Exponential growth has limits
David Kind
http://physics.ucsd.edu/do-the-math/2011/07/galactic-scale-energy/
Mike Boyd
> Really interesting link on the limits of exponential energy growth.
>
> http://physics.ucsd.edu/do-the-math/2011/07/galactic-scale-energy/
Some choice quotes:
[extracts start]
...
Plotting data from the Energy Information Agency on U.S. energy use since
1650 (1635-1945, 1949-2009, including wood, biomass, fossil fuels, hydro,
nuclear, etc.) shows a remarkably steady growth trajectory, characterized by
an annual growth rate of 2.9% (see figure). It is important to understand
the future trajectory of energy growth because governments and organizations
everywhere make assumptions based on the expectation that the growth trend
will continue as it has for centuries‹and a look at the figure suggests that
this is a perfectly reasonable assumption.
...
For a matter of convenience, we lower the energy growth rate from 2.9% to
2.3% per year so that we see a factor of ten increase every 100 years. We
start the clock today, with a global rate of energy use of 12 terawatts
(meaning that the average world citizen has a 2,000 W share of the total
pie). We will begin with semi-practical assessments, and then in stages let
our imaginations run wild‹even then finding that we hit limits sooner than
we might think. I will admit from the start that the assumptions underlying
this analysis are deeply flawed. But that becomes the whole point, in the
end.
...
The merciless growth illustrated above means that in 1400 years from now,
any source of energy we harness would have to outshine the sun.
Let me restate that important point. No matter what the technology, a
sustained 2.3% energy growth rate would require us to produce as much energy
as the entire sun within 1400 years.
...
Stop the Madness!
The purpose of this exploration is to point out the absurdity that results
from the assumption that we can continue growing our use of energy‹even if
doing so more modestly than the last 350 years have seen. This analysis is
an easy target for criticism, given the tunnel-vision of its premise. I
would enjoy shredding it myself. Chiefly, continued energy growth will
likely be unnecessary if the human population stabilizes. At least the 2.9%
energy growth rate we have experienced should ease off as the world
saturates with people. But let¹s not overlook the key point: continued
growth in energy use becomes physically impossible within conceivable
timeframes. The foregoing analysis offers a cute way to demonstrate this
point. I have found it to be a compelling argument that snaps people into
appreciating the genuine limits to indefinite growth.
...
[extracts stop]
Regards, Mike
--
Mike Boyd (also at) <mi...@green43.demon.co.uk>