The Science Behind Fuel Cells – How They Powered Spacecraft, Cars And Sometimes Phones

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For the last 50 years every crewed mission to space launched by the US has been powered by fuel cells, these directly convert the fuel’s chemical energy into electrical power without an intermediate mechanical step. So, let’s try and explain how they work, and how there are many types of fuel cell technology which have their own advantages and disadvantages.

  1. StYxXx

    Fuel cells are also used to power and heat homes using natural gas. At least in Europe and especially Asia they’re commercially available. There are several types in use, like solid oxide fuel cells and proton-exchange membrane fuel cells.
    Oh I just see that Wikipedia has an article about that:

  2. lukamon2

    So thats why shutting off the fuel cells was a big deal in apollo 13! I always wondered why on earth you would install one shot valves on something so critical ; shutting the valves means the cell cools down and cant be heated up to operating temp again. TIL.

  3. Wroger Wroger

    Annies Node and Kathies Node.
    OK what now?

  4. Daniel Leca

    Unfortunately hydrogen fuel cells are expensive due to the materials they are made from, they are fussy in their operation cycle and most of all, hydrogen takes up a lot of volume and it evaporates over time. Too bad for Lockheed Martin’s Venture Star really…

  5. Charlie Devine

    This is a very good summary of fuel cells. I think the methanol-water fuel cell and the solid oxide natural gas fuel cell both convert the fuels to hydrogen then the hydrogen does the work.

  6. Carlo Roosen

    Didn’t Elon state that the energy density of current state batteries is already higher than fuel cells?

  7. Amer istanbouli

    So the main challenges are to ionise hydrogen at low temp and the proton exchanger ?

  8. Carl Kirchhoff

    Am I the only one who uses fuel cells to power my KSP spacecraft?

  9. dkosmari

    Mmmm… Bacon fuel cell…

  10. Peterkjaerhtc Larsen

    Hi x 8

  11. Dead Shush


  12. Frozen FPV


  13. New World Disorder

    Electrical videos

  14. Joel Hageman

    Epic tales to be told.

  15. william armstrong

    Fuel cell tech for cars is dead tech. There is no way Hydrogen can be stored and supplied in a city or urban areas where the words Blast Radius need adding to the planning application!
    For ships, trains and possibly Trucks and Buses where refueling can be done safely I can see few problems so long as regular inspections (daily) can be undertaken by qualified staff.

  16. David Burgin

    5:45 in the chart why would solar be separated from photovoltaic? Are they not the same?

  17. Annoson

    Scott you need to make a video about the new ULA upperstage fuel cell. I think its ACES.

  18. Kenneth Ferland

    No surprise that Dragon lacks Fuel-cells, Musk calls them Fool-cells after all.



  20. CptAJbanned

    That controller was a hero

  21. Jared Kennedy

    One of the earliest vehicles developed to run on fuel cells was a tractor. Allis-Chalmers built 10 fuel cell powered tractors in 1959. I haven’t been able to find specifics on the type of cell, but it seems to use atmospheric air and hydrogen.

  22. Lawrence D’Oliveiro

    6:18 Interesting that they used 31 cells in series at a nominal potential of 1V each. I believe the power supply was nominally 28V. Maybe the extra 10% was to cater for quality variation and degradation over time.

  23. Gsup7s


  24. Sam M

    Magic. Got it.

  25. 5Andysalive

    And we all know Power for Battery powerd cars comes just magically to the plug.
    And massive batteries are brought by the battery fairy at night with no environmental issues whatsoever.
    Wereas nasty Hydrogen has to be produced.

  26. Drunken Hobo

    And run them in reverse and you get a nice dehumidifier.

  27. Eric Lotze

    How close are we to methane-air / oxygen ones at lower temperature and pressure?

  28. Good

    as an added bonus to the mechanism for a photoelectric chemical battery one can use Kelvin generator cross circuits to increase ionic voltages across the bridge as a kelvin generator liquid coil. to compound what was said below.

  29. Comment Highlighted


  30. 54nathanael

    Where are the camper’s fuel cells available?

