MadSci Network: Environment & Ecology

Re: Can solar power wear out the sun?

Date: Tue Apr 12 09:36:47 2005
Posted By: Steve Nelson, research physicist
Area of science: Environment & Ecology
ID: 1113172002.En

This is a good question!  Actually, the energy generated in the Sun that we
see now was already created millions of years ago as the Sun fused the
nuclei of light atoms into heavier ones.  That energy took millions of
years to reach the surface as heat, and then the light and heat radiated
from the sun actually takes a little over 8 minutes to reach us.  The
energy being produced by the Sun now will emerge the same way in millions
of years whether we use the energy that's currently hitting us or not.  If
we convert some of the sunlight incident on the Earth into electrical power
instead of it being lost as heat, it will eventually become heat again as
that electrical power is used.  So the answer is no, we have no effect on
the sun.  

Not to worry, even if solar power did have an effect on the Sun (which it
can't) the amount of sunlight that hits the earth is approximately
approximately one part in 2 billion of its output.  (I calculated this from
the apparent area of the Earth when looking at the sun, compared to the
area of the whole sky at the Earth's distance.)

The same can be said of hydroelectric power since it's a form of solar
power!  The energy to heat water and make clouds (hence rain) comes from
the Sun.  That lifts the water up, and it rains down.  We use a few hundred
feet of gravity pulling a tiny fraction of this water downward again to
generate power, but we use only an incredibly small fraction of the rain
that falls on the Earth for power.  This process of creating clouds uses
far more solar energy than human solar farms could ever achieve.  I recall
reading that a single thundercloud contains enough water to fill enormous
railroad tank cars in a train over 20 miles long...just one cloud, and
that's about a mile up in the sky!  Imagine how much power is released when
the clouds around the globe make rain, it's  a truly mind-boggling amount
of energy from solar power released every day, it dwarfs all our tiny
man-made methods of energy production.  And it's a form of solar power.  If
you become a scientist someday, figure out how to use a large natural power
source like that and you'll solve a lot of the world's problems (and
probably become exceedingly wealthy).


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