Imagine a power source that used cheap and plentiful fuel, produced one million times more energy than a chemical reaction such as burning, generated no greenhouse gasses, and no harmful waste. That power source is nuclear fusion and progress is being made towards fusion being a viable power source.
Fission vs. Fusion
Fission: Current nuclear reactors use nuclear fission as power. Fission occurs when an atom is split when hit by a subatomic particle. In a nuclear reactor the fuel is a relatively unstable atom such as Uranium or Plutonium and the splitting of their atoms creates a chain reaction as neutrons released by each fission triggers the splitting of other atoms. When fission occurs it creates a great deal of energy.
Fusion occurs when two nuclei of atoms join. This fusing creates a great deal of energy – about 3-4x more than that created by fission and one million times more than chemical reactions. Fusion is the process by which the sun and other stars work. In stars, immense gravity causes hydrogen and other ions to fuse.
Early nuclear weapons utilized fission while more advanced ones utilize fusion. IFOD on Atomic vs. Hydrogen Bombs
How a Fusion Reactor Might Work
On Earth we don’t have the ability to create the immense gravity necessary to cause fusion like a star does. Instead, fusion can be achieved by heating up gas to create super-hot plasma. When hot enough, the atomic nuclei overcome their mutual repulsion and collide fusion can result. IFOD on Plasma. In order to create fusion, the plasma must be heated to over 180 million degrees. That is about 6 times hotter than the sun’s core!
Super hot plasma cannot be contained by any known material. In a fusion reactor, a magnetic field is used to contain the plasma.
Thus far, nuclear fusion has been achieved for short periods of time in experiments. The big obstacle is that thus far the amount of energy necessary to super-heat the plasma and run the strong magnetic fields is 2x or more greater than the amount of energy produced by the fusion reaction. Theoretically, however, a fusion reaction should be able to output much more energy than is is necessary as an input.
There is a potential second approach. According to the New York Times: “A second approach uses large, intense lasers to bombard a frozen pellet of fusion fuel (deuterium and tritium nuclei) to heat the pellet and cause fusion to occur in a billionth of a second. Whereas magnetic fusion holds a hot plasma indefinitely, like a sun, the second approach resembles an internal combustion engine, with multiple mini-explosions (about five per second).”
Some Potential Amazing Benefits of Fusion
Fuel Source: Fusion reactors will use two types of hydrogen isotopes as fuel. These isotopes are abundant in seawater and in lithium, both of which are abundant and cheap.
Waste: A huge drawback of nuclear fission is that it generates radioactive waste that must be disposed of. Also, the fissile material and waste must be controlled and guarded as it can be used to make nuclear weapons. Fusion reactors should produce scant or no radioactive waste.
Pollution: Nuclear fusion creates no pollution! No greenhouse gasses!
Safety: Creating a “star in a jar” sounds very dangerous. However, unlike a fission reactor which can “melt down” and release deadly radioactive fallout – as occurred at Chernobyl and Fukushima – a fusion reaction gone awry would quickly burn out with little or no damage beyond the reactor itself.
Current Fusion Projects
ITER (International Thermonuclear Experimental Reactor): 35 nations and five lead members ( China, the European Union, India, Japan, Korea, Russia and the United States) have combined to work on the ITER – the largest prototype fusion reactor. This prototype is being built in France and is a “Tokamak” style reactor which uses a doughnut shaped chamber and a magnetic field to contain the superhot plasma. More on ITER here.
Lockheed-Martin, the American defense firm, has been working on a “compact fusion reactor” through its “skunkworks” division. The compact reactor uses a magnetic field like a tokamak reactor, but uses different technology to achieve containment. Instead of a building-sized reactor, the skunkworks reactor would be about the size of a cargo container. More on the Compact Fusion Reactor here and here.
US National Ignition Facility at the Lawrence Livermore National Laboratory. This lab, run by the US Government, uses high-powered lasers aimed at a small packet of fuel to create a fusion reaction. It is a different technology from the other ones.
EAST ( Experimental Advanced Superconducting Tokamak). EAST is a fusion reactor based in Hefei, China. EAST, like ITER, is a tokamak style reactor. But, unlike ITER, its a small reactor – only a few meters across. It is an experimental reactor. Information on EAST here.
When Can We Expect Fusion to Work as a Power Source?
Humanity has been working to achieve usable fusion power for over 60 years and has always seemed “about 20 years away.” ITER expects to generate more power than is consumed by the late 2030s or 2040s. EAST is hoping to achieve net positive fusion quicker than that. Lockheed-Martin is more secretive about their progress, but as of 2014 they projected they would achieve positive net energy within 5 years (so – that means any day now).
Game Changing Applications
Fusion reactors would be an absolute game changer. According to Lockheed-Martin, here are potential uses for nuclear fusion: