It seems that with recent advances in battery and capacitor tech the future of fuel cells appears to be dim...in spite of the hundreds of millions of dollars already spent on it. If the new breed of batteries developed by Altair and Toshiba can be recharged in minutes, what need would there be for fuel cells...particularly in the case of vehicles???
http://www.newscientist.com/article.ns?id=dn7081

fuel cells can still be 60% efficient.. thus they can be used at charging stations.
-MT

Also they are already in use in some situations for back up power, for use in space etc. They are also getting along quite well for use for mobile phone charging.

On the other hand, i dont expect them to be in every house and every car, ever.

Well if we find a cheap way to acquire an abundant supply of hydrogen and oxygen, then I can assure you fuel cells will never be doomed.

Well if we find a cheap way to acquire an abundant supply of hydrogen and oxygen, then I can assure you fuel cells will never be doomed.

Well, oxygen is NO problem (just take a deep breath!) :D

Hydrogen, however, is a much different story.

And to the original question - the title of the thread - absolutely not. There are already plenty of appliclations where they fit very nicely and others will be developed.

Now if you're talking about automotive fuel cell, they probably are stalled. At least until we build more fission plants or finally develop fusion power. Anything that requires hydrogen produced by conventional means is actually a power sink rather than a source.

Lets not get into the problem of safe and easy storage of the hydrogen. Just about every method has drawbacks and dangers, so again, I dont expect to see them everywhere in a few years.

Hi there:

Fuel cells are very much promissing.

There is a series of different fuel cell technologies depending upon the operating temperature and electrolite.

There are many, many applications where the fuel cells can be employed.

Fuel cells are very much environmnetally friendly and operate with basically no emissions and no noise.

Fuel cells love hydrogen. Therefore, we will see the introduction of both hydrogen economy and fuel cell applications down the road.

Thanks,

Gordan

It seems that with recent advances in battery and capacitor tech the future of fuel cells appears to be dim...[/url]I skimmed your reference, but did not see any mention of new capacitor technology. (Reason I went there.) What are you talking about?

I know that the energy stored in a capacitor is basicly the stress on the dielectric. I think a bronze spring can store more enery per pound than a capacitor can, (storing it also as stress. - Wind up cars anyone?) ;)
Compared to chemical energy, stress energy in a capacitor will always be very small, pound for pound.

If you want to store energy with stress, use the stress limit to let you get a lot of rotational kinetic energy stored - I.e. use a super flywheel. - They can do better than batteries and much much better than capacitors, I am almost certain, but I would like to read some solid argument that I am wrong.

I skimmed your reference, but did not see any mention of new capacitor technology. (Reason I went there.) What are you talking about?

Using the new nanogate capacitor tech would be even better, considering that they are much lighter in weight and store far more energy than traditional caps.

I didn't mention capacitors in my orginal post, but using the new nanogate capacitor tech would be even better, considering that they are much lighter in weight and store far more energy than traditional caps.

Indeed you did, and I quote: "It seems that with recent advances in battery and capacitor tech ..."

And like Billy T., I too would like to see something that even remotely indicates that capacitors could become useful as a practical means of storing energy for applications that require a laege amount of it. I'm very doubtful of something of that nature but am willing to keep an open mind.

Somebody help me remember: can fuel cells be designed to run on a fuel other than hydrogen?

And, help me think about this, are there any circumstances where we might want to travel through places where we would not find a recharger, but could carry a big tank of fuel?

Capacitors have had the disadvantage of leaking charge out. I am not up to date on state of the art capacitors. Is there a capacitor expert in the audience?

