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Topic: Answer to the Fermi Problem
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Richard Hake

Posts: 1,228
From: Woodland Hills, CA 91367
Registered: 12/4/04
Answer to the Fermi Problem
Posted: Feb 10, 2012 6:40 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply
att1.html (4.1 K)

Some subscribers to MathEdCC might be interested in the answer to a
recently posed "Fermi Problem." It's in a recent post "Could the U.S.
Significantly Reduce Its Yearly Emission of CO2 By Covering Its
Rooftops With Photovoltaic Panels? #2" [Hake (2012b)]. The abstract
reads:

*************************************************
ABSTRACT: In a previous post "Concentration of Energy by Photovoltaic
Solar Panels" [Hake (2012a) I posed the following "Fermi Problem":

"What fraction 'f' of the yearly total U.S. fossil-fueled electrical
energy (and thus fraction of yearly tons of CO2 emission from U.S.
fossil-fueled electrical energy production) could be eliminated if
all rooftops in the U.S. were covered by photovoltaic solar panels?"

In this post I estimate f = 1.1 - considerably larger than the
estimate f = 0.08 of MathEdCC's Guy Brandenburg. Perhaps others would
like to consider this problem.

In Hake (2012a) I warned (paraphrasing): "Before recommending that
all U.S. rooftops be covered with PhotoVoltaic Solar Panels one
should consider the EMERGY associated with such a plan. Odum wrote:
"EMERGY measures both the work of nature and that of humans in
generating products and services. . . . The photovoltaic power grid
at Austin, Tex., evaluated by King & Schmandt (1991), is taking more
EMERGY out of society than it is generating."

So is the motto of Solar Forward <http://solarforward.com/>: "SAVING
THE PLANET, ONE SOLAR SYSTEM AT A TIME" a deception? I THINK NOT
because the evaluation of King & Schmandt (1991), failed to consider
the devastating decrease in EMERGY due to global warming if the
world's dependence on fossil fuels is not reduced.
*************************************************

To access the complete 18 kB post please click on <http://bit.ly/zT7dKj >.

Richard Hake, Emeritus Professor of Physics, Indiana University
Honorary Member, Curmudgeon Lodge of Deventer, The Netherlands
President, PEdants for Definitive Academic References which Recognize the
Invention of the Internet (PEDARRII)
<rrhake@earthlink.net>
<http://www.physics.indiana.edu/~hake>
<http://www.physics.indiana.edu/~sdi>
<http://HakesEdStuff.blogspot.com>
<http://iub.academia.edu/RichardHake>


REFERENCES [URL's shortened by <http://bit.ly/> and accessed on 09 Feb 2012.]
Hake, R.R. 2012a. "Concentration of Energy by Photovoltaic Solar
Panels" online on the OPEN! AERA-L archives at
<http://bit.ly/wdkAoL>. Post of 6 Feb 2012 09:59:03-0800 to AERA-L
and Net-Gold. The abstract and link to the complete post are being
transmitted to several discussion lists and are also on my blog
"Hake'sEdStuff" at <http://bit.ly/Aimt1K> with a provision for
comments.

Hake, R.R. 2012b. "Could the U.S. Significantly Reduce Its Yearly
Emission of CO2 By Covering Its Rooftops With Photovoltaic Panels?
#2" online on the OPEN! AERA-L archives at <http://bit.ly/AsRbCR>.
Post of 10 Feb 2012 13:43:02 -0800 to AERA-L and Net-Gold. The
abstract and link to the complete post are being transmitted to
several discussion lists and are also on my blog "Hake'sEdStuff" at
<http://bit.ly/yPUZ6u> with a provision for comments.





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