It’s no secret that our current methods of electricity generation produce a significant amount of pollution. With recent demands from around the world to radically restructure our energy industries, clean sources of electricity are once again in the spotlight. Yet, many of these carbon-free energy sources have their own disadvantages, from being unreliable to disrupting local ecosystems. One source, however, has become a clear frontrunner: nuclear energy, which, in 2019, produced more of the U.S.’ electricity than all renewables combined (1).
Currently, the nuclear industry relies on nuclear fission. In this process, neutrons are fired at heavy atoms, usually uranium. Since these atoms are unstable, when one absorbs a neutron, the atom splits and releases energy as it transforms into a more stable state (2). It also releases more neutrons, setting off a chain reaction. Fission, however, has its own set of problems: the atoms that result from the split are highly radioactive and end up as nuclear waste, the chain reaction can spiral out of control and cause a meltdown (such as in the case of Chernobyl (3)), and the specific uranium isotope used in fission is difficult to obtain.
To maintain the high energy production of nuclear power while eliminating its deleterious environmental effects and sourcing problem, researchers have been looking to the stars. In the core of a star, two hydrogen isotopes are pushed together under intense heat and pressure to form helium. Unlike heavier atoms like uranium, hydrogen is more stable when combined together instead of split apart. Thus, the fusing of the two atoms releases energy (4). This process is known as nuclear fusion, and it is capable of producing four times the amount of energy released from fission. Since the fusion process takes in hydrogen atoms (found in water) and outputs helium (a common element in the environment), it is essentially renewable and produces no harmful waste (5). Moreover, chain reactions do not occur during nuclear fusion, which erases the risk of a meltdown.
Fusion reactions have taken place on Earth in the form of hydrogen bombs, which unleash an enormous amount of energy in seconds. For electricity generation, however, we need a device that can contain and maintain the heat and pressure required to overcome the repelling force between hydrogen atoms (4). Essentially, we must reproduce the conditions found within our Sun’s center. This is the main challenge that scientists face: how can we efficiently sustain both a temperature of over 100 million degrees Celsius and a pressure that will push the atoms within a femtometer of each other? As of now, the most promising fusion device is the tokamak, a donut-shaped chamber developed by Soviet physicists in the 1960s. Inside a tokamak, heating systems transform hydrogen gas into a superhot plasma. Powerful magnets control the movement of the plasma, increasing the likelihood of collisions between atoms (6). Tokamaks have been successful at producing fusion reactions; however, none have managed to output more energy than they have taken in. The current record is held by the Joint European Torus (JET), which produced 16.1 megawatts of fusion power with an input of 24 megawatts (7). This record is set to be broken by the International Thermonuclear Experimental Reactor (ITER), a tokamak that is expected to generate ten times as much power as it uses after its completion in 2025 (8).
Tokamaks aren’t the only candidate for fusion reactors. For instance, Dr. Heinrich Hora, a physicist at University of New South Wales, suggested utilizing sophisticated lasers to accelerate atoms into each other (9). Yet, every design has its weaknesses, and we always seem to be “thirty years away” from achieving our goal. If we look at the progress that has been made within the last century, however, we can see that our fusion technologies have vastly improved. Groundbreaking innovations are being integrated into our nuclear research every day, meaning that an energy-efficient reactor is bound to be constructed. When it is, it will forever change the way we power our world.
References:
- “What is U.S. electricity generation by energy source?” U.S. Energy Information Administration, 27 February 2020, https://www.eia.gov/tools/faqs/faq.php?id=427&t=2.
- “Nuclear explained.” U.S. Energy Information Administration, 17 April 2020, https://www.eia.gov/energyexplained/nuclear/.
- “Chernobyl Accident 1986.” World Nuclear Association, 2020, https://www.world-nuclear.org/information-library/safety-and-security/safety-of-plants/chernobyl-accident.aspx.
- “Nuclear Fusion.” American Nuclear Society, 2018, http://nuclearconnect.org/know-nuclear/science/nuclear-fusion.
- “Advantages of fusion.” ITER, 2020, https://www.iter.org/sci/Fusion.
- “What is a tokamak?” ITER, 2020, https://www.iter.org/mach/Tokamak.
- “JET History.” EUROfusion, 2020, https://www.euro-fusion.org/index.php?id=136&L=450.
- “Milestones around the world.” ITER, 2020, https://www.iter.org/sci/BeyondITER.
- “Our Technology.” hb11, 2020, https://www.hb11.energy/our-technology.