Researchers Propose On-Board Fuel Processing with Carbon Capture for Zero-GHG, Hydrogen-Fueled Combustion Engine Vehicles
11 February 2008
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| The vision of a sustainable carbon economy for transportation relies on the on-board conversion of a liquid hydrocarbon fuel with CO2 capture and recycling. Click to enlarge. |
Researchers at the Georgia Institute of Technology are exploring a conceptual strategy to capture, store and eventually recycle carbon dioxide emissions from mobile and small distributed stationary sources—such as automobiles, transportation vehicles and distributed industrial power generation applications (e.g., diesel power generators). Nearly two-thirds of global carbon emissions are created by such mobile and stationary sources.
Georgia Tech’s strategy involves using an on-board fuel processor to reform a liquid hydrocarbon fuel (fossil or synthetic) to produce hydrogen to power the vehicle or stationary source. The carbon in the original fuel is captured and stored on board in a liquid form, until it is disposed of at a refueling station.
While the researchers see the carbon then being transported and sequestered in the short term, for the longer term they propose recycling the captured carbon back into a synthetic liquid transportation fuel to complete what would become a close-loop cycle.
The Georgia Tech team has already designed a fuel processor, called CO2/H2 Active Membrane Piston (CHAMP) reactor, capable of efficiently producing hydrogen and separating and liquefying CO2 from a liquid hydrocarbon or synthetic fuel used by an internal combustion engine or fuel cell. After the carbon dioxide is separated from the hydrogen, it can then be stored in liquefied state on-board the vehicle. The researchers have filed a patent application on the device.
The fuel processor produces the hydrogen on-board the vehicle from the hydrocarbon fuel without introducing air into the process, resulting in an enriched carbon byproduct that can be captured with minimal energetic penalty. Traditional combustion systems have a combustion process that combines fuel and air—leaving the carbon dioxide emissions highly diluted and very difficult to capture.
We had to look for a system that never dilutes fuel with air because once the CO2 is diluted, it is not practical to capture it on vehicles or other small systems.
—David Damm, lead author
The research, funded by NASA, the US Department of Defense NDSEG Fellowship Program and Georgia Tech’s CEO (Creating Energy Options) Program, was published in Energy Conversion and Management.
The Georgia Tech team compared the proposed system with other systems that are currently being considered, focusing on the logistic and economic challenges of adopting them on a global scale. In particular, electric vehicles could be part of a long-term solution to carbon emissions, but the team raised concerns about the limits of battery technology, including capacity and charging time.
And while liquid-based hydrogen carriers could be conveniently transported and stored using existing fuel infrastructure, the distribution of gaseous hydrogen would require the creation of a new and costly infrastructure of pipelines, tanks and filling stations.
Resources
David L. Damm and Andrei G. Federov, Conceptual study of distributed CO2 capture and the sustainable carbon economy. Energy Conversion and Management, Article in Press, Published online doi:10.1016/j.enconman.2007.11.011
GA Tech MITf Research Overview Fall 2007
US Patent Application #20070243127, Hydrogen-generating reactors and methods
Apparently, the hydrogen highway has no off-ramps. No proposal, no matter how abstruse, is ever nipped in the bud. On-board fuel reforming plus carbon capture just so you can run an ICE on H2? Please, with stationary sources such as coal- and gas-fired power plants plus heavy industry plus home heating plus fossil fuel production (incl. gas flaring) all belching vast quantities of CO2 into the atmosphere, it makes no sense whatsoever to invest this much into eliminating CO2 emissions from mobile sources - which are by far the most expensive to clean up. Always pick the low hanging fruit first.
Meanwhile, focus on reducing vehicle weight and running cars directly on genuinely renewable hydrocarbons and/or electricity. Minimize the amount of energy consumed in vehicle production and the number of energy conversions in their operation. Complexity kills not just reliability but end-to-end efficiency as well. Biomethane is a good place to start, as are alcohols from cellulose, BTL plus hydro and (buffered) wind and solar power. The direct cost will be higher than for fossil fuels, but waging war for oil in faraway places is not free just because it's your children and grandchildren footing the bill.
In addition, focus on reducing annual mileage so those genuine renewables can represent a substantially larger share of the energy supply for the transportation sector. That implies urban planning and road design optimized for fuel economy, e.g. roundabouts instead of four-way stop signs, bicycle lanes, publicly accessible electricity outlets and especially, urban densification. All of this is much easier to achieve in greenfield developments but up to a point, existing communities must get creative and do their part as well - even if their policies take decades to deliver the desired aggregate benefits.
Posted by: Rafael Seidl | 11 February 2008 at 04:31 PM
overly complex- instead of using a hydrogenated carbon liquid as the hydrogen carrier why not zinc, aluminium or magnessim pellets (or pastes) in a metal-air fuel cell? It would be more energy efficent and much simpler to recycle.
Posted by: Ben | 11 February 2008 at 05:03 PM
An attempt to avoid the problems of distributing and carrying H as a vehicle fuel.
IMO Rafael has the right take on this. i.e. for vehicles it seems complex. And unlikely to be either efficient or affordable.
