[ExI] Efficiency of wind power.

[Eugen Leitl]

On Mon, Apr 11, 2011 at 07:45:58PM -0700, spike wrote:

> We suffer from an illusion created by living where there are lots of people, where the natural environment has been changed considerably.  Everywhere we ever go is on a road, with roads everywhere.  Next time you fly, look out the window and estimate the total effect of humanity on albedo.  Or if you don’t want to spend the money on a plane ticket, go into GoogleEarth and look around.  Randomly choose a spot.  Do you see any roads or houses?  
> 
> Or do the following BOTEC: the typical house is about 2000 ft^2 and there are… say, ~100 million of them in the US, so just say about 2E11 ft^2 of roof area and a square meter is about ten square feet, so about 2e10 m^2 of roof area, and for estimation purposes the US is close enough to 5e6 by about 3e6 meters, so about 1.5e13 m^2, so all the roof area in the US combined is on the order of around 1 to 1.5 parts per 1000 in area, a tenth of a percent, without looking up anything.  I wouldn’t be a bit surprised if all the road surfaces combined have a similar magnitude or perhaps about a magnitude more road area than roof area, still all told perhaps a few tenths of a percent.
> 
> When you finish with that BOTEC, consider most of this globe is ocean.  Roads and roofs are not causing this old planet to warm.

About 12% of Germany's surface is altered. If you consider HANPP
http://www.eoearth.org/article/Global_human_appropriation_of_net_primary_production_%28HANPP%29
then we definitely have an impact on Earth's albedo http://en.wikipedia.org/wiki/Albedo

There has been some work on putting the numbers on it.

http://www.climatechange.ca.gov/events/2008_conference/presentations/2008-09-09/Hashem_Akbari.pdf

Notice that PV would have very little impact 
http://www.californiavalleysolarranch.com/deir/070710%20Data/Impact%20of%20PV%20Systems%20on%20Local%20Temps%207-6-10%20FINAL.pdf
and more than offset that by being greenhouse-neutral.


-- 
Eugen* Leitl <a href="http://leitl.org">leitl</a> http://leitl.org
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