What is Fuel cells: Definition and 42 Discussions

A fuel cell is an electrochemical cell that converts the chemical energy of a fuel (often hydrogen) and an oxidizing agent (often oxygen) into electricity through a pair of redox reactions. Fuel cells are different from most batteries in requiring a continuous source of fuel and oxygen (usually from air) to sustain the chemical reaction, whereas in a battery the chemical energy usually comes from metals and their ions or oxides that are commonly already present in the battery, except in flow batteries. Fuel cells can produce electricity continuously for as long as fuel and oxygen are supplied.
The first fuel cells were invented by Sir William Grove in 1838. The first commercial use of fuel cells came more than a century later following the invention of the hydrogen–oxygen fuel cell by Francis Thomas Bacon in 1932. The alkaline fuel cell, also known as the Bacon fuel cell after its inventor, has been used in NASA space programs since the mid-1960s to generate power for satellites and space capsules. Since then, fuel cells have been used in many other applications. Fuel cells are used for primary and backup power for commercial, industrial and residential buildings and in remote or inaccessible areas. They are also used to power fuel cell vehicles, including forklifts, automobiles, buses, boats, motorcycles and submarines.
There are many types of fuel cells, but they all consist of an anode, a cathode, and an electrolyte that allows ions, often positively charged hydrogen ions (protons), to move between the two sides of the fuel cell. At the anode a catalyst causes the fuel to undergo oxidation reactions that generate ions (often positively charged hydrogen ions) and electrons. The ions move from the anode to the cathode through the electrolyte. At the same time, electrons flow from the anode to the cathode through an external circuit, producing direct current electricity. At the cathode, another catalyst causes ions, electrons, and oxygen to react, forming water and possibly other products. Fuel cells are classified by the type of electrolyte they use and by the difference in startup time ranging from 1 second for proton-exchange membrane fuel cells (PEM fuel cells, or PEMFC) to 10 minutes for solid oxide fuel cells (SOFC). A related technology is flow batteries, in which the fuel can be regenerated by recharging. Individual fuel cells produce relatively small electrical potentials, about 0.7 volts, so cells are "stacked", or placed in series, to create sufficient voltage to meet an application's requirements. In addition to electricity, fuel cells produce water, heat and, depending on the fuel source, very small amounts of nitrogen dioxide and other emissions. The energy efficiency of a fuel cell is generally between 40 and 60%; however, if waste heat is captured in a cogeneration scheme, efficiencies of up to 85% can be obtained.

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  1. BWV

    Methanol - H fuel cells for marine transport

    This privately held company developed a technology to extract H from methanol stored onboard marine craft, then the H can be used in a fuel cell for power. I assume the reason for a H fuel cell vs a direct methanol fuel cell (DMFC) in a marine vessel is that direct methanol cannot deliver large...
  2. J

    Nernst Equation with Pressure Differences

    I'm working with the Nernst equation with pressure differences right now: ## E = E_t + \frac{RT}{nF}ln ((P/P_0)^{\Delta \eta_G})## I'm assuming pure reactants here so, so I'm omitting the product terms: ##\frac{\Pi_{products} x_i ^{\nu_i}}{\Pi_{reactants} x_i ^{\nu_i}}## which would normally...
  3. srinaath

    Why do we need to supply air to the cathode of a hydrogen fuel cell

    I am trying to understand the working of simple hydrogen fuel cell. We have anode (negative terminal), cathode (positive terminal), catalyst at anode to separate negative and positive ions of hydrogen atoms and electrolyte which allows only positive ions. We will be sending hydrogen fuel at...
  4. J

    Microbiological Fuel Cell: Negative Voltage

    Hello! I've been working on a few soil based MFCs and I have been monitoring my voltage and energy output for a week now. I've made the electrodes by covering stainless steel metal meshes with activated carbon using epoxy. I've gotten some funky results as attached. As you can see... the...
  5. bbbl67

    Automotive Gasoline Fuel Cells: Energy, Weight & Efficiency

    I understand that there is some research going on into gasoline (i.e. petrol) fuel cells (as opposed to the more typical hydrogen or alcohol fuel cells). How much energy can be released through a gasoline fuel cell, as opposed to simply burning it in an internal combustion engine? Will more...
  6. N

    Fuel Cells for Isolated Electric Generation

    Hello, I am researching about fuel cells that use Ethanol as a fuel, because I want to buy a equiptment of approximate 5 Kw (Electric) that uses Ethanol as a fuel for electric generation in anyplace, where yet there is not supply of electrical Energy by wire. Have you heard anything about this...
  7. anorlunda

    Residential Fuel Cells: Japan vs US/EU

    For several years, I've been seeing mention of growing number of residential fuel cells in Japan. But in the USA and the EU, hardly a mention. Does anyone know why the puzzling discrepancy? The American company Plug Power has been pushing fuel cells since 1997, but their penetration seems...
  8. P

    Hydrogen fuel cells in small applications

    Hello internet! Please excuse any silly questions as I am not (obviously) a professionally educated physicist (yet!). I was doing a school project on alternative energy sources and became rather interested in hydrogen fuel cells, specifically to replace batteries in small scale, high energy...
  9. M

    Exploring the Future of Fuel Cells: A Ph.D Student's Perspective

    Hi My name is Mesut. I am a Physics Ph.D. student at University of Arkansas at Little Rock. I am working on Fuel Cells. Thanks
  10. M

    Fuel Cells; PEMFC; Cause of Proton Movement

    Lately I've started learning about fuel cells, particularly proton exchange membrane fuel cells (PEMFC), and a fairly basic question that has been bugging me is: Since the cathode is positive, it is clear why the electrons flow through the load and to the cathode, but why do the...
  11. J

    Why aren't drones and aircraft using hydrogen-oxygen fuel cells?

