Birth of a Star – Nuclear Fusion’s Bold Dream
Bearing little resemblance to prototypical lasers, NIF's laser (pictured above) is not merely the largest in the world, it may one day be capable of harnessing energy similar to a star.
Searching for an answer to the global energy crisis, government scientists are attempting to create a high energy reaction using nuclear fusion which would have similar potential energy to a small star.
The Lawrence Livermore National laboratory has created a laser the size of three football fields — easily the largest laser in the world – for the purpose of creating the reaction.
“We have a very high confidence that we will be able to ignite the target within the next two years,” thus proving that controlled fusion is possible, said Bruno Van Wonterghem, a manager of the project, which is called the National Ignition Facility (NIF).
Cynics point to the fact that nuclear fusion was introduced five decades ago as a potentially credible energy source and has thoroughly failed to live up to its hype.
Worse yet, this month the U.S. Government Accountability Office released the results of an audit at NIF which lists technical difficulties to be overcome, inexplicable delays in implementing prior recommendations and poor managerial decisions as reasons the project has stalled. That being said, the US GAO still seems to support the project if NIF can improve their implementation of recommendations on this go-round.
The recipe for creating the proposed nuclear fusion reaction, described in layman’s terms, sounds very much like an explanation typically given in a Grade B science fiction novel.
- Build an enormous laser.
- Split the laser into 192 separate beams.
- Concentrate all 192 beams on a single point.
- Apply reactive isotopes of hydrogen in a gold capsule to the focal point of the beams.
NIF anticipates that the nuclear reaction they plan on creating will produce more intense heat than is located at the center of the sun.
The project designers hope that the resulting reaction will produce more than 100 million degrees Celsius – hotter than the center of the sun – and exert more pressure than 100 billion atmospheres. Ideally the hydrogen isotopes will smash together with sufficient force and heat that their nuclei will fuse, sending off energy and neutrons.
Project spokeswoman Lynda Seaver claims that the endeavor does not pose any risk to public health. “There’s no danger to the public,” said Seaver. “The [worst possible] mishap is, it doesn’t work.”
This summer, NIF hopes to try its first test run, creating a star that will be 5 microns (smaller than the width of a human hair) and die 200 trillionths of a second after it’s ignited.
“This is something you’re going to tell your grandchildren about,” Seaver told CNN. “You were here when they were about to get fusion ignition.
“It’s like standing on the hill watching the Wright brothers’ plane go by.”
25 years ago: “Nuclear Fusion is just 10 years away”
15 years ago: “Nuclear Fusion is just 15 years away”
5 years ago: “Nuclear Fusion is just 20 years away”
today: “Nuclear Fusion is just 2 years away… well no not really, it’s more like like in 2 years we’ll be able to create a fusion reaction that lasts 1/200,000,000,000,000 seconds. But that means that a full sized fusion plant is only 25 years away.”
25 years from now: “Me hit Cong with big rock. Make Boom”
Even after fusion is workable , you
still need a steam plant. The same heat transfer limitation that
make nuke plants, coal plants, and CCGT expensive to build and
operate will make a fusion steam plant expensive.
Of course expensive power plants make
cheap electricity because of economy of scale.
That’s be amazing if it works, but also a little frightening.
For photovoltaics, the efficiency level is low enough (and the whole concept weather-dependent enough) that it’s not particulary suitable way to single-handedly supply the world’s energy. Now, imagine if you could capture more of the sun’s energy in a non-weather-dependent fashion. I think that’s what they’re going for.
We need to remember that wind, solar and cow flatulence will only supplement our power needs. These will be able to supply may 10% of our energy needs. To power the 21st century, we need some SERIOUS POWER-nuclear and fusion.
(note Helium here refers to helium 3)
The problem still remains in the high neutronicity of the deuterium-tritum fusion and the deuterium-deuterium. Neutronicity refers to the amount of energy associated with the release of a neutron from the reaction/fusion. Simplistically a high value means a high energy neutron is formed which will structurally degrade the reactor walls in a matter of seconds. The JET in the UK has a plasma lifetime of 20-60 seconds max.
The problem is that reactions that do not produce a high neutronicity are generally very ‘slow’ reactions. An example is the Deuterium-helium fusion which is 83 times ‘slower’ than the deuterium-tritum fusion. It is also 10-20 times more difficult to ‘ignite’/start. This leads to a lower power density/power output (1-2 orders of magnitude) which is a simple estimate of the economic potential.
Thus the main issue with fusion energy is either building a reactor that is capable of withstanding the neutron release or some process for generating He 3 that does not impact economics (potentially mining on the moon is one source). The only other likely candidate is the proton-boron fusion but this has more extreme constraints in temperature, plasma confinement and exceedingly low power density.
Getting a fusion going is relatively easy. Sustaining it at the power densities required is the difficult part. On that line I do not see how the use of gigantic lasers will help.
I read a book called “Mining the Sky”, by a retired NASA engineer. he talked about Helium 3, and mining it on the moon, or other planets.
It only makes sense from an EROEI point of view, if you are using the He3 to make your rocket fuel (and everything else).
Fusion power is the energy equivalent of the trophy wife – beautiful and impossible to resist, but expensive, high maintenance, and, ultimately, not worth the cost.
Even if NIF attains scientific breakeven, they are a long way from a power plant. To get a functioning power plant one needs a high rep rate, and you can’t do that with a glass laser because the glass degrades with every shot. The NIF facility is basically a test bed to see if the physics works out. If the gain is low then they will need to wrap a fission blanket around the system to amplify the 14 Mev neutrons you get from fusion. It’s pretty silly to us 14 Mev neutrons to make heat. But then the fusion-fission system has competition from the fast breeder reactor, which we know works. We don’t know if laser fusion will ever work. It’s research at this point, not development.