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Direct Methanol Fuel Cells

Discussion in 'Energy, Environment, and Policy' started by maxwellwsson, Apr 9, 2009.

  1. maxwellwsson

    maxwellwsson New Member

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    #1 maxwellwsson, Apr 9, 2009
    Last edited: Apr 9, 2009
    Methanol fuelcell to quadruple energy density of Tesla?

    DailyTech - Samsung Unveils New Military Fuel Cell

    This methanol fuel cell stores 1800Wh of electricity per 3.5kg (not sure if it includes the mass of the methanol)
    that compares to Tesla Roadster's 450Kg 50000Wh lithium battery pack
    You only need 27 of these fuelcells to match the Roadster's battery and that equates to 97kg.

    So it more than quadruples the energy density of the current Tesla's battery and the recharge time is practically same as the gasoline cars, you just need to refuel it with methanol.

    Did I make a wrong calculation?
     
  2. AnOutsider

    AnOutsider S532 # XS27

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    I think you're on point... I added it up to be about 230,000 Kwh for a 450Kg pack
     
  3. stopcrazypp

    stopcrazypp Well-Known Member

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    No, I think your math is correct. Gravimetric energy density was always better for fuel cells, even for hydrogen fuel cells. Methanol fuel cells are certainly interesting technology, offering better energy density over even hydrogen, both gravimetric & volumetric. It still has that infrastructure problem, but being a liquid fuel, it should be easier to fuel & transport than hydrogen.

    If the technology is cheap enough it might be a good option for transportation. But methanol fuel cells are not zero emissions (in addition to water, they also emit carbon dioxide), methanol is toxic and can't easily be made by renewable energy, so they aren't going to get as much green cred, which is probably why automakers aren't looking at them.
     
  4. Serge

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    I think it's time to start a separate topic about one of the few [IMHO] fuel cell technologies to possibly get excited about.

    Reuters (found via ABG) has an article discussing movement of direct-methanol fuel cell startup Oorja Protonics into automotive market.

    Their current commercial offering for materials handling market (OorjaPac) has the following characteristics (day is 20 hrs, or two shifts);
    Energy Output: 400-800 Ahr/day
    Voltages supported: 24, 36, and 48 V
    Operating Temperature: 0° C to 40° C
    Weight: 250 lbs
    Consumption: 3-6 gallons per day.
    Cost: $16,500

    It's not completely clear from their brochure what maximum power-output their unit is capable of. As far as energy output is concerned, given that minimum/maximum fuel consumption is a factor of 2 most likely scenarios for those characteristics are: 1) 400 Ahr at 24 V (3 gallons) and 2) 800 Ahr @ 24 V or 400 Ahr @ 48 V (6 gallons). In that case, energy output is 800 Ahr * 24 V = 19.2 kWh, with energy density of 19.2 kWh / 250 lbs / .45 = 170 Wh / kg. Not bad and quite comparable to a good lithium ion pack.

    If my calculations are correct, current cost is just under $1,000 / kWh, which is comparable to retail prices for A123 Cells. Would be interesting to learn if this type of fuel cell also (like hydrogen ones) requires exotic catalysts, what the reliability record is, other drawbacks?
     
  5. Serge

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    No doubt, given that using natural gas to power a fuel cell directly, instead of trying to convert it to hydrogen first, makes much more sense [to me].

    What generated interest about methanol fuel cells for me is:
    1) Portability of fuel, which is liquid and can be produced from a number of sources
    2) Reasonable commercial pricing without benefits of high volume production yet (potential for cost cutting).
     
  6. doug

    doug Administrator / Head Moderator

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    Lets try to keep this thread on the topic of methanol fuel cells.


    My understanding is that the power density with current technology is fairly low and may be the limiting factor for automotive applications. However, it probably merits further R&D.

    Like hydrogen, when compared to BEVs, methanol fuel cells aren't particularly efficient. But it's ease of storage and transport, and compatibility with the current gasoline infrastructure gives it some clear advantages over pure hydrogen.

    The other thing to consider, as with hydrogen, is the source of the methanol. We touched on it a bit here, where some have suggested producing it out of atmospheric CO2. This a pretty poor idea, however, since CO2 makes up a very small portion of the atmosphere. You're much better off capturing it from the exhaust of a power plant. But then to produce methanol from CO2 you also need hydrogen. So at least one more (probably energy costly) step is needed to produce methanol this way beyond what is required to make hydrogen. Of course methanol can also be made from biomass or fossil fuels (most often natural gas).

    Still one wonders why we don't hear more about methanol fuel cell vehicles (MFCVs). Of the four "miracles" required for HFCVs (Steve Chu refers to four anyhow), which I'll label as Production, Storage, Distribution, and (cost and feasibility of) the Fuel Cells themselves, MFCVs eliminate the middle two. Why then is the auto industry to comparatively interested HFCVs?

    Anyhow, Wikipedia seems to have some good info on the methanol topic: Methanol economy - Wikipedia, the free encyclopedia

    Of the listed "methanol economy advantages compared to a hydrogen economy", this one is huge:
     
  7. Serge

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    So it's the same situation as with other high energy density technologies, such as Lithium-Air.

    Likewise, while not a very good "main" traction power source, DMFC does look like a potentially decent range extender. Imagine Model S having a 100 mile main lithium ion pack, which is primarily charged via plugging in for everyday driving, and a methanol-powered generator for longer trips.