    I've heard they were much more efficient then li-ion batteries and anything else really.. and drones today are all about flight time, wouldn't hydrogen fuel cells result in a great flight time advantage? why are they not in use?
  12. P

    Fuel Cells -catalyst converter

    Homework Statement Do fuel cell vehicles have a catalytic converter? Where is it located? The attempt at a solution[/b] I am guessing that the the question qould be referring to precious metal catalyst located at anode region which breaks the fuel into protons and electrons?
  13. B

    Using a Catalyst With Fuel Cells: Benefits and Challenges

    With galvanic cells, we assume that the redox reaction is kinetically inhibited so that equilibrium takes a long time to reach, so we can make a good measurement of the potential difference V. I thought fuel cells were the same originally, except that we recycle in reactants and products to make...
  14. B

    Determining efficiency of fuel cells

    Hi I need to compare solid working with \frac{1}{2}O_{2}+H_{2}O+2e^{-} \rightarrow 2OH^{-} and H_{2}+2OH^{-} \rightarrow 2H_{2}O+2e^{-} and liquid fuel cells working with H_{2}\rightarrow 2H^{+}+2e^{-} and \frac{1}{2}O_{2}+2H^{+}+2e^{-} \rightarrow H_{2}O My...
  15. L

    Why would fuel cells be good for the economy?

    Congratulations, you've created a fuel cell car! Now you need electricity or fossil fuels to create hydrogen to fuel the car. So burn some coal to get electricity. How exactly does this help the environment again? What am I missing here?
  16. R

    Help in Understanding Hydrogen Fuel Cells?

    I'm doing a presentation on Hydrogen Fuel Cells for my class, but I'm having a hard time understanding how exactly it is that they work. I'm only able to find information on fuel cells and they tend to not be descriptive on the hydrogen part. If someone could please link some articles that...
  17. M

    Is the Carnot efficiency valid for fuel cells?

    So, I've read in books and on Wikipedia (see for instance http://en.wikipedia.org/wiki/Carnot%27s_theorem_%28thermodynamics%29#Applicability_to_fuel_cells_and_batteries) that the Carnot efficiency cannot be applied to a fuel cell because it is not a heat engine that produces work, operating...
  18. M

    Exploring Hydrogen Fuel Cells: Questions & Answers

    Homework Statement hi I've got to do a project for college and need some direction I want to know a few things more so if you can help let me know. some of the things include (if you could answer any it would be useful): why can't we make a longer electric current to harness all the...
  19. M

    PEM Fuel Cells vs Batteries: Understanding the Difference

    hi I've got to do a project for college and need some direction I want to know a few things more so if you can help let me know. some of the things include (if you could answer any it would be useful): why can't we make a longer electric current to harness all the electricity produced in a...
  20. G

    About magnet field in solid oxydes fuel cells

    Hello! I don't understand one easy moment in high temp solid oxydes fuel cells (SOFC): 1. Oxygen ions are moving always via solid electrolite ZrO2? SOFC without load and SOFC in short circuit modes. (High temp is default mean) 2. Electrolises process need electric energy and external...
  21. S

    Fuel Cells Q&A: Explaining Hydrogen, Electrochemical, & Polymer Cells

    Could somebody expain me the following questions: 1)Why hydrogen fuel cell needs catalyst (such as platinum) to operate, while elcectrochemical elements (such as zinc-air) do not? 2)Why power density increase in fuel cells leads to efficiency decrease while in electrochemical batteries it...
  22. N

    Can I Pursue a Career in Hydrogen Fuel Cells?

    Hi all, I recently made my own hydrogen fuel cell and really enjoyed the process and everything I learned. I didn't know much about electronics or cells, so it was a great learning experience. In my research I found that chemical engineers made a nanometal to work as a catalyst instead of the...
  23. K

    60 Minutes: Could Fuel Cells Revolutionize Energy Use

    What is your opinion of http://www.cbsnews.com/video/watch/?id=6228923n&tag=related;photovideo" segment which appeared on "60 Minutes today (February 21)? It would, if it proves out, apparently make the "fuel Cell" a feasible idea for mass use. KM
  24. G

    Fuel cells versus batteries

    From what i understand, the only thing that makes using fuel cells in cars versus lithium batties less desirable, is the cost of hydrogen. If hydrogen can be produced extremely cheaply, assuming the same standards for compressing and transporting and storage of hydrogen, would it be better...
  25. S

