Jennifer Granholm, the secretary of energy, praised the achievement as “one of the most impressive scientific feats of the 21st century” when the Lawrence Livermore National Laboratory in California successfully achieved a nuclear fusion reaction that results in a net energy gain on Tuesday.
The sun and all other stars in the universe are powered by nuclear fusion, after all. If it can be captured and replicated, humanity will eventually have access to a nearly infinite supply of energy that won’t exacerbate the climatic problem brought on by the burning of fossil fuels.
But what exactly is nuclear fusion, and how did the Californian team of scientists succeed in making what Granholm called a breakthrough?
Learning from the sun
When two atoms of a light element, like hydrogen, are heated and fused together, a heavier element, like helium, is created. This process is known as nuclear fusion. The atoms need to be subjected to extremely high pressures and temperatures for that process to take place. Energy is released when the chemical reaction takes place.
Fission vs. Fusion
Nuclear fusion releases energy by joining together heavy atoms, whereas nuclear fission does the opposite. In terms of greenhouse gas emissions, fusion and fission both produce clean energy, but fission has a glaring drawback.
“Nuclear fission power plants have the disadvantage of generating unstable nuclei; some of these are radioactive for millions of years,” the International Atomic Energy Agency states on its website. “Fusion, on the other hand, does not create any long-lived radioactive nuclear waste.”
When compared to fission, the waste output from fusion reactions is significantly less radioactive and decays much faster.
Scientists have long been aware of the advantages of fusion over fission.
According to the IAEA, fusion may produce four times as much energy per kilogram of fuel as fission (used in nuclear power plants) and approximately four million times as much energy as burning coal or oil.
Star power
Researchers at the National Ignition Facility used the most powerful lasers in the world — 192 of them, to be exact — and further compressed their intensity before firing them into a cylinder the size of a small pebble that contained a small portion of hydrogen encased in diamond in order to simulate the chemical reaction that powers star in the universe.
The chemical reaction, which released 3 megajoules of energy, was accomplished by blasting the hydrogen pellet with 2.05 megajoules of energy, which the New York Times reported is equivalent to a pound of TNT.
No small feat
Since the 1960s, scientists from 50 different nations have been attempting to recreate and utilize the energy of a fission reaction. The Livermore laboratory made a movie outlining its work and broadcast it in 2009, the year the National Ignition Facility started operating in earnest.