Jed Rothwell wrote,
Conventional nuclear plants are not good at turning on and off
quickly, so we would need a buffer of dispatchable generation
capacity, probably natural, hydrogen or biomass.
This is true, but it does not mean that there is not a potential
synergy with solar (i.e. solar and nuclear used together).
Because the steam temperature which can be used with conventional
nuclear is limited by many metallurgical issues, the Carnot
efficiency is not normally very high, but that is where
concentrated solar energy could possibly be used to advantage.
This is especially relevant since peak solar hours usually
coincide with peak electrical demand (due to air-conditioning). If
the normal limits of nuclear steam are 1000 F and concentrated
solar can boost that steam to 1500 F, this makes a large Carnot
efficiency difference... and for the pyrolysis, i.e.
thermo-chemical splitting of water, the temperature-boost is even
more important. However, to my knowledge there are no hybrid
nuclear/solar plants in operation (or even planned).
Incidentally, here is another idea for solar hydrogen
generation, from the Weitzman Institute in Israel:
http://www.energycooperation.org/solarh2.htm
"The new solar technology . . . [creates] an easily storable
intermediate energy source form from metal ore, such as zinc
oxide. With the help of concentrated sunlight, the ore is heated
to about 1,200°C in a solar reactor in the presence of wood
charcoal. The process splits the ore, releasing oxygen and
creating gaseous zinc, which is then condensed to a powder. Zinc
powder can later be reacted with water, yielding hydrogen, to be
used as fuel, and zinc oxide, which is recycled back to zinc in
the solar plant."
Yes, and elemental Zinc for the Zinc-air battery for automotive
may be an even better use for their process - as this is a lighter
battery than most, but the main drawback is that zinc needs
replacement rather than a simple home recharge. One could
conceivably mount solar a few solar concentrators over converted
filling stations to provide some of the zinc for refills -
possibly even around a home or farm if some clever inventor comes
up with some kind of 'cassette' or cartridge so that molten metal
or fumes or never an issue .
The "big picture" will surely be a mix of many diverse
technologies - and the risk of that is that to get the lowest cost
in any one technology - the manufacturer needs to get to volume
production. For wind energy this would be very important as mass
production of common parts would save a huge amount. I suspect
that if government were to step-in now and say - yes we are going
to order a thousand nuclear plants before 2020 and that same
energy level in wind farms etc - and then divide up the tasks to
the most qualified parties at cost-plus (foregoing some of the
capitalist mentality) - then far lower installed prices are
possible... Perhaps not as low as that Russian News article: ha! a
$200K nuclear plant is impossible (they must be using a very old
exchange rate ;-) - but standardization is the sane way to do
this - and one of the reasons the French are doing well
economically these days.
Jones
