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Electrons flow in the opposite direction to conventional current. The arrows with e- should be reversed. Could someone please correct this?
-- The direction of the flow is correct -- Electrons flow from the anode side(H2) to the cathode side(O2). The arrows would need to be reversed only if instead of indicating a flow of e-(electrons) it were labeled as i (current), which would flow from cathode to anode. What is incorrect in the image is the (+)label on the anode and the (-)label on the cathode. These two should be reversed. -- fiera 19:36, 31 May 2006 (UTC) Done. Mion 02:40, 1 June 2006 (UTC)
-- The direction of flow of electrons is INCORRECT, somebody please change the diagram ---
Electrons flow from the anode(H2) to the cathode(O2) through the external circuit, as correctly stated above. At the anode oxidation of H2 takes place producing electrons and protons, making the anode negative due to excess electrons. Here, as with all electrochemical cells the anode is negative. As opposed to semiconductor or vacuum tube devices with polarity, where the anode is positive. At the cathode O2 is reduced to water by taking electrons from the cathode and protons from the electrolyte, making the cathode electron deficient and therefore positive. As with all electrochemical cells, here the cathode is positive, whereas in semiconductor or vacuum tube devices with polarity the cathode is negative.
When dealing with electrochemical cells (fuel or battery cells), the best way to determine which electrode is the cathode and which one is the anode, is to remember that negative ions, anions are always going towards the anode, and positive ions, cations are always going to the cathode. i.e. anions to anode, cations to cathode.
In the case of the hydrogen fuel cell example, the protons, positive ions, cations are heading to the cathode. They do so because they are diffusing down a concentration gradient, from a high concentration of protons to a low concentration of protons.
So, the only thing that is incorrect in the diagram is that the flow of electrons should be in the opposite direction to that shown, everything else is correct.
Oenus 16:59, 12 June 2006 (UTC)
This article is currently more focused on fuel cell cars than on actual fuel cells. I would like to move a lot of the vehicle-related text to the hydrogen car or similar article, so that this one can focus more on the fuel cell itself.
For the record, I personally don't believe in fuel cell vehicles, but this is not the reason why I want to move the text. It is simply in the wrong place.
-- PeR 08:26, 20 February 2006 (UTC)
"about 80% of the world's carparks have the legal requirment that cars should be able to start in sub-zero temperatures."
???
Are there any metals used in the construction of a fuel cell for which there is not a large supply, or known reserves of?
Platinum is required for a PEM fuel cell. I think research is being done to try to find another catalyst because platinum is too expensive.
"While higher current densities can be achieved in fuel cells using electrodes containing precious metals, the researchers found that good current densities can be generated using a simple carbon anode." -- http://www.spacedaily.com/news/energy-tech-04zzg.html
More generally, others on this site have pointed out that palladium and rhodium have been used with success in PEM. I have also seen some work with cobalt porphyrins, but the cobalt doesn't stand up well in the acidic environment of the membrane, even when encapsulated in the porphyrin molecule. AFCs, of course, do not have this problem, and operate quite happily with non-noble metals as catalysts. Nickel anodes and silver cathodes have been used for decades in terrestrial AFCs, cobalt porphyrin is quite stable, and other catalysts have been tested. -- Thopper 04:48, 8 January 2006 (UTC)
I think this section is unnecessary now. I will read through it properly when I get the time.
Brianjd 12:26, Nov 5, 2004 (UTC)
I have archived the old talk in Talk:Fuel cell/Battery? and summarised it below. Note that all the blockquotes are actually quotes. Brianjd 10:14, 2004 Nov 16 (UTC)
Jerzy argues that a fuel cell *is* a battery and not merely *like* a battery, that therefore all battery laws also apply to fuel cells, and that even if this is wrong, a clear explanation of the difference should be given.
Mkweise argues that a battery is an ESD (energy storage device) and a fuel cell as an ECD (energy conversion device).
Jerzy says that the lead-acid automotive battery and the pumped storage plant are both ECDs, agrees that a fuel cell "cannot be reasonably construed as an ESD" and provides the following thought experiment:
But a better approach is to think about a system with a primary battery that is is not storing energy, but only converting it from chemical to electrical form. It's tempting to say that just disconnecting the charging system doesn't change the function of the disconnected at any given moment, and periodically they change roles. You, or your robot battery restorer, is at work on the disconnected battery: the depleted electrolyte gets dumped in the road and replaced from your sulphuric acid tank, while the sulphated electrodes get pulled out and stuffed in the trunk (for trade in), and fresh lead-metal electrodes, delivered like belted machine-gun ammunition, get installed in their place, so that battery is rebuilt and ready to take its turn as active battery. The tank and electrode magazine are storing energy as the fuel-cell tank does, but the electrolyte and electrodes in the lead-acid ECD have an energy storage function no more than is does the fuel in the space between the electrodes of the fuel cell; this kind of storage is merely incidental to the ECD process. Thus i think we have an "open ended", ESD-free, lead-acid battery ECD.
(I haven't checked the battery (electricity) article to be sure whether you've been misinformed by it or misinterpreted it; if you want to point out specifics, i'd be willing to express an opinion as to which applies.)
Jerzy believes that the same physical laws apply to both batteries and fuel cells:
(We're not, for instance, talking about cold fusion here; if new principles in chemistry had been involved, i'm confident i'd have heard about that.)
From the viewpoint of pure physics (which you seem to be taking), batteries and fuel cells would both be referred to as electrochemical cells. They are fundamentally the same, just as motors and generators are - but from a functional viewpoint they are completely different: One is a closed system that holds an exhaustible supply of energy, while the other depends on a continuous external fuel supply. Think of a syringe vs. an IV line. Or, to use your own analogy: you wouldn't think of saying that a blast furnace is a type of forge (or that a forge is a type of blast furnace)—would you? And yes, all ESDs except capacitors internally employ two-way energy conversion but that, again, is beside the point as these are also functionally (as opposed to fundamentally) defined terms.
Hankwang believes that the definition of a battery is too vague to resolve this debate and suggests:
So, choose either "a kind of battery" or "similar to a battery" in the description of a fuel cell. In both cases, describe the important features that distinguish a fuel cell from what is commonly called a battery, mainly the fact that the latter normally is a chemically closed system. But then, a zinc-air battery for hearing aids isn't closed either.
Summary of a post signed "bblakemo@ford.com 8/10/2004":
Unlike capacitors, complex and multiple chemical reactions happen in batteries so they are difficult to model, and they are really ECDs (energy conversion devices, as opposed to ESDs - energy storage devices). Also, in a hydrogen-oxygen fuel cell, hydrogen should be called the anode and oxygen should be called the cathode (rather than the membrane and catalyst being called the cathode and anode). "I understand that this is a somewhat simplified view that does offer some problems in practice but would ask the reader to consider the Nickel Hydrogen battery in which gaseous Hygrogen is truely considered the Anode."
The article states (in a US-centric view maybe) that the first public H2 station was opened in Washington, DC, in november 2004. I was in Reykjavik in november 2003 and I visited the local H2 station. Maybe it boils down to the word "public". What is meant by that? If it is providing only for 6 state-owned vehicles, it's less public than Reykjavik's, which supplies a couple of hydrogen buses (which are regularly used by the public, bus route number 2 I think). See this link. Orzetto 12:06, 10 Dec 2004 (UTC)
...Since no objections are raised, I'll substitute in the Reykjavik station instead of the Washington one. Orzetto 09:06, 14 Dec 2004 (UTC)
If someone here is interested in the subject and speaks some german you can find in interesting article about a new form of fuel cell developed by the Fraunhofer Institute in Germany here: http://www.n-tv.de/5465399.html Cheers, -- Jpkoester1 11:25, Dec 21, 2004 (UTC)
I always used to think this is a good reason against hydrogen economy until i came across the post i have linked at the end this talk. "The hydrogen typically used as a fuel is not a primary source of energy: it is only an energy carrier, and must be manufactured using energy from other sources. Some critics of the current stages of this technology argue that the energy needed to create the fuel in the first place may reduce the ultimate energy efficiency of the system to below that of the most efficient gasoline internal-combustion engines; this is especially true if the hydrogen has to be compressed to high pressures, as it does in automobile applications (the electrolysis of water is itself a fairly efficient process)." This is from the main page. The main argument is hydrogen is not a source of energy, but what the argument avoids to say is gasoline is not a source of energy also. Once you agree with the fact that gasoline(Also a store of energy) is not a source of energy, the above argument becomes mute. This post nicely summarize the whole argument. [4] Note, even if you don't believe the above, hydrogen would still be a better option in that it would allow centralization of the gasoline usage. This would mean easy control of emission. In short, that argument is hopelessly weak
What do you mean with Fuel cells are electrochemical devices, so they are not constrained by the maximum thermal (Carnot) efficiency? I thougth that second thermal law and Carnot's theorem should always stands. AnyFile 21:09, 30 Jan 2005 (UTC)
By definition a fuel cell can be operated in reverse. Reversible fuel cells should not be considered a separate type of fuel cell. I realize that the page for reversible fuel cells states:
"So while the reversibility is applicable in principle to any fuel cell device, a practical device may not be built with this intent. Hence the distinction between reversible fuel cells, and generic fuel cells."
However, this does not mean it is a different type of fuel cell. Operating a fuel cell in reverse is simply a matter of configuration/capability and has nothing to do with "types" of fuel cells, which should only distinguish between cells which utilize different fuels and/or different half-cell reactions.
My suggestion is that the page simply state:
All types of fuel cells can also be operated in reverse. However, most fuel cells are constructed for the purpose of generating electricity only and therefore may require alterations before a reversible process can be run. For more information, please see Reversible Fuel Cell.
Faraz Syed 02:04, 30 August 2005 (UTC)
As per
Wikipedia:External links, I've removed a large number of links. If there are any that really scream to be replaced, here's a good place to talk about it.
brenneman
(t)
(c)
06:55, 26 September 2005 (UTC)
Added a section for links on research development for fuel cells, as I think this is really needed, especially since fuel cells are still under researched and being continually developed.
The link I have placed is a huge break though in hydrogen fuel cells, allowing for cars to store hydrogen (for use in a fuel cell) without a potentially dangerous compressed hydrogen tank. So that is why I thought it would be important to add in.
If anyone has any other links for future or previous dates which reveal a breakthrough in research development into fuel cells, then please add them.
"Fuel cells running on compressed hydrogen may have a power plant to wheel efficiency as low as 22%"
What is the purpose of stressing how low an efficiency a fuel cell may have? Aren't we more concerned with the current and theoretical maximum efficiencies of fuel cells? Anyone can make an engine with 1% efficiency, or lower.
A number of experts in fuel cells, including Karl Kordesch, have noted that the main advantages and disadvantages of a fuel cell stem from its electrolyte, and that this is why fuel cells are classified by their electrolyte. It seems that the Wikipedia article underemphasizes the importance of the electrolyte by placing the "Types of Fuel Cells" section at the bottom, and not providing any discussion or comparison at all of the various types.
