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Fusion energy is the source of energy at the center of stars, including our own sun. Stars, like most of the universe, are made up of hydrogen, the simplest and most abundant element in the universe, created during the big bang. The center of a star is so hot and so dense that the immense pressure forces hydrogen atoms together. These atoms are forced together so strongly that they create new atoms entirely—helium atoms—and release a staggering amount of energy in the process. This energy is called fusion energy.
More energy than chemical energy
Fusion energy, like fossil fuels, is a form of stored energy. But fusion can create 20 to 100 million times more energy than the chemical reaction of a fossil fuel. Most of the mass of an atom, 99.9 percent, is contained at an atom’s center—inside of its nucleus. The ratio of this matter to the empty space in an atom is almost exactly the same ratio of how much energy you release when you manipulate the nucleus. In contrast, a chemical reaction, such as burning coal, rearranges the atoms through heat, but doesn’t alter the atoms themselves, so we don’t get as much energy.
Making fusion energy
For scientists, making fusion energy means recreating the conditions of stars, starting with plasma. Plasma is the fourth state of matter, after solids, liquids and gases. Ice is an example of a solid. When heated up, it becomes a liquid. Place that liquid in a pot on the stove, and it becomes a gas (steam). If you take that gas and continue to make it hotter, at around 10,000 degrees Fahrenheit (~6,000 Kelvin), it will change from a gas to the next phase of matter: plasma. Ninety-nine percent of the mass in the universe is in the plasma state, since almost the entire mass of the universe is in super hot stars that exist as plasma.
To make fusion energy, scientists must first build a steel chamber and create a vacuum, like in outer space. The next step is to add hydrogen gas. The gas particles are charged to produce an electric current and then surrounded and contained with an electromagnetic force; the hydrogen is now a plasma. This plasma is then heated to about 100 million degrees and fusion energy is released.
Fusion and climate change
Fusion reactions, unlike the chemical reactions from burning coal or natural gas, do not release any of the greenhouse gases that are causing climate change. For this reason, reliable, affordable fusion power could help meet the world's energy needs without contributing to the warming of our planet.
One of the benefits of fusion is that it is an on-demand energy source: you can create and use it when needed. The fuel source, hydrogen, is everywhere—if you take the top inch of water off the Boston Harbor, this would give us enough hydrogen to power Boston for 50 years. Since fusion creates electricity, it would plug right into our existing electric infrastructures. It will need to be deployed at large scales though, because it needs a minimum amount of output power to work. So you cannot have fusion powering just one home, like solar panels; the minimum would be about 1,000 homes.
Using fusion energy for electricity is still a few years away, as scientists are still figuring out how to keep a man-made star burning on earth and produce electricity from it economically.
Published September 4, 2020.