Written By: Ryan Ripsman, Science Staff Writer
Every second, the Sun produces enough energy to power the world for six-hundred million years. For years, scientists have worked to harness a fraction of this energy, using solar panels, which now produce about 2.5% of the world’s electricity. While this is an admirable goal, other scientists have an even more ambitious goal – to employ similar methods to the Sun to produce energy here on Earth. For many years, this idea was considered a utopian pipedream, but recent developments have made this technology feasible. Currently, countries across the globe are racing to perfect the technology that could permanently solve the energy crisis. Everyone is hoping to be the first to build a working fusion reactor.
Fusion converts mass into energy in a similar manner to fission, which is the more conventional nuclear power exploited by all modern nuclear power plants. But that is where the similarities between these two power sources end. Nuclear fission occurs when the nucleus of a heavy radioactive element, such as uranium, is broken down into two smaller nuclei, which together weigh slightly less than the original nucleus. Nuclear fusion, on the other hand, is the exact opposite process. Two small nuclei are combined to form one big nucleus that weighs slightly less than the original two nuclei combined.
In principle, nuclear fusion sounds simple – it fuses two nuclei and produces energy. The difficulty lies in getting nuclei close enough to fuse. Nuclei are composed of positively charged protons and neutral neutrons, giving them an overall positive charge. According to Coulomb’s law, one of the fundamental principles of physics, particles with opposite charges attract, and particles with the same charge repel. Because of this law, nuclei repel each other, making it virtually impossible to bring nuclei close enough to fuse under normal conditions. It is only possible to fuse nuclei under extreme conditions.
In order to make fusion a viable source of power, scientists are trying to reproduce the conditions at the center of the sun. On Earth, there are three common states of matter: solid, liquid and gas. The center of the Sun is composed mainly of hydrogen in a fourth state of matter, called plasma. Plasma is produced when a gas is heated to the point where its electrons separate from its nuclei. Nuclei in a plasma are moving fast enough that they can overcome the repulsive Coulomb force and fuse with each other.
Producing and controlling plasma for fusion is a difficult process which requires very precisely built reactors. The most common type of fusion reactor today is called the tokamak. In a tokamak reactor, all the air is removed from a large chamber and replaced with gaseous fuel. To convert the fuel into plasma, the fuel is heated and powerful electrical currents are run through it. The fuel is controlled using powerful magnets, to prevent fuel from escaping the machine. The plasma fuses and produces large amounts of heat. This heat is used to boil water, which will spin a turbine producing electricity. If the fusion reactor is built correctly, the reactor will produce more energy than it consumes.
Over the last eighty years, billions of dollars have been invested in developing fusion power. Scientists justify this expenditure by pointing to the myriad of benefits of fusion. Fusion doesn’t produce any greenhouse gasses, making it more environmentally friendly than conventional sources of energy, like natural gas and coal. Unlike fission power, it produces very little harmful waste. Safely storing the waste products from a fission reactor is a difficult process, requiring significant time, money and space. Fusion’s only by-products are helium and neutrons, neither of which need to be stored long-term. Since fission reactors rely on a carefully controlled chain reaction, the loss of control introduces the potential for a meltdown, which is a massive release of radiation and energy. This is not possible in a fusion reactor. Fusion requires a constant supply of new fuel and heat to ensure there is enough hot plasma to fuse, making an uncontrolled chain reaction impossible. Finally, unlike a fission reactor, none of the materials used or produced in a fusion reactor can be used to create weapons.
Fusion also has advantages when compared to renewable energy sources. Unlike hydroelectric and geothermal energy, fusion reactors can be built anywhere. They don’t rely on natural or environmental features. Unlike wind and solar energy, fusion does not require specific weather patterns and can be produced consistently throughout the day.
Some scientists point out that there are some unsolved issues associated with producing energy using fusion. One problem with fusion power relates to the massive water consumption from the process, which could strain our water supply. Furthermore, fusion reactors will be fueled by a combination of deuterium, an atom that is found in water, and tritium, which is a scarce element. Some scientists argue that fusion will not be practical long-term because we will quickly use up our limited supply of tritium. Proponents of fusion contend that this won’t be an issue, since tritium can be produced during fusion and harvested to act as the fuel in future fusion reactions. The largest criticism of fusion is that, after years of research, no one has been able to build a fully functional fusion reactor. Scientists working on fusion are optimistic that this will be remedied in the next five to ten years.
While scientists have been working on nuclear fusion since the 1940s, things are starting to heat up now. With the threat of climate change looming, there is more incentive to find efficient and clean energy sources. At the same time, advancements in computing technology and plasma physics have made fusion power viable. Currently, countries across the globe are constructing their first fusion reactors. One of the largest fusion projects called ITER is a joint project supported by 35 countries. Over the last ten years, ITER has been constructing a prototype fusion reactor in France. They intend on producing plasma for the first time in 2025.
Outside of this global cooperation, many countries have developed a domestic nuclear fusion program. Countries like Japan, China, the United States, and the United Kingdom all have invested billions of dollars into fusion programs. South Korea has built a prototype fusion reactor that has maintained a stable plasma at a temperature of over 100 million degrees Celsius – more than five times the temperature of the Sun’s core – for 20 seconds.
Canada is also working on a fusion program. Canada intends on building a prototype fusion reactor by the year 2030. While it is exciting that all these countries are preparing fusion reactor prototypes, it will be many years before these reactors can begin to supply our energy needs. Hopefully, in our lifetime, all our energy needs will be provided by clean and safe fusion reactors.
