Russell,

On Thu, 08 Sep 2005 15:49:42 +1200, Russell McMahon wrote:

> Solar insolation / day is about 1.3 kWh/m^2 x disc area in m^2 x 24 hrs/day kWh

Errr - hang on, that fails dimensional analysis!  You can't have kWh at both ends and also multipy by 24hrs... 
Do you mean 1.3kW/m^2 ?  (and if so, I don't think anywhere on Earth gets this much for 24hrs/day :-)

> Albedo sees some of that reflected back.
> If we get 10% retained (low?) ...

According to Vengelis' musical number of the same name, the Earth's albedo is 0.39, so as a planet we get to 
keep 61%.  Some of that will be lost by re-radiation of course, but by building collectors in a nice stylish 
matt black the albedo of the collection system will be reduced, and keeping them cool we can collect more and 
re-radiate less.

> Hmm - that's about 60 megawatt hours per person per day.

And it's "renewable".  There's just the old problem of collecting the energy where it's available and 
transporting it to where it's needed.  And since most of our uses of the energy end up with it as heat, which 
it was going to be anyway, we shouldn't upset things much by gathering it and using it for other things before 
it turns back to heat.
 
> E&OE. Your assumptions may vary.
> Do not staple, spindle fold or mutilate. YMMV

I wouldn't dare!  :-)

> Either way, there's a lot of energy there.

Cheers,


Howard Winter
St.Albans, England


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