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alternative to solarcellss - dish? heat gathering dish?

Discussion in 'Home Power and Microgeneration' started by ...D., Aug 24, 2004.

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  1. ...D.

    ...D. Guest

    I just saw a segment on a hybrid hydrogen car on "screen savers", and it was
    mentioned and shown an alternative to using solar energy over photovoltaic -
    it just looked like a big satellite dish. All it does I think is gather heat,
    and this powers something that makes your hydrogen fuel from water -

    OK, does anyone know what this technology is called so I cam look further into
    it? The company said they were just now starting to make these things and
    that they are cost effective, much better than even today's panels - and I got
    the impression it would become very cheap in a few years..


    P. S. as a side note the hydrogen hybrids were 1 mil a year ago to make, this
    years 100 thou, next year cheaper, and in a couple of years cheaper to make
    than regular because less moving parts..
  2. Try "solar thermal hydrogen". I did a quick google search and found
    things like these... Article - RECO.pdf

  3. One alternative to PV that seems promising is solar-fired Stirling
    engine driving electrical generator.

    For a parabolic reflector / Stirling example under development, see:

    I've seen another plan for trough-reflector / Stirling / generator
    combinations and the outfit was predicting twice the overall
    electrical output / insolation efficiency of PV, but I can't put my
    hands on a link right now.

    I'm glad this stuff is looking good and all, but speaking selfishly,
    my problem is generating power when the sun *isn't* out. My PV system
    is fine, what I need is wood-fired Stirling.

    But that's me, the frozen Canuck.

  4. ....
    You might look into the possibility of storing the solar hot as 100C water,
    then using a low temperature difference engine to get the power out. A
    slightly more complex system would use the very hot focus of the solar
    concentrator and atmospheric to produce power, then use the power to pump
    heat from a mixed fluid system with fresh water packets that can transition
    to ice and back, into a 100C stratified tank. Reversing the heat pump, or a
    separate heat engine then gets it out, and you do not have the loss of
    simply collecting it at 100C rather than 300-500C where more of the energy
    is available. A thermal storage battery.
  5. Interesting thoughts Fred, but again, my problem is power when the sun
    don't shine. I'm already fully equipped to store a week's worth of
    juice with the PV/battery setup. But for two or three socked-in weeks
    in December, say, I need something that isn't solar-powered, at least
    not directly, or I'm gonna need a lot of storage.

    Over time I'll be evaluating wind options here, but as I'm burning
    wood to stave off the -20 to -40 C temps in the winter anyway, when
    insolation is scarce and even sunny days are short, it seems a shame
    not to cogenerate a few watts to keep the paycheque generating
    apparatus (a.k.a. notebook) fired up.

    I don't need a lot. One kWhr / day, on average, would be utterly
    luxurious. Half of that -- I'd still be laughing.

    The solution at present is to burn a tankful of dinosaur juice once in
    a while, which is convenient and easy. I just don't happen to like
    that solution.

  6. You are missing the core of this. Well, one core anyway. By setting the
    temperature difference at 100C, ice on bottom and 100C water on top, we have
    a thermal version of a battery. This stores a lot of energy. You just need
    to build a relatively efficient heat engine to use it. Common processes use
    a low boiling point liquid and construct a steam engine using say butane
    under pressure, water under vacuum, things like that. A sterling engine
    would work well, but you need a pretty big one to work with this small
    temperature difference. And there are other simple engines you could
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