Fusion Takes a Big Step But Far from Its Last
What Hurdles Fusion Energy Needs To Overcome Next.
Scientists from the National Ignition Facility at Lawrence Livermore Labs in the bay area of California announced Tuesday that for the first time they have developed a fusion reaction that produced more energy than it took in. This is a very important but very small step toward one day using fusion reactors to provide energy with limited byproducts.
What is fusion?
A fusion reaction creates energy by forcing atoms together causing them to release energy as they combine. This is how the sun generates energy. Current nuclear reactors use fission, which splits an atom apart to release energy. Neither nuclear reaction emits carbon dioxide, but fission reactions do generate a significant amount of long-lived radioactive byproducts. Fusion reactions produce only short-lived radioactive byproducts. Also a cup of hydrogen fuel used for a fission reaction could potentially power a house for a hundred years.
So What Did They Do Here?
The National Ignition facility used the “world's biggest laser” focused on a cylindrical device with a capsule about the size of a pea, designed based on work with computer models to optimize its reaction. That capsule was filled with isotopes of hydrogen, deuterium and tritium, aka D-T fuel. Laserbeams heated the capsule contents into a plasma that fused the atoms into helium and released energy and neutrons. At 1:03 AM on December 5th, the process was able to produce 3.15 megajoules of energy, 50 percent more than the 2.05 megajoules used by the 192 laser beams-- about the same energy used by a hair dryer running for 15 ionizes, but compressed into a millionth of a second. Still, that's only 1.1 megajoules. Enough to boil water in a. Couple of of kettles.
Late last year, scientists at the Joint European Torus - aka JET-- in the UK generated. Record 59 megajoules by fusion, however they used more than 59 megajoules to generate it.
It's important to note that the experiment produced more energy than went in to the experiment, but that is not the same as producing more energy than was used in the experiment overall. The lasers are very inefficient. It took more than 300 megajoules of energy to create the 2.05 megajoules that the lasers put out. This is still scientifically important, because we've shown that if we had a perfectly efficient input, fusion could generate net positive energy. But it's not a practical demonstration of a reactor we could use today. To do that we'll have to see if we can repeat the process using more energy-efficient lasers or other methods like the magnetic devices used at Jet and the ITER Tokamak reactor in France.
There are other practicalities to overcome as well. This was one short reaction that destroyed the capsule and the sensors around it. To be commercially viable, the technology will need to create multiple ignitions per minute wihtout destroying everythign nearby. Something of a trick when each ignition is designed to crush and obliterate your fuel capsule into helium. And the experiment cost a few billion dollars just to crush he one capsule, so the cost needs to be brought down.
At a press conference, Kim Budil, Lawrence Livermore National Laboratory director, said "We need the private sector to get in the game. It’s really important that there has been this incredible amount of US public dollars going into this breakthrough, but all of the steps that we’ll take that will be necessary to get this to commercial level will still require public research and private research.” Among the private companies working on fusion are Tokamak Energy in the UK and Commonwealth Fusion Systems which spun out of MIT.