I'd like to add a section either just before or just after the "Science" section that lists the types of fuel cells and their relative strengths and weaknesses, and perhaps some operating characteristics (such as temperature range). This would still leave the separate pages for each type to go in to details regarding how each type of fuel cell works. Any suggestions or comments? -- Thopper 00:30, 8 January 2006 (UTC)
Also, the diagram of the alkaline fuel cell, showing water flowing out with the excess hydrogen flow, is only correct for immobilized electrolyte designs such as those used in the Space Shuttle. Terrestrial AFCs typically have mobile electrolyte, allowing water management to be mediated through the electrolyte itself. I'm not quite sure how to capture this, and certainly haven't the artistic skill to update the diagram. -- Thopper 00:34, 8 January 2006 (UTC)
Hi! I just came to think whether it can be explained: is it possible to carry out virtually any oxidation thermal generation process to a fuel cell process via catalyzation? I mean, in theory it involves exchange of electrons, and essentially represents a reaction whose anergy could be trapped by a wise invented (or accidentally found) catalyst and membrane.
What I wanted to ask may be is this theoretically possible: to generate electricity by mere catalytic oxidation of natural oil or other fuel instead of simply burning it in air stream, to avoid Carnot process? -- mtodorov_69, 16 February 2006
Is it possible to build a nuclear device that will directly transform nuclear bond energy to electricity, without using intermediate thermal stage of energy conversion? Is it possible to covert directly from chemical and nuclear to mechanical, without intermediate thermal or electrical? This could be at least in "See Also", please, this is very intereseting. I hope it's not SF.
Coming here to see how a fuel cell works, I eventually spotted the diagrams hiding at the bottom of the article. I understand that not all fuel cells work the same, but one or two of these diagrams, with appropriate explanation, would make the "Science" section a lot more useful to the unknowledgeable reader, if you ask me. - IMSoP 01:05, 28 January 2006 (UTC)
As far as low efficiency as a standalone electrolyzer goes, we need to understand a bit about fuel cells. In particular, all fuel cells use a membrane to only allow only ionic species to flow into the reaction zone. That is, the reactants are forced to undergo an ionization process at the surface of the membrane, by either giving off or accepting electrons, before they are granted free passage into the reaction zone. Once ionized, the concentration gradient pulls the ionic species across the membrane, to the reaction zone, where the ionic species are consumed, thus keeping the concentration near 0 on the reaction side, and the gradient across the membrane active. Without the separation membrane the reactants could simply jump and react each other, without giving us the electrical way to tap the energy. With direct reaction we would only get heat, which, according to the principles of the Carnot Cycle, is an even more inefficient way to tap energy - most internal combustion engines are limited to 10-40% efficiency, while fuel cells can beat that easily, providing 40-70%, still falling short of batteries that can return over 65-90% of the available chemical energy as useful work.
The giving off or accepting electrons is the process that harvests the bulk of the available chemical energy. Still, like in any conversion process, not 100% energy becomes available, a lot is wasted. For example, some energy is consumed/wasted because there is electrical resistance by the membrane against the current flow carried by the ions - the ions bounce against the membrane atoms, and generate waste heat in the process, just like electricity passing through an incandescent bulb filament heats it up, consuming energy. The longer the path travelled by the current flow, the more energy is wasted. For this reason a good fuel cell membrane is as thin as possible, and as highly conductive ionically as possible. Also, a good fuel cell has as large a surface area as possible, because a large surface area lowers the overall membrane electrical resistance as well. There is always a balance in how big and thin you can physically stretch a membrane, without risking pinholes or large holes in the membrane, that would completely ruin your cell's efficiency, so the ionic conductivity of the membrane material remains a key player, limited by the available materials science technology at the time.
Low temperature fuel cells make very expensive electrolyzers, because of the special nature of the membrane surface, which needs a platinum coating. The reason for this platinum catalyst is to provide a low activation energy for the H2 → 2H reaction, the breaking of the hydrogen molecules into atomic species. This reaction is an energy intensive process, but still, like all chemical reactions, in an equilibrium, and any equilibrium can be driven by concentration gradients in either direction. Such catalyst is not necessary for the backwards process, for electrolyzing water, because 2 nascent and reactive hydrogen atoms or oxgyen atoms freely recombine as pairs into a stable, lower energy molecules, which bubble up to the surface. That is, you can effectively electrolyze water with two metal rods, even copper or steel, and produce molecular oxygen and hydrogen gas from the nascent atoms that form at two electrodes, however, you could not use such two-metal rod electrolyzers backwards as a fuel cell, because, even if you bubble hydrogen or oxygen to their surface, they wouldn't be able to generate the needed atomic/ionic species, without either high temperature (600 to 1000 °C), or a low temperature catalytic activity that platinum has. The known catalysts, the metals that are highly active at gaseous molecule splitting at room temperature, are either very expensive precious metals — platinum, palladium — or sophisticated blends of lower cost, but still expensive metals, such as those used in NiMH (nickel-metal-hydride) cells. NiMH batteries blur this boundary between batteries and fuel cells somewhat, at least the hydrogen side of things — the atmospheric oxygen activation may still be an issue - hemoglobin anyone? True, that while almost any metal can be used to electrolyze water, there is the factor of electrode overpotential that limits the efficiency of electrolysis, and these low activation energy catalytic metals make the very best electrodes. Still, there is no need for a membrane for electrolysis, but only for the forward, fuel cell mode of operation. Ideally, the metal side of the membrane would be flooded with the highly conductive water electrolyte for electrolysis, the electrolyte being in direct contact with the metal without a separation membrane, but dry it off and keep the electrolyte on the other, nonplatinated side, during operation as a fuel cell, to force all ions to travel through the membrane.
High temperature fuel cells such as solid oxide membrane (e.g. zirconia) fuel cells have no catalyst-expense limitation, but they are similarly costly because of the very nature of high temperature operation, slow startups (up to 8 hours), bulky size and the need of thermal insulation. High temperature electrolysis is currently an area of active research because it can directly utilise cheap heat energy, partially replacing the expensive electric energy needed to split water. This is based on the thermodynamic entropic drive in the reaction 2H2O → 2H2+O2, 2 moles reacting to for 3 moles of product, therefore increasing entropy, so forward reaction favored at higher temperatures, becoming spontaneous at the impractically high temperature 2500 °C. At temperatures below this point some electricity is required, but the closer the reaction is done to 2500 °C, the less extra 'nudge' needs to be supplied by electric energy. The highest practical temperatures are near 1000 °C, using a solid oxide fuel cell exactly in reverse mode. Even in view of the above cited thermodynamic advantages, this method has its own disadvantages, namely having to separate the reactant steam from the product hydrogen, by energy wasting cooling to liquid water, then having to reheat it back to the reaction temperature to complete the recycling step.
Mostly likely the most efficient large scale industrial water electrolysis method is, as described in the patent literature, via lower temperature steam injected into molten alkali metal hydroxide, near 200–400 °C, this molten electrolyte being hygroscopic enough so that not much steam evaporates with the product gases so no expensive separation step is needed. Molten alkali hydroxides have very high ionic conductivities, allowing very low resistive losses, and extremely high current densities.
nice text, is going to be integrated in Fuel Cell. Mion 10:19, 9 April 2006 (UTC) Coming from Reversible fuel cell Mion 23:19, 10 April 2006 (UTC)
... here: http://www.anl.gov/Media_Center/Image_Library/engtrans.html about fuel cell.
-- Harp 07:39, 19 April 2006 (UTC)
I removed the following from the article:
"Critics of fuel cells have also pointed out that their proposed use in aircraft (in order to cut the use of kerosene, which contributes massively to global carbon emissions) would have little or no impact on mitigation of climate change, since water vapour, itself a greenhouse gas, would be emitted."
First, there needs to be a source for this statement. Second, it is incorrect. Water vapor is a greenhouse gas, but its concentration in the atmosphere is not changed much directly by human activities. Water vapor is important in that increased carbon dioxide levels, causing global warming, may increase evaporation and therefore the level of water vapor in the atmosphere, increasing the greenhouse effect even further. The warmer temperatures may cause more water to be evaporated, which would increase the greenhouse effect further, causing a runaway greenhouse effect. Also, the burning of kerosene produces water vapor and carbon dioxide, instead of just water vapor, so even if water vapor was a problem, at least carbon dioxide would not be released as well (it is released during some types of hydrogen production, however). -- Kjkolb 17:28, 24 April 2006 (UTC)
"Fuel cells differ from batteries in that they consume reactants, which must be replenished, while batteries store electrical energy chemically in a closed system."
This distinction seems a little weak. Both batteries and fuel cells consume reactants. Most modern batteries cannot be replenished, but archaic ones like gravity cells could (replacing the anode and the electrolyte was routine).
Can someone clarify the distinction? Kurzon 00:10, 21 January 2007 (UTC)
From an intrinsic point of view, fuel cells and batteries are exactly the same: both generate compound by means of a chemical reaction, where the side effect is electricity and heat. But in reality comparing them is almost like comparing apples and oranges.
Any weak distinction made, is only arbitrarily come up with a definition for fuel cell Vs battery. Exceptions to the definitions will arise.
--
Fieraloca
04:00, 7 February 2007 (UTC)
The distinction may be arbitrary, but it is nevertheless important and valuable. All of the reactant in a battery is contained in the cells. If you want to increase capacity(Amp-hours), then you have to increase the size or number of cells. That is expensive. If you want to increase power output(kW), you also have to increase size of number of cells. This is not true with a fuell cell. Capacity is based on how big your reactant tanks are, and they are cheap compared the cost of battery cells. Power output determines the size and number of fuel cell stacks.
Also, storage batteries (not the ones that you throw away) are rechargable. This means that when the terminal voltage is raised above the cell voltage the reactants will chemically transition to their original states. Fuel cells cannot turn their products (water and heat for a H-O fuel cell) back into the original reactants. —The preceding unsigned comment was added by 149.37.200.150 ( talk) 14:10, August 23, 2007 (UTC)
Electro-galvanic fuel cells have been used for decades for measuring oxygen concentration in a breathing mixture. Would a short description or a reference to the article / use be appropriate? Especially as to how the concentration of oxygen gives a difference in voltage, which is converted to a displayed oxygen concentration. -- Seejyb 20:12, 20 May 2006 (UTC)
Who removed the image from commons ? its a GFDL licensed image from the French wiki. Fuelcell.en.jpg Reg . Mion 05:46, 16 June 2006 (UTC)
1989 A so-called water fuel cell is an unrelated claim of a perpetual motion device, which in fact was not claimed to function the way a fuel cell does.
