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Catalytic Carbon Extraction in Fuel Cell Production?
garyebickford asks: "I've been following the discussions in the media regarding fuel cells & hydrogen fuel. I have an idea (really a set of ideas) for handling the CO2 issues, which could make fuel cells a better solution. Perhaps someone who know about such things can tell me whether it's workable or not. Speculating wildly, if the carbon could be retained in the process (in a discharge tank, for instance), then it might even be useful as a feedstock for plastics, for example. How might a fuel cell process (both production and use), possibly multistage or incorporating a catalytic pre-process, emit carbon in non-gaseous form? What about a fuel cell that just converted ethanol or higher weight hydrocarbons to methanol, or perhaps a nitrite or another byproduct? Consumers could then recycle this waste to the fuel station at the next fill-up. Even this incomplete process can provide more energy per weight or volume than hydrogen, in theory. Would such a process be possible, or feasible?"
"Many fuels can be used in fuel cells, including hydrogen, methane/methanol, ethanol, and ammonia. One of the problems with all these, in fact any system that consumes hydrocarbons (either biomass or petroleum), is that at some point in the process the carbon is released as carbon dioxide. For H2 and NH3 the problem is in the production facility; for hydrocarbon fuels the fuel cell itself emits carbon in some form. Perhaps fuel cell research has tended to think in terms replacing the existing combustion model, with the given that output will be H2O and CO2. Is anyone studying the possibility of fuel cells that have other output chemistry?"
Build the fuel cell into a laser printer, and have it dump the carbon dust right into the toner cartridge. :)
Do it so I can plug my computer and display into it, and power them too, and I'll buy two.
I have a layman understanding of physics. This means I can read about advances in the field of physics and sometimes understand what is going on. This does not mean that I can propose new ways of looking at things in the field of physics. Why? Because every physicist has a layman's understanding of physics. Anything that you can come up with, they've already thought of it.
Thankfully this doesn't happen in computer science very often. It does happen though. I remember having a long conversation with a guy who thought he had a great idea for a replacement for floppy disks (this was pre-USB). His idea was that the monitor could read the data from a device people carry around. At first I thought I misheard him. Then I calmly explained to him that monitors are output devices, not input devices. Then he asked what the difference was. Eventually he turned red and asked how you could do it. We had a discussion about flash memory and interface standards and then he got bored and went away.
Which is typically the flow of these conversations, so excuse me for not entertaining your brilliant idea.
How we know is more important than what we know.
Combining Carbon with Oxygen or Hydrogen with Oxygen produces energy - but splitting up a chain of carbon and hydrogen to get the individual atoms to do that with requires some energy, though it's a lot less than burning the C and H will provide. Catalytic Converters on cars take the unburned hydrocarbons in the exhaust, split them and burn them before they get out the exhaust pipes, and take partially burned carbon monoxide and finish burning it. It's a waste of energy, but it was going to be wasted anyway - the reason to do this is that hydrocarbons and CO lead to air-pollution problems including smog. (They also split various nitrogen oxides to give nitrogen and oxygen; I don't know if this is exothermic or if it's using heat generated by the other reactions.)
You can't split the CO2 up into C and O2 without putting back the energy you got out of that reaction, so a catalytic converter won't help you. You could do things like combine it with calcium oxide to make calcium carbonate, and store that, but the usual way to make calcium oxide is by heating calcium carbonate to get rid of the CO2, so that's really no help.
Bill Stewart
New Fast-Compression-only CPR http://preview.tinyurl.com/dy575ks
Yeah.
On of the big questions you have to ask yourself is, "What problem am I trying to solve?"
The real problems facing fuel cells-the reasons why fuel cells aren't widely used-are the cost of producing them, and the difficulties in creating fuel. You're not trying to address either of those issues. In addition, you advocate replacing hydrogen fuel cells by fuel cells based on different chemisty. Making hydrogen fuel cells cheaply is hard. Now you're adding in a different, potentially brand new chemistry - you can't just throw any old fuel into a fuel cell and expect it to work, the entire design would potentially need to be reworked, which means that your fuel cells are even more expensive.
The other question is "Why bother?" Whatever non-CO2 carbon byproduct you make, it'll yield much less energy than if you completed conversion to CO2. For what gain? High CO2 emissions aren't hurting current energy generation techniques. Due to efficiency over internal combustion, just converting to regular fuel cell will reduce the CO2 emissions at the end use point anyway.
