Update 12-19-2022: An edited version of this appeared in the Sunday 12-18-2022 Waco "Tribune-Herald" paper as a board-of-contributors column.
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With scientists achieving “breakeven” at the national ignition
facility, their press release has been
ballyhooed into notions that fusion is here to save us immediately from energy
shortages and climate change. Wrong!
Excerpted from an NBC News release 12-13-2022:
“While the Livermore team achieved
what researchers call a scientific break-even or energy gain, it did not
achieve an engineering break-even: The inefficient lasers used in the
experiment required about 300 megajoules of energy to fire just 2 megajoules of
energy into the experiment. The reaction produced about 3 megajoules of energy.”
and
“Scientists must now find ways to
reduce inefficiencies, burn a larger portion of available fuel during the
reaction and harness the energy for use as electricity, said Troy Carter, a
professor in UCLA’s department of physics and astronomy and the director of the
Plasma Science and Technology Institute.”
And here is an image of the target bay:
My take on it:
Figured as output/input, the scientists are comparing fusion energy
released (as heat) to the incident laser light energy on the fuel pellet that
compressed it: 3 megajoules/2 megajoules
= 1.5, which is greater than 1, indicating they got more fusion-derived heat
energy out, than they put in as laser
light energy (or magnetic confinement energy,
or whatever type of energy the experiment used).
That definition of the ratio is
termed “scientific breakeven”, and this
is the first time that ratio has ever exceeded 1 in anybody’s experiment! That is quite the significant achievement! However,
bear in mind that many experimenters have been trying to do that ever since
the early 1950’s (some 7 decades ago).
That achievement says getting
energy from fusion is actually theoretically possible. But it ignores the efficiency of producing
the input laser (or other) energy, and it
ignores the efficiency of utilizing the output heat to make usable
electricity. The second quoted paragraph
above says exactly that, but without any
numbers to “calibrate” the notions. Allow me to “calibrate” it for you:
Per the quoted data in the first
quoted paragraph, the efficiency of
producing those 2 megajoules of laser energy is 2 megajoules/300 megajoules =
0.67%, which is really, really low!
A heat engine is required to
produce electricity from the released heat of fusion. The best of those that we have, are the steam-powered generators at power
plants, which are limited by the laws of
thermodynamics to efficiencies in the range of 25-50%. I will use that value range for illustration.
What all that really says, from the viewpoint of any engineer actually tasked
to build a powerplant, is that the
output should be the producible electricity,
say 25-50% x 3 megajoules, or 0.75-1.5
megajoules. The input is the energy
required to actually produce the laser energy in this case, which is the 300 megajoules quoted.
Looked at that way, the ratio is 0.75-1.5 megajoules/300
megajoules, or about 0.25-0.50%, and very likely lower than that. And yet THAT is the ratio that really
needs to be greater than 1 for a real-world powerplant design to work! That would be “engineering breakeven”.
It took 7 decades to achieve
“scientific breakeven”. It is
unrealistic to expect that reaching “engineering breakeven” won’t require a
similar number of decades.
*************************
What we face:
We face a shortfall of grid
capacity as the population increases and as motor fleet electrification
proceeds, plus we face a climate
disaster already in progress. For our
energy and climate needs, it is obviously
wiser to count on techniques that we already have operational. Those are fossil
fuels, hydroelectric, nuclear fission, solar,
and wind. Nothing else is
operational.
How we can face it:
All the fossil fuels produce
greenhouse gas emissions, and the
technologies to reduce or prevent that are simply not operational. Of the fossil fuels, the one cleanest of both ordinary pollution
and greenhouse gas emissions is natural gas.
But you must pay careful attention to stopping the leaks from, and the freezing of, those pipelines and distribution
infrastructure. We know how to do
that, but we have yet to make those into
regulatory requirements. So, change that lack!
Hydroelectric capacity cannot be
expanded much further: we have already
dammed all the dammable rivers in the US.
Solar and wind are already 20+% of
the Texas grid capacity, but because of
their intermittent nature and long-distance transmission losses, they cannot be much more than that percentage,
until “grid-scale” energy storage is
operational. It is not yet operational.
That leaves nuclear fission, which is free of conventional pollution and free
of greenhouse emissions, but does incur
radioactive wastes and risks! It has to
be done “right”, which prioritizes
safety over profit, which the US Navy
has long-demonstrated really works. It
also needs a short-term and a long-term solution for dealing with the nuclear waste
stream.
The short-term nuclear waste
solution is using the Yucca Mountain disposal facility already constructed in
Nevada, but so far never used. Long-term,
we need to re-process spent nuclear fuel, which might reduce the waste stream amounts, by a factor approaching 10.
Just cut the red tape (while
maintaining and enforcing the safety requirements) and get on with building
nuclear plants as rapidly as we can! We
already know how. No, it’s not the cheapest source of electricity, but it alone meets all the steady generation-capacity
and emissions requirements.
My recommendations in a nutshell:
Bill Gates says that the nuclear waste that currently exist in the US could be used to power fast reactors. Gates, of course, is currently investing in a particular type of fast reactor. Bill Gates estimates that the spent fuel that currently exist in the US is worth more than $100 trillion dollars in clean electricity production.
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