    The nice thing about having an on-board generator is that [as long as there is methanol fuel] there is a contingency plan. So when one drives to Yosemite and finds overnight charger, which was reported in good working order just last week, suddenly inoperable/taken/unavailable, now there is an option to leave the on-board generator on all night to top off the depleted main pack.

    A BEV/DMFC hybrid can take advantage of each power sources' particular strengths. Local trips are covered by very efficient battery, while efficiency on long trips is still higher than ICE-power (either as engine or range-extender).

    Whatever it is currently, methanol is ridiculously cheap. According to a Mid-August report
    An excellent question which I am very interested in exploring as well. I will reserve my [mainly speculative] input for now until more is learned.

    I'll also keep digging for specific power density info. Thanks for the links on Samsung DMFC development.
     
  8. qwk

    qwk Model S P2681

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    gasoline has a 14.7:1 stoich ratio and methanol is 6.4:1 stoich. There is over twice the energy in gasoline as methanol.

    Another reason you don't see to many methanol vehicles, methanol pulls moisture from the air when the container housing it is not completely sealed.
    Fuel + water dont mix.
     
  9. stopcrazypp

    stopcrazypp Well-Known Member

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    A minimum requirement of a "range extender" is enough power to maintain highways speeds. I'm not sure if DMFCs are there yet; if they are, then they are potentially a decent range extender.
     
  10. Serge

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    True, but volumetric density of Roadster's pack is even lower; it's all about how efficiently the fuel is transformed into energy of motion.

    While a bad thing for methanol ICE, water is actually required for reactions to take place in a DMFC.

    Indeed. I usually consider sustained 20 kW a minimum requirement for highway travel. I couldn't find any direct confirmation of power density for the latest model being developed by Samsung in conjunction with ViaSpace for the Army. However, earlier prototypes, targeted primarily at portable electronics market, had power output of 20 Watts. The new models supposedly:
    This power output level seems to be targeted to a specific application (military). Note, for example, that a common military rechargeable battery BB 2590 has 15 W of power. It also appears that DoD is upping the ante. In 2007 Wearable Power Prize competition the devices had to satisfy the following power/energy requirements properties.
    The winning team's (DuPont/SFC Smart Fuel Cell) DMFC was slightly heavier (3.7 kg) than Samsung's (3.5 kg). Can we assume that Samsung's unit is also capable of delivering 200 W if for a short period of time? If so, what prevents the operation at that power output level for longer periods of time?
     
  11. doug

    doug Administrator / Head Moderator

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    Stumbled upon this older ABG article,
    Will direct methanol fuel cell beat li-ion plug-in hybrids in the long run? - Autoblog Green,

    which refers to this piece in the HuffPost from last December (before the Obama administration).
    Patrick Takahashi: Is There An Option More Promising Than The Plug-In Electric Vehicle?

     
  12. Serge

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    Found a German company, named Smart Fuel Cells, which already has commercial offerings.

    For example, check out their new product to be released in Oct. (Pro 2200):
    Output is 90 W from a 8.8 kg device. Not yet good enough for a highway range-extender (hypothetical 20 kW units weighs a hefty 200 kg), but it's 38% improvement in power output over their current Pro 1600 (65W) model. Since unit weight is roughly similar (8.4 vs 8.8 kg) and fuel consumption is the same (.9 l/kWh), looks like improvement in power output was achieved via higher efficiency.
     
  13. Serge

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    I wonder if "prohibition" is indeed in place. DoE's methanol site doesn't have much info, with main future benefit listed as methanol being a potential feedstock for hydrogen production.
     
  14. Serge

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    One of the drawbacks shared by DMFCs and HFCs is [currently high] use of [very] expensive platinum as catalyst. The other is [relatively] low efficiency.

    Apparently, the following research seeks to address both problems at the same time: Carbonized Titanium Dioxide Nanotubes Could Significantly Increase the Efficiency of Methanol Fuel Cells
     
  15. doug

    doug Administrator / Head Moderator

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  16. Serge

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    Good find, Doug. Presentation, I find, provides good insight into challenges that DMFC technology faces or faced a couple of years ago. I wasn't able to find an updated presentation, but the latest mention of Panasonic's DMFC development is this 2008 article. It looks like volumetric density comparable to Li-Ion battery has been achieved, indicating that Panasonic is at the tail end of Phase I (according to chart on pg.15)

    Nice to actually see a list of technical breakthroughs required for Stage 2 commercialization, which I understand would be a roll out of first commercial product:
    1. Power density needs to be greatly increased:
    2. Energy density needs to be greatly increased:
     

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  17. doug

    doug Administrator / Head Moderator

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    #18 doug, Sep 18, 2009
    Last edited: Sep 18, 2009
    Yes, the x-axis is year, y-axis says energy density. The inset key from top to bottom says: 2nd generation lithium ion battery, 1st generation lithium ion battery, nickel metal hydride battery, nickel cadmium battery.
    (fyi: the non-Chinese characters are actually phonetic English. enerugii, richiumu ion, nikkeru kadomiumu...)
     
  18. Serge

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    Cool, Doug! I thought the first line was DMFC. I wonder now what is this 2nd generation li-ion battery (>600 Wh/L) and is that's what's in the Roadster?

    BTW, I tried real hard, but didn't see any "non-Chinese characters;" all look like hieroglyphs to me.
     
  19. doug

    doug Administrator / Head Moderator

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