If the water fuel cell has its own article it could be referenced on, it makes people more critical about real inventions and hoaxes, //Enron/Tesla Motors. Mion 16:31, 19 June 2006 (UTC)
In which disambig page ? Mion 19:14, 11 August 2006 (UTC) , and read the first part of the sentence, If the water fuel cell has its own article it could be referenced on, the second part was my personal view. Mion 19:14, 11 August 2006 (UTC) thats why i put it back.
and another one, there are loads of patents given on the design, it has the design of a fuel cell, the fact that we didn't see one working , tja. Mion 19:14, 11 August 2006 (UTC)
ok, i missed the top link to the disamb page, and which article, did i ask you ? well , i think it still belongs in the history section of fuel cells, or are we making only an article about fuel cells that where succesfull ? in that case there is more to clean out. reg. Mion 23:24, 11 August 2006 (UTC)
Yes, which takes hydrogen and oxygen as fuels to create a current. see Reversible fuel cell. reg. Mion 11:26, 12 August 2006 (UTC)
well, can the process be reversed in a fuel cell? Mion 13:45, 13 August 2006 (UTC)
First, the fact that the water fuel cell was granted a patent is absolutely irrelevant; in fact the patent was granted on the basis of construction of the invention, and not on whether the invention actually works.
Second, Nope, a fuel cell does not have to be used with H2 and O2 only, don't forget direct methanol fuel cells, solid oxide, etc etc etc. What characterizes the fuel cell is not the reactants it uses, but the exchange of protons between the cathode and the anode via dielectric media. -- Fieraloca 04:15, 7 February 2007 (UTC)
http://www.wired.com/news/planet/0,2782,69713,00.html Mion 13:12, 16 July 2006 (UTC)
If the water is not evaporated quickly enough, it reduces efficiency, and if it is evaporated too fast, it can crack the fuel cell. So, if used in, say, an automobile, does it have to keep operating all the time even when the car is parked, or can it be shut down, unlike the ones used in the Apollo space missions? (Jim Lovell on Apollo 13 knew that if they shut down the fuel cells as Mission Control told them to, they could not be restarted.) GBC 17:21, 11 August 2006 (UTC)
Once the membrane is hydrated within the break-in period of a new fuel cell, full performane can be achieved within minutes. Continuous operation is not necesary. Water is not evaporated from a fuel cell; the gas diffusion layer moves the water into the flow field of the current collectors.--
Fieraloca
08:34, 12 November 2006 (UTC)
It should be noted that start up time depends heavily on type of FC, modern PEMFCs can start within a few seconds. The startup time of a fuel cell system usually depends on time required to get the ion conductivity layer to produce adequate conductivity for the current required. Nafion, a popular material for PEMFC ion conductivity layer (electrolyte) can operate lower than 0 C (32 F). SOFCs need to reach about 600-800 C to start conducting ions for efficient operation.
Oxford dictionary: • noun:
[ [5]] Mion 11:52, 11 September 2006 (UTC)
Hi Mion or Anyone can help-- Please. . .
As ESL (English as second laguage) person I need help in writing an article on what I beleive it could be a break through in Fuel Cell research.
If you can help me in anyway please foreward me a note at ephitran at gmail.com
Many Thanks.
Phi
You are talking about a galvanic cell. Yes, you can get a galvanic potential when you place certain dissimilar metals together e.g. zinc and copper. There's no particular use for such as power source in real life.--
Fieraloca
08:29, 12 November 2006 (UTC)
The paragraph about combined heat and power (CHP) appears to contain contradictory information. It states that fuel-to-electricity conversion is "typically 15-20%". Toward the bottom of the same paragraph, however, it states that PAFCs, which dominate the CHP market provide electric conversion efficiencies typically around 45-50%.
I don't know which range of numbers is more accurate, but it would seem that at least one of them is wrong. -- jfinlayson 10:59, 18 October 2006 (UTC)
"Water management (in PEMFCs). In this type of fuel cell, the membrane must be hydrated, requiring water to be evaporated at precisely the same rate that it is produced. If water is evaporated too quickly, the membrane dries, resistance across it increases, and eventually it will crack, creating a gas "short circuit" where hydrogen and oxygen combine directly, generating heat that will damage the fuel cell. If the water is evaporated too slowly, the electrodes will flood, preventing the reactants from reaching the catalyst and stopping the reaction. Methods to dispose of the excess water are being developed by fuel cell companies."
Fuel cells virtually never run at an ideal condition, where "the same amount of water generated is PRECISELY evaporated". The gas diffusion layers (GDL) take care of the water management. If you have ever ran a fuel cell, you would know that the excess water is continuously discharged through the cathode side. -- Fieraloca 08:17, 12 November 2006 (UTC)
This phrase: "In 2008 UTC Power has 400kw Fuel cells for $1,000,000 per 400kW installed costs." is confusing. If it is "per 400kW installed cost" it is redundant. The intersting data here will be the cost per kW. -- Nachoj ( talk) 15:58, 27 April 2008 (UTC)
Propose to remove Metal Hydride Fuel Cell MHFC and Direct Boro-Hydride FC from the chart of different types of fuel cells.
Metal hydrides and Sodium-Borohydrides are HYDRIDES not fuel cells. They are H2 storage media. The H2 obtained from these two types of hydrides are usually fed into PEMFC.-- Fieraloca 08:21, 12 November 2006 (UTC)
You got my vote to taking this paragraph out. If you write something like this in a freshmen physics exam on thermodynamics, you have to repeat the class. The Carnot limit is fundamental and follows immediately from the second law, which is nothing else than the definition of temperature. A fuel cell just like a solar cell (non-experts make exactly the same mistake with those) is subject to it like EVERYTHING else. When the temperature increases on a fuel cell or a solar cell, the max. achievable voltage goes down and so does the efficiency. Period. No discussion.
As long as this stays in, the whole article belongs into the garbage. Literally.
--- Anonymous --- (Sorry... got no account, yet. But I did read this article and it pisses me off big time. There are way better science articles on Wikipedia.) —Preceding unsigned comment added by 69.3.190.146 ( talk) 23:20, 5 August 2008 (UTC)
Using cell voltage as an indicator of efficiency is the biggest non-sense that I have ever heard!!!
Example: Take a perfect fuel cell; at an open cell potential of 1.23V, the current is Zero, thus the amount of H2 consumed is also Zero. Which means that you have just invented a perpetual motion machine, no need to feed H2, just 1.23V of pure Potential?!?!?
The efficiency of a fuel cell has to be measured as a ratio between the amount of energy obtained Vs the total enthalpy differential. Or other methods would also be fine.
-- Fiera 08:52, 12 November 2006 (UTC)
In calculus there is the idea of limits. The open cell potential is always an ideal approximation - you measure it with a multimeter that draws a few picoamps, never 0. Similarly, the amount of H2 consumed due to these picoamps is a few femtomoles, which is still quite a few atoms considering avogradro's number is about 6x1023. When you talk about voltage, or potential energy in general (voltage in an electric forcefield, height/pressure/liquid head in a gravitational forcefield, pressure/spring constant in an electric forcefield between atoms), you always talk about rate of change, energy gained vs. distance traveled, motion. It's how much energy I would get per foot if I traveled north down this hillisde, there is an idealized answer to that, similarly like there is an idealized answer to an open cell potential, how much energy you would get per electron flowing through your wire, how many volts it carries. But you don't actually get any energy if you don't take a step, just sit still. Measuring the energy you have to move by a millimeter down the hillside, record the results to calculate how much you would get per meter. Similarly, if I have a pipe with 20 psi pressure of water meaning each cubic centimeter could give me such and such energy if I let it flow through my turbine/electric generator, the higher the pressure the more energy I'd get per cc of liquid. Staring at the pressure gauge on the pipe expressing to me the "pure potential" does not mean I have a perpetual motion machine because nothing is moving. In fact all pressure gauges obtain their reading by moving, whether a few millimeters against a spring load, or a few nanometers against a piezoelectric membrane. Sillybilly 13:12, 12 November 2006 (UTC)
Uhm... yea... i think i was being sarcastic when I said I invented the perpetual motion machine. What I am referring to is the following quote from the main fuel cell page, under "efficiency":
The efficiency of a fuel is very dependent on the current through the fuel cell: as a general rule, the more current drawn, the lower the efficiency. A cell running at 0.6V has an efficiency of about 50%, meaning that 50% of the available energy content of the hydrogen is converted into electrical energy; the remaining 50% will be converted into heat. For a hydrogen cell the second law efficiency is equal to cell voltage divided by 1.23, when operating at standard conditions. This voltage varies with fuel used, and quality and temperature of the cell. The difference between enthalpy and Gibbs free energy (that cannot be recovered) will also appear as heat.
What I'm saying is that this entire parragraph is pure non-sense. Whoever wrote this believes that the current stays constant with changing cell potential, that energy is measured in Volts, and that the open cell potential would yield a perpetual motion machine. Paragraph will be deleted unless objected by anyone. -- Fieraloca 04:45, 7 February 2007 (UTC)
I would suggest to ask an electrochemist to clarify this point. The entry about fuel cell efficiency and thermodynamics ruins the quality of the whole article. I would suggest taking the whole section out until someone with a background in fuel cells can take a shot at it. My criticism as a reader, not an editor, would be as follows:
Fuel cells are just as much thermodynamic devices as anything else in the universe. The second law holds and the Carnot Cycle is indeed a hard limit for fuel cell efficiency, except that it is not obvious what temperatures to throw into the Carnot limit equation. If I had to wing it, I would say that the lower temperature has to be the temperature at which the cell operates, and the upper temperature is probably the theoretical combustion temperature of the ideal fuel/oxidizer mix (at the partial pressure equivalent to the concentrations of the fuel and oxidizer?). Since that temperature is very high compared to the cell temperature, the Carnot limit will be somewhere above 90%. Now, the reactions inside a fuel cell are not equivalent to a Carnot Cycle because there is interaction between the fuel, oxidizer, the solvant and the electrodes, therefor the theoretical efficiency has to be less than the prediction of the Carnot Cycle. Any real science argument would obviously start with the well known ways to calculate dynamics of ionic reactions in solvents in, not the basic equations of thermodynamics for beginners.
I am a physicist, not an electrochemist and I do not have the detailed knowledge of fuel cell chemistry required to explain this quantitatively or even qualitatively. Anything I could write would therefor not approach a scientific quality standard. All I can tell is that the way it is written right now leaves a very bad impression to those with even a minimum of physics literacy. --[J.L.]
Mkultra, if that book was checked out, then just borrow any book on fuel cells, and read the chapter that discusses the efficiency. Since you're missing my point I'll try to make it more clear:
Efficiency = output power / reactant energy flow Reactant energy flow = constant * current (We'll disregard leak currents and wasted reactant for now) Output power = voltage * current
Combined, these three equations give:
Efficiency = voltage / constant
The section (9.7) that I referred to above actually discusses first law efficiency, and in that case efficiency is , not , so it's not an exact match. I could probably find an exact reference if I searched a bit, or rewrite the section to discuss first law efficiency instead (which is the most commonly used definition of efficiency anyways), but I can't be bothered right now.
