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Friday, October 22, 2021

Column: The two faces of fusion

Clean energy is a term bandied about quite a bit these days. We think of Al Gore and Toyota hybrids, solar power and biking to school or work (which most of you do anyway). Whether or not you believe the statistics about how much fossil fuel we have left, it is impossible to deny that supplies will eventually run out. It might be during our lifetime or even our children’s lifetimes, but the fact is, those reserves will run dry. What happens then? What happens when Earth’s gas tank reads empty?

Fusion is two faced – it’s the Harvey Dent of science. On one side, it has the ability to unleash great terrors upon the earth; atomic bombs irradiate large tracks of land, mutate living tissue and cause hundreds of thousands of deaths. But on the other side, fusion is our salvation. Fusion could provide a green source of energy available to everyone, with relatively little upkeep.

All of atomic energy is based on Einstein’s equation, E=mc2. Einstein’s theory was that an object’s mass was proportional to its energy. A fission reaction is one in which an atom is broken apart, releasing a quantity of energy, and a fusion reaction is one in which two atoms are forced together. In fusion, the resulting mass is less than the combined mass of the original two, and that mass difference is converted to energy. Fission is well understood in theory as well as practice. The United States alone has over 100 nuclear fission reactors and a huge percentage of our nuclear arsenal consist of fission warheads. UC Davis houses one of the few civilian, experimental nuclear reactors at the Crocker Nuclear Lab.

Fusion is well understood as a method of destruction (see Hydrogen Bombs), but unlike fission it is still not a commercially viable source of energy.

A few different research institutions are currently attempting to initiate a fusion reaction; the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory in California, and the International Thermonuclear Experimental Reactor (ITER), in France. NIF is using an array of lasers to superheat and compress nuclear fuel (tritium and deuterium) until the molecules fuse together. The pellets of fuel, which are about the size of Whoppers malted milk balls, implode to fuse the different fuels. NIF has been able to generate fusion, but they have not yet figured out how to generate more energy than it took to start the reaction.

ITER is exploring a tool for fusion called a Tokamak reactor. Inside a Tokamak reactor, hydrogen atoms are super-heated until they create plasma, which is trapped inside a donut-shaped magnetic field. The heat from the plasma is captured to create energy.

Despite the horrendous potential of weaponized fusion reactions such as hydrogen bombs, the benefits of fusion over fission make it an avenue we should pursue. John Conway, a physics professor here at UC Davis, said fusion has the benefit of having virtually no waste products. The only waste from a fusion reactor is the material of the reactor itself. Over time, the reactor walls become radioactive from the impact of ionized atoms that escape the magnetic confinement of the reaction. Compared to the large amounts of highly radioactive waste from fission reactors that have to be transported and stored, fusion would be a huge leap toward a green energy future.

Another huge benefit of fusion over fission is the availability of fuel sources. Fission reactors require rare isotopes like tritium and deuterium. Fusion requires only hydrogen, the most abundant element in the universe. Also, there is no possibility of a runaway fusion reaction. As soon as hydrogen is no longer being added to the reaction, fusion will cease within milliseconds.

Just think of the potential. What if the world had an unlimited supply of clean energy? Once the cost of energy is no longer a factor, we could accomplish so much. Unfortunately, the U.S. has lost much of the “explore-the-frontiers” attitude we once had in abundance. Now we are more concentrated on short-term fixes and making a quick buck.

With cheap energy for construction projects, we could rebuild national infrastructure like freeways and power-grids, which are in dire need of repairs. We could replace expensive, polluting, inefficient coal-burning plants. We could put the money we save toward the economically starved education system, and just as importantly, we could stop the environmentally degrading practices of burning fossil fuels and strip mining.

Of course, the monetary cost of fusion research is huge, but think about this. The relatively small amount of money we would need to borrow to fund fusion research would be paid off within a few years of not importing oil from other countries. The amount of government subsidies that coal and oil receives, if put toward fusion and other clean energy sources, would be enough to turn the U.S. into a 100 percent green energy country within a few decades.

Science is awesome, and the biggest blockage on the road to the future is the public’s fear of “nuclear” power and all of the negative associations that come with it. Education on the topic is the key to leading humanity into a safer and more economically secure future.

HUDSON LOFCHIE was inspired by an article in Scientific American about the National Ignition Facility’s progress on initiating a fusion reaction. Follow him on Twitter @HudtaciularSci, or contact him at hclofchie@ucdavis.edu.

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