Re: [Amc-list] Hydrogen power

[adh@xxxxxxxxxxxxxxxxx (Sandwich Maker)]

" From: Archimedes <Freedom@xxxxxxxx>
" 
" 
" 
" If nukes were required to compete with all other energy sources on a level playing field, there simply are no insurance companies that will cover a nuclear accident.  Being uninsurable alone would prevent the construction of any more plants, and probably the continued operation of existing plants, until the technology was very safe -- which is a long way off.

iirc a major reason nukes haven't been built here since the '70s.

" Tom Jennings <tomj@xxxxxxx> said:

me, actually

" >iirc they can only burn about -1%- of
" >the nuclear load before the fuel rods must be yanked and discarded....
" >
" >more efficient approaches that have near-total consumption of the
" >fissionable load, with safety 'baked in', are on the drawing boards.
" >these even largely solve the disposal problem by leaving little or
" >nothing but lead to dispose of.  
" 
" 
" Curious - is this basically what breeder reactors do?

yes, especially the proposed thorium reactors; th-232 must be bred up
to u-233 to be fissionable and make power, and needs a uranium 'spark
plug' to start it up.  the hot topic is the 'slow breeder', which
breeds fuel only as fast as it's fissioned so that no excess hot stuff
accumulates, and an addition to the approach is the 'liquid fueled
slow breeder' which allows in situ continuous fuel reprocessing to
remove the lead as it's produced, and 'top up' the fuel.

the lead output from these reactors is 'hot' by association, but not -
or only sparingly - inherently radioactive.  storage for hundreds of
thousands of years is not necessary.

a further note: if we could actually build these efficient nukes, we
have enough uranium already refined to power our grid for the next 5
centuries.

" >how about solar power satellites, constructed in space from lunar-mined
" >material?  the startup costs are about as staggering as you can
" >imagine, but once you could pop one out it'd be a self-sustaining
" >industry.  i've been re-reading gerard o'neill's 'the high frontier'.
" >some of his economics is hopelessly optimistic, but still...
" 
" 
" Some of that may be closer than you think.  With space elevators, the cost of getting things into space is actually not prohibitive.

i've been following that, somewhat.  but siting the bulk of the
industry on the moon would still be desireable - no problems with
mining pollution, for example.  and we're starting to approach our
dear planet's limits in population; there's enough resources in our
solar system which would be accessible to space-based
colonies/settlements to support some 3000 times our current 6 billion.
that's elbow room!  though at historic growth rates, for a shockingly
short time...

" adh@xxxxxxxxxxxxxxxxx (Sandwich Maker) said:
" 
" 
" >taking the field in, and not forgetting what's manufacturably
" >practical, imho the best alternative fuel is biodiesel.  better fuel
" >crops are needed and subfreezing fluidity needs to be improved, but
" >it's a straight sub for diesel fuel and heating oil.  diesels that run
" >all the time can easily switch to straight vegetable oil, which works
" >very well when heated to coolant temps.  cold starting is svo's only
" >weakness.
" 
" 
" Biodiesel is a good short-term alternative, but once again it has "cons" as well.  The vegetable oil has to come from somewhere; and for the same reason ethanol can't supply US fuel needs even if every square inch of arable land was planted with crops, there still wouldn't be enouh.

true, although your estimates are based on food-crop productivity.
better fuel crops are needed, and without food-oriented constraints!
oil palms can produce 5x what the best temperate-zone food crops do, 2
tons per acre, but only grow in tropical climates...  there's an
african plant commonly planted on field borders in some places which
produces a poisonous [to people] oil, but i don't know how productive
it is or what its soil needs are.

and an important 'side effect' of large scale biodiesel production
must be and is being addressed: glycerine production, about 1 lb per
gallon of fuel.  there are industrial and cosmetic uses for glycerine,
but biodiesel production could supply these markets 100 times over.
can you really use 20 lb of soap -per-week-?!?  but it might turn out
to be a good plastics feedstock.
________________________________________________________________________
Andrew Hay                                  the genius nature
internet rambler                            is to see what all have seen
adh@xxxxxxxxxxxxxxxxx                       and think what none thought
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