If you don't now enough on the subject to say that the text is wrong, then you're better off letting the people who do know the subject decide on whether the text should be removed, referenced or not. I'll not revert you any more. I suspect somebody else will do it soon, and otherwise I hope you revert yourself once you've gotten that book from the library. -- PeR 21:06, 27 June 2007 (UTC)
PeR, The statement is absolutely wrong and should be deleted!!!!! You are trying to explain a very complex thing (fuel cell efficiency) though Voltage only? You are completely disregarding the stoichiometric flow through each cell!! Are you saying that a cell running at 0.6V and a stoich of 5 has the same efficiency than a cell running at 0.6V and a stoich of 1.2???? You assume constant current? Oh wait, you are ALSO assuming constant stoich. ok.
How about O2 diffusion efficiency? air contains 20.9% O2, your statement does not address how the diffusion plays a role in efficiency and real Vs theoretical stoichiometric values at the reactions sites. Nor does the statement address catalyst utilization/ reactivity. And you do not address proton trasport resitance. And crossover? So that too? you are also assuming that these factors are constant?
Let me see if I understand your statement. If every single operating parameter of a fuel cell is kept constant. Then efficiency is measured with voltage.
Trying to explain efficiency by Voltage only, is a little bit of an oversimplification, dont you think?
--
Fieraloca
23:32, 12 November 2007 (UTC)
I noticed the efficiency information on this article as well as its calculations are wrong. Fuel cells using hydrogen oxygen to water reaction can easily get 80% efficiency in the conversion from chemical hydrogen and 20% oxygen atmosphere in to electricity.
potentially the 50% statement may be closer to correct if a reformer is required, IE converting fossil fuels in to hydrogen, but this is not the goal of most of the fuel cell industry as it negates the goal of eliminating fossil fuel usage
1 of my sources I had handy
[8]
The statement about drawing current lowers voltage = less efficiency is totally false.
If you start at 1.5v at .5A and you add to the load pulling it down to .5V at 1.5A you still have .75W of energy.(these numbers are examples).
watts law amps*volts=watts watts = energy witch has direct conversions to horsepower, BTU, calories, and joules take your pick.
When I get some free time ile start cleaning up this article using verifiable sources.
Eadthem (
talk)
04:25, 5 December 2008 (UTC)
One cited article [9] in the history section claims that the fuel cell was not invented by Groove in 1839, but by Schoenbein, and that Groove did not build a fuel cell until 1842.
Most fuel cell related articles, in the "background" or "history" section will cite Groove as the inventor and the year as 1839. (See, for example, [10] or [11])
Does anyone know the truth behind this? I think the article needs to be clarified.
-- PeR 12:31, 29 November 2006 (UTC)
There is mention of cars and other vehicles that use fuel cells but not other vehicles. Perhaps there should also me mention of the first space craft. This submarine also uses Fuel Cells. I do not know if there were any before it. http://en.wikipedia.org/wiki/Type_212_submarine
Yewenyi 04:12, 6 December 2006 (UTC)
Consider the following section:
The efficiency of a fuel is very dependent on the current through the fuel cell: as a general rule, the more current drawn, the lower the efficiency. A cell running at 0.6V has an efficiency of about 50%, meaning that 50% of the available energy content of the hydrogen is converted into electrical energy; the remaining 50% will be converted into heat. For a hydrogen cell the second law efficiency is equal to cell voltage divided by 1.23, when operating at standard conditions. This voltage varies with fuel used, and quality and temperature of the cell. The difference between enthalpy and Gibbs free energy (that cannot be recovered) will also appear as heat.
This is confusing. Firstly, it says the efficiency is current dependent. Next, it gives an estimate of efficiency for a particular voltage. This needs to be clarified.
Ordinary Person 06:28, 6 December 2006 (UTC)
Paragraph should be deleted. Inaccuracies cited under discussion --- Correction to fuel cell efficiency ---
Fuel cell efficiency is dependent on several factors (stoichiometric flow of reactants, recirc vs non-recirc systems, parasitic loads, humidification of reactants, cell impedance and resistance, diffusion properties of the microporous layers, catalyst activity, etc etc etc. Voltage alone says nothing.-- Fieraloca 04:54, 7 February 2007 (UTC)
It is a simpler design and is more efficient. It is expected to first be incorporated in smaller engines like those found in lawn mowers. That should make in impact, since they are not regulated. [12] Brian Pearson 23:05, 16 January 2007 (UTC)
Take a look at [13]. DFH 20:31, 8 February 2007 (UTC)
New offshoreship with FC tech coming soon [14] --OddMartin 23:42, 22 February 2007 (UTC)
User talk:80.123.226.133 asked about Fe + 2FeCl3 = 3FeCl2 + energy. I found one Google hit. Could someome discuss it with him/her? Simesa 13:42, 26 April 2007 (UTC)
Anyone seen this? Efficiency of 49%. October, 2006: [15] Simesa 00:11, 30 April 2007 (UTC)
"In the archetypal example of a hydrogen/oxygen proton exchange membrane fuel cell (PEMFC), which used to be called solid polymer electrolyte fuel (SPEFC) around 1970 and now is polymer electrolyte membrane fuel cell (PEFC or PEMFC, same as the short writing of proton exchange membrane) while the proton exchange mechanism was doubted," I don't get this. What happened while the mechanism was doubted. Is this thing still happening or did the doubt stop? -- Gbleem 12:17, 22 May 2007 (UTC)
so if we go H2 + O2 ---> 2H2O, aren't we trapping O2 (breathable oxygen) in H2O molecules? won't we eventually run out of O2? Sahuagin 01:39, 28 May 2007 (UTC)
UTC's Power subsidiary was the first company to manufacture and commercialize a large, stationary fuel cell system for use as a co-generation power plant in hospitals, universities and large office buildings. UTC Power continues to market this fuel cell as the PureCell 200, a 200 kW system.[8] UTC Power continues to be the sole supplier of fuel cells to NASA for use in space vehicles, having supplied the Apollo missions and currently the Space Shuttle program, and is developing fuel cells for automobiles, buses, and cell phone towers; the company has demonstrated the first fuel cell capable of starting under freezing conditions with its proton exchange membrane automotive fuel cell.
In 2006 Staxon introduced an inexpensive OEM fuel cell module for system integration. In 2006 Angstrom Power, a British Columbia based company, began commercial sales of portable devices using proprietary hydrogen fuel cell technology, trademarked as "micro hydrogen."[9][10]
This needs to be moved or removed from the article. It has nothing to do with history that Staxon in 2006 put out a cheap FC...
The UTC part is even worse, it is manipulative, UTC might be the first to put out that specific type of backup power, but Japan have been using stationary power plants for many years. And most hitech firms have some sort of fuel cell production / development going on these days, with my limited knowledge, i do not recall having heard of one car firm using UTC cells in demonstration projects. No doubt UTC plays a major role in developing backup power systems, and due to the instability on the US power grid, there is a major demand for super reliable systems, that can also keep power flowing for many hours, maybe even days, but that should go in a separate article. Unless someone provides counter argument, i will move the staxon part to news, and remove the UTC thing. ( Larkuur 14:20, 12 August 2007 (UTC))
Update: Moved Staxon part, since the wikibot considers me a newbie (true), it wont let me delete anything... I still believe any one with the powers should remove the UTC part from the article, maybe move it to the UTC main article. (
Larkuur
16:35, 13 August 2007 (UTC))
Hiya, I'm a really bold dumbass who feels qualified to rewrite and even create whole new paragraphs when all I know about the subject I learned from reading Wikipedia. In other words, I know very little about fuel cells, so would someone check my rewrite of the first two or three 'graphs of "Fuel cell design" to make sure I didn't get it completely wrong?
One thing, as noted by User:Gbleem above, is that reference to the "early 1970s" and the proton exchange mechanism not being understood. I moved this, and reworded it to make what sense I could out of it, but there's actually no cite for this claim, and I was tempted to remove it. I decided not to, on the theory that whoever added it probably knows more than me. If it doesn't make sense, tho, someone who knows that should remove it. In any case, I think my layman's introduction paragraph is an accurate overview of the mechanism. Am I right? Eaglizard 21:06, 19 September 2007 (UTC)
Just deleted links to non existent wiki articles Fuel cell system and Fuel cell module. Could someone who has a good idea of fuel cell systems , WGS and PROX start these articles? shampoo 05:59, 27 October 2007 (UTC)
--outdent
Done. Please check content for sensibility. The original seemed to be written in a very stop-start style, which only makes it worse :). User A1 ( talk) 14:27, 8 September 2008 (UTC)
--outdent2
I did, great work, maybe de:Kværner-Verfahren next ? :) Mion ( talk) 15:28, 8 September 2008 (UTC)
--outdent3
Fuel Cell Markets is one of the leading online resources for Fuel Cells and contains a depth of information on business opportunities, recruitment, products and information about fuel cell resources.
Fuel Cell Markets facilitate the introduction and development of strategic partnerships and joint ventures towards building the global fuel cell supply chain and assisting with the creation of the hydrogen and fuel cell economy.
Piyush.fcm.kumar ( talk) 11:47, 12 December 2007 (UTC)
I've added an interesting link to Water fuel cell in the see also section. -- CyclePat ( talk) 21:42, 19 March 2008 (UTC)
In introduction there is a sentence "Some HHo fuel cells convert water to Hydrogen and oxygen that is in an excited state and hold its electrical potential until it recombines on burning releasing the energy and reconverting to water." It sounds like perpetuum mobile of first kind. It probably should be removed from introduction or rewritten in much clear way. Plus no any reference in the whole article what that “HHo” means. Do I horribly miss something here? --- MxM ( talk) 19:33, 1 July 2008 (UTC)
1.Design issue section:
Cost issue:
No definition of the term "cost" exists here - production cost? - shelf price? Also this part in the article lacks the fact that a manufactured product's cost generally depends on production numbers. In other words mass-production lowers the final product's cost. Hence this regards the final shelf-price for the end consumer, the material cost of the manufacturer as well as cost of manufacture.
This part of the article creates the idea that a fuel cell is too expensive, too cost-intensive, to be mass manufactured.
Do you think this is a neutral viewpoint?
2.Design History
Wilson, Mahlon S., Ph.D.,is not even being named here?
pfff
check out this:
http://www.lanl.gov/orgs/mpa/mpa11/bio-wilson.htm
and this:
http://www.freepatentsonline.com/6808838.html
and make you own assumption... —Preceding unsigned comment added by 77.185.223.145 ( talk) 19:37, 26 September 2008 (UTC)
In the Design Issues section, one point mentions the cost in US Dollars, while another mentions Euros. Since dollars are used in other sections, the Euros cost should be restated in dollars.