You also ignore the regeneration of the waste. What chemistry would you use? Where would you get the energy from? If from fossil fuels, you'll still be generating CO2 - probably more than what would be generated by burning the fossil fuels directly, due to the second law of thermodynamics. If from biomass, the CO2 question is moot - the CO2 you release today is going to be reincorporated into plants tommorrow (and thus into your fuel in a week). Zero net CO2, and you don't even have to collect any waste. If the energy is from solar/wind/hydro/nuclear, you can generate H2 directly without CO2 discharge, or can create hydrocarbons/alcohol from CO2 and H2O (so you'll get no net gain in CO2 upon complete combustion).
In short, the problem you're trying to solve is not currently limiting anyone in any fashion, and even if CO2 emiting fuel cells were in popular use, your proposed techniques likely would be either superfluous or distinctly counter-productive.
You can reduce more complex things like carbon dioxide or hydrocarbons to carbon with a reaction known as reduction if you have heat and something to react with. Something like hydrogen at a hot enough temperature and pressure will do it (from hazy memory) - but since the point is to have an energy source that doesn't produce CO or CO2 you don't want to consume more energy cleaning things up than you get out of your fuel.
Methane probably has more energy in it than gasoline. It has four high-energy hydrogen bonds while gasoline only has something like 2 per carbon, and the weight of a purely hydrogen and carbon hydrocarbon is pretty close to proportional to the number of carbons. Hydrogen gas has a LOT more energy in it than gasoline per unit mass. They used to power the Space Shuttle booster rockets with it before they switched to solid state fuels (Think plastic explosives). They might not have switched at all, except that they need oxygen to burn it with.
This is what is known to the world as Carbon Sequestration, and in fact many very important advances need to be made in this arena. So far, it seems that Germany is leading the world in this area, especially with their development of a carbon-emissions-free coal power plant (by actively capturing carbon in the process.)
While I don't see much good in utilizing hydrogen-carrying fuels over non-carbon-emission methods including hydrogen itself, since one set of methods creates Carbon Dioxide and another set creates water (I hope someone starts an electrolysis debate), you'll still get mad props and points (at least from people like me) if you can get this to work, because I don't see how it could really be problematic especially due to the numerous capture-condusive properties of carbon in its many molecular forms.
This field of research is ripe for harvest, and I'd be willing to bet there are a lot of financial backers willing to invest in working demonstrations.
--I gots 99 problems but a new machine ain't one!
AMD! Asus! Whoot! 6 years!
Put a gaseous carbon in a balloon.. dip it into liquid nitrogen... the balloon will shrivel like cojones in alaska. . Not you could achieve that without using more energy than the fuel provides like you said.. If it were a liquified metalic salt you could plate it. . Isn't that kind of what those "Ionic Breeze" things do? Is carbon plated on the "collection grid?" It's just an ion engine right?
Alright, so I'm a molecular biologist and I work with a bunch of chemists and biochemists on alternative fules. So, I have some expertise on this, but not enough that I couldn't be understood (think it though). So, here's my understanding. First off, fule cells don't make CO2, that's their big advantage. They convert H2 and O2 into H2O. If they did (and it's possible to design one that does, if you make the hydrogen on the spot from coal, which is one way to avoid running around in a car with a pressurized H2 tank) then it would take energy to pressurize the CO2 for later reclamation. This energy would be taken off of the energy efficency of the car and likely render it less than efficiant. If it used a catylitic process to turn ethanol into ethyl aldahyde and liberated hydrogen (as is possible with enzyme aid, I'm kind of working on that problem), then it would be possible to use the spent ethylaldahyde later to regenerate ethanol for further use. There are two problems: First, this is all equilibrium chemistry. That means that you need a greater concentration of ethanol than ethyl aldahyde to make the reaction proceed forword (for the technical folks, I'm symplifying here, don't complain). That means that if you want the car to use more than half a tank of fuel and you want to seperate the byproduct for reclamition, you need some way to seperate ethyl aldehyde (or whatever) from the ethanol. How the hell do you do that? Current ways of doing this are large, expensive, and energy intensive. It could happen in the future (in theory), but we have no current means. Second, converting the byproduct (ethyl aldehyde) back into ethanol is an energy intensive process. We have no current easy and environmentally friendly means of doing this. One possible future hope (which I would like to develop and exploit in about ten years) would be to bioengineer photosynthetic bacteria to harness sunlight to convert these byproducts back into their fuel product, and then use some purification process (as yet undefined, see above) to reprocess them into stock fuel. Such bacteria does not yet exist, nor (to my knowledge) do the enzymes necessary to make it function. So, in short, yes what you propose is possible. No, it can't be done yet, nor in the next five years. I hope to see such a scheme comming along to market in possibly twenty years, at best. Even then, such a system would only be a very complex and efficient battery for storing the energy of the sun (as all renewable life and fuel is). This would limit the total energy expenditure possible to a maximum of the amount of energy poured on the earth by the sun. We are already dangerously close to using that amount of energy, in twenty years we will likely be using more and all of our various renewable energy schemes will be insufficant. We have only two options, conservation or fusion power (or malthusian disaster, but no one likes that one). I leave it to the rest of you to choose which.
