really concerns them.
Posted by: G. R. L. Cowan, boron combustion fan | 30 September 2006 at 11:49 AM
GRL Cowan -
carbon monoxide is clearly poisonous and was the cheif motivation for the introduction of oxidation catalysts for vehicles. There are also rules about the proper ventilation of household furnaces. Gas-related accidents at coal mines are sometimes associated with carbon monoxide but more typically with methane; again, proper ventilation is key. Carbon dioxide can be dangerous at very high concentrations, but those can only occur in unventilated enclosed spaces.
I cannot remember a single instance in the past several decades of fatalities due to either carbon monoxide or dioxide released in an accident at a power station. Of course, the accumulation of CO2 in the atmosphere is no accident - which is precisely why we must seek to curb its production so future generations will still have a planet worth living on.
The slag powder left over does need to be handled with care, since it is fine particulate matter. The higher grades are used as a supplement to Portland cement in certain types of concrete.
By contrast, the 1986 Chernobyl accident caused many deaths locally (some only decades later) as well as sterility and other ailments in the workers involved in the clean-up. The plume was first detected in Sweden but reached all the way to the UK, where it was blamed for a spate of livestock deaths. In Ukraine and Belarus, an area half the size of France (or Texas, if you will) is either entirely unfit for human habitation or subject to medical supervision. This situation will persist for centuries.
The events at Sellafield, Three Mile Island and Tokaimura all underline that even when operated in a culture of safety, there is a non-zero risk of an accident whose consequences could be serious and especially, semi-permanent.
Moreover, the problem of where to permanently store the spent fuel rods and/or reprocessed waste plus debris from future decommissioning efforts remains unsolved, technologically as well as politically. The costs associated with this legacy are usually grossly underestimated by nuclear advocates, in effect because they will have to be borne by future generations.
Posted by: Rafael Seidl | 30 September 2006 at 01:20 PM
If it is a choice between coal and nuclear I'll take nuclear. However that should be for baseload generation not as part of some chemical industry complex. When oil is gone let biofuels + electrification + conservation take over transport needs. If you agree with climate scientists we must put the squeeze on coal burning until half or more of present levels are banned. If some coal burning is unavoidable it should survive under a carbon cap. So far there is no convincing evidence that geosequestration or flue gas algae will work on a massive scale. As Lovelock points out if there were fewer of us the environment could cope with the emissions. Now it's a crisis.
Posted by: Aussie | 30 September 2006 at 02:25 PM
FORGET ALL THOSE NUKES...WHAT TO DO WITH THE RADIOACTIVE WASTE??? NOT IN MY BACKYARD!
Let's keep the coal fired plants (we have over a 200 year supply of coal)...gasify the coal...
use the fuel created from the gasification process of the coal to run the electrical turbines and use the GSCT CO2 Bioreactor to sequester the CO2 by feeding it to ALGAE (which thrives in high CO2 atmospheres)convert the Algae into Biodiesel & gasify the remainder of the algae not converted to biodiesel into syngas & convert the syngas into ethanol using the FT process...
http://www.gs-cleantech.com/product_desc.php?mode=3&media=true
Posted by: Tom Catino | 30 September 2006 at 05:15 PM
Can anyone tell me how you turn CO2 and H2 into ethanol? What is the chemistry involved and what kind of plant/lab/distillery/black box do you need to make it happen? Is this currently being done anywhere and if so what are the economics of it like?
Posted by: Matt | 30 September 2006 at 07:37 PM
Matt , the process is called "Coal to Liquids" or simply Gasification and uses a fairly old chemical process called the "Fischer-Tropsch Process" you can Google the terms for further research.Here is a description of how GSCT will use the technology
Biomass Gasification
When biomass is heated with little oxygen needed for efficient combustion, the biomass breaks apart into its molecular constituents, or it gasifies, into a mixture of carbon monoxide and hydrogen gas called synthesis gas, or syngas. This is similar to the process that occurs with wood in a fireplace. As the wood becomes very hot, it gives off its volatile gases – syngas – and it falls apart into a relatively low volume of ash. Because there is an open flame and ample free oxygen, the syngas emitted by wood in a fireplace combusts immediately and produces fire.