![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 | Archive 2 | Archive 3 | Archive 4 |
Electrons flow in the opposite direction to conventional current. The arrows with e- should be reversed. Could someone please correct this?
-- The direction of the flow is correct -- Electrons flow from the anode side(H2) to the cathode side(O2). The arrows would need to be reversed only if instead of indicating a flow of e-(electrons) it were labeled as i (current), which would flow from cathode to anode. What is incorrect in the image is the (+)label on the anode and the (-)label on the cathode. These two should be reversed. -- fiera 19:36, 31 May 2006 (UTC) Done. Mion 02:40, 1 June 2006 (UTC)
-- The direction of flow of electrons is INCORRECT, somebody please change the diagram ---
Electrons flow from the anode(H2) to the cathode(O2) through the external circuit, as correctly stated above. At the anode oxidation of H2 takes place producing electrons and protons, making the anode negative due to excess electrons. Here, as with all electrochemical cells the anode is negative. As opposed to semiconductor or vacuum tube devices with polarity, where the anode is positive. At the cathode O2 is reduced to water by taking electrons from the cathode and protons from the electrolyte, making the cathode electron deficient and therefore positive. As with all electrochemical cells, here the cathode is positive, whereas in semiconductor or vacuum tube devices with polarity the cathode is negative.
When dealing with electrochemical cells (fuel or battery cells), the best way to determine which electrode is the cathode and which one is the anode, is to remember that negative ions, anions are always going towards the anode, and positive ions, cations are always going to the cathode. i.e. anions to anode, cations to cathode.
In the case of the hydrogen fuel cell example, the protons, positive ions, cations are heading to the cathode. They do so because they are diffusing down a concentration gradient, from a high concentration of protons to a low concentration of protons.
So, the only thing that is incorrect in the diagram is that the flow of electrons should be in the opposite direction to that shown, everything else is correct.
Oenus 16:59, 12 June 2006 (UTC)
This article is currently more focused on fuel cell cars than on actual fuel cells. I would like to move a lot of the vehicle-related text to the hydrogen car or similar article, so that this one can focus more on the fuel cell itself.
For the record, I personally don't believe in fuel cell vehicles, but this is not the reason why I want to move the text. It is simply in the wrong place.
-- PeR 08:26, 20 February 2006 (UTC)
"about 80% of the world's carparks have the legal requirment that cars should be able to start in sub-zero temperatures."
???
Are there any metals used in the construction of a fuel cell for which there is not a large supply, or known reserves of?
Platinum is required for a PEM fuel cell. I think research is being done to try to find another catalyst because platinum is too expensive.
"While higher current densities can be achieved in fuel cells using electrodes containing precious metals, the researchers found that good current densities can be generated using a simple carbon anode." -- http://www.spacedaily.com/news/energy-tech-04zzg.html
More generally, others on this site have pointed out that palladium and rhodium have been used with success in PEM. I have also seen some work with cobalt porphyrins, but the cobalt doesn't stand up well in the acidic environment of the membrane, even when encapsulated in the porphyrin molecule. AFCs, of course, do not have this problem, and operate quite happily with non-noble metals as catalysts. Nickel anodes and silver cathodes have been used for decades in terrestrial AFCs, cobalt porphyrin is quite stable, and other catalysts have been tested. -- Thopper 04:48, 8 January 2006 (UTC)
I think this section is unnecessary now. I will read through it properly when I get the time.
Brianjd 12:26, Nov 5, 2004 (UTC)
I have archived the old talk in Talk:Fuel cell/Battery? and summarised it below. Note that all the blockquotes are actually quotes. Brianjd 10:14, 2004 Nov 16 (UTC)
Jerzy argues that a fuel cell *is* a battery and not merely *like* a battery, that therefore all battery laws also apply to fuel cells, and that even if this is wrong, a clear explanation of the difference should be given.
Mkweise argues that a battery is an ESD (energy storage device) and a fuel cell as an ECD (energy conversion device).
Jerzy says that the lead-acid automotive battery and the pumped storage plant are both ECDs, agrees that a fuel cell "cannot be reasonably construed as an ESD" and provides the following thought experiment:
But a better approach is to think about a system with a primary battery that is is not storing energy, but only converting it from chemical to electrical form. It's tempting to say that just disconnecting the charging system doesn't change the function of the disconnected at any given moment, and periodically they change roles. You, or your robot battery restorer, is at work on the disconnected battery: the depleted electrolyte gets dumped in the road and replaced from your sulphuric acid tank, while the sulphated electrodes get pulled out and stuffed in the trunk (for trade in), and fresh lead-metal electrodes, delivered like belted machine-gun ammunition, get installed in their place, so that battery is rebuilt and ready to take its turn as active battery. The tank and electrode magazine are storing energy as the fuel-cell tank does, but the electrolyte and electrodes in the lead-acid ECD have an energy storage function no more than is does the fuel in the space between the electrodes of the fuel cell; this kind of storage is merely incidental to the ECD process. Thus i think we have an "open ended", ESD-free, lead-acid battery ECD.
(I haven't checked the battery (electricity) article to be sure whether you've been misinformed by it or misinterpreted it; if you want to point out specifics, i'd be willing to express an opinion as to which applies.)
Jerzy believes that the same physical laws apply to both batteries and fuel cells:
(We're not, for instance, talking about cold fusion here; if new principles in chemistry had been involved, i'm confident i'd have heard about that.)
From the viewpoint of pure physics (which you seem to be taking), batteries and fuel cells would both be referred to as electrochemical cells. They are fundamentally the same, just as motors and generators are - but from a functional viewpoint they are completely different: One is a closed system that holds an exhaustible supply of energy, while the other depends on a continuous external fuel supply. Think of a syringe vs. an IV line. Or, to use your own analogy: you wouldn't think of saying that a blast furnace is a type of forge (or that a forge is a type of blast furnace)—would you? And yes, all ESDs except capacitors internally employ two-way energy conversion but that, again, is beside the point as these are also functionally (as opposed to fundamentally) defined terms.
Hankwang believes that the definition of a battery is too vague to resolve this debate and suggests:
So, choose either "a kind of battery" or "similar to a battery" in the description of a fuel cell. In both cases, describe the important features that distinguish a fuel cell from what is commonly called a battery, mainly the fact that the latter normally is a chemically closed system. But then, a zinc-air battery for hearing aids isn't closed either.
Summary of a post signed "bblakemo@ford.com 8/10/2004":
Unlike capacitors, complex and multiple chemical reactions happen in batteries so they are difficult to model, and they are really ECDs (energy conversion devices, as opposed to ESDs - energy storage devices). Also, in a hydrogen-oxygen fuel cell, hydrogen should be called the anode and oxygen should be called the cathode (rather than the membrane and catalyst being called the cathode and anode). "I understand that this is a somewhat simplified view that does offer some problems in practice but would ask the reader to consider the Nickel Hydrogen battery in which gaseous Hygrogen is truely considered the Anode."
The article states (in a US-centric view maybe) that the first public H2 station was opened in Washington, DC, in november 2004. I was in Reykjavik in november 2003 and I visited the local H2 station. Maybe it boils down to the word "public". What is meant by that? If it is providing only for 6 state-owned vehicles, it's less public than Reykjavik's, which supplies a couple of hydrogen buses (which are regularly used by the public, bus route number 2 I think). See this link. Orzetto 12:06, 10 Dec 2004 (UTC)
...Since no objections are raised, I'll substitute in the Reykjavik station instead of the Washington one. Orzetto 09:06, 14 Dec 2004 (UTC)
If someone here is interested in the subject and speaks some german you can find in interesting article about a new form of fuel cell developed by the Fraunhofer Institute in Germany here: http://www.n-tv.de/5465399.html Cheers, -- Jpkoester1 11:25, Dec 21, 2004 (UTC)
I always used to think this is a good reason against hydrogen economy until i came across the post i have linked at the end this talk. "The hydrogen typically used as a fuel is not a primary source of energy: it is only an energy carrier, and must be manufactured using energy from other sources. Some critics of the current stages of this technology argue that the energy needed to create the fuel in the first place may reduce the ultimate energy efficiency of the system to below that of the most efficient gasoline internal-combustion engines; this is especially true if the hydrogen has to be compressed to high pressures, as it does in automobile applications (the electrolysis of water is itself a fairly efficient process)." This is from the main page. The main argument is hydrogen is not a source of energy, but what the argument avoids to say is gasoline is not a source of energy also. Once you agree with the fact that gasoline(Also a store of energy) is not a source of energy, the above argument becomes mute. This post nicely summarize the whole argument. [4] Note, even if you don't believe the above, hydrogen would still be a better option in that it would allow centralization of the gasoline usage. This would mean easy control of emission. In short, that argument is hopelessly weak
What do you mean with Fuel cells are electrochemical devices, so they are not constrained by the maximum thermal (Carnot) efficiency? I thougth that second thermal law and Carnot's theorem should always stands. AnyFile 21:09, 30 Jan 2005 (UTC)
By definition a fuel cell can be operated in reverse. Reversible fuel cells should not be considered a separate type of fuel cell. I realize that the page for reversible fuel cells states:
"So while the reversibility is applicable in principle to any fuel cell device, a practical device may not be built with this intent. Hence the distinction between reversible fuel cells, and generic fuel cells."
However, this does not mean it is a different type of fuel cell. Operating a fuel cell in reverse is simply a matter of configuration/capability and has nothing to do with "types" of fuel cells, which should only distinguish between cells which utilize different fuels and/or different half-cell reactions.
My suggestion is that the page simply state:
All types of fuel cells can also be operated in reverse. However, most fuel cells are constructed for the purpose of generating electricity only and therefore may require alterations before a reversible process can be run. For more information, please see Reversible Fuel Cell.
Faraz Syed 02:04, 30 August 2005 (UTC)
As per
Wikipedia:External links, I've removed a large number of links. If there are any that really scream to be replaced, here's a good place to talk about it.
brenneman
(t)
(c)
06:55, 26 September 2005 (UTC)
Added a section for links on research development for fuel cells, as I think this is really needed, especially since fuel cells are still under researched and being continually developed.
The link I have placed is a huge break though in hydrogen fuel cells, allowing for cars to store hydrogen (for use in a fuel cell) without a potentially dangerous compressed hydrogen tank. So that is why I thought it would be important to add in.
If anyone has any other links for future or previous dates which reveal a breakthrough in research development into fuel cells, then please add them.
"Fuel cells running on compressed hydrogen may have a power plant to wheel efficiency as low as 22%"
What is the purpose of stressing how low an efficiency a fuel cell may have? Aren't we more concerned with the current and theoretical maximum efficiencies of fuel cells? Anyone can make an engine with 1% efficiency, or lower.
A number of experts in fuel cells, including Karl Kordesch, have noted that the main advantages and disadvantages of a fuel cell stem from its electrolyte, and that this is why fuel cells are classified by their electrolyte. It seems that the Wikipedia article underemphasizes the importance of the electrolyte by placing the "Types of Fuel Cells" section at the bottom, and not providing any discussion or comparison at all of the various types.