The refueling station gets some sort of carbon based or saturated liquid and then sends it where? For what purpose?
The capture mechanism might be better suited to ships. OTOH ships might just adopt liquid H as fuel and avoid any and all carbon headaches. (they have the room for large well insulated tanks)
Posted by: K | 11 February 2008 at 05:09 PM
LH2 tanks on a ship might be a bad idea: if water makes contact with the tank wall the heat transfer will burst the tank and the vaporizing hydrogen will expand explosively and if there is an ignition source in that blast then its a double BOOM!
Posted by: Ben | 11 February 2008 at 05:18 PM
Next time I'm down at Georgia Tech I'm going to ask them to look into harnessing the energy generated by people moaning every time a story about hydrogen is posted on here. God knows that is both abundant and renewable.
Posted by: Matthew | 11 February 2008 at 05:27 PM
Hey Hydogen may become the future fuel by shire force and hype, be dammed if anything else is easier to implement or is more energy efficient.
Posted by: Ben | 11 February 2008 at 05:45 PM
Hey, why not put some bio-reactors on the roof to grow algae from the CO2 then put a bio-fuel extraction processor in the trunk ;)
Posted by: Neil | 11 February 2008 at 06:24 PM
Just asked God and she knows "nothing."
But it was worth the try.
Since when did mobile mobile and inustrial uses amount to 66% of global emissions.
God did confirm however that H accounts for slightly more or 68.5% of global B.S. emissions.
Posted by: arnold | 11 February 2008 at 06:32 PM
I also think that Rafael is on the money here. The problem in the short term is not the micro scale (individual vehicles) but at the macro scale (what fuels these vehicles and how efficiently they are used).
I would love to see some theoretical efficiency numbers for their (GT) strategy. I'd be curious about energy density as well. After all, much of the energy stored in a hydrocarbon is in the form of....CARBON. Right? C42H86: don't burn the carbon and you forfeit a lot of energy (too lazy to do the calc). Perhaps GT doesn't count the carbon as an energy loss because it is "still available" after the hydrocarbon is processed?
Surely, as Ben said, storage in the form of aluminum or zinc would have to be better/denser.
Posted by: GreenPlease | 11 February 2008 at 08:09 PM
Rafael
I agree with you, this proposal is so complicated that it would be just as costly as it woul be inefficient and as you point out, CO2 from transportation are just 25% of total emissions so much pain for little effect.
As for hydrogen based transportation where you first have to make electricty then to convert it to H2 then convert it back to electricity, it just doesn't make any sense. And to achieve this you have to spend trillion of $US to developp: efficient electrolysis, storage inboard, fuel cell, and eventually high tech pipe to carry the hydrogen, each of these development being a tremendous challenge, when in the same time you just need to spend a few billioms $ to improve the performances of battery to have PHEV vehicles that will be zero emission most of the time.
Posted by: Treehugger | 11 February 2008 at 08:16 PM
There are 3 things you can count on;
1. Death
2. Taxes
3. The PTBs (powers that be) doing anything to maintain the Status Quo.
Who's funding this "research?"
Oh yes the Government (by way of NASA and the US Department of Defense)
Posted by: ai_vin | 11 February 2008 at 08:37 PM
Engineering by a Dr. R. Goldberg.
Posted by: Cervus | 11 February 2008 at 08:43 PM
This looks like an oil-industry attempt to convince folks that gasoline can be carbon-neutral, therefore Nothing Needs To Change (at least, nothing that would threaten their revenues).
We'd be a lot better off with PHEV's charged by carbon-sequestered plants, and biofuels for the rest. That said, it is damned clever.
Posted by: Engineer-Poet | 11 February 2008 at 09:32 PM
Keep it simple s......!
Skip hydrogen vehicles altogether, and go all electric. Sequester carbon to grow algae, to make biodiesel, to generate electricity, to transmit on existing power lines, to charge vehicles and light the world. Carbon generated goes back to growing algae, the worlds fastest growing plant, that is half oil. Using, www.valcent.net, vertigro, closed loop system, where they claim, one acre of non productive land can produce 33,000 gallons of biofuel, a year, compared to 18 gallons of corn, taken off of the dinner table. Excess electricity can be stored on site as hydrogen to make more electricity for peak demand. Half the worlds aircraft fleet can be replaced by high speed maglev trains. The other half can be fueled by low emission algae biodiesel. Simple!
Posted by: solarnano | 11 February 2008 at 09:41 PM
All these proposals to increase the density of population just so that the people in the dense area don't move around too much, completely overlooks the need to provide these citizens with goods brought from outlying regions and and provide waste removal back to those outlying regions for processing. In any case, the volume or quantity of inbound or outbound materials to be moved, doesn't change.
IOW, It still takes as much energy to move the mountain to a centralized collection of Mohammed's as it does to move the mountain to a decentralized collection of Mohamed's. Probably more so with fighting congestion, and other concerns.
It just makes it more difficult to do and more dangerously concentrated to mishap.
