🚀 go-pugleaf

"D.A.Kopf" wrote:
> 
> Murray Love wrote:
> >
> > "D.A.Kopf" <dak@dakx.com> wrote in message
> > news:3942D053.82030642@dakx.com...
> > > Murray Love wrote:
> > > <snip>
> > > >
> > > > I have another question for the "clean energy" proponents.  Assume for the
> > > > sake of argument that a nuclear energy technology is developed that
> > > > a) Cannot melt down;
> > > > b) Produces a vastly reduced amount of unusable waste;
> > > > c) Operates passively to shut down the reaction if anything goes wrong;
> > > > d) Produces inexpensive 24/7 baseload.
> > > > e) Is scalable (can be very large or quite small)
> > >
> > > Is this hypothetical process also sustainable, or just a short-term fix
> > > that makes it easy to postpone long-term thinking?
> >

Perhaps if you were more specific about the time-frame you are using to
determine the meaning of "sustainable" and "long-term".  If human
population levels off at 10 Billion in 2100 as expected, then about
3,500 GW of nuclear electricity could provide about half of projected
electricity demand while allowing the global GDP to grow 25 times 1990
levels and stabilizing atmospheric CO2 concentrations at or below twice
pre-industrial levels (according to IPCC LESS scenario).

3,500 GW of nuclear electricity would be sustainable for hundreds of
years using Thorium,  Uranium, and Plutonium as fuel with a modified
fuel cycle.  If folks in the 22nd century act so as to gradually reduce
human population from 10 B to, say, 2 B by the year 2300, then there
will be no need to sustain 3,500 GW of nuclear electricity more than a
few hundred years.

Since a closed nuclear fuel cycle is adequate to handle this load
indefinitely, and since CO2 emissions would be curtailed to avoid
massive global climate change, then yes, the nuclear option is
sustainable, if it can be packaged in a form that is socially acceptable
to all but committed anti-nuclear fundamentalists. 

> 
> Well, current nuclear production has a rather poor thermal efficiency, putting
> two units of heat energy into the plant environs for every one unit of
> electricity produced. Consumption of this one unit of course also ultimately
> ends up as heat.

Waste heat can cause local environmental disturbances, hence cooling
towers.  A ten-fold increase in nuclear generation per the IPCC LESS
scenario outlined above would throw off 10 times the heat, to be sure. 
I'm not enough of a physicist to be able to calculate whether that is a
non-trivial addition to Earth's radiation budget, but Cesar Marchetti
has suggested that 10^12 people could be sustained indefinitely using
nuclear power as long as they used albedo control to maintain the
Earth's heat balance.  

I once calculated that painting an area the size of Europe and Australia
white would be the extent of albedo control required to offset global
warming -- probably more practical just to build ten times more nuclear
power generating capacity (of the extremely safe, socially acceptable
variety, of course).

-dl