NetNews Usenet Archive 1993 #1/NN_1993_1.iso/spool/sci/physics/fusion/3228

Internet Message Format | 1993-01-09 | 3.6 KB

Path: sparky!uunet!munnari.oz.au!uniwa!fennel.cc.uwa.oz.au!tiq
From: [e-mail] (Todd Green)
Newsgroups: sci.physics.fusion
Subject: Re: Reply to Jed Rothwell/E=Mc2
Date: 9 Jan 93 15:35:47 +0800
Organization: University of Western Australia
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Message-ID: <[e-mail]>
References: <[e-mail]>
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In article <[e-mail]>, [e-mail] writes:

> While educating about He3, gammas, neutrons, and other nuclear emissions is
> evidently sorely needed, perhaps quoting from a recent paper by Dave Buehler,
> Lee Hansen, Larry Rees and myself will help chip away at this type of fixation:
>
> "...at the Nagoya meeting and elsewhere, we found that errors and uncertainties
> in current experiments prevent unambiguous interpretation of claims of excess
> heat generation.  Hence, this paper also outlines criteria for establishing
> calorimeter performance for definitive measurements of "excess heat" in cold-
> fusion experiments."
> (There follows an extensive discussion on difficulties of calorimetric
> measurements, precautions, etc. mostly by Prof. Lee Hansen of BYU.  We also
> discuss the use of an X-ray spectrometer as a critical means of probing for
> nuclear origins of heat, when the precise nuclear reaction is unknown.  I have
> posted notes on this, here, some months ago.)
> "Because all electrochemical calorimetric experiments intended to demonstrate
> 'excess heat' require correction for the heat of the electrolysis reaction,
> the expected reaction must be verified and quantified.  Otherwise an incorrect
> value for the thermoneutral potential will be used in the correction.  For
> example, deposition of an alkali metal under a silicate (or aluminate or
> borate) coating on an electrode in aqueous solution is possible at cell
> voltages near 3 volts.  The thermoneutral potential for Li is about 2.9 volts,
> compared to 1.5 volts for hydrogen.  An xs heat rate proportional to the rate
> of deposition of Li would thus be found if the reaction were assumed to be
> strictly generation of hydrogen.  The accuracy of the thermoneutral potential
> must also be assessed.  A value derived from a single source or type of
> measurement cannot be considered reliable.

This is a valid point but codeposition of lithium at the cathode would produce
an energy deficit and NOT excess energy if a thermoneutral potential of 1.53
volts was assumed. The thermoneutral potential for lithium deposition at the
cathode and an oxygen evolving anode is approximately 3.5 volts, so if, say,
10% of the electrolysis was due to Li+ reduction and the rest D2O reduction,
then the effective thermoneutral potential, Eth,  would be 1.73 volts.
Then, the Joule heating calculated by (Ecell-1.53)*I would clearly overestimate
the actual input power, and an apparent negative energy balance would be
calculated.

In general, the occurrence of a chemical/electrochemical process other than
oxygen evolution(anode)/deuterium evolution(cathode) will lead to apparent
excess heat if the thermoneutral potential of that process is < 1.53 volts
and "negative" excess heat when E > 1.53 volts.

One other point is that lithium deposition is rather unlikely under most
conditions because of the extremely negative standard electrode potential
(-3.05 V) for the reaction Li+ + e- ---> Li. There is a possibility that
there might be an underpotential deposition of Li on Pd (i.e. its occurrence
at a potential more anodic than -3 volts) but I don't think there is much
evidence supporting this to date.

Todd