I'd like to add a section either just before or just after the "Science" section that lists the types of fuel cells and their relative strengths and weaknesses, and perhaps some operating characteristics (such as temperature range). This would still leave the separate pages for each type to go in to details regarding how each type of fuel cell works. Any suggestions or comments? -- Thopper 00:30, 8 January 2006 (UTC)
Also, the diagram of the alkaline fuel cell, showing water flowing out with the excess hydrogen flow, is only correct for immobilized electrolyte designs such as those used in the Space Shuttle. Terrestrial AFCs typically have mobile electrolyte, allowing water management to be mediated through the electrolyte itself. I'm not quite sure how to capture this, and certainly haven't the artistic skill to update the diagram. -- Thopper 00:34, 8 January 2006 (UTC)
Hi! I just came to think whether it can be explained: is it possible to carry out virtually any oxidation thermal generation process to a fuel cell process via catalyzation? I mean, in theory it involves exchange of electrons, and essentially represents a reaction whose anergy could be trapped by a wise invented (or accidentally found) catalyst and membrane.
What I wanted to ask may be is this theoretically possible: to generate electricity by mere catalytic oxidation of natural oil or other fuel instead of simply burning it in air stream, to avoid Carnot process? -- mtodorov_69, 16 February 2006
Is it possible to build a nuclear device that will directly transform nuclear bond energy to electricity, without using intermediate thermal stage of energy conversion? Is it possible to covert directly from chemical and nuclear to mechanical, without intermediate thermal or electrical? This could be at least in "See Also", please, this is very intereseting. I hope it's not SF.
Coming here to see how a fuel cell works, I eventually spotted the diagrams hiding at the bottom of the article. I understand that not all fuel cells work the same, but one or two of these diagrams, with appropriate explanation, would make the "Science" section a lot more useful to the unknowledgeable reader, if you ask me. - IMSoP 01:05, 28 January 2006 (UTC)
As far as low efficiency as a standalone electrolyzer goes, we need to understand a bit about fuel cells. In particular, all fuel cells use a membrane to only allow only ionic species to flow into the reaction zone. That is, the reactants are forced to undergo an ionization process at the surface of the membrane, by either giving off or accepting electrons, before they are granted free passage into the reaction zone. Once ionized, the concentration gradient pulls the ionic species across the membrane, to the reaction zone, where the ionic species are consumed, thus keeping the concentration near 0 on the reaction side, and the gradient across the membrane active. Without the separation membrane the reactants could simply jump and react each other, without giving us the electrical way to tap the energy. With direct reaction we would only get heat, which, according to the principles of the Carnot Cycle, is an even more inefficient way to tap energy - most internal combustion engines are limited to 10-40% efficiency, while fuel cells can beat that easily, providing 40-70%, still falling short of batteries that can return over 65-90% of the available chemical energy as useful work.
The giving off or accepting electrons is the process that harvests the bulk of the available chemical energy. Still, like in any conversion process, not 100% energy becomes available, a lot is wasted. For example, some energy is consumed/wasted because there is electrical resistance by the membrane against the current flow carried by the ions - the ions bounce against the membrane atoms, and generate waste heat in the process, just like electricity passing through an incandescent bulb filament heats it up, consuming energy. The longer the path travelled by the current flow, the more energy is wasted. For this reason a good fuel cell membrane is as thin as possible, and as highly conductive ionically as possible. Also, a good fuel cell has as large a surface area as possible, because a large surface area lowers the overall membrane electrical resistance as well. There is always a balance in how big and thin you can physically stretch a membrane, without risking pinholes or large holes in the membrane, that would completely ruin your cell's efficiency, so the ionic conductivity of the membrane material remains a key player, limited by the available materials science technology at the time.
Low temperature fuel cells make very expensive electrolyzers, because of the special nature of the membrane surface, which needs a platinum coating. The reason for this platinum catalyst is to provide a low activation energy for the H2 → 2H reaction, the breaking of the hydrogen molecules into atomic species. This reaction is an energy intensive process, but still, like all chemical reactions, in an equilibrium, and any equilibrium can be driven by concentration gradients in either direction. Such catalyst is not necessary for the backwards process, for electrolyzing water, because 2 nascent and reactive hydrogen atoms or oxgyen atoms freely recombine as pairs into a stable, lower energy molecules, which bubble up to the surface. That is, you can effectively electrolyze water with two metal rods, even copper or steel, and produce molecular oxygen and hydrogen gas from the nascent atoms that form at two electrodes, however, you could not use such two-metal rod electrolyzers backwards as a fuel cell, because, even if you bubble hydrogen or oxygen to their surface, they wouldn't be able to generate the needed atomic/ionic species, without either high temperature (600 to 1000 °C), or a low temperature catalytic activity that platinum has. The known catalysts, the metals that are highly active at gaseous molecule splitting at room temperature, are either very expensive precious metals — platinum, palladium — or sophisticated blends of lower cost, but still expensive metals, such as those used in NiMH (nickel-metal-hydride) cells. NiMH batteries blur this boundary between batteries and fuel cells somewhat, at least the hydrogen side of things — the atmospheric oxygen activation may still be an issue - hemoglobin anyone? True, that while almost any metal can be used to electrolyze water, there is the factor of electrode overpotential that limits the efficiency of electrolysis, and these low activation energy catalytic metals make the very best electrodes. Still, there is no need for a membrane for electrolysis, but only for the forward, fuel cell mode of operation. Ideally, the metal side of the membrane would be flooded with the highly conductive water electrolyte for electrolysis, the electrolyte being in direct contact with the metal without a separation membrane, but dry it off and keep the electrolyte on the other, nonplatinated side, during operation as a fuel cell, to force all ions to travel through the membrane.
High temperature fuel cells such as solid oxide membrane (e.g. zirconia) fuel cells have no catalyst-expense limitation, but they are similarly costly because of the very nature of high temperature operation, slow startups (up to 8 hours), bulky size and the need of thermal insulation. High temperature electrolysis is currently an area of active research because it can directly utilise cheap heat energy, partially replacing the expensive electric energy needed to split water. This is based on the thermodynamic entropic drive in the reaction 2H2O → 2H2+O2, 2 moles reacting to for 3 moles of product, therefore increasing entropy, so forward reaction favored at higher temperatures, becoming spontaneous at the impractically high temperature 2500 °C. At temperatures below this point some electricity is required, but the closer the reaction is done to 2500 °C, the less extra 'nudge' needs to be supplied by electric energy. The highest practical temperatures are near 1000 °C, using a solid oxide fuel cell exactly in reverse mode. Even in view of the above cited thermodynamic advantages, this method has its own disadvantages, namely having to separate the reactant steam from the product hydrogen, by energy wasting cooling to liquid water, then having to reheat it back to the reaction temperature to complete the recycling step.
Mostly likely the most efficient large scale industrial water electrolysis method is, as described in the patent literature, via lower temperature steam injected into molten alkali metal hydroxide, near 200–400 °C, this molten electrolyte being hygroscopic enough so that not much steam evaporates with the product gases so no expensive separation step is needed. Molten alkali hydroxides have very high ionic conductivities, allowing very low resistive losses, and extremely high current densities.
nice text, is going to be integrated in Fuel Cell. Mion 10:19, 9 April 2006 (UTC) Coming from Reversible fuel cell Mion 23:19, 10 April 2006 (UTC)
... here: http://www.anl.gov/Media_Center/Image_Library/engtrans.html about fuel cell.
-- Harp 07:39, 19 April 2006 (UTC)
I removed the following from the article:
"Critics of fuel cells have also pointed out that their proposed use in aircraft (in order to cut the use of kerosene, which contributes massively to global carbon emissions) would have little or no impact on mitigation of climate change, since water vapour, itself a greenhouse gas, would be emitted."
First, there needs to be a source for this statement. Second, it is incorrect. Water vapor is a greenhouse gas, but its concentration in the atmosphere is not changed much directly by human activities. Water vapor is important in that increased carbon dioxide levels, causing global warming, may increase evaporation and therefore the level of water vapor in the atmosphere, increasing the greenhouse effect even further. The warmer temperatures may cause more water to be evaporated, which would increase the greenhouse effect further, causing a runaway greenhouse effect. Also, the burning of kerosene produces water vapor and carbon dioxide, instead of just water vapor, so even if water vapor was a problem, at least carbon dioxide would not be released as well (it is released during some types of hydrogen production, however). -- Kjkolb 17:28, 24 April 2006 (UTC)
"Fuel cells differ from batteries in that they consume reactants, which must be replenished, while batteries store electrical energy chemically in a closed system."
This distinction seems a little weak. Both batteries and fuel cells consume reactants. Most modern batteries cannot be replenished, but archaic ones like gravity cells could (replacing the anode and the electrolyte was routine).
Can someone clarify the distinction? Kurzon 00:10, 21 January 2007 (UTC)
From an intrinsic point of view, fuel cells and batteries are exactly the same: both generate compound by means of a chemical reaction, where the side effect is electricity and heat. But in reality comparing them is almost like comparing apples and oranges.
Any weak distinction made, is only arbitrarily come up with a definition for fuel cell Vs battery. Exceptions to the definitions will arise.
--
Fieraloca
04:00, 7 February 2007 (UTC)
The distinction may be arbitrary, but it is nevertheless important and valuable. All of the reactant in a battery is contained in the cells. If you want to increase capacity(Amp-hours), then you have to increase the size or number of cells. That is expensive. If you want to increase power output(kW), you also have to increase size of number of cells. This is not true with a fuell cell. Capacity is based on how big your reactant tanks are, and they are cheap compared the cost of battery cells. Power output determines the size and number of fuel cell stacks.
Also, storage batteries (not the ones that you throw away) are rechargable. This means that when the terminal voltage is raised above the cell voltage the reactants will chemically transition to their original states. Fuel cells cannot turn their products (water and heat for a H-O fuel cell) back into the original reactants. —The preceding unsigned comment was added by 149.37.200.150 ( talk) 14:10, August 23, 2007 (UTC)
Electro-galvanic fuel cells have been used for decades for measuring oxygen concentration in a breathing mixture. Would a short description or a reference to the article / use be appropriate? Especially as to how the concentration of oxygen gives a difference in voltage, which is converted to a displayed oxygen concentration. -- Seejyb 20:12, 20 May 2006 (UTC)
Who removed the image from commons ? its a GFDL licensed image from the French wiki. Fuelcell.en.jpg Reg . Mion 05:46, 16 June 2006 (UTC)
1989 A so-called water fuel cell is an unrelated claim of a perpetual motion device, which in fact was not claimed to function the way a fuel cell does.
