Re: [asa] vast new gas supplies

From: Iain Strachan <>
Date: Mon Dec 07 2009 - 07:37:02 EST

On Mon, Dec 7, 2009 at 11:36 AM, David Clounch <>wrote:

> I think of it in terms of what is available. When will it be depleted
> and when will that sub-industry collapse, leaving humanity without energy?
> Of course there will be economic collapse long before actual depletion.
> Unless there are vast new sources of uranium we don't yet know about I don't
> see a long term answer to energy supply.
On the contrary, nuclear is an extremely long term answer to energy supply.
 Existing fission reactors use only U-235, which is 0.7% of natural uranium.
 As such it is a limited resource. But fast breeder reactors can be used to
convert the U-238 (99.3%) of natural uranium to the fissionable product
Pu-239. According to Wikipedia there is enough U-238 around to be an energy
supply for five billion years, but I think this must be a mistake - I would
have put it at several thousand years.

In addition it is possible to use U-233 that is bred from Thorium - an
element that is 3.5 times as common as uranium, as an intermediate term

For the long term solution, one must look to Nuclear Fusion. Current
reactors are based on a D-T reaction which requires the breeding of Tritium
from Lithium - an abundant element, which according to Wikipedia would last
3000 years if all the worlds energy came from this source. If it became
feasible in the future to have sustainable power from a D-D fusion reaction
then (again according to Wikipedia) there would be sufficient for 150
billion years.

I wouldn't trust any of these figures, to be honest. For a better estimate,
consult David MacKay's book "Sustainable Energy without the Hot Air", which
is available on the web. However, Fusion is an extremely long term
solution, and it appears that, given Thorium and Fast breeder reactors, that
nuclear fission is almost certainly a sufficiently long medium-term solution
to allow the fusion solution to be developed.


Non timeo sed caveo
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Received on Mon Dec 7 07:37:16 2009

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