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Richard Hake
Posts:
1,251
From:
Woodland Hills, CA 91367
Registered:
12/4/04
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Answer to the Fermi Problem
Posted:
Feb 10, 2012 6:40 PM
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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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