  31. Rob Highfill

    One week after the scheduled launch of Crew DM2 will be the 55th anniversary of the last launch of American astronauts from US soil in a spacecraft not powered by fuel cells.

  32. Maldus Alver

    Scott Manley as consultant for Kerbal Space Program 2.

  33. Eric Fermin

    I like my methanol with water too.

  34. tehllama42

    If this pans out, there might be some justification to look into methane or hydrogen storage that would work well for vehicle applications, which really is the limitation on why hydrogen fuel cells never caught on – the volume and weight of an adequate pressure vessel is the real limit, and this might surpass that to the point where this can become viable.

  35. Gordon Richardson

    Fourteen minutes on why fuel cells are interesting! Thirty seconds on why SpaceX won’t be using them…

  36. FairFireFight

    Why can’t Scott be my Online School Teacher , he explained a full chapter of chemistry in 15 mins while it took my teachers 3 weeks.

  37. ZockerTwins

    1:13 you forgot the l in sulphate

  38. Milo B

    God you are just brilliant you constantly provide genuinely useful and fact packed universally brilliant content. Thanks Man,ley

  39. Matt Long

    Hey Scott, there are bloom fuel cells behind the parking structure at the Ikea in Emeryville. I was really surprised when I discovered them. Not sure why Ikea needs them but hey still pretty cool.

  40. Lin Yen Chin

    This is a fine topic!

  41. mongke

    SpaceX 😍

  42. Gordon Marshall

    I saw a fueling station for fuel cell cars. That can’t be efficient. There seemed to be a huge power consumption to fuel the cars

  43. Ken Leach

    Interesting, thanks

  44. Lawrence D’Oliveiro

    11:15 Not sure what you mean by “pure-electrical”. Do you mean ones using rechargeable batteries?

  45. Wroger Wroger

    Just when you mentioned the fuel cell that was leaking hydrogen across the barrier, to the oxygen bit… I had a motorcycle, that because of my ignorance, the electrolyte had dropped, and it exposed the plates, and a tiny crumb of metalic oxide had bridged the plates in one of the cells…. and that detonated some 500cc’s of the hydrogen and oxygen mixture in the top of the battery and blew out the top of the side of the battery… I was trying to start the bike, and I jumped with fright, as it sounded exactly like some one with a sawn off shot gun had pointed it about a foot to one side of my head and fired it, from a bush 10 feet away….

    I contemplated why no one had ever made a cryogenic bomb – being a mixture of liquid hydrogen and liquid oxygen, in the absolutely ideal stroichimetric ratio for the optimum bang, and keeping it at super duper low temperatures until dropped….

    In terms of “the primary” explosive – this is the “go to” fundamental horror.

    The drawback is that liquid hydrogen and liquid oxygen react at cryogenic temperatures and explode anyway….

    But if you could mix it and prevent it from exploding and then suddenly raise the mixture to say 1200*C through out… Whammo! Mega Double Plus extra Good Good. The issues of ENERGY from detonating at say minus 250*C, to detonating at 1200*C – Whooooooooooooooooaaaaaaaaaaaaaaaaaaaaaaaaaaa Mega Bang.

    Point of note here. Initially, I would only experiment with detonating hydrogen and oxygen in at least small amounts, and in a fairly safe kind of a way…. Building a scale model F1 Apollo Engine in the back yard… first I would gain LOTS of experience, and then gradually work my way towards an engine test stand, and a concrete bunker a long way away from the test stand…..

  46. steve shoemaker

    Thanks Scott…!

  47. Philip Mangiovillano

    Love this stuff

  48. Deadzio

    I didnt understand a thing but good video as usual :D

  49. Kyle Brown

    well, Dragon v2 will be the first new human-rated spacecraft in 39 years anyway

  50. cloaking oak

    Scott you sexy beast! Back at it again answering questions nobody knew they wanted to know.

  51. Cameron Jenkins

    A video on examples of astronaut badassery would be awesome!

  52. Good

    if one alternates the 589nm & 425+nm photo cylinders the ionic water charges will behave as an alternating AC ion wave. instead of DC.

  53. Stan Burton

    A bit over 15 years ago, i worked on a research project that was run by Reliant Resources, (and of course funded by the DOE) that was intended to be distributed power generation fuelled by natural gas that was steam cracked and fed to a PEM fuel cell array. Thisxwas intended to be a device aboutvthe size of a large outdoor AC condensing unit consisting of a cracking unit, PEM array, and inverters. Each subsystem was contracted out to different suppliers, our group was in charge of the PEM array, as well as final integration. The cracker was a majorcstumbling block, i do not believe the contractor had any intention of delivering a functional product, mercaptans were a problem as the sulphur poisoned the Nafion PEM membranes. Water was necessary to keep the Nafion membranes moist at all times and water purity was an issue. The cells had a limited lifetime (but we were working on that, it was a materials issue that i was working with the metallurgists to help solve due to my background with high performance ceramics and plastic seals) we were able to generate 21KW out of 6 PEM cells, and that was with 30% inverter losses. But the cracker delays as well as the political issues of the time ended up killing the project.

  54. ElectronAsh

    This was brilliant.

    OK, aide from your pronunciation of “Gemini”. ;)

  55. Jaffar Hatami

    When I was in school we were taught one of the main problems with hydrogen fuel cells was storage — namely embrittlement of the containment vessel which can lead to catastrophic failure under pressure. Is this no longer a valid concern?

  56. Addmix

    How are they related to the creation of bacon. I need to know

  57. Ravi Nidumolu

    Hey Scott Manley, could you make a million more videos on rocket engines plz :) ? I’m helping run a liquid bipropellant rocket engineering club and your vids are perfect for member education, which is a big hurdle.

  58. frognik79

    Can you do a video on all the things invented for space flight that we use in our every day lives?

  59. Nudgeworth

    Wow! I now know what fuel cell are and how they work!
    Thank you so much!

  60. isgota

    Hello! Great video about fuel cells on spacecraft.

    About fuel cells on vehicles another issue, aside refueling stations, is fuel cost. FCH2 is more expensive than electricity even when produced from cheap natural gas. To be competitive you would need almost free electricity from off-peak nuclear or wind or so much solar than middle day becomes off-peak. We are still many years to that situation I’m afraid.

  61. Lawrence D’Oliveiro

    10:50 You mean ground vehicles? Spacecraft are vehicles, too.

  62. Good

    before I forget. the pure water will become conductive as the IONS become more common in parts per billion.

  63. Josh Hayes

    Electric Videos are dominating my screen! thanks for the great video MR. Manley!

  64. David Beal

    Thanks for bringing these concepts down to a level most anyone can understand. Nice Job Scott!

  65. Aluminum Oxide

    I use fuel cells a lot in my Kerbal Skylab Workshop Station

  66. CCCircuit

    I very much appreciate you rigorously going through the details of technology. Thank you!

  67. Lawrence D’Oliveiro

    6:55 No, you mean 3 batteries. You already said each one was made of 31 cells.

  68. Michael Thompson

    I love the insight this video brought to fuel cells, at least for this guy.
    Thanks man! :)

  69. Jim Feig

    Wait so the hydrocarbon fuel cells release CO2? Why not just run an engine at that point.

  70. Pratty

    Love how scott slipped and fell back into the queens English and said Gemini (Gem-in-eye) btw its the right way.

  71. Laélien Rivière

    Seriously, the quality on these Scott… Can we like a video more than once?

  72. Nova Fawks

    11:40 why hello there, I see my city :) smack in the middle of SF and sac

  73. Kevin Street

    Thank you for this video! I love it when you explain stuff, and this is a really interesting subject that I don’t know much about. So your video was awesome.

  74. The Cheaterman

    Always a pleasure to learn new things with you, Scott. Thanks! I didn’t realize there were so many planned applications for fuel cells outside of aerospace!

  75. edding8400

    Excellent video. I have worked on solid oxide fuel cells when I was doing by bachelors degree. The most common problem with the SOFC is the adherence of carbon on the anode surface.

  76. Random Someone

    I understood 0% of this video yet still enjoyed it.

