Re: Solar and renewable energy

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

Rick,

Currently available silicon solar cells have efficiencies that are about 25%
and amorphous silicon sheet converters have efficiencies of 18 to 20%.
However, not all the solar energy has to go into electricity.  Solar thermal
for hot water and heating is quite practical, at much higher efficiencies.

Mark Shapiro
http://chaos.fullerton.edu

-----Original Message-----
From: Rick Tarara [mailto:rbtarara@SPRYNET.COM]
Sent: Wednesday, June 20, 2001 10:41 AM
To: PHYS-L@lists.nau.edu
Subject: Re: Solar and renewable energy


A couple of nitpicks:

The 30 square meter figure generates 7.2 kW AT 100% EFFICIENCY!  At least in
the photovoltaic world, currently 15% is about tops and maybe 30% ultimately
attainable.  So that number looks too low by a factor of at least 3 and
maybe 5!

To supply transportation needs (portable fuel) and the like, there will be
considerable conversion losses and then perhaps some thermodynamic
efficiency factors depending on how the fuels are used.


The .02% solar harvest figure doesn't agree with the 30 m^2 figure either.
At 30 m^2 the total collection area would be 180,000 km^2 while the .02%
figure gives 515 million km^2.

All calculations were done quickly, so I might have made an error--have to
run.

Rick Tarara

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----- Original Message -----
From: "Larry Woolf" <larry.woolf@GAT.COM>
To: <PHYS-L@lists.nau.edu>
Sent: Wednesday, June 20, 2001 11:25 AM
Subject: Solar and renewable energy


> To: Phys-L list
>
> Given all of the discussions about solar energy and renewables, I thought
> you might find the following letters of interest.  The IEEE is quite
> involved in this area.
>
> Regards-
> Larry Woolf
>
>
> -------------------------------------------------------
>
> Following is an interesting and fundamental perspective on the abundance
of
> solar energy from Professor Helmut Burkhardt of Ryerson
> University.
> For an overview forecast of economic and practical potential of
renewables,
> including solar, to meet our long term energy needs, see
> Walter Short's  Seattle presentation recorded in IEEE Power Engineering
> Review, April 2001, Page 12.
> Regards;
> Jim McConnach
> Secretary and Acting Chair
> IEEE WG on Implementing Technology to Limit Climate Change
>
> --------------------------------------------------------------------------
--
> ------------
>
> Ryerson; June 19, 2001
>
> Dear Jim;
> Thank you for the information. You have created a most interesting IEEE
> group .  I would like to get a message to groups like yours.
> Scientifically, humankind has no energy problem.  The sun delivers to
> the surface of the earth 25 000 kW for each one of the planets 6 billion
> citizens, 0.24 kw/m2 on a yearly global average on a horizontal surface.
> The global average total energy use rate is presently 2.3 kW per person.
> A decent European life style can be sustained with 5 kW for each human
> being. This means, we have to harvest only 0.02% of the sunlight to
satisfy
> our
> energy needs forever.
>
> With technically reasonable efficiency, and solar cogeneration we need a
> collector surface of 30 m2 /person to have all the energy needs,
> including transportation hydrogen, industry and home electricity and heat.
> By
> comparison, sustainable agriculture requires 2000 m2 of fertile land to
> grow the food for one person.  Everybody should know this scientific
> feasibility of solar energy; it is a simple back of the envelope
calculation
> for
> engineers.
>
> A solar world energy system is also technically feasible, and economic
> feasibility is already achieved in some situations, and close in general
> if we consider the environmental and social cost of other options.
> However, few realize that we have this abundance of power delivered to our
> doorsteps. We are stuck in the idea of needing fossil fuels or nuclear
> energy; this
> lack of awareness of the huge potential of solar energy is obvious in US
> President Bush's reaction to the California electricity shortage:  --
> Drill for more oil.
>
>
> Regards, H.
>
>  Helmut (Ken) Burkhardt
>  Adjunct Professor of Physics
>  Ryerson Polytechnic University
>  Toronto ON Canada M5B 2K3
>
>  Tel: 416-979-5000 x 7246
>  Fax: 416-698-1214
>
>  Email: burkhard@ryerson.ca