Nuclear fusion, the ultimate clean energy
Fusion energy has been a dream for 60 years, but the future looks promising
Thor A. Larsen
Nuclear fusion is the joining of two or more atomic nuclei to form a new, distinct nucleus and in the process give off a very significant amount of energy. The energy given off does not contain any radioactive elements, so the energy given off is totally “clean.” Please note that fusion is distinct from fission, the nuclear process used in atomic energy production. To create electricity from successful fusion would be for the heat generated to be harnessed to drive a steam turbine, for example.
Early work on nuclear fusion occurred in the 1930s and 1940s in the U.S. and Germany. The fusion being explored was the fusing of two “heavy” hydrogen nuclei, one, known as deuterium, having one neutron, and the other, tritium, having two. The complete atom of each nucleus is one electron. (As an aside, during WWII in Rjukan, the power plants produced “heavy water,” which meant that the water had a percentage of heavy hydrogen atoms.)
A standard hydrogen atom has a nucleus of only one proton and no neutron, as well as one electron. The heavier nuclei of deuterium and tritium makes them attractive to each other, due to nuclear attraction forces that can potentially overcome the electrostatic forces separating the atoms. In summary, to realize an energy gain the fusion of those two heavy nuclei created a heavy helium atom and the release of very significant energy, (14.1 MEV), as shown in figure 1.
The process described is what occurs in the stars, including our sun. It’s a perfect energy source, so why has the development of nuclear fusion power generation taken so long? Research in fusion began in earnest in the 1950s, mostly government funded. Research centers in the U.S., Europe, and Russia explored various approaches, but none were successful until very recently. (I had the good fortune to learn about nuclear fusion in the summer of 1961, when I operated nuclear fusion experiments at the United Aircraft Research Center in West Hartford, Conn.)
What are some of the reasons nuclear fusion is so difficult to acheive? First of all, for the reaction of two hydrogen nuclei to fuse to form a helium nucleus requires very high temperatures. The high temperatures enable the hydrogen atoms to overcome the natural electrical forces that keep the atoms apart and come close enough to fuse. However, gases at very high temperatures expand, hence the very heated hydrogen gases create enormous pressures and are difficult to contain.
Over the past 50 years of no success in realizing fusion, recent literature gives me significant hope for success in the next few years. Briefly, “success” means that more energy is released than that which is applied. Without recounting all the efforts in the past, I just want to mention a couple of promising projects in nuclear fusion underway now. The NIF (National Ignition Facility), a $3.5 billion facility connected with Lawrence Livermore National Laboratory in California, recently came close to success. Using a large array of lasers to create tightly focused energy, the array target was a pencil-sized chamber target of deuterium and tritium. They successfully realized fusion of deuterium and tritium to create helium and significant energy release. However, the net energy difference was not positive. Edward Moses, the director of NIF, indicated that the two jugs of water (heavy water located in the facility) would provide the energy equivalent of a supertanker of oil when fully successful.
Another approach for fusion uses magnetic confinement. The U.S. still has a program in this area at Princeton University, but a much larger, international program (ITER) has been building facilities in France. After many years and many dollars, approaches seem less promising than the laser approach.
However, instead of multi-billion dollar government-funded programs, several small, innovative programs driven by small companies seem promising. These efforts are funded by venture capitalists. One very promising company is Helion Energy of Redmond, Wash. Helion Energy is a small company currently funded with $5 million of venture capital. Their “fusion engine” is a 26-ft. prototype having a burn chamber where two clouds of hot ionized gases (plasmas) of hydrogen isotopes (deuterium and tritium) collide. This approach is illustrated in figure 2.
An electromagnet surrounding the above chamber effectively “squeezes” the plasmas, creating very high pressure and high temperature so that the charged ions come closer and closer together, eventually overcoming the electrostatic forces keeping the ions apart and thereby realizing fusion of the deuterium and tritium nuclei. For a brief time, in 2008, the system realized fusion! This system, which produces short-term periods of fusion, continues to work well, but requires considerable scale-up to use for utility application. The estimated financial infusion of between $15 and $20 million would be needed. If funded, the management expects a working system within 10 years.
Amongst other small fusion start-up companies are Tri-Alpha Energy in Foothill Ranch, Calif., and General Fusion in Vancouver, Canada. Both have received venture capital funding to develop prototypes. Then there is Lockheed, which is working on a system called Dynomak that Lockheed thinks can realize viable fusion power stations, cost competitive with coal.
As noted before, viable fusion power systems have thus far eluded researchers for 60 years and there remain many skeptics who say a solution is always “30 years in the future.” I will continue to be skeptical on large federal/industry collaboration, but the emergence of entrepreneurs with the outside-the-box thinking to realize small, compact systems using innovative techniques like Helion Energy’s stand the best chance of success.
• “Is Fusion Power Finally Real?” Popular Mechanics, June 21, 2011.
• “Why It’s Taking the U.S. So Long to Make Fusion Energy Work.” Huffington Post, Jan 20, 2015.
• “VC Funding, Y Combinator Power Up Nuclear-Fusion Co. Helion Energy.” Venture Capital Dispatch, Aug 14, 2014.
• “Nuclear Fusion.” Wikipedia.
This article originally appeared in the March 20, 2015, issue of the Norwegian American Weekly. To subscribe, visit SUBSCRIBE or call us at (206) 784-4617.