... the new nanogate capacitor tech would be even better, considering that they are much lighter in weight and store far more energy than traditional caps.Do tell. describe or give referece I can read. thanks

Do tell. describe or give referece I can read. thanks
Just edited my previous post. You can unearth a pile of articles just by typing "nanogate capacitors" into Google.
Heres a few examples:
www.worldandi.com/subscribers/feature_detail.asp?num=23938

www.jeol.co.jp/english/newsroom/2003/031003.htm

Somebody help me remember: can fuel cells be designed to run on a fuel other than hydrogen?
The best hope is problably for methanol fuel cells. There are far too many problems with using pure hydrogen gas:
http://www.dpreview.com/news/0406/04062401toshibafuel.asp

http://www.pcworld.com/news/article/0,aid,110120,00.asp

http://www.benwiens.com/energy4.html

...
www.worldandi.com/subscribers/feature_detail.asp?num=23938 ...Thanks for the very interesting references. - The first was so good, that I only fully read it. I now believe some of the short-term (“peaking” & “buffering”) applications described in your first reference may ultimately be both possible and economically attractive.

I also suggest the possibly application to the super flywheels in a hybrid systems, probably more for stationary applications than cars, but flywheel buses etc. with fixed routes between electric recharge centers, are already in use in Sweden and totally non polluting in the urban area, etc. (Ultra capacitors in flywheel busses etc could reduce the size and weight of flywheel’s motor/ drive system, if more time were available to store the energy recovered in regenerative breaking. E.g. 10 seconds for increasing spin rate, instead of only a small fraction of a second. Perhaps a well designed system might only be recharged while the driver eats his lunch - a once per day “dual charge“ period for the bus/driver system. :)

Note a bus route has zero net change is gravity potential and is low speed with very little energy lose to air resistance. There is some friction lose in the rolling stock, but I think the "Stop and Go" loses are most of the total daily energy lose - if this and the speed gain on any downhill sections can always be limited by recovery into flywheel, looks like a real energy saving system to me. (I have long been for banning most private cars for city centers, supporter of public transport + bicycles in not too hilly cities, etc.) We could make cities a very desirable place to live, instead of respiratory health hazzards.

From your first reference (above also):

“When paired with fuel cells in stop-and-go mobility applications, such as forklifts, ultracapacitors provide burst power for lifting and acceleration and enable regenerative braking; in backup power applications [ranging from hospitals to office buildings, factories, and homes], they provide instantly available short-term bridge power. In many applications they buffer power demand peaks, allowing our scalable fuel cell systems to be optimized for size and low cost."

The capacitor (only) powered car is nonsense (almost certain) and I misread your post as indicating capacitors as attractive stand alone alternative.

Also from that reference:

"in mid-1980 a 2.3-volt ultracapacitor rated at 470 farads and manufactured by Panasonic (Matsushita Electric) cost roughly $2 per farad. Today, that same ultracapacitor would cost one-twentieth as much at 10 cents per farad, and costs continue to decrease rapidly as ongoing automation replaces hand assembly. According to informed sources, when ultracapacitor costs decrease by another factor of 20 to below 0.5 cents per farad, these components will be affordable in mass-market automotive applications."

I recall the energy stored, in Joules, is QV/2 = (C/2)V^2 = ~(250)x4* = 1000J for above capacitor. You typically can get approximately 100Amps out of car battery for short time. If 100amps at 10V is maintained for 1 second, you also have extracted 1000J from the battery. I think the capacitor will take this at least 1000 times more than the battery will before failing, but I am just guessing.

A concern mine, not discussed in the one reference I read is diffusion. Dielectrics only a nanometer thick are going to fail by diffusion, but I do not know if it is in one hot summer day or 20 years. Any of the other reference you may have read give an honest discussion of this? How much of a temperature rise in the extremely thin dielectric if it is full charge /discharge cycled once every 10 seconds? - Possible in stop&go urban traffic jam with regenrerative braking.

The reference indicated that 5 Farad/gram is now achieved an 30 in the nanogate units is possible. lets assume 10 and 95% energy recovery in the charge/discahrge cycle. Thus the 500F capacitor weighs 50 grams and each cycle dumps 50 J in it. As I recall, 4.86J = 1 calory. so even if it had the heat capacity of water, which it surely does not, four cycles would raise temp of it all 1degree C (if Ihave not made a mistake) but this is if the whole 50 grams is taking up the heat disipation. In fact it is almost all going into the dielectric. This appears to be a real problem - perhaps a "show stopper" at least for the ultra designes.
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*2V assumed as save working design for Capacitor with 2.3V rating, especially if my concern about diffusion is real limit.

Fuel cells are very much environmnetally friendly and operate with basically no emissions and no noise.Welcome to Sciforums!

I have to disagree here. Fuel cells are not particularly environmentally friendly until we can develop an environmentally friendly source of hydrogen. Until then fuel cells and hydrogen power in general are a bad idea from an environmental perspective.

The problem is that there are currently only two methods to get hydrogen. One is to strip it off of hydrocarbons, in which case you have pretty much the same emissions problems as you have with gasoline. The other method is to use electrolysis to split water into hydrogen and oxygen. So where do you get the electricity? In the US, the answer is primarily from coal. So a hydrogen fuel cell based vehicle is essentially a conversion from a relatively efficient gasoline-powered vehicle to a relatively inefficient coal-powered vehicle.

Fuel cells are an environmentalist "sucker's bet" overall until a cheap and environmentally friendly source of electricity is developed. I think that biofuels are a much better option for vehicles.

-Dale

(I have long been for banning most private cars for city centers, supporter of public transport + bicycles in not too hilly cities, etc.) We could make cities a very desirable place to live, instead of respiratory health hazzards.
Yes, the two biggest problems with modern north american cities are the height of buildings and the internal combustion engine...particularily bus and truck engines which are the biggest producers of both noise and air pollution.

In many european cities there are strict limits on the height of buildings and this helps disperse the population density downtown.

Perhaps it would be best the arrange cities in the style of ancient rome, with narrow streets for vehicles only (no sidewalks) and huge open courtyard settings for homes and businesses.

The problem is that there are currently only two methods to get hydrogen. One is to strip it off of hydrocarbons, in which case you have pretty much the same emissions problems as you have with gasoline. The other method is to use electrolysis to split water into hydrogen and oxygen. So where do you get the electricity? In the US, the answer is primarily from coal. So a hydrogen fuel cell based vehicle is essentially a conversion from a relatively efficient gasoline-powered vehicle to a relatively inefficient coal-powered vehicle.

I don't think hydrogen gas is a good way to store energy, but I don't see why it can't be produced commercially from WATER using a catalyst... like in the high school science class demo.

You know, the teacher takes a bottle filled with water, funnels in some lye powder and a section of aluminum foil, fits a ballon over the top and presto....it fills up with the hydrogen produced from the chemical reaction.

No electricity required.

I don't think hydrogen gas is a good way to store energy, but I don't see why it can't be produced commercially from WATER using a catalyst... like in the high school science class demo.

You know, the teacher takes a bottle filled with water, funnels in some lye powder and a section of aluminum foil, fits a ballon over the top and presto....it fills up with the hydrogen produced from the chemical reaction.

No electricity required.

And exactly where would this supply (which would need to be continuous) of aluminum come from? And do you know what it takes to produce aluminum? Electricity - "tons" of it.

...I don't see why it can't be produced commercially from WATER using a catalyst... some lye powder and a section of aluminum foil, fits a ballon over the top and presto....it fills up with the hydrogen produced from the chemical reaction. No electricity required.Not produce this way as much cheaper to produce by electrolysis.

The problem is that there are currently only two methods to get hydrogen. One is to strip it off of hydrocarbons, in which case you have pretty much the same emissions problems as you have with gasoline. The other method is to use electrolysis to split water into hydrogen and oxygen. So where do you get the electricity? In the US, the answer is primarily from coal. So a hydrogen fuel cell based vehicle is essentially a conversion from a relatively efficient gasoline-powered vehicle to a relatively inefficient coal-powered vehicle.-Dale


Actually there is another method of producing hydrogen from water using sunlight. It's currently being developed because at this point of time it's still not really effecient.

Apparenly it involves using titanium oxide ceramics to split water down into hydrogen gas and oxygen gas in the presence of sunlight.

