Do you know why the sun is a
sweltering ball of gas and burning plasma, radiating heat and light for millions of kilometers? It's because under intense heat and gravitational forces, hydrogen atoms crash into one another
at the core of the sun and create helium. And many scientists are very eager to replicate this process here on Earth, claiming that it would mean a virtually limitless non-carbon energy supply. "It's very important to develop nuclear fusion now so that we have it when we need it." "We're going to make it here on Earth." Billions are being poured into
nuclear fusion development right now, from both public and private institutions. The aim is: limitless clean energy. So, how exactly does nuclear fusion work? And can it really help to combat the climate crisis? Let's take a closer look at the sun. The core of the sun is a perfect environment for fusion. The sun's huge gravitational forces and
temperatures reaching 15 million degrees Celcius cause the atoms in its core to collide at very high speeds. Because of the density and high temperature, the hydrogen atom nuclei fuse and become helium. During the process, some of the mass is converted into energy. This is the fusion everybody is talking about. To replicate this process on Earth,
you need to recreate the conditions of the sun. First, you need two types of hydrogen: deuterium and radioactive tritium. You put these two into a vacuum vessel. This one, for example, will be 11.4 meters high. Then, you need very strong magnets to keep the plasma floating in the right position. The next thing you need to do is to
heat up the inside of the chamber. "We need temperatures of 100 to 200 million degrees (Celsius) for the fusion reactions to go. To do that, we use magnetic fields and we add heat." That's Tim Luce. He works for ITER, the biggest fusion experiment in the world. 100 million degrees Celcius... let that sink in. That's more than six times hotter than the temperature in the core of the sun. Researchers reach those temperatures
with magnetic fields and microwaves. Like heating your leftover soup, but on steroids. And on top of that, they add a plasma neutral beam injection. This means shooting loads of highly accelerated neutral atoms at the gasses. The deuterium and tritium inside get super hot and become plasma. Because of the heat and the magnetic pressure, they fuse into helium. The reaction releases an energetic neutron. "Neutrons carry 80% of the fusion energy with them, and as they slow down in lithium, they also produce heat." This is Daniel Jassby, a retired research physicist who worked for many years at the Princeton Plasma Physics Laboratory. Deuterium, by the way, is common in seawater, so quite easy to acquire. Tritium is a lot harder to come by. But we'll get to that later. Although fusion uses radioactive material, it shouldn't be confused with nuclear fission. Nuclear fission occurs when a neutron slams into a larger atom, forcing it to excite and split into two smaller atoms. That's the reaction that is used in nuclear power stations today. The problem: the nuclear fission method creates high-level nuclear waste and poses the risk of a nuclear meltdown. But a fusion reactor wouldn't run that risk. If anything happens to the reactor, the plasma just cools within seconds and the reaction stops. Nuclear fusion could also release four times more energy per kilogram of fuel than nuclear fission. Another positive aspect: fusion produces no high-level nuclear waste. "For fusion, what we expect is the only residual radioactivity will be the structural materials, and by improving the design, we believe we can reduce the long term waste, both the time it is radioactive and the amount. But even now, with existing technologies, we're looking at lifetimes on the order of a 100 years for the radioactive waste, not tens of thousands of years." The physicists aim to use the plasma,
with its millions of reactions per second, to create a huge, constant supply of energy with only very small amounts of fuel – and eventually, power the grid with it. Once fusion reactors are built,
and as long as you would need to heat them up with renewables and later on without external help, they could be low carbon or eventually carbon free. Sounds too good not to pursue it, right? The EU-funded, UK-based JET tokamak – a fusion device – says it can handle plasmas
"hotter than anywhere in the solar system." About 350 scientists take part in
experiments at the test facility each year. ITER, the colossal supranational project, which is supported by 35 nations, aims to construct a massive
fusion test reactor in southern France. And dozens of so-called "fusion start-ups" are also pushing toward commercialization. Many plan to use magnetic confinement, like ITER. Some are also raising money for
different kinds of technical approaches, such as using lasers instead of magnets
to replicate the conditions on the sun. The Fusion Industry Association, an industry trade group, says that the start-ups have disclosed a total of more than 4 billion dollars in private funding up to 2021. But all types of reactors face the same problem. It takes enormous amounts of energy to heat them up. For fusion power to be worthwhile, the fusion reaction itself must release more energy than was input – the "break-even". No experiment has managed that... yet. So, how far away are we from reaching that point? In August 2021, scientists at the
