X-Message-Number: 2034
Date: Fri, 26 Mar 93 12:02:13 CST
From: Brian Wowk <>
Subject: CRYONICS Unbelievable Economy

        So far I have proposed using the Peltier effect for three 
        a)      As an active heat pump between the LN2 reservoir
                and the room, as part of the thermoregulatory
        b)      As a passive heat flow system, carrying heat from
                the room periphery to the LN2 reservoir without
                temperature gradients.
        c)      As a thermoelectric generator utilizing the temperature
                difference between LN2 and the vault foundation to
                provide ~50 watts for operating fans and thermostats.
Now here comes the biggie:
        d)      As a thermoelectric refrigerator (no moving parts) 
                between the -130'C in the room and the vault 
                foundation, utilizing external electric power when 
If we have power available from the utility company, why not use it?  
The economics appear staggeringly favorable.  A refrigerator operating 
between 10'C and -130'C would have a thermodynamic efficiency of
                        T1/(T2-T1) = 100%
(This result is not an error; household refrigerators have efficiencies 
of hundreds of percent because of the small temperature difference they 
operate between.)  Even if we assume a real efficiency of only 50%, 
then only 1kW continuous electric power will be needed maintain the 
room at -130'C, holding down LN2 consumption to near nil.  At 10 cents 
per kilowatt-hour this gives an annual operating cost (excluding 
amortization of capital) of $876 dollars for a 132 patient storage 
unit!  This compares to $20,000 per year for exclusive LN2 cooling.
        Am I missing something here?  This is too good to be true.  
Even if the semiconductor elements needed to pump 1kW cost $40,000, the 
system will pay for itself in TWO YEARS.
        This dramatic improvement in economy occurs because LN2 is a 
horribly inefficient way to cool things.  In the above system, LN2 will 
now only serve two purposes.  Because a failsafe thermoregulatory 
system works best by controlling LN2 boiloff, we will continue to 
control temperature in the room by boiling off small amount of LN2 
continuously.  Also the 2000 liters of LN2 is a cooling backup.  It 
gives you a week to clear rubble off your vault after terrorists blow 
up your building, disrupting external power.
        Another advantage of Peltier refrigeration: Alcor will never 
need to buy a nitrogen liquefier.  If external LN2 supplies and 
electric power are disrupted by civil unrest, you use a backup diesel 
generator for electric power.  Hell, a few square meters of SOLAR CELLS 
will even do the job (charging batteries for nighttime as well).
        I still have no idea of the capital cost, but again I reiterate 
that thermoelectric refrigerators exist commercially so the technology 
can not be that outrageously expensive.  I will be looking at this 
very, very seriously.
                                                --- Brian Wowk
P.S. You will all be relieved to hear that I'm on my way out of town, 
     and will be unable to clog your email boxes again until next
     weekend.  If no one else tackles it, I will also answer the recent 
     radiation question at that time.           

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