The Massachusetts Institute of Technology (MIT) and Commonwealth Fusion Systems (CFS) recently unveiled plans to have commercially viable nuclear fusion energy systems in 15 years. The partnership between MIT and CFS is backed by funding from the Italian firm ENI worth $50 million. This is only an initial investment and it is expected that the venture will have more funding in the coming years, considering that a full-fledged power plant can cost upwards of a billion dollars.
Nuclear fusion is the power behind the sun’s energy. The sun uses light chemicals, specifically hydrogen, and fuses it with other hydrogen atoms to create energy. This reaction occurs in the center of stars which reach extreme temperatures in the hundreds of millions of degrees Celsius.
Researchers trying to recreate this nuclear fusion here on earth first had to overcome the heat problem. Metals would melt before reaching sun-level temperatures and matter would exist as plasma. To keep the heat under control, magnets are used to control the plasma.
The CFS and MIT collaboration is not a magnet science experiment. Its goal is to create an economically viable fusion reactor. The MIT solution (called “Sparc”) revolves around newly-developed magnets built around a superconducting material. With it the MIT scientists are designing a much smaller and less expensive fusion chamber. The material is called yttrium-barium-copper oxide or YBCO, and it is fabricated as a coating for a tape.
Sparc project leaders, Georg Bednorz and K. Alex Muller were awarded the Nobel Prize in 1987 for their research on high temperature superconductivity with the use of a lanthanum-based material. Further research by Ching Wu-Chu, professor of Physics at the University of Houston led to the discovery that replacing lanthanum with yttrium would raise the required temperature for superconductivity to 92K.
The advantage of this method is that liquid nitrogen could be used to cool the material due to its boiling point of 77K at normal atmospheric pressure. Liquid nitrogen is commercially available, and its most popular use is in modern commercial kitchens.
Notable Nuclear Fusion Research
There have recently been other notable discoveries in the field of conductivity conducted at the University of Alabama and University of Houston. In March 2010, Roy Weinstein, professor emeritus of Physics at the University of Houston was awarded a patent for superconductive magnets cooled by liquid nitrogen. He applied for the patent in March 1990.
The magnet Weinstein developed has a strength of 2 tesla. As of March 2018, the world record for magnet strength is held by a YBCO magnet which was created by the National High Magnetic Field Laboratory. It has a strength of 32 tesla.
With the YBCO superconducting magnet, less energy is used to create the stabilizing magnetic fields. It also has a stronger magnetic field, which in turn squeezes more energy out of the fusion fuel. The MIT project will be about 1/65th the size of the International Thermonuclear Experimental Reactor (ITER) which is currently under construction in southern France.
There are other technologies being developed worldwide to harness nuclear fusion. Besides Sparc and ITER, there is also the Wendelstein 7-X stellarator project in Germany. With the initial investment of $50 million, Sparc will be used to study the use of the YBCO super magnets and how capable the material is in keeping a “stable reaction.”
A stable reaction is when the resulting fusion sustains itself within the plasma enclosure, with fusion continuing until all the hydrogen fuel material is spent, or the fusion process is shut down by the researchers. Once that happens, it means that fusion can be controlled with the use of super magnets and the plasma chamber configuration.
Nuclear fusion would provide an alternative energy source to fossil fuels. It would also relieve the reliance on nuclear fission which yields nuclear waste. Successful development of a working nuclear fusion plant will enable harnessing huge amounts of energy enough to reverse the results of burning coal and oil.
Proponents of the project understand that developing a full-scale nuclear fusion plant capable of producing 100-500 megawatts of energy will cost billions of dollars. If the super magnet experiments provide positive results, it would be much easier to raise the needed money for the succeeding phases of development.
Development Efforts Not A Race
Here’s what makes these bold actions by different development groups truly unique. They aren’t competing with one another. The various research projects working towards a nuclear fusion reactor are not racing to see who creates it first or to prove this technology is superior to that. Rather, these varied projects, along with other research projects worldwide, are meant to tackle specific pieces of the problem. The resulting information or research breakthroughs are intended to be shared among the other teams.
The situation is much like the development of the first nuclear reaction where there were also multiple engineering problems and approaches under development at the same time. Today’s research projects may or may not lead to new technologies individually, but the results of each provide direction for other projects.
Nuclear Fusion Benefits
Research into nuclear fusion has been going on since the first nuclear fusion bomb was first tested in November 1952. Two of the things that immediately hampered development of nuclear fusion reactors were the amount of energy required to start a reaction and the high temperatures following a reaction. Keeping a reaction under control has been another stumbling block to development.
The advantages of nuclear fusion, however, are tremendous:
• A purely fusion-based nuclear reactor does not have any radioactive by-products
• Fusion does not release extra neutrons which can produce radioactive materials
• The reaction only requires hydrogen as fuel which is plentiful element
• The reaction releases an enormous amount of heat and energy
Initiating the Reaction
In 1977, the Lawrence Livermore National Laboratory built the Shiva laser to study inertial confinement fusion (IFC). Shiva was a powerful infrared neodymium glass laser composed of 20 beams pointing at a single target. Shiva was named after the Hindu god with multiple arms, in reference to the multiple lasers it uses.
The goal of the Shiva experiments was to recreate temperatures found in the center of the sun. If they could do that, for a split-second there would be enough heat to generate a nuclear fusion reaction.
Short of a nuclear fusion explosion, the concentrated heat of the lasers was the only method believed to be able to spark a fusion reaction. Scientists using different lasers as well as an increasing number of lasers worked on this problem for almost 40 years. Although promising, the main hurdle of using lasers is the cost in terms of energy used. The energy used was more than the energy produced, which made commercial production impractical.
The use of lasers led to new machines which tried to create a reaction. These efforts resulted in even larger machines and more costly experiments and failures. Eventually researchers decided that further studies couldn’t be sustained by only one country. This lead to an agreement between the United States and the then Soviet Union to jointly develop a laser initiated nuclear fusion development project.
Called ITER, the original collaborators included the United States, the Soviet Union, the European Union and Japan under the International Atomic Energy Agency (IAEA). Since the 1980s, other countries have joined the research effort, including India, the South Korea and China. The ITER site is currently under construction in the south of France. The ITER is expected to cost more than $20 billion when it is finished.
Controlling the Reaction
Since regular materials are not able to hold and keep the reaction in a stable state, other ways have been developed to enable a controlled chain reaction. Scientists now use a torus-shaped containment chamber with powerful magnets to create a magnetic field strong enough to control the confined plasma. Called a tokamak, this has proven to be the most promising solution to house a nuclear fusion reaction.
In 2015, a German research center successfully fired up the Wendelstein 7-X stellarator. It was developed over a period of ten years at a cost of more than $1 billion. Although technically still a torus, the stellarator functions more like a Moebius strip as super magnets twists the plasma around inside the containment unit. The size of the stellarator is a relatively small 16-meters wide, with 50 6-ton magnet coils inside. The resulting plasma twists help to make the reaction more stable.
The Wendstein 7-X has proven to have a 1 in 100,000 error rate, which the researchers called “unprecedented accuracy.” After providing a small-scale proof of concept for stabilizing the reaction, the next step will be to make it efficient. with the goal being to produce considerably more energy output than the energy used.
Each one of these research projects provides an important step towards harnessing nuclear fusion. Once the reaction is both stable and controllable, we’ll be on our way to having a nearly inexhaustible, clean and natural source of energy.