Gasification converts carbonaceous materials into syngas, and a biomass gasifier is a system that can gasify biomass such as coal, wood waste, municipal waste, or agriproducts into syngas. Importantly, syngas produced in a biomass gasification process can be converted into liquid fuels and other products through a catalytic chemical reaction called the Fischer-Tropsch process.
GS CleanTech’s biomass gasifier is designed to standardize variable biomass feeds and optimize high yields of high-quality syngas in real-time with greatly increased capital and operating cost efficiencies at smaller scales as compared to traditional gasification technologies. The syngas output of GS CleanTech’s gasifier can either be used to generate heat and power with standard generation equipment or catalyzed into liquid fuels such as ethanol or diesel substitutes with the Fischer-Tropsch process.
GS CleanTech is currently deploying its first commercial scale biomass gasification system and anticipates using the technology to add to the corn to clean fuel conversion efficiency by gasifying the remaining 16 pounds of defatted DDG in the above example and using the resultant syngas to generate electricity to offset virgin power consumption and to produce additional clean fuels with the Fischer-Tropsch process.
Posted by: Tom Catino | 30 September 2006 at 08:16 PM
Matt,
It takes high temperatures, but it's not all that difficult. CO2 + H2 react to give CO + H2O. Cool the CO + H2O in a counterflow heat exchanger (heating the CO2 + H2), and the water vapor condenses, leaving CO. Then add H2 to the CO, and you have synthesis gas--the "open sesame" to all kinds of hydrocarbon syntheses, depending on pressure, temperature, catalysts, and the H2 to CO ratio. Ethanol is the end product of one of the synthesis pathways, but it's not the easiest or most efficient.
The idea of burning coal to produce electricity, and then using heat and electrity from nuclear power to produce hydrogen to turn the resulting CO2 into a liquid hydrocarbon strikes me as a rather perverse way to approach CTL. It's hard to imagine it being more efficient than a straight CTL process driven by hydrogen and external heat. But perhaps the sunk costs of existing coal-fired power plants make it economically attractive.
Posted by: Silverthorn | 30 September 2006 at 08:37 PM
The water-gas shift is usually from CO + H2O to CO2 + H2, not the reverse. It's used to create hydrogen (from CO) to produce the hydrogen for hydrocarbon synthesis in F-T, among other things. At high temperature it can be driven the other way, but that's energetically uphill.
Posted by: Engineer-Poet | 30 September 2006 at 09:08 PM
Nuclear waste is much less of a problem than coal or oil waste. The only unsolved problems are politcal.
Rafael, your example of Chernoble, the only nuclear accident that killed anyone, is deceptive because, as you probably know, the nuke industry recognized it as an accident waiting to happen before it happened. It was government central control that produced that mess, not the nuke industry. In any case, nukes have an outstanding safety record.
Posted by: Freedom_First | 30 September 2006 at 09:29 PM
Seidl doesn't seem to disagree with anything in my first comment but offers a peculiar emphasis. If the past month, or the century so far, had seen some fatal nuclear accidents, would this, in his view, be mitigated by the existence of rules and principles aimed at preventing them?
He then rushes off to other matters, inexcusably failing to acknowledge the retreat. Yes, the 1999 Tokai-Mura accident had permanent consequences. Does this somehow distinguish it from the recent gas explosions in Germany?
Posted by: G. R. L. Cowan, boron combustion fan | 30 September 2006 at 11:26 PM
Rafael:
Thank you for bringing our attention to this terrible issue. In the time of Chernobyl accident I lived in Ukraine, and worked at university envirolab. I have my personal friends perished due to radiation exposure, and many of them are lined to grave yard prematurely as I print this message. Explosion and consequent fire of ONE OF FOUR reactors on Chernobyl power station was by far not the worst scenario accident. Couple of dozen firefighters suppressed reactor building fire and prevented fire expansion to other reactor’s buildings. All of them died terrible death in couple of days later. However, there was not reactor core run-out melt down, and total amount radioactive material being air borne was no more then 2% of total junk in the reactor core and surrounding adsorption panels. Still the release of radioactivity was million times more then in Hiroshima.
Whatever is being told about authoritarian USSR, in this case, with understandable two week delay, totalitarian measures mitigated the consequences of the accident quite effectively. Most of 3-million population of affected zone (mostly Kiev ) vas bullied to have all pregnant women to have abortion. Thousands of military conscripts by the price of their life and health made terrific job to close radiation emission of reactor’s rubble, and until up to date two reactors of Chernobyl nuclear plant (1GW each) continued to supply power to Ukraine economy. Price in life of the accident is clearly in hundreds of thousands, and couple of millions people’s health is seriously affected.
I am mortified to think that anything even remotely comparable (yet technically nuclear power station accident could potentially be 10 times more devastating) will happen in the West, where governments are inherently incapable to force anyone to patch the breach by their own body, as it was the cause in Chernobyl.
Posted by: Andrey | 01 October 2006 at 03:58 AM
"Global warming is a serious issue, but so is nuclear waste. Out of the fire, into the frying pan hardly amounts to a solution - in either direction, btw."
There is no way that GW is comparable to nuclear waste. GW is not just a serious issue, but is the most important environmental issue facing all human and non human species. Tons of nuclear waste have already been generated; a solution will have to found to store it regardless of whether we stop nuclear generation tomorrow or decide to ramp it up to mitigate carbon dioxide production. Coal plants are killing people and poisoning fish and other wildlife now. Although a highly improbable nuclear accident could kill thousands of people, that does not compare to the damage that global warming has done and will do.
If we are going to increase our reliance on solar and wind, we need a baseload to back that up. Let that be nuclear, at least on a transitional basis. Coal is killing now and is condemning the planet and its inabitants to a grim future.
I used to be against nuclear power, the main reason being that it would require a "nuclear priesthood" to take care of the waste for thousands of years. Well, while that is probably true, we will need that priesthood regardless of how we proceed from here. The cat is out of the bag and so we might as well make the best of it.
Posted by: t | 01 October 2006 at 07:33 AM
t, that's pretty much the tack I'm on as well. It's really a matter of the lesser of two evils.
Posted by: Tripp | 01 October 2006 at 09:02 AM
I heard that you could power Japan off the energy in the waste heat from US power plants. We waste so much it is rediculous. If we just went for efficiency (conservation has become a "treehugger" word) and used renewables we would not need any new nukes nor old coal plants. I am for upgrading coal plants to modern standards and replacing nukes that have been decommisioned. ZPG for nukes and IGCC for new coal plants.
Posted by: SJC | 01 October 2006 at 09:37 AM
Just wondering about the total efficiency of this approach:
electricity from nuclear: ca. 30%
*
hydrogen from electricity: ?
*
ethanol from hydrogen + CO2: ?
*
efficiency of ICE: ca. 25% ?
Compare this with a Plug-in hybrid car, where you still need to produce the electricity, but after that you have very good efficiency with storage in e.g. Lithium Ion batteries (I didn't find exact numbers, but my guess is about 95 % conversion efficiency) and back to electricity (ca. 95 % conversion efficiency) to power the motor (ca. 95 % conversion efficiency). In total about 85% conversion efficiency. This looks to me far better (and cheaper!) than the ethanol from hydrogen + CO2 approach with maybe 5-10% total efficiency.
By the way, the electricity does not need to be produced by nuclear, e.g. also wind turbines may do...
Posted by: Renewable Guy | 01 October 2006 at 09:54 AM
Actually, if you look at the heats of formation of the two sides, you'll find that the reaction is remarkably close to neutral. -396.3 kJ/mole for CO + H2O, vs. -393.5 kH/mole for CO2 + H2. It can be driven easily in either direction by the concentrations of reactants. High temperature has little effect on the equilibria, but is necessary for kinematics.
