The onslaught of articles following yesterday’s Press Conference by the National Ignition Facility of the Lawrence Livermore National Laboratory have caused several friends who know my academic background to ask me what I thought its significance was.
I did attend the Press Conference, because my interest was stoked by the astute “leakage” on the WaPo and, like any other soul with some knowledge about nuclear power, I have been following the slow march of fusion towards feasibility since the day I graduated in Nuclear Engineering in June, 1981.
I have written elsewhere about the difference between Fission and Fusion, so I don’t need to repeat that here.
The concept itself is simple enough, and it took only 20 years to go from the initial 80-tons thermonuclear bomb concept imagined by Edward Teller to miniaturized bombs deployed on MIRV ICBMs or submarine-mounted missiles.
But if it’s relatively simple to blow things up, doing so in an orderly manner to generate electricity is many orders of magnitude more difficult, the main hurdle being of course the containment of plasma which needs to be heated to 150 million °C.
Obviously, given the extreme temperatures, a physical vessel is out of question, and two containment technologies were both initially proposed in the 50s, about at the same time when President Truman decided to go ahead with the H-bomb: the first is a magnetic bottle in the shape of a donut (due to Russian scientists Tamm and Sakharov – not everybody knows that the word “tokamak” used to indicate this technology is a Russian language acronym for “Toroidal Chamber with Magnetic Coils”) and the second (initially developed by the LLNL itself) is an inertial containment system obtained by bombarding a tiny (about 10mg) fuel pellet with high energy particles which causes the outer layer to explode sending shock waves into the rest of the pellet which gets immensely compressed to the point fusion is ignited; this compression mechanism is very reminiscent of the thermonuclear bomb principle, but while in the bomb this compression is achieved through the explosion of a trigger fission bomb, here the high-energy particles are shot through an array of lasers.
Each of the two approaches faces immense technical hurdles: the magnetic containment camp needs to overcome magnetic field intensity and stability issues, while the inertial containment camp needs to make sure the hundreds of lasers are focused on exactly the same position and fire at the same instant to avoid asymmetries in the shockwaves.
Many competing research programs have sprung up over time: the NIF at LLNL, the international ITER program located in France, the Joint European Torus in Oxford (UK) , Germany’s Wendelstein 7-X stellarator, China’s own EAST research program.
For both camps, obviously, the goal is to produce more energy than it’s put in, but this task is so daunting it has been broken into intermediate steps, measured by the progress in the so called Gain Factor (or Q):
- achieving a self-sustaining reaction (Q>1) when the energy generated is more than the energy impinging on the fuel
- achieving combustion (Q>5 est.) when the energy generated is more than the energy needed to service the fuel (e.g. heating it or cooling the lasers)
- achieving ignition (Q=∞) when the energy generated requires zero energy input
An FPP (fusion power plant) can be connected to the grid when it achieves goal #3. Since the late-90s various programs have announced to have achieved goal #1, but since Europe and magnetic containment seemed ahead of the game having achieved Q>1 since last year (a lag also admitted by one of the NIF scientists during the press conference, even though their claimed Q=1.7 is a bit higher than the JET’s own Q=1.25) the LLNL announcement sounded more like a catch-up by the inertial confinement camp, almost a mighty sigh of relief for having proven “it can be done” via inertial containment as, after almost 70 years, it was still in doubt and therefore funding might be cut. I also noticed a creepy insistence by several speakers who stated that the value of this achievement lied in the “further enhancement of our nuclear weapons development” and preservation of “our nuclear deterrent”.
[EDIT Dec. 19th: turns out I was not alone in being disturbed about this: https://bit.ly/3PDw37f%5D
Issues I have
Not a single word was uttered in favor of “clean, abundant energy for all” and THIS remains my biggest gripe about fusion, because I think technology eventually will get there: maybe it will take another 50 years, maybe less; I suspect however that the capital costs of these FPP will be so large to require gargantuan power outputs to give them a chance to compete with ever cheaper renewables, dwarfing the 7-8GW of today’s largest NPPs.
As a consequence, as it happens in conventional nuclear, wind, hydro or solar, while the marginal cost might be zero (or very close to), the produced energy will not be free at all, because the immense upfront cost of the plant needs to be repaid.
Secondly, what worries me is not the technology but the governance of a 100GW FPP: at nuke-level (=very high) capacity factors, ONE such plant would produce TWICE the total electricity consumption of a medium-sized economy like Italy, France or the UK – do I feel comfortable with the idea of one person/entity controlling the EE powering a whole country or two?
Am I confident humanity knows how to protect itself from the risk associated with such a huge single point of failure?
No.
Last but not least, what happened to the rare earths scare? I am constantly bombarded with idiots wringing their hands about the scarcity of Lithium, Cobalt, Neodymium,… you name it (I tried to address these fears here), where are all those people today? If you’re thinking a FPP uses Hydrogen as a fuel (the most abundant element blah, blah, blah…) you could not be more wrong as it does not use the plain-vanilla kind (difficult and expensive enough to make on Earth) but a mixture of two much rarer isotopes of H called 2H or Deuterium (which has one additional neutron in its nucleus) and 3H or Tritium (which has two).
While Deuterium is relatively abundant, Tritium is almost non-existent on our planet and needs to be made by man. In an interesting twist of events, the most economic way to make Tritium is by irradiating……… Lithium !
Son of GeekTalk 