You can read more about it here
http://www.pureenergysystems.com/news/2004/08/27/6900038_SolarHydrogen/

But again, since you've already gotten the hydrogen, why not then use it to power hydrogen fueled engines and power whatever you want to power?

Seems a little confusing now because if somehow we manage to get a clea and abundant supply of hydrogen gas, why waste it on fuel cells? Just burn it.

....
Apparenly it involves using titanium oxide ceramics to split water down into hydrogen gas and oxygen gas in the presence of sunlight....I hope this old idea can be made practical, but it has not been in the 30 or so years I have known of it. There are several fine dust semiconductors that will decompose H2O at realtively slow rates on the dust grain surfaces. One problem, not too serious, is getting the bubbles of two H2 & one O2 molecule mix to separate from the dust* (deabsorb) then you must separted the two gasses.

Also you have the same cost problem, not widely appreciated, that fundamentally stems from fact solar power is available (without concentrator expense) only at very low concentration.(Compare to chemial / flame etc.) For example, even if solar cells were completely free, the cost of solar photovoltaic would be reduced by less than a factor of two. (Called BOS, or Ballance Of System, cost.) I think when the cost of separating the two mixed gasses is added to the regular BOS cost, it is very unlikely that this 30 year old fact is anything more than interesting surface chemistry. :(
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*As I recall, process is in tray of liquid , acidic I think. A liquid based system, can not use significant concentration mirrors etc. to over come even partially the BOS cost.

PS - If I were writting funding proposals to the government, I would not mention these facts either.

I guess I should have been more precise. There are many ways to produce useable hydrogen. But I only know of two methods that could be used to produce it in the enormous industrial quantities necessary to run e.g. the US fleet of cars and trucks.

I don't see why it can't be produced commercially from WATER using a catalyst... like in the high school science class demo.

You know, the teacher takes a bottle filled with water, funnels in some lye powder and a section of aluminum foil, fits a ballon over the top and presto....it fills up with the hydrogen produced from the chemical reaction.

No electricity required.Yes, there are many chemical reactions you can use to generate hydrogen gas, but in each case it requires reagents rather than just catalysts. In this example you use up your aluminum foil and lye, which take more energy to produce than is contained in the hydrogen generated.

Actually there is another method of producing hydrogen from water using sunlight. It's currently being developed because at this point of time it's still not really effecient.

Apparenly it involves using titanium oxide ceramics to split water down into hydrogen gas and oxygen gas in the presence of sunlight.

You can read more about it here
http://www.pureenergysystems.com/news/2004/08/27/6900038_SolarHydrogen/
This is very interesting, I didn't know about it before. But it sounds both expensive and slow, at least currently. However, it might eventually be useful for large ocean-borne hydrogen gas facilities once it is developed further. Since there is such a huge surface area that is not used for anything right now (other than weather) it may be very worthwhile at some point.

Seems a little confusing now because if somehow we manage to get a clea and abundant supply of hydrogen gas, why waste it on fuel cells? Just burn it.Is burning it or using it in fuel cells more efficient? I would guess that the fuel cells are more efficient because of the lower heat. But that would just be a guess.

-Dale

One problem, not too serious, is getting the bubbles of two H2 & one O2 molecule mix to separate from the dust* (deabsorb) then you must separted the two gasses.

This brings up another major problem of H2 gas as a fuel, often not appreciated by those enamoured of hydrogen. It has one of the widest explosive mixture ranges of any flamable gas. In air, something like 15 to 95 percent hydrogen by volume doesn't burn, it explodes. In O2 it's even greater. I for one wouldn't want to be anywhere near one of these solar units if it were producing significant quantities of (optimum) hydrogen/oxygen mix.

Any kind of gas is too difficult to manage in so many ways. All things considered, I should have called this thread 'Are Batteries Doomed?'.

Even if capacitors can store just as much energy as batteries this still doesn't come close to the quantity of energy stored in a liquid fuel like alcohol.