If the water fuel cell has its own article it could be referenced on, it makes people more critical about real inventions and hoaxes, //Enron/Tesla Motors. Mion 16:31, 19 June 2006 (UTC)
In which disambig page ? Mion 19:14, 11 August 2006 (UTC) , and read the first part of the sentence, If the water fuel cell has its own article it could be referenced on, the second part was my personal view. Mion 19:14, 11 August 2006 (UTC) thats why i put it back.
and another one, there are loads of patents given on the design, it has the design of a fuel cell, the fact that we didn't see one working , tja. Mion 19:14, 11 August 2006 (UTC)
ok, i missed the top link to the disamb page, and which article, did i ask you ? well , i think it still belongs in the history section of fuel cells, or are we making only an article about fuel cells that where succesfull ? in that case there is more to clean out. reg. Mion 23:24, 11 August 2006 (UTC)
Yes, which takes hydrogen and oxygen as fuels to create a current. see Reversible fuel cell. reg. Mion 11:26, 12 August 2006 (UTC)
well, can the process be reversed in a fuel cell? Mion 13:45, 13 August 2006 (UTC)
First, the fact that the water fuel cell was granted a patent is absolutely irrelevant; in fact the patent was granted on the basis of construction of the invention, and not on whether the invention actually works.
Second, Nope, a fuel cell does not have to be used with H2 and O2 only, don't forget direct methanol fuel cells, solid oxide, etc etc etc. What characterizes the fuel cell is not the reactants it uses, but the exchange of protons between the cathode and the anode via dielectric media. -- Fieraloca 04:15, 7 February 2007 (UTC)
http://www.wired.com/news/planet/0,2782,69713,00.html Mion 13:12, 16 July 2006 (UTC)
If the water is not evaporated quickly enough, it reduces efficiency, and if it is evaporated too fast, it can crack the fuel cell. So, if used in, say, an automobile, does it have to keep operating all the time even when the car is parked, or can it be shut down, unlike the ones used in the Apollo space missions? (Jim Lovell on Apollo 13 knew that if they shut down the fuel cells as Mission Control told them to, they could not be restarted.) GBC 17:21, 11 August 2006 (UTC)
Once the membrane is hydrated within the break-in period of a new fuel cell, full performane can be achieved within minutes. Continuous operation is not necesary. Water is not evaporated from a fuel cell; the gas diffusion layer moves the water into the flow field of the current collectors.--
Fieraloca
08:34, 12 November 2006 (UTC)
It should be noted that start up time depends heavily on type of FC, modern PEMFCs can start within a few seconds. The startup time of a fuel cell system usually depends on time required to get the ion conductivity layer to produce adequate conductivity for the current required. Nafion, a popular material for PEMFC ion conductivity layer (electrolyte) can operate lower than 0 C (32 F). SOFCs need to reach about 600-800 C to start conducting ions for efficient operation.
Oxford dictionary: • noun:
[ [5]] Mion 11:52, 11 September 2006 (UTC)
Hi Mion or Anyone can help-- Please. . .
As ESL (English as second laguage) person I need help in writing an article on what I beleive it could be a break through in Fuel Cell research.
If you can help me in anyway please foreward me a note at ephitran at gmail.com
Many Thanks.
Phi
You are talking about a galvanic cell. Yes, you can get a galvanic potential when you place certain dissimilar metals together e.g. zinc and copper. There's no particular use for such as power source in real life.--
Fieraloca
08:29, 12 November 2006 (UTC)
The paragraph about combined heat and power (CHP) appears to contain contradictory information. It states that fuel-to-electricity conversion is "typically 15-20%". Toward the bottom of the same paragraph, however, it states that PAFCs, which dominate the CHP market provide electric conversion efficiencies typically around 45-50%.
I don't know which range of numbers is more accurate, but it would seem that at least one of them is wrong. -- jfinlayson 10:59, 18 October 2006 (UTC)
"Water management (in PEMFCs). In this type of fuel cell, the membrane must be hydrated, requiring water to be evaporated at precisely the same rate that it is produced. If water is evaporated too quickly, the membrane dries, resistance across it increases, and eventually it will crack, creating a gas "short circuit" where hydrogen and oxygen combine directly, generating heat that will damage the fuel cell. If the water is evaporated too slowly, the electrodes will flood, preventing the reactants from reaching the catalyst and stopping the reaction. Methods to dispose of the excess water are being developed by fuel cell companies."
Fuel cells virtually never run at an ideal condition, where "the same amount of water generated is PRECISELY evaporated". The gas diffusion layers (GDL) take care of the water management. If you have ever ran a fuel cell, you would know that the excess water is continuously discharged through the cathode side. -- Fieraloca 08:17, 12 November 2006 (UTC)
This phrase: "In 2008 UTC Power has 400kw Fuel cells for $1,000,000 per 400kW installed costs." is confusing. If it is "per 400kW installed cost" it is redundant. The intersting data here will be the cost per kW. -- Nachoj ( talk) 15:58, 27 April 2008 (UTC)
Propose to remove Metal Hydride Fuel Cell MHFC and Direct Boro-Hydride FC from the chart of different types of fuel cells.
Metal hydrides and Sodium-Borohydrides are HYDRIDES not fuel cells. They are H2 storage media. The H2 obtained from these two types of hydrides are usually fed into PEMFC.-- Fieraloca 08:21, 12 November 2006 (UTC)
You got my vote to taking this paragraph out. If you write something like this in a freshmen physics exam on thermodynamics, you have to repeat the class. The Carnot limit is fundamental and follows immediately from the second law, which is nothing else than the definition of temperature. A fuel cell just like a solar cell (non-experts make exactly the same mistake with those) is subject to it like EVERYTHING else. When the temperature increases on a fuel cell or a solar cell, the max. achievable voltage goes down and so does the efficiency. Period. No discussion.
As long as this stays in, the whole article belongs into the garbage. Literally.
--- Anonymous --- (Sorry... got no account, yet. But I did read this article and it pisses me off big time. There are way better science articles on Wikipedia.) —Preceding unsigned comment added by 69.3.190.146 ( talk) 23:20, 5 August 2008 (UTC)
Using cell voltage as an indicator of efficiency is the biggest non-sense that I have ever heard!!!
Example: Take a perfect fuel cell; at an open cell potential of 1.23V, the current is Zero, thus the amount of H2 consumed is also Zero. Which means that you have just invented a perpetual motion machine, no need to feed H2, just 1.23V of pure Potential?!?!?
The efficiency of a fuel cell has to be measured as a ratio between the amount of energy obtained Vs the total enthalpy differential. Or other methods would also be fine.
-- Fiera 08:52, 12 November 2006 (UTC)
In calculus there is the idea of limits. The open cell potential is always an ideal approximation - you measure it with a multimeter that draws a few picoamps, never 0. Similarly, the amount of H2 consumed due to these picoamps is a few femtomoles, which is still quite a few atoms considering avogradro's number is about 6x1023. When you talk about voltage, or potential energy in general (voltage in an electric forcefield, height/pressure/liquid head in a gravitational forcefield, pressure/spring constant in an electric forcefield between atoms), you always talk about rate of change, energy gained vs. distance traveled, motion. It's how much energy I would get per foot if I traveled north down this hillisde, there is an idealized answer to that, similarly like there is an idealized answer to an open cell potential, how much energy you would get per electron flowing through your wire, how many volts it carries. But you don't actually get any energy if you don't take a step, just sit still. Measuring the energy you have to move by a millimeter down the hillside, record the results to calculate how much you would get per meter. Similarly, if I have a pipe with 20 psi pressure of water meaning each cubic centimeter could give me such and such energy if I let it flow through my turbine/electric generator, the higher the pressure the more energy I'd get per cc of liquid. Staring at the pressure gauge on the pipe expressing to me the "pure potential" does not mean I have a perpetual motion machine because nothing is moving. In fact all pressure gauges obtain their reading by moving, whether a few millimeters against a spring load, or a few nanometers against a piezoelectric membrane. Sillybilly 13:12, 12 November 2006 (UTC)
Uhm... yea... i think i was being sarcastic when I said I invented the perpetual motion machine. What I am referring to is the following quote from the main fuel cell page, under "efficiency":
The efficiency of a fuel is very dependent on the current through the fuel cell: as a general rule, the more current drawn, the lower the efficiency. A cell running at 0.6V has an efficiency of about 50%, meaning that 50% of the available energy content of the hydrogen is converted into electrical energy; the remaining 50% will be converted into heat. For a hydrogen cell the second law efficiency is equal to cell voltage divided by 1.23, when operating at standard conditions. This voltage varies with fuel used, and quality and temperature of the cell. The difference between enthalpy and Gibbs free energy (that cannot be recovered) will also appear as heat.
What I'm saying is that this entire parragraph is pure non-sense. Whoever wrote this believes that the current stays constant with changing cell potential, that energy is measured in Volts, and that the open cell potential would yield a perpetual motion machine. Paragraph will be deleted unless objected by anyone. -- Fieraloca 04:45, 7 February 2007 (UTC)
I would suggest to ask an electrochemist to clarify this point. The entry about fuel cell efficiency and thermodynamics ruins the quality of the whole article. I would suggest taking the whole section out until someone with a background in fuel cells can take a shot at it. My criticism as a reader, not an editor, would be as follows:
Fuel cells are just as much thermodynamic devices as anything else in the universe. The second law holds and the Carnot Cycle is indeed a hard limit for fuel cell efficiency, except that it is not obvious what temperatures to throw into the Carnot limit equation. If I had to wing it, I would say that the lower temperature has to be the temperature at which the cell operates, and the upper temperature is probably the theoretical combustion temperature of the ideal fuel/oxidizer mix (at the partial pressure equivalent to the concentrations of the fuel and oxidizer?). Since that temperature is very high compared to the cell temperature, the Carnot limit will be somewhere above 90%. Now, the reactions inside a fuel cell are not equivalent to a Carnot Cycle because there is interaction between the fuel, oxidizer, the solvant and the electrodes, therefor the theoretical efficiency has to be less than the prediction of the Carnot Cycle. Any real science argument would obviously start with the well known ways to calculate dynamics of ionic reactions in solvents in, not the basic equations of thermodynamics for beginners.
I am a physicist, not an electrochemist and I do not have the detailed knowledge of fuel cell chemistry required to explain this quantitatively or even qualitatively. Anything I could write would therefor not approach a scientific quality standard. All I can tell is that the way it is written right now leaves a very bad impression to those with even a minimum of physics literacy. --[J.L.]
Mkultra, if that book was checked out, then just borrow any book on fuel cells, and read the chapter that discusses the efficiency. Since you're missing my point I'll try to make it more clear:
Efficiency = output power / reactant energy flow Reactant energy flow = constant * current (We'll disregard leak currents and wasted reactant for now) Output power = voltage * current
Combined, these three equations give:
Efficiency = voltage / constant
The section (9.7) that I referred to above actually discusses first law efficiency, and in that case efficiency is , not , so it's not an exact match. I could probably find an exact reference if I searched a bit, or rewrite the section to discuss first law efficiency instead (which is the most commonly used definition of efficiency anyways), but I can't be bothered right now.
