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Re: [All-E] Group keeps hope alive for battery-powered personal vehicles

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  • jeff buderer
    hey guys thanks for the feedback... ... Fuel cells efficiency ranges dramatically. PEMs have more direct efficiency because they have less heat loss, while
    Message 1 of 35 , Nov 1, 2003
      hey guys thanks for the feedback...
      > > > I have heard that in terms of energy efficiency
      > > > battery powered cars are be more efficient than
      > fuel cells. Does anyone know if this is true?
      > > >
      > > Yes. Electrical-to-Electrical efficiency of
      > hydrogen fuel cells is
      > > about 50%.
      > Hrrrm. So, if I expend a kilowatt-hour of
      > electricity using
      > elctrolysis to make hydrogen, then pipe that
      > hydrogen directly into a
      > fuel cell, I can only expect 500 watt-hours of
      > elctricity back out?
      > I thought it was a bit higher than that, honestly.
      > Do you happen to
      > have a link to s source for this?

      Fuel cells efficiency ranges dramatically. PEMs have
      more direct efficiency because they have less heat
      loss, while solid oxides and molten carbonates have
      lower electrical efficiencies by higher heat loss but
      they can be used in cogeneration.

      > > When you consider compressing the hydrogen,
      > carrying the
      > > extra weight of the storage container, and
      > distilling the water
      > before
      > > electrolysis, it's even lower.

      I was not sure about was the 90 percent efficency of

      The relevance of fuel cells relates to how they are
      developed and the number of energy conversions needed
      to keep these systems running. Looking back at the
      research about Hydrogen I am little disappointed, I
      think it is quite reductionistic focusing PEM fuel
      cells with external reformers and natural gas and
      water hydrolysis to provide hydrogen for these
      systems. However i still think fuel cell technologies
      are promising but I am specifically talking about
      stationary applications like the ones being developed
      by Fuel Cell Energy that can run on biogas, coal gas,
      natural gas, propane and even desiel with minimal
      emissions. The key difference is that these larger
      fuel cells rely on an internal reforming process that
      is integrated with the cogeneration process. The gases
      used for cogeneration also are used to ensure the
      complete combustion of hydrocarbons, therefore
      emissions from such facilities are nearly zero.

      It sounds like the battery car program is being
      ditched and all our energy is now being focused on
      fuel cell cars when eletrical technologies can with
      the proper funding probably achieve the same goals
      (zero emission cars) at a considerably higher rate of
      efficiency. And people wonder why alternative energy
      does not live up to its potential?


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    • michael light
      I agree that it will be necessary for fuel cell vehicles to be equiped with on-board reforming to make them an efficient system. Ballard seems to be on the
      Message 35 of 35 , Nov 11, 2003
        I agree that it will be necessary for fuel cell vehicles to be equiped with on-board reforming to make them an efficient system. Ballard seems to be on the forfront of mass producing fuel cells specifically designed for vehicle mass production, but they are not going in the direction of on-board reforming. It's too bad. I think it puts us in the position of NEEDING mass distribution of hydrogen, which means large production facilities to reform fossil fuels instead of water and the big question; Where do they get the electricity. British Petroleum and RoyalDutch/Shell are europes biggest promoter of this as well as some of the american oil companies, i think because it sustain the power structure that DG and onboard reforming threaten. One of the questions I have is why are BP and Shell so interested in renewables. It doesn't make any sense. The other question I have is how can the DOE possibly think that their road map if they are going to stay geared toward the use of fossil fuel-stock and electricity from the national grid. It will never make it affordable, nor will it guarantee a permanent source of fuel-stock. It's like using natural gas to power the nation and then having to import it due to dwindling supplies. Oil cannot last forever. Even if hydrogen or fuel cells aren't the complete answer they do have some benefits, if they are used properly; ie. water reforming and renewable source electricity. The main benefit is that it may be able to shore the gap between the 2-4% increase in demand and the sortfalls in new energy production allowing deregulation to progress under a market system instead of a monopoly that will never be able to think environmentally. Some of these, if not all are opinions, but the questions are real curiosities.

        Michael DeWolf <m_dewolf@...> wrote:
        michael light <hydrogensun@y...> wrote:
        > During this phase, TMI demonstrated passive reversible cells and
        stacks that met many of the performance targets including reversible
        efficiency and life. Several conditions were evaluated to understand
        the sensitivity of performance on operating variables such as
        temperature and current density. The highest reversible efficiency
        (DCVolts_Out / DCVoltage_In) measured was 90.8% at 925 �C and 50 mA/cm.

        I did some research, and the TMI fuel cell has a 90.8% efficiency
        *when the heat from the fuel cell is used to make the electrolyser
        more efficient*.  Novel, for sure.

        For transportation, however, this would not be possible. 

        I have heard, though, that Solid Oxide fuel cells are more efficient
        than PEM fuel cells.  Maybe hydrogen generation is another use for
        'waste heat'.


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