RE: Biomass Hydrogen Paper in 29 August Nature

From: Glenn Morton (
Date: Wed Sep 04 2002 - 09:15:52 EDT

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    Rich Blinne September 03, 2002 4:16 PM

    What I don't see in the article or the review is any mention of how much
    energy must be spent to get that hydrogen. The only energy balance they
    mention is that you get 1 kW per liter volume of the reactor. What is
    needed before this becomes an energy SOURCE is how much energy is spent per
    liter volume of the reactor in operating it plus the fixed cost of building
    the darn thing (steel manufacture, transporation energy, construction energy
    etc). I can't see that this process would be more efficent than other uses
    of biomatter. If it takes more energy to manufacture the hydrogen than that
    which you get out of the process, it is not useful for an energy source.
    With ethanol, that highly touted alternative energy we find:

            ėThe total fossil energy expended to produce 1 liter of
    ethanol from corn
    is 10,200 kcal, but note that 1 liter of ethanol has an energy value of only
    5130 kcal. Thus, there is an energy imbalance causing a net energy loss.
    Approximately 53% of the total cost (55 c per liter) of producing ethanol in
    a large, modern plant is for the corn raw material. The total energy inputs
    for producing ethanol using corn can be partially offset when the dried
    distillers grain produced is fed to livestock. Although the feed value of
    the dried distillers grain reduces the total energy inputs by 8% to 24%, the
    energy budget remains negative.î David Pimentel et al, ėRenewable Energy:
    Economic and Environmental Issues,î BioScience 44(1994):8:536-547, p. 538

    Just performing a chemical reaction doesn't mean it is useful, economical,
    or viable.


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