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A cheaper, better way to make hydrogen (82% efficiency)

Discussion in 'Fuel Cell Vehicles' started by usbseawolf2000, Jun 26, 2015.

  1. austingreen

    austingreen Senior Member

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    Catalytic electrolysis has a theoretical maximum efficiency of 83% @ STP. If the stanford team if they have gotten 81.5% that is very good.
    286 KJ are required to disassociate one mole of water to produce 1 mole of hydrogen (H2) and 0.5 moles of O2. When they are combined you can get 237 KJ in tha reaction but of course a fuel cell is lousy. The extra energy heats the electrolyte and electrodes. Now it takes money but compressors use 2kwh-7kwh to compress and chill 1 kg of hydrogen to 10,000 psi. If we use the lower figures.

    33.7 kwh electricity/gge /81.5% + 2 kwh (really efficient expensive compressor and chiller) = 43.3 kwh or 1.3 GGE of electricity to make 1 gge of hydrogen (77.7% efficiency) which is better than we see in commercial production but definitely feasable with this technology. Use the compressor heat to heat the electrolyte (or maybe burn some natural gas) and efficiency can theoretically be improved.

    1.3 GGE of electricity could fuel a 67 mpge fcv (mirai) for 67 miles.
    1.3 GGE of electricity could fuel a tesla model S 85D for 129 miles (using unronded figures) or 192% of the mirai.
    The same electricity could fuel a bmw i3-bev 160 miles or 238% of the mirai.

    This is less of an advantage than some articles claim (3 to 4 times) because this new method is more efficient for lower costs if it works. There are costs for the compressor and electrolysis over the simple efficiency gain though. Both the bev and electrolyzed hydrogen will have the same loss from source to plug so it can be ignored.
     
    FL_Prius_Driver likes this.
  2. Trollbait

    Trollbait It's a D&D thing

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    There were incentives in place for FCEVs around the time for hybrids, because the hydrogen fuel cell lobby said the cars would come. Well, they expired before the cars were ready, and cars are still not ready commercially. The incentives have helped the plugins, but the cars' prices didn't have to be dropped below production costs before incentives. And the plugins didn't need a massive amount of public funds in order to just be able to be driven in every state of the Union.

    I'm fine for government money for fuel cell research. It could have applications beyond transportation, but they aren't ready to be commercialized. The refueling pressure of the stations California is building now might be too low for the next generation of FCEVs in the near future. The Mirai can already be filled to higher than the 10k psi of those stations now.
     
  3. austingreen

    austingreen Senior Member

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    This even under bush/CARB hydrogen plan in 2003 seemed a California only dream.



    I'd say the incentives are there though 2017 and the experiment in the US should go forward, if only to get rid of some of the wacky claims.

    R&D should definitely go forward pass or fail, that is only a tiny portion of the budget, and who knows it could work. This electrolysis if it gets cheap enough could use wind in the gulf coast refineries to produce hydrogen to offset some of the natural gas used in refining, even if it doesn't work in a hydrogen station model.

    I'd really like to see federal funds for this this test restricted to southern California if this test fails to bring the 10s of thousands of fcv CARB and the CFCP has promised. There is no reason to be spending $2M/station in hopes of demand for these things all over the country.
     
  4. hill

    hill High Fiber Member

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    I tried to find it with no luck, but I thought usb already got shot down for dragging out this yarn. As long as Toyota thinks folks take readers at face value, I suppose it's worth the spin.
    That said, even Mitsubishi's SUV plug in out does the toyota hydrogen vehicle - as even their SUV is over 100mpge. It's not a pretty picture once you look at all the data.
    You are confusing "it works" ... with the notion of whether it's "impractical". You can extract gold out of sea water, but it's not cost effective. The military can order up nuke carriers with lots of stealth fighters & cruise missles, but it bankrupts the country. And yes ... you can extract hydrogen ... store it at 10,000 lbs ... continually replace the auto's plumbing & fuel container as the hydrogen slowly takes its toll. That can't make it profitable - w/out government incentives unwillingly taken from taxpayers, so that japan can "maybe someday" have a better import fuel. Still, I cheer for the technology, even though it has defied physics versus profit now for well over a half century. Toyota has to pretty much tell a little fib, in order to make it even partially plausible, and that's what really irks me . . . . half truths.
    .
     
    #64 hill, Jul 1, 2015
    Last edited: Jul 1, 2015