    Cost estimate of Hydrogen Fuel Cells versus Gasoline

    Although a complete cost analysis is much more complicated, the particular question only requires the following: an energy cost estimate (in terms of $/Joule). This was directed to be done by taking volumetric or mass based costs of each fuel as well as the associated energy conent or energy...
  26. A

    Questions on Electrolysis and Fuel Cells

    Hey all, This is just a post about some questions I had regarding electrolysis and fuel cells. I know that when electricity is forced through water the water molecules split, and produce hydrogen and oxygen gas. I was wondering how things like the electrode material and how far apart they are...
  27. S

    Extended essay about PEM fuel cells

    I am doing the IB and have an extended essay to write. I intend to write it in Physics. I am thinking of doing something with my PEM fuel cell. However, I've found it hard to constrain the topic into the core of physics as fuel cell theory is mostly electrical chemistry. Any suggestions for a...
  28. O

    Fuel cells versus Batteries

    batteries or fuel cells? hydrogen costs too much to be an effective fuel alternative? the catalyst required for the electrochemical conversion reaction is pricey platinum? Using hydrocarbons as a source for hydrogen we have more CO2 in the atmosphere? and require a high temperature...
  29. Topher925

    Why are heat pipes not used in PEM fuel cells?

    Just curious as to why you don't find heat pipes or any passive cooling in larger PEM type fuel cells. I have seen them used in methanol fuel cells but not FCs for hydrogen. Is there a good reason for this? Is it because the power density of fuel cells is typically higher than that in many...
  30. Topher925

    PEM fuel cells, why the membrane?

    For those of you that arent very familiar with PEM fuel cells, their shortcomings basically revolve around the carbon/platinum membrane and is essentially the "heart" of the fuel cell. But why does a fuel cell need a membrane to function? If you think about it, just about all energy conversion...
  31. E

    Operating temperature of Fuel Cells

    What does the operating temperature of a fuel cell mean? Is this the temperature the cell generates or the temperature the cell is brought to so that it can operate? I see articles that state operating temperatures for different fuel cell systems---i.e. solid oxide 600 to 1000 C, phosphoric acid...
  32. D

    Hydrogen Fuel Cells: Challenges and Benefits - django

    Hi! I'm django, new member. Right, I would like to talk about fuel cells. At first glance they are great, right! 99% fuel efficieny. But what most peopkle don't realize, is that although hydrogen might well be the most predominant element in the Universe, it is not available on Earth in...
  33. D

    Please answer this one quick question (about fuel cells)

    I'm a physics student trying to do a project on fuels cells. One thing I don't get is, when the atom goes through the electr-- whatever, how does it separate into electrons and protons. I thought the only way to separate electrons from the nucleus is by extreme heat and pressure, like that...
  34. D

    Solutions for High Temperature Fuel Cells

    Hey everyone, I found this really interesting article on Technology Review about a new technology that could remove the sulpur from high-temperature fuel cells. The sulpur causes the eventual shut down of these fuel cells, but with this new technology the cells continue working and are...
  35. P

    Exploring Hydrogen Fuel Cells for Energy

    i was thinking over how a hydrogen fuel cell works, seperating the electrons and protons (into its ions like any other way of converting electrical energy to chemical) but i wondered if the protons as well as the electrons could be used as a current to creat a circuit such as the electrons do...
  36. Pengwuino

    Zinc-air fuel cells, advantes/disadvantages?

    So my uncle approaches me today with some investor guide dealy. It takes albout some Power Airtech company and how it is going to introduce some zinc-air fuel cell that they developed with LLNL. Can someone explain the advantages and disadvantages of such a system. They made it out to be greater...
  37. B

    Exploring the Unfulfilled Promise of Fuel Cells

    About an year ago, i had heard a lot about the upcoming technology of fuel cells. i was pretty intrigued by the description that it combined, hydrogen and oxygen to form pure water. no wastage. i believed it would be the alternative fuel we were in search of. why then is there not much...
  38. D

    Fuel Cells that Run off Ethanol or Sugar Possible?

    Is it possible to make fuel cells that run of ethanol or even sugar? :confused: Is it a good idea? Why/Why not?
  39. N

    Infinite Energy With Fuel Cells?

    I've got a problem. I tried to see what would happen when putting a fuel cell and electrolysis in a circle. I end up with infinite energy, so I must be doing something wrong. Electrolysis 4 H2O -> 4 H+ + 4 OH- 4 H+ + 4 e- -> 4 H -> 2 H2 || The H2 is lead to the fuel cell anode 4 OH- ->...
  40. I

    Why Hydrogen is the Only Fuel for Fuel Cells

    My chemistry book says it is impossible to use anything but hydrogen in a fuel cell, but does not say why. does anyone know why?
  41. J

    Hydrogen Fuel Cells: Ups Backup Source Experience

    Does anyone have any hands on expierence with Hydrogen fuel cells used as the backup source on UPSs.
  42. A

    Understanding PEM Fuel Cells: Exploring the Process and Benefits

    Being fairly new to the whole fuel cell thing (or at least how it works), I have a couple questions. I have learned so far that Proton Exchange Membrane (PEM) fuel cells work using the following device and process: * Why must the hydrogen be combined with oxygen at the end of the process...