Re: Solar-hydrogen home power system?

From: Ray Drouillard (cosmicpam2_at_comcast.net)
Date: 10/20/04 

Date: Wed, 20 Oct 2004 19:12:58 -0400

"Don Lancaster" <don@tinaja.com> wrote in message
news:4176820E.1CB40A0D@tinaja.com...
> Glenn Martin wrote:
> >
> > "Don Lancaster" <don@tinaja.com> wrote in message
> > news:4175DF4C.6B1FB4D5@tinaja.com...
> > >
> > > Exergy is a measure of the thermodynamically reversibly
recoverable
> > > energy fraction.
> >
> > Don, what does this mean? What is an enrgy fraction? What does
"reversibly
> > recoverable" mean?
> >
> > Why do you apply "amortization"; a financial term, to physical
measurements
> > of energy conversion efficiency?
> >
> > Glenn Martin
>
> This is all carefully explained in
> http://www.tinaja.com/glib/energfun.pdf
> Or http://www.tinaja.com/glib/hack64.pdf for a thermodynamics intro.
>
> A reversible thermodynamic process kicks off zero unrecoverable low
> grade heat.

Do you know of any?

> If you go electricity ---> room heat ----> electricity, you get
> virtually none of your electricity back because Carnot's Law prevents
> even a theoretical low delta-T recovery of more than a percent or two.
> Going electricity ---> hydrogen ---> electricity is considerably WORSE
> than this today.

I don't think so. It looks like you can get somewhere between 25% and
75% back. I don't know what the theoretical limit is. We are not,
after all, working with a Carnot cycle engine.

>
> Exergy is the measure of this fraction and thus the energy value. If
you
> can convert the present energy form into another and back again with
> most of it left, you have high exergy. If not, you have low exergy or
> (in the case of hydrogen) negative exergy.

In other words, it's jargon for 'efficiency', or maybe 'theorietically
achievable efficiency', depending on the context.

>
> Exergy is also easily quantifiable. The Gibbs Free Energy is one
> pre-amortization measure that applies to certain classes of fuels.

Why are you suddenly switching from engineering to economics. Exergy,
as you defined it above, is a scientific term, and has absolutely
nothing to do with economics.

>
> The amortization directly enters into the recoverable energy fraction
> you can get back.
> If you get back two cents worth of electricity and the interest on the
> system is three cents, you have a net energy sink and are destroying
> gasoline.

What does gasoline have to do with it? We were talking about
electricity and hydrogen. Then, you toss in amoritization. Now, you're
talking about gasoline.

>
> The equivalance between dollars and energy can be observed by the
large
> sign out front that says UNLEADED $1.97. Ultimately all of economics
is
> dictated by the underlying net energy sources.
>
> Yes, if the price of gas goes up, the exergy of hydrogen goes down.
> That is the beauty of exergy. It tracks the true costs of reversible
> fraction recovery.

You had defined exergy as an intrinsic value. Now, you're defining it
as an extrinsic value. Please make up your mind.

>
> See http://www.fes.uwaterloo.ca/u/jjkay/pubs/exergy/ for an
independent
> tutorial.
>
> There are also something like 17,000 Google hits on exergy.
>
> Exergy is THE measure of the competitive viability of an energy
delivery
> system.
>
> And positively, emphatically, and absolutely GUARANTEES us that
> electrolysis from high value grid or pv sources for bulk hydrogen
energy
> flat out ain't gonna happen.
>
> --
> Many thanks,
>
> Don Lancaster
> Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
> voice: (928)428-4073 email: don@tinaja.com
>
> Please visit my GURU's LAIR web site at http://www.tinaja.com

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