Re: OT: need some help with fuel cells

On Fri, 2008-04-25 at 13:22 -0700, Technomage-hawke wrote:
> On Thursday 24 April 2008, koder wrote:
>
> >
> > Recreational vehicles and yachts use solar panels to power some decently
> > sized storage batteries. If you put up enough of them you can run a
> > computer system.
> batteries are all fine and good, but require frequent replacement (every 1-2
> years down here in the desert), and have hazardous materials in large
> quantities.
>
> >
> > Unfortunately the cost of solar is escalating. My original system cost
> > under a thousand dollars. Today it would probably be twice that.
> yep. that makes it harder for those on a fixed income to get anything
> worthwhile out of such systems as well (cost higher than cash available).I am
> sure I could build a full sized panel over time (by adding smaller modules to
> it).
>
> >
> > Of course when I build the next one I will ask it to do more with the
> > additional expense.
> >
> > My wish list consists of more panels, bigger batteries, and a wind
> > powered generator for cloudy days.
> same here, except I would like to build all my stuff from easily available
> materials. call it a poor man's energy policy. :)
>
> >
> > There are a number of sites in the net dealing with the topic of solar
> > direct to batteries. They are far from complete. You will have to
> > supplement with written material.
> I'm already getting that and worse. a lot of the diagrams online for any fuel
> cell are of the simple overlay type that are meaningless to those of us who
> want to build such a unit. so far, I have found NO technical diagrams or even
> any materials lists for something as simple as a PEM fuel cell. Now I have
> found plenty of places that sell individual parts for such (such as the
> backing plates, the PEM material itself and the field flow plates).
>
> >
> > This is some different from the fuel cell systems you asked about, but
> > the fuel cells are using battery and solar and adding in the
> > inefficiency of the hydrogen. The hydrogen is great for energy
> > containment and transportation such as powering your car, but the
> > equipment is a bit pricey.
> actually, from my reading, hydrogen is very efficient (unless you "burn" it in
> a system similar to internal combustion engines, then you are stuck with the
> waste heat, mechanical losses, etc). Direct conversion to electricity is 5-6X
> more efficient at a minimum (unless you are having to convert carbon heavy
> fuels using a reformer, then it drops below 50%).
>
> >
> > Cost will be directly related to how much electric you intend to use and
> > store. You can start with part of it and expand as budget, knowledge and
> > goals expand.
> well, from what I have been able to determine, one can get (from a properly
> designed fuel cell) approximately 3 watts/cm^2 of fuel cell surface area.
> that means that you don't need something monstrous to power a house. a fuel
> cell stack made up of plates 10x10 cm 10 cm deep will give you roughly 3 KW
> of usable energy. This is not theoretical, its the same type of units they
> use on the space shuttle.
>
> >
> > If you want to go further let me know. There are several people in the
> > area working on this.
>
> I definitely do. hey, if it means getting a paying job to do this as well, I'm
> all in!
>

A paying job? Argh, that is a supreme sacrifice.

I am seeing fuel hydrogen cells offered for about $10.00 per watt of
output. Larger models will lower cost per watt. The thing is how to
obtain the fuel for it. If you are going to use solar panels you will
need a lot of them. It can be done, but it will cost. Hydrogen, if you
are going that route, will be just a storage medium. You lose degrees of
efficiency each time you convert from one type of energy to another.

A system designer needs to sit down with their "slip stick" and figure
out how much power they want to supply for what. How you are going to
store if for times the sun is not out, and how you are going to get it
back out of storage when you need it.

When you do your calculations don't forget that the difference between
12 volts and 120 is a factor of ten. A single digit slip like that will
cause yo a great deal of embarrassment and grief.

Heating and cooling will use astounding amounts of energy.

Harold

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