From: Dani Eder (danielravennest@yahoo.com)
Date: Tue Jun 26 2001 - 12:39:43 MDT
The idea that the world is using up it's resources
and as a consequence civilization will fall is wrong
on two critical points.
The first is that the resources of the planet don't
get 'used up'. Atoms last forever (on human time
scales at least). The carbon atoms that used to
be in the Amazon rain forest got turned into CO2,
which then get incorporated into American forest
biomass. Contrary to common wisdom, the total
biomass in the US's forests is _increasing_, mostly
due to less farming in the eastern US after
1900.
I tend to view landfills as future resource
stockpiles, awaiting an efficient way to separate
the components.
The second error is considering the Earth as a
closed system. It's almost closed in matter
terms, but damn near wide open in energy terms.
Turn off the Sun and the atmosphere loses temperature
with a time constant of about 10 days (30 degrees
K/day
versus a starting temperature of 300 K).
The annual solar flux on a relatively sunny location
is 7.2GJ/m^2. Assume that you need no more than the
most energetic chemical reaction to transform your
raw materials. Splitting water into O2 and H2 takes
15 MJ/kg. This is about the most energetic reaction,
which is why it is used as rocket fuel going the other
way. Therefore you can convert 480 kg/m^2/yr into
whatever. A square kilometer can convert 480,000
tonsper year. The total mass throughput in the US
is around 20 billion tons (as an aside, the largest
single mass flow item is crushed stone for concrete.
Who says we ever left the stone age :-) ). So
40,000 square km of sunny land can support the
entire US civilization's mass flow. That's around
0.5% of the land area. And a lot of the mass
flow doesn't need anywhere near as much energy/kg
as we assumed.
We don't synthesize plastic from scratch because
crude oil has components that are already close
in chemical structure to what we want. We don't
pull aluminum and iron from random rocks because
it's cheaper to do so from decent ores. But if
we had to, we could, and it wouldn't take an
impossible amount of land to power it purely from
solar sources, much less possible fission and
fusion sources, and the possibility of power
stations in space powering industry out there or
sending power down to the ground.
Dani
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