Let's making diamonds!
Electric vehicles are 3 times more efficient, 2.5 times cheaper today (although still too expensive), today Li-ion EVs have better range than Honda's FCX, refuelling won't be a big issue since Li-ion batteries can be charged pretty quickly these days (like within minutes to 80% capacity) but it doesn't really matter because 80% of our driving is within 35-ish km's anyway.
Hydrogen fuel was proclaimned to be dead 2 weeks ago at the Lucerne Fuel Cell conference because it is not sustainable (since EVs are 3 times more efficient). Another fuel that is not sustainable is ethanol by the way, even cellulosic ethanol because of nutrient depletion.
I have an idea where we take the CO2 from the air and convert it to sugars and other chemicals needed to sustain the reaction in reactor that I call a Photosensitive Living And Natural Thing (PLANT, for short). The PLANT device catalyzes the carbon into long chains made up of broken down water molecules, so you have chemicals made with H, O and C. Let's call those "hydrocarbons". Then, we extract them, mix them with some other PLANT-derived chemicals (say something like C2H5OH), and end up with an energy-dense liquid. This liquid can then be placed in tanks, pipelines, or directly into some (wise) consumer's vehicles.
We will call this miracle chemical "Bio-Diesel".
45-50 mpg in the VW TDI, and my exhaust smells like french fries, baby!
I want to delete my account but Slashdot doesn't allow it.
I have a cocksure attitude towards just about any subject you can think about. This means I can read someone's legitimate musing on a subject and sometimes (quite often, actually) trot out the tired old "oh, if that could have been done don't you think someone would already have done it?" straw dog (and trash it soundly!) That does not mean I can keep my big flapper shut. Why? Because I have to make myself at least feel like I'm superior to each and every egghead or eggheaded notion I encounter. Anything that you can come up with, I can slap with my little label and make myself feel superior.
So excuse me for not entertaining your brilliant idea, I'm too busy nursing my sprained arm.
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This is a bit outside my area of expertise (diesel emission catalysts), but if you want to dive deeper into this, start with these topics:
Fischer-Tropsch synthesis
Bosch reaction
Sabatier process
All have decent Wikipedia entries.
Chemically, I think the proposed process would be possible (i.e., you can do it in the lab.) Economically, it's probably a non-starter for this type of application. The biggest challenge in these areas is making it small, mobile, low to zero maintence, yet still inexpensive.
CO2 released after combustion (clean combustion) is the result of enough heat, presure and other activation energy on the fuel.
It is, by all practical purposes the lowest energy state you can have with those items in mixture (Carbon, Oxygen).
This is due to the fact that Oxygen likes to bond to stuff.
Getting the carbon apart then, will take energy. Which without additional fuel additives means a catalyst won't work. The heat of oxidization of the carbon has been released and you can't re-pack heat energy without adding another endothermic reaction (additional stuff) or some other work (heat pump, etc.)
Carbon, after all, is a fuel you could use to cook tasty steaks on... CO2 in gaseous or solid form is not.
You are much better off trying to get the absolute cleanest burning possible, best efficiency, and finding an efficient and renewable way to fuel the system in the first place.
Thermodynamics and entropy say there is no free lunch. Don't mistake your poop for peanut butter and put it back on your sandwich.
First off, it depends on your fuel source. Are you considering C or CO as the fuel source?, then no, you'll need to attach O to it to get any energy out at all. CH3OH (methanol) would probably work, but won't have the energy of pure CH4. If you're thinking CH4 as a fuel source, then it should (in theory) be possible to strip the H from the C, combine it with O for power, and retain the C as (solid) waste.. it all depends on whether you can develop a process that gets more energy out than it needs to put in. Cracking H off C is typically done with very high temperatures, but if you don't loose any of it as waste heat, it should be farily efficient. I've read of efforts to create an efficent, small-scale cracker, but clearly it it isn't ready yet (if it were, we'd all know about them by now).
