Re: Fuel Cells and "green" energy

["Shapiro, Mark" <mshapiro@EXCHANGE.FULLERTON.EDU>]

Jim,

There also is a considerable energy overhead in producing nonrenewable
energy.  This includes the energy expended in exploration, extraction,
transportation, and refining (in the case of oil).

I believe Rick estimated something like 40,000 sq. mi. of photovoltaics in
order to make a major dent in US electric production.  (I think this is a
high estimate, given the improving efficiency of solar voltaics.)  This at
first glance seem like a lot of area to devote to solar panels; however, in
reality this can be readily achieved by a combination of approaches
including the installation of solar panels on residential and commercial
rooftops in the high insolation areas, and the judicious use of land in the
desert southwest.

When you are being force to pay $1,500 per megawatt-hr by the Enrons of the
world, solar and wind start to look pretty good.

Mark

http://www.IrascibleProfessor.com


-----Original Message-----
From: Jim Green
To: PHYS-L@lists.nau.edu
Sent: 6/14/2001 7:15 PM
Subject: Re: Fuel Cells and "green" energy

>  Anyway, to get
> large amounts of solar and wind into the system as 'energy on demand'
> sources may require up to 4x the generators and solar collection areas
as
> would be needed if these were used directly. Such a system would then
> require tens of thousands of square miles of photovoltaics and 10s of
> millions of large (megawatt) wind generators.

We have not yet discussed the "amount of energy" (Ugh!) needed to
manufacture, repair, and replace the photovoltaics and wind generator
towers and turbines -- losses well beyond the thermal losses.

And would somebody be willing to venture a guess as to the number of
square
miles of turbines and photovoltaic fields which would be required to
make
any sort of meaningful difference in the whole issue.


Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen