[extropy-chat] Solar math (was: Nuke 'em)

[Russell Wallace]

On 10/26/05, Eugen Leitl <eugen at leitl.org> wrote:
>
> So we don't even need those 1.2%. Can you crunch through
> the numbers, assuming 100 kWh for 1 m^2/year (at 10% efficiency,
> half that at 5% efficiency)?


Let's take 10%, solar panels or heat engines give you maybe 20-30% but much
of it will have to be stored and recovered so you'll take losses there. 100
kWh/year works out to average 12 watts delivered, which sounds like a
plausible figure for cloudy northern climates. Say 5 kW/person (I've seen it
quoted that Americans use 10 kW, but presumably they do that because it's
cheap, and would cut back if it stops being cheap). That's 400 m^2, or a
square 20 m on a side. You won't get it all from rooftops alone (though
rooftops might supply a lot of domestic usage), but it's not a huge amount
compared to total land use, so at the end of the day switching everything to
solar looks doable (though not cheap) with present day technology.

- Russell
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