  77. USWaterRockets

    Using Bacon’s Law, how many degrees of separation are there between Tom Bacon and Kevin Bacon?

  78. Lawrence D’Oliveiro

    10:01 Ah, you forgot to say “jemmin-ee” and went “jemmin-eye” instead. Which I think I prefer anyway. ;)

  79. Paul Mckenzie

    7:00 chef boyardee cooking up a spicy fuel cell

  80. Morgan Sinclair

    “Where’s the kaboom? There was supposed to be a shuttle shattering kaboom!”

  81. Kineth1

    7:45 Hehe, “kiliwatts”

  82. Raghu Chowdhry

    You lost me in the first minute. But I haven’t gone to high school yet so I think I’m fine

  83. Krzysztof Czołczyński

    I’ve got a kind of Pavlov response with automatic “it’s gonna be a good video” when I hear “Hullo”

  84. Tyler Cragun

    Always fun to log in to youtube and find a new Scott Manly Video Fresh off the Press!

  85. Mark Schenher

    I worked for the company that made the Apollo and Shuttle fuel cells
    You did an excellent job describing them

    Sadly this small division was spun off after the grounding of the Shuttle and soon thereafter the new company went bankrupt
    A foreign company now make stationary fuel cells at the factory

  86. Exotic Dva

    I lost you at the first second.

  87. Samira Peri

    “Astronaut badassery” must be a thick book.

  88. Pim Manders

    Very interresting, could you explain again…please. 🤔 i lost you after “hello, scot manley here…..”

  89. Gary Hillis

    The lack of fuel cells on the Dragon isn’t that surprising given that battery power density has increased dramatically in fifty years, that Elon Musk runs a company that makes batteries, and that the spacecraft doesn’t use hydrogen for other purposes so incorporating it is not incremental in nature.

  90. Cody'sLab

    I have a 1.4kw hydrogen fuel cell I plan to use at ChickenHole Base. 😊

  91. Hydrochloric Acid

    We covered fuel cells and batteries in last year’s chemistry lesson on reduction/oxidation. Thank you for reminding me that I’ve already forgotten about its contents.

  92. Alexander Sannikov


  93. pentagramprime

    How many beers would Scott need to accurately recreate the landing of the “KABOOM CASE” in KSP?

  94. HebaruSan

    11:01 – “In the 2010s, the Bush administration spent…”
    The Bush administration ended in January 2009. I assume this was the Obama administration?

  95. Lewis Massie

    I’m very interested in this chart 5:44 anywhere I can get a better breakdown/ higher res image?

  96. Shrike DeCil

    A battery is basically a fuel cell and a fuel tank sealed up together and intermingled. This is handy, concise, and pretty accurate. All the mechanical shenanigans, temperature optimization, fuel-purity requirements – all of it – is the effort to “grow” the fuel tank aspect *without* growing the (complex, expensive, heavy) electrode/electrolyte interface part. (Which is often amazing looking at how much extra gear that’s taking!) The fussing with “what is the electrolyte” and “what is the anode/cathode” are all the precise same problems of batteries (although fuel cells often involve more dinking with gases).

  97. Niklas211

    Just did my Bachelor’s thesis on Fuel Cells; I gotta say that you’re spot on with your vid! :)

  98. Hat Man


    I work on KC-135 jet engines for a living.

    Occassionally I see something that shocks me… In this case, all the hardware in this photo, such as the style of canon plugs, excessive amounts of safety wire, etc, looks insanely familiar… Because it’s exactly the sort of stuff my jet’s made out of. I occassionally get these sobering reminders just how OLD my jet it.

    Similarly, I once saw videos of the interiors of B-17s and DC-4s… I swear to god, we use identical light fixtures and seat racks as these WW2 planes.

  99. Jesse Carozza

    And in 15 minutes, Scott summarizes the thesis chapter that took me six months to write. :p

  100. Sean McDonough

    1:48 – Note that this happens even without a load connected, because even dilute sulphuric acid corrodes lead and lead dioxide (albeit slowly), evolving hydrogen and oxygen in the process; this is why lead-acid batteries have such a short storage life.

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