A lot of people resist electric cars because our power grid isn’t green enough, with 60 percent of our electricity generated by fossil fuels. The remainder is roughly split between renewable energy (wind and hydro, primarily) and nuclear fission. The latter has been on a steady decline since the 2011 Fukushima disaster, but in February there was good news on the vastly more earth-friendly and renewable nuclear fusion energy front.
In late 2021, the U.K.-based Joint European Torus (JET) lab broke the world record it set in 1997 for energy extracted by fusing isotopes of hydrogen to form helium—16.4 kWh of energy in 5 seconds. That’s only enough to drive about 50 miles in an EV, and even ignoring energy expended initiating the reaction, the device invested triple the energy produced during the reaction. Nobody’s hoisting a “Mission Accomplished” banner, but 5 seconds is forever in fusion-reaction terms, and this result convinced scientists that longer energy-positive reactions are possible. Let’s review how fusion energy works.
At the temperatures and pressures powering fusion in stars like our sun, most elements lighter than iron (atomic number 26) can fuse, releasing energy in the process. Fusing two isotopes of hydrogen (atomic number 1) to form helium (2) happens at lower temperatures and releases more energy than fusing heavier elements, so current nuclear fusion energy research focuses on fusing H2 isotopes deuterium and tritium. The nucleus of the former consists of one neutron and one proton, while the latter has two neutrons and a proton. In fusing, a bit of mass is lost with that surplus neutron, so to balance Einstein’s equation E=mc2, energy gets released with that mass.
Intense gravitational pressure within the sun lets this reaction happen at a temperate 10 million degrees C, but here on Earth we must crank the heat to above 100 million degrees. At those temperatures, the hydrogen gas atoms split into positively and negatively charged particles called plasma (a lightning bolt is plasma). Since no material can contain such temperatures, the reaction must take place in a vacuum with the fuel “contained” by an intense magnetic field. Shaping the vacuum chamber and magnetic field like the inside of a donut mold (a torus) allows these superheated molecules to zing around in circles as they’re electrically or magnetically heated until they crash into each other and fuse. (Look up “tokamak” and “stellarator” for more on these magnetic containers.)
The reaction at JET, powered by two 500-MW flywheels, only lasted 5 seconds because that’s how long it took for the copper electromagnets managing that intense containment field to overheat. But the considerably larger International Thermonuclear Experimental Reactor (ITER) under construction in Cadarache, France, will employ supercooled magnets. That device is intended to demonstrate the feasibility of sustainable, net-positive nuclear fusion. The recent JET experiment verified the calculations that suggest ITER will be successful when it commences fusion experiments in 2035.
Why is fusion safer? First, there’s nothing about the reaction itself that must be restrained to prevent a meltdown like Fukushima. If the containment field fritzes, the reaction just stops. The radioactivity involved is vastly lower. Tritium fuel is mildly radioactive, but it’s used in small quantities and its radiation leaves the human body quickly. Highly energetic neutron emissions generate some radioactivity, but it’s easily contained and decays quickly. The fuel gets completely used, producing harmless helium and leaving no harmful waste.
Almost no mining is needed. Deuterium occurs naturally (accounting for one of every 5,000 hydrogen atoms in seawater), and although tritium is rare in nature, it can be made by exposing lithium to the energetic neutrons emitted by the fusion reaction, so a working reactor can generate its own tritium locally.
How soon can we power our cars with fusion? The largely government-funded researchers aim for 2050, but a recent surge in private-sector funding makes me hopeful that timeline can be compressed—like what happened in the mRNA vaccine field. Isn’t global warming an even bigger threat than COVID?
Keyword: Could Fusion Energy Break Out of the Experimental Phase and Eventually Reach Cars?