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Re: [Phys-l] global temperatures -- a modest proposal



On 04/06/2009 09:42 AM, David Appell wrote:

In 50 years we will probably have used up most of the oil, but then, if
nothing else is available, we will switch to coal, of which there is
enough to last a few hundred years.

Are you sure of that? On a worldwide basis?

When I do the numbers, it looks like if present trends continue
within a few decades we will have used up all (not just most)
of the world's oil, all of the world's coal, all of the world's
natural gas, and all of the world's 235U.

The numbers might /appear/ different if you include only the
current US trends, because the US has a disproportionately
large share of the world's coal yet is burning it at a
disproportionately low rate, preferring (for the moment) to
burn imported oil.

To repeat: On a worldwide basis, including coal does not solve
the problem, and even including 235U does not solve the problem.

There are only two ways out: renewable energy and/or breeder
reactors.

Breeder reactors can get energy from 238U, which is 200 times
more abundant than 235U. Also thorium. This could provide
energy for a few centuries (not just a few decades). However,
almost* nobody wants to propose this as a solution, because it
makes the weapons proliferation problem so much worse. Also
the track record for breeder reactor safety is not good.

(*) There are folks in India who want to build a thorium-based
breeder. Apparently India has indigenous supplies of thorium
but not much uranium. The safety and proliferation issues
remain.