On another point, I agree with Renewable Guy that plug-in hybrids are a much more efficient way to go. The amount of liquid hydrocarbon fuel we will need after PHEVs become common will be less than a third of what we're currently consuming. But we will still need some, and synthesis from hydrogen and CO2 is a feasible way to get it.
One good source of CO2 that hasn't been mentioned is the manufacture of cement.
Posted by: Silverthorn | 01 October 2006 at 01:17 PM
Actauly what they realy want to do is position a type 4 nuke plant and a 0 emssions coal plant together. The type 4nuke plant produces even more power then a type 3 did and produces a rather large h2 stream as well all with the same fuel as used by the type 3.
Now rather then count on h2 being used directly they burn the coal making co2 and then combine the co2 from the coal plant with with excess h2 from the nuke plant and a ton of waste heat from the nuke plant and boom you have a liquid fuel and all the power from both the coal and nuke plants.
Of course the instant that ehtanol gets burned the co2 gets into the air...
Posted by: wintermane | 01 October 2006 at 02:34 PM
Maybe you don't know that the new nuclear reactors RECYCLE the waste and lead to ZERO emission! U238 to Pu239 and so on...
Nuclear is the ONLY future solution! The cleanest and safest in all ways! Keep that in mind!
Posted by: Cuny | 01 October 2006 at 04:01 PM
Maybe you don't know that the new nuclear reactors RECYCLE the waste and lead to ZERO emission! U238 to Pu239 and so on...
This is nonsense. All nuclear plants produce fission products, which are not recycled. Breeder reactors that would produce as much Pu as they consume have proven to be unreliable and uneconomical. Even reprocessing thermal reactor fuel is economic idiocy -- the Pu extracted has negative value, since the cost of fabricating fuel from it is higher than the cost of the enriched uranium it replaces. By the way, even advanced reprocessing will still leave .1% of the actinides in the waste stream, so it most certainly will remain dangerous.
However, I disagree with the earlier poster who pulled his hair over the waste issue. The most obvious thing to do with spent fuel is seal it into dry casks and let it sit. Don't reprocess, don't bury. Eventually, centuries down the road, we may want to do something else with it, but the technology of that distant time will be far advanced over our own (if not, at least we've delayed the cost of performing the current solutions while the waste became easier to handle).
Posted by: Paul Dietz | 01 October 2006 at 04:16 PM
Silverthorn,
Thanks for the information. The CO2 + H2 -> CO + H2O was the step I was missing. I agree that it seems like a waste to use CO2 from coal to generate the CTL. If we could get the CO2 from somewhere else, that would be better. On the other hand, if the coal is already being burned might as well use all of that concentrated CO2 for something.
Renewable Guy,
I don't know the answer to your question, but it is a good one. Checkout this slideshow from Tesla Motors. It compares wells to wheels energy use for electric battery cars with other forms of alternative fuels. The EVs always come out a head by a long shot.
Posted by: Matt | 01 October 2006 at 05:05 PM
You can pull CO2 from the atmosphere by chemical means, for example:
http://adsabs.harvard.edu/abs/2002AGUSMGC31A..03D
Blueskying here:
Nuke power to suck CO2 from the atmosphere, pull H2 from water, run reverse water-gas shift reaction to make syngas and from there FT reaction to produce artificial liquid fuels.
Could this be a way to at least partially address the approaching liquid fuels crisis and global warming at the same time: manufacture liquid hydrocarbons using carbon extracted from the atmosphere?
Posted by: Steve | 01 October 2006 at 06:46 PM
You can take CO2 from the air using plants. Just gasify biomass, extract the H2 and sequester the CO2 in empty NG wells.
Posted by: SJC | 01 October 2006 at 08:18 PM
Hello, Silverthorn! Small world.
Yes, Steve, that's the "nuclear gasoline" plan. Like many another scheme, it could definitely work, with much lower environmental impact than any Earth-based renewable approach, so it definitely allows postponing an all-renewable energy economy for many centuries to many millennia. A minor variation would be to hydrogenate CO2 to methanol and then polymerize and dehydrate the methanol.
Posted by: G. R. L. Cowan, boron combustion fan | 01 October 2006 at 11:57 PM