[Gasification] Simple math

[Daniel Chisholm]

On Sun, 2007-18-03 at 20:40 -0500, David G. LeVine wrote:
> This planet has a mean diameter of 13,000 KM and looks like a circle 
> of 1.3x10^8 KM^2 or 1.3x10^14 M^2.  We receive about 1 KW/M^2 so we 
> see about 1.3 x 10^17 watts on the circular projection of the earth, 
> ignoring the atmospheric losses.  Humans generate MAYBE 10^12 Watts 
> (that's about 100,000 10 MW nuclear power plants.)

IIRC it's more like 1.4kW per square metre, so your calculation is a
conservative one (according to Wikipedia, see below, the figure is 1.74
x 10^17 watts)

FWIW nuclear plants more more like 1000MW, not 10MW.

Here's a page that has these sorts of interesting figures:

http://en.wikipedia.org/wiki/Orders_of_magnitude_(power)#Terawatt_.281012_watt.29

Humans actually generate more than 10^12 watts (1TW, TeraWatt) of
electrical power, it's 1.7TW according to that page.  And total power
consumption is 13.5TW (hey, there's more to life than _just_
electricity ;-).  But look at the other interesting figures that will
give you an idea of how big (or small!) we are w.r.t. Mother Nature:

44 TW - heat flux from Earth's interior
75 TW - photosynthesis (good to know for figuring out order-of-magnitude
limits to biomass energy potential!)
1,400 TW - heat flux transported by Gulf Stream
4,000 TW - heat flux transported by the atmosphere and oceans away from
the equator towards the poles
174,000 TW - power received by the Earth from the Sun

> The total power output of all human endeavors is less than 10 part 
> per million.  This makes suspect any claim that human thermal loads 
> are the prime mover of climatic change.

Agreed.

For fun, if you want to see how big-but-small 13.5TW is, run it through
E=mc^2, but backwards.  I get the result that the entirety of Man's
energy consumption is provided by the conversion of 4730kg of mass into
energy annually (or 0.54 kg per second, or 19 ounces per second).



And if you like orders of magnitude: When I was in university, a couple
of us calculated the power of the sun (take the power density 1.4kW/m^2
that we receive here at Earth, and our orbital radius...), and ran that
backwards through E=mc^2.  The amount of mass that the sun is converting
to energy, per second, is a most impressive figure.  All the moreso when
you realize that a nuclear fission reaction is only consuming less than
1% of the mass of the reactants, and a nuclear fusion reaction less than
5% (number from memory).

I will refrain from posting the figure that we calculated, so that
others can experience the revelation...!



-- 
- Daniel
Fredericton, NB  Canada