So, can it be done? With the right fuel, theoretically. However, the engineering to turn theory into an energy efficient solution is the whopper. Give it some thought.. look up the process of cracking H from hydrocarbons and see if you can build an efficient cracker. Realistically, you don't have much chance -- there's a lot of equally bright people out there trying to solve the same problem with better training and better funding.. but that doesn't mean you won't combine some other knowledge you have into a novel aproach they haven't thought of.
Oh, by the way, solid C is useless as a plastic feedstock.. plastics are polymerized hydrocarbons, so you'd need to add H to the C and then polymerize it, which is a net-endothermic process. Doesn't mean ubiquitous quantities of solid C don't have some value.. just not that one. You could reintroduce it back into the geologic C cycle at a point where it'd take a long time to get released (e.g. dump it in the ocean.. environmental impact aside).
Caveat.. I probably don't know what I'm talking about :-) It's been many years since I was looking up reaction energy requirements of reactions and messing about in chem labs with CO fuel cells.. I've probably forgotten more than I ever knew about it by now.
So if you can get carbon monoxide out of the process - say by incomplete conversion of methanol - you can copolymerize this using late metal catalysts with something like ethylene to make alternating ethylene-CO copolymers. Not really anything useful though....
I thought it was a good idea
Capturing carbon from the air is the hard part. If you can keep hold of that carbon and recycle it without diluting it by three thousand to one and re-concentrating it, you've saved yourself a huge amount of effort (and not having to discard the entropy saves a huge amount of energy).
Switchgrass is far less efficient than PV panels, and some schemes yield photolytic hydrogen. If you can turn e.g. methanol and oxygen into CO2 and H2O at one end, and CO2 and hydrogen into methanol and H2O at the other, you've got a cycle which can produce far more energy per square meter than a field of grass. The only thing you'd use grass for is to feed carbon into the system and replace losses.
Sustainability and energy independence essay
I've always wished there was a way to recharge a battery simply by emptying the acid out and refilling it with fresh acid, then recycling the spent acid. But unfortunately, that's not the way batteries work, it's the metal plates that are chemically altered in the process of making electricity, not the acid.
If only someone were to devise a fuel cell that has a fresh liquid input and used liquid output, or even a Part A and a Part B mixing in the cell, and spent Part A+B coming out that could be reversed back into Part A and Part B.
Yeah, yeah, I know, hydrogen and oxygen are the Part A and Part B and water is the A+B that comes out of present day fuel cells, but what I'd like to see is something that stays liquid at room temperature and atmospheric pressure that can be replenished with the ease of self-serve, and can be recycled with the ease of pouring the spent juice in a big tank, and pipe it into a reformer that recharges it (or separates it back into the two components and fills up two smaller tanks) at the same rate that you can charge a typical battery. And of course, the reformer could be run off of anything from solar power to nuclear power and everything in between.
I work for a large global company as an R&D engineer and have a material science background. The problem with Solid Oxide Fuel Cells and PEM fuel cells is that they are so efficient that there are no solid wastes. There is little to no CO2 output in the case of the SOFC either due to highly efficient reations in a properly made cell. The by products are H20 and pure heat, at about 800C to 1000C. Fuel cells have not taken off yet only because of the cost to manufacture. We are addressing this now. We will make them cheaper, and this will make them economical. I'd expect to see the first systems in Europe in about 2-3 years. Within 10 years the technology should be widespread. SOFC's can burn methane (natural gas) no problem. they are even more efficient burning pure hydrogen. However, coming up with the source fuels is not an easy thing to do. So, the problem with fuel cells is: Nickel Oxide, YSZ, and LSM/LSCO variants are expensive materials to make fuel cells that need to replaced every couple of years. If they do become cheaper and "economically viable" - where do you get the increased demand for methane/NG/biogases, etc.
"To the best of my knowledge, a chemical reaction that "burns" must include a hydrocarbon."
Not at all. Hydrogen is not a hydrocarbon. Ever see a shuttle launch?
"Burning" is an exothermic reaction. You don't even have to have oxygen. You can burn Hydrogen with fluorine and get a pretty good flame and a lot of heat.
Yes CO burns very well. It was a common component of coal gas that was used for lighting in the 1800s. You can also burn a diamond in a pure oxygen atmosphere. You can even burn steel. Take some fine steel wool and you can actually light it and get a flame.
So yep you where totally wrong. Your redeeming statement was "To the best of my knowledge" which shows a willingness to learn.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.