National Ignition Facility (NIF), in Califonia, shattered their own fusion record using powerful lasers to produce 1.3 megajoules of energy. That's 70% of the 1.9 megajoules
of energy that had been pumped in. But in practice, this is roughly equivalent to the energy required to boil a kettle. NIF shoots its lasers only a few times per day. A laser fusion power plant would need to vaporize hydrogen pellets at a rate of several per second to create greater amounts of energy. In February 2022, JET reached 150 million degrees Celsius, breaking the record by producing 59 megajoules of energy over five seconds. The highest amount of energy ever generated by a nuclear fusion reactor. But to put that into context, that is only enough to boil about 60 kettles worth of water. Not exactly limitless energy powering the grid 24/7, right? Are those breakthroughs really a crucial step forward? "Things have changed. We've learned a lot, first of all, about the plasma itself and how to control it, how to make it do what we want it to do." Athina Kappatou is a researcher at the Max Planck Institute for Plasma Physics who works at the European joint project JET. Through multiple experiments, JET scientists discovered that by changing the material of the vacuum vessel's wall from carbon to tungsten and beryllium, less tritium would get sucked up into the wall, and more reactions would be possible. After all, heating the gasses is one thing. But keeping the plasma stable enough
to keep reacting is a different story. "We need to both make our plasma such that it doesn't destroy the wall and the wall itself then affecting the plasma. But also the materials need to be appropriate so that they can both withstand these heat loads and neutrons and everything." And then, there's the minor tritium
supply issue we mentioned earlier. There just isn't enough of it around. Tritium is only found in trace amounts in nature. The effect of cosmic rays on the outermost layers of the Earth's atmosphere produces anywhere from a couple of grams to a couple of kilograms every year – the estimates vary. "We're trying to ensure that the reactor becomes self-sufficient, so that we don't constantly need this resource. But tritium can be used in a cycle. Tritium can be bred in the device and used again." But that's where Heinz Smital disagrees. He is a nuclear physicist and works for Greenpeace. "ITER will consume all of the tritium in the world. We don't have the fuel for the fusion reactors. And the process of self-processing tritium breeding does not exist anywhere in the world. That's a fact." And coming back to the radioactive waste, scientists say we will have to deal with contaminated power plant material from these fusion reactors, meaning parts of the walls must be replaced periodically. And let's keep in mind, we're still
talking about test fusion reactors. They're not meant to power the grid. They're only mini versions of potential,
full-fledged reactors of the future. "So, there will be no electricity [even] when ITER is up and running and has all the results. So then we need to build another fusion reactor machine. It will be called demo, and it's very unclear whether it will ever be produced." So can we expect to see fusion energy actually hit the grid? "I would say sometime between 2060 and 2070 is when we'll be able to see substantial power plants on the line – if there is an investment path that is starting to prepare for it now." "I would put the 100 years as the scope of where to have the fusion electricity to the grid from fusion power plants." "Chances that it [nuclear fusion] will fail to provide a wide-scale source of energy is at least 50%. It's absolutely not certain that it will work on a large scale, it's not certain that it will work at all, even in an individual facility." And there are uncertainties about the fusion startups as well. "Of course there are predictions of energy break-even and electrical power production in the next decade [from fusion start-ups]. Nothing but fantasies in my opinion." "I see it positively. I say that the more people work on this and with more different aspects, the better it is." It is impressive that the scientific community is taking a long view and plans to stay on track for decades. If only we didn't face the pressing problem of global heating. So, should we be investing in something
as uncertain as fusion? Or wouldn't it be better to spend the
money on sure bets now, like renewables? Well, it depends on whom you ask. "I think it's necessary to invest in long-term solutions because it's hard to see that renewables will be 100% of the solution." "There's lots of research going on in solar with multilayer solar panels. So, there will not be an economical relevance for a fusion reactor." "The 2050 questions is unlikely to be answered by fusion, but the 2100 question, 2200 questions beyond. I think fusion is the only answer I know of that will address those for a growing society that needs more energy production even than we make now." So, what do you think? Will you recharge your phone battery with
solar panels on your roof in the future, or will you have a mini fusion reactor in your backyard instead? Don't forget to subscribe to our channel. We post new videos every Friday.