If you don't now enough on the subject to say that the text is wrong, then you're better off letting the people who do know the subject decide on whether the text should be removed, referenced or not. I'll not revert you any more. I suspect somebody else will do it soon, and otherwise I hope you revert yourself once you've gotten that book from the library. -- PeR 21:06, 27 June 2007 (UTC)
PeR, The statement is absolutely wrong and should be deleted!!!!! You are trying to explain a very complex thing (fuel cell efficiency) though Voltage only? You are completely disregarding the stoichiometric flow through each cell!! Are you saying that a cell running at 0.6V and a stoich of 5 has the same efficiency than a cell running at 0.6V and a stoich of 1.2???? You assume constant current? Oh wait, you are ALSO assuming constant stoich. ok.
How about O2 diffusion efficiency? air contains 20.9% O2, your statement does not address how the diffusion plays a role in efficiency and real Vs theoretical stoichiometric values at the reactions sites. Nor does the statement address catalyst utilization/ reactivity. And you do not address proton trasport resitance. And crossover? So that too? you are also assuming that these factors are constant?
Let me see if I understand your statement. If every single operating parameter of a fuel cell is kept constant. Then efficiency is measured with voltage.
Trying to explain efficiency by Voltage only, is a little bit of an oversimplification, dont you think?
--
Fieraloca
23:32, 12 November 2007 (UTC)
I noticed the efficiency information on this article as well as its calculations are wrong. Fuel cells using hydrogen oxygen to water reaction can easily get 80% efficiency in the conversion from chemical hydrogen and 20% oxygen atmosphere in to electricity.
potentially the 50% statement may be closer to correct if a reformer is required, IE converting fossil fuels in to hydrogen, but this is not the goal of most of the fuel cell industry as it negates the goal of eliminating fossil fuel usage
1 of my sources I had handy
[8]
The statement about drawing current lowers voltage = less efficiency is totally false.
If you start at 1.5v at .5A and you add to the load pulling it down to .5V at 1.5A you still have .75W of energy.(these numbers are examples).
watts law amps*volts=watts watts = energy witch has direct conversions to horsepower, BTU, calories, and joules take your pick.
When I get some free time ile start cleaning up this article using verifiable sources.
Eadthem (
talk)
04:25, 5 December 2008 (UTC)
One cited article [9] in the history section claims that the fuel cell was not invented by Groove in 1839, but by Schoenbein, and that Groove did not build a fuel cell until 1842.
Most fuel cell related articles, in the "background" or "history" section will cite Groove as the inventor and the year as 1839. (See, for example, [10] or [11])
Does anyone know the truth behind this? I think the article needs to be clarified.
-- PeR 12:31, 29 November 2006 (UTC)
There is mention of cars and other vehicles that use fuel cells but not other vehicles. Perhaps there should also me mention of the first space craft. This submarine also uses Fuel Cells. I do not know if there were any before it. http://en.wikipedia.org/wiki/Type_212_submarine
Yewenyi 04:12, 6 December 2006 (UTC)
Consider the following section:
The efficiency of a fuel is very dependent on the current through the fuel cell: as a general rule, the more current drawn, the lower the efficiency. A cell running at 0.6V has an efficiency of about 50%, meaning that 50% of the available energy content of the hydrogen is converted into electrical energy; the remaining 50% will be converted into heat. For a hydrogen cell the second law efficiency is equal to cell voltage divided by 1.23, when operating at standard conditions. This voltage varies with fuel used, and quality and temperature of the cell. The difference between enthalpy and Gibbs free energy (that cannot be recovered) will also appear as heat.
This is confusing. Firstly, it says the efficiency is current dependent. Next, it gives an estimate of efficiency for a particular voltage. This needs to be clarified.
Ordinary Person 06:28, 6 December 2006 (UTC)
Paragraph should be deleted. Inaccuracies cited under discussion --- Correction to fuel cell efficiency ---
Fuel cell efficiency is dependent on several factors (stoichiometric flow of reactants, recirc vs non-recirc systems, parasitic loads, humidification of reactants, cell impedance and resistance, diffusion properties of the microporous layers, catalyst activity, etc etc etc. Voltage alone says nothing.-- Fieraloca 04:54, 7 February 2007 (UTC)
It is a simpler design and is more efficient. It is expected to first be incorporated in smaller engines like those found in lawn mowers. That should make in impact, since they are not regulated. [12] Brian Pearson 23:05, 16 January 2007 (UTC)
Take a look at [13]. DFH 20:31, 8 February 2007 (UTC)
New offshoreship with FC tech coming soon [14] --OddMartin 23:42, 22 February 2007 (UTC)
User talk:80.123.226.133 asked about Fe + 2FeCl3 = 3FeCl2 + energy. I found one Google hit. Could someome discuss it with him/her? Simesa 13:42, 26 April 2007 (UTC)
Anyone seen this? Efficiency of 49%. October, 2006: [15] Simesa 00:11, 30 April 2007 (UTC)
"In the archetypal example of a hydrogen/oxygen proton exchange membrane fuel cell (PEMFC), which used to be called solid polymer electrolyte fuel (SPEFC) around 1970 and now is polymer electrolyte membrane fuel cell (PEFC or PEMFC, same as the short writing of proton exchange membrane) while the proton exchange mechanism was doubted," I don't get this. What happened while the mechanism was doubted. Is this thing still happening or did the doubt stop? -- Gbleem 12:17, 22 May 2007 (UTC)
so if we go H2 + O2 ---> 2H2O, aren't we trapping O2 (breathable oxygen) in H2O molecules? won't we eventually run out of O2? Sahuagin 01:39, 28 May 2007 (UTC)
UTC's Power subsidiary was the first company to manufacture and commercialize a large, stationary fuel cell system for use as a co-generation power plant in hospitals, universities and large office buildings. UTC Power continues to market this fuel cell as the PureCell 200, a 200 kW system.[8] UTC Power continues to be the sole supplier of fuel cells to NASA for use in space vehicles, having supplied the Apollo missions and currently the Space Shuttle program, and is developing fuel cells for automobiles, buses, and cell phone towers; the company has demonstrated the first fuel cell capable of starting under freezing conditions with its proton exchange membrane automotive fuel cell.
In 2006 Staxon introduced an inexpensive OEM fuel cell module for system integration. In 2006 Angstrom Power, a British Columbia based company, began commercial sales of portable devices using proprietary hydrogen fuel cell technology, trademarked as "micro hydrogen."[9][10]
This needs to be moved or removed from the article. It has nothing to do with history that Staxon in 2006 put out a cheap FC...
The UTC part is even worse, it is manipulative, UTC might be the first to put out that specific type of backup power, but Japan have been using stationary power plants for many years. And most hitech firms have some sort of fuel cell production / development going on these days, with my limited knowledge, i do not recall having heard of one car firm using UTC cells in demonstration projects. No doubt UTC plays a major role in developing backup power systems, and due to the instability on the US power grid, there is a major demand for super reliable systems, that can also keep power flowing for many hours, maybe even days, but that should go in a separate article. Unless someone provides counter argument, i will move the staxon part to news, and remove the UTC thing. ( Larkuur 14:20, 12 August 2007 (UTC))
Update: Moved Staxon part, since the wikibot considers me a newbie (true), it wont let me delete anything... I still believe any one with the powers should remove the UTC part from the article, maybe move it to the UTC main article. (
Larkuur
16:35, 13 August 2007 (UTC))
Hiya, I'm a really bold dumbass who feels qualified to rewrite and even create whole new paragraphs when all I know about the subject I learned from reading Wikipedia. In other words, I know very little about fuel cells, so would someone check my rewrite of the first two or three 'graphs of "Fuel cell design" to make sure I didn't get it completely wrong?
One thing, as noted by User:Gbleem above, is that reference to the "early 1970s" and the proton exchange mechanism not being understood. I moved this, and reworded it to make what sense I could out of it, but there's actually no cite for this claim, and I was tempted to remove it. I decided not to, on the theory that whoever added it probably knows more than me. If it doesn't make sense, tho, someone who knows that should remove it. In any case, I think my layman's introduction paragraph is an accurate overview of the mechanism. Am I right? Eaglizard 21:06, 19 September 2007 (UTC)
Just deleted links to non existent wiki articles Fuel cell system and Fuel cell module. Could someone who has a good idea of fuel cell systems , WGS and PROX start these articles? shampoo 05:59, 27 October 2007 (UTC)
--outdent
Done. Please check content for sensibility. The original seemed to be written in a very stop-start style, which only makes it worse :). User A1 ( talk) 14:27, 8 September 2008 (UTC)
--outdent2
I did, great work, maybe de:Kværner-Verfahren next ? :) Mion ( talk) 15:28, 8 September 2008 (UTC)
--outdent3
Fuel Cell Markets is one of the leading online resources for Fuel Cells and contains a depth of information on business opportunities, recruitment, products and information about fuel cell resources.
Fuel Cell Markets facilitate the introduction and development of strategic partnerships and joint ventures towards building the global fuel cell supply chain and assisting with the creation of the hydrogen and fuel cell economy.
Piyush.fcm.kumar ( talk) 11:47, 12 December 2007 (UTC)
I've added an interesting link to Water fuel cell in the see also section. -- CyclePat ( talk) 21:42, 19 March 2008 (UTC)
In introduction there is a sentence "Some HHo fuel cells convert water to Hydrogen and oxygen that is in an excited state and hold its electrical potential until it recombines on burning releasing the energy and reconverting to water." It sounds like perpetuum mobile of first kind. It probably should be removed from introduction or rewritten in much clear way. Plus no any reference in the whole article what that “HHo” means. Do I horribly miss something here? --- MxM ( talk) 19:33, 1 July 2008 (UTC)
1.Design issue section:
Cost issue:
No definition of the term "cost" exists here - production cost? - shelf price? Also this part in the article lacks the fact that a manufactured product's cost generally depends on production numbers. In other words mass-production lowers the final product's cost. Hence this regards the final shelf-price for the end consumer, the material cost of the manufacturer as well as cost of manufacture.
This part of the article creates the idea that a fuel cell is too expensive, too cost-intensive, to be mass manufactured.
Do you think this is a neutral viewpoint?
2.Design History
Wilson, Mahlon S., Ph.D.,is not even being named here?
pfff
check out this:
http://www.lanl.gov/orgs/mpa/mpa11/bio-wilson.htm
and this:
http://www.freepatentsonline.com/6808838.html
and make you own assumption... —Preceding unsigned comment added by 77.185.223.145 ( talk) 19:37, 26 September 2008 (UTC)
In the Design Issues section, one point mentions the cost in US Dollars, while another mentions Euros. Since dollars are used in other sections, the Euros cost should be restated in dollars.