Posted by: Stan Peterson | 11 February 2008 at 11:40 PM
To all the guys that are so keen on algae : where do you plan to get all the CO2 for you algae farm ? At the moment, it is all coming from fossil carbon, so using the carbon only twice before dumping it into the air.
If these engineers think they can make what they tell, I might buy one once.
Consider that if you use H2O as the oxygen source for oxydising the fuel, the lost energy in the oxidation of the carbon is minimal. So, for every carbon atom, you get four extra hydrogen atoms.
A small convertor could convert it, and directly fueling the H2 to a fuel cell and to electricity. This could be the perfect range extender for a plug-in electric car.
Since the total efficiency (fuel to miles) would probably be at least double that of an ICE, a small fuel tank could deliver the same disance as a large one with an ICE. So there is plenty of room for the extra H2O tank and CO2 tank. Since the fuel and water are liquid, it will not take extra energy to liquify the CO2. Moreover, since the pressure of liquid CO2 is much lower than that of liquid hydrogen or even LPG, the tank can be made cheap and light.
I could even imagine using another compact unit (at home or at the fueling station) converting the CO2 back to liquid hydrocarbon using water and (solar) electricity.
Since you start with normal fuel, such cars can be used initially where the CO2 can be recycled or sequestered cheaply. As the marked expands, its use can be expanded also.
Don't just shoot the idea at the moment, this might be very convenient soon.
An adequate carbon tax on any fossil fuel can be a good incentive to use biofuel to start with, and then recycle it over and over again. Cheaply and safely.
Posted by: Alain | 12 February 2008 at 03:44 AM
Hey Folks,
I think you may be missing the point about bioalgae fuels. You don't need fossil fuels. Bioalgae makes the fuels you need to have all electric transportation and power for all of our electric needs. The carbon emitted by the electric generators never invades the atmosphere as it goes directly back into a closed loop system to grow more algae and generate more power over existing powerlines. Clean, clean , clean and no fossil fuels. You don't even need fossil fuels to start the system. Just use recycled vegetable oil from the fryer. Simple!
Posted by: solarnano | 12 February 2008 at 05:19 AM
Chrysler did run the NECAR fuel cell vehicle on hydrogen reformed from methanol and it worked. I do not know how cost effective it was, but it got around the high pressure H2 tanks.
Some fuel cells like Franklin SOFC can take liquid fuels right into the stack after being vaporized. I think that they just wanted to see if this could be done to provide another option.
Posted by: sjc | 12 February 2008 at 07:01 AM
Its a simple plan realy.
1 Take the military side project of an ALL fuels car/truck that can both run on any liquid fuel AND provide h2 for an apu with a civ side eventual co2 capture tech. Not exactly subcompact friendly BUUT rather good for say converting busses trains ships blah blah blah.
Posted by: wintermane | 12 February 2008 at 08:24 AM
This is like doing dentistry through the nose. There is an easier way: EV.
Posted by: DS | 12 February 2008 at 08:38 AM
This is a case of putting the feedbag on the wrong end of the horse. Biofuels can be carbon neutral much easier than trying to convert 100s of millions of cars.
By not using the carbon's energy means you will use much more fuel per mile plus the cost of the reformer plus the cost, weight, and space penalty of carrying around all that CO2. It is amazing how dumb some highly educated people can be.
Posted by: tom deplume | 12 February 2008 at 09:07 AM
Wow, seems to be a pretty inefficient idea.
A Direct Carbon Fuel Cell (DCFC) would be much more feasible, because it yields a highly pure CO2 stream. It's also twice as efficient as other fuel cells.
Moreover, it allows you to use biomass directly, at 80% efficiency. If you capture the CO2 from biomass and store it, you go carbon-negative... and you would actually be taking historic CO2 out of the atmosphere!
A closer look at Direct Carbon Fuel Cells: the ultimate biomass conversion technology?
Posted by: Jonas | 12 February 2008 at 09:29 AM
Thank you Rafael.
Posted by: Emphyrio | 12 February 2008 at 10:44 AM
==I think you may be missing the point about bioalgae fuels.==
I think you're missing this point.
Photosynthesis if a very thermodynamically inefficient way to capture sunlight.
greyfalcon.net/algae4
greyfalcon.net/algae
greyfalcon.net/sugarsolar
Much of the hype you hear about Algae is hugely exaggerated. (Or has since been redacted. "PhotoBioReactors" for instance)
Posted by: GreyFlcn | 12 February 2008 at 11:10 AM
I am with Matthew here. Harness the energy from the people moaning about hydrogen stories. That would be massive.
This idea is just one path, of which there are many paths, into changing the way our vehicles are powered, and should be looked upon as such. Real solutions, and the benefits they give, will be determined by pure economics of the solution. Ultimately, I feel electric vehicles will be our future, powered by what is to be determined.
I would much rather see many varying ideas being brought forward than putting all our energies into one solution, such as the biofuel corn derived ethanol (gasohol) solution, which will have many far reaching negative implications in our not too distant future.
Perhaps some major breakthrough in hydrogen generation, storage, or refueling is just around the corner. Then we will be in!
Posted by: Mark A | 12 February 2008 at 11:32 AM