How have scientists in the United States created energy with fusion? – news Trøndelag

– This is a big day. This is the first time something like this has happened in a laboratory. This is a BFD, US Energy Secretary Jennifer M. Granholm said at a press conference on Tuesday. BFD stands for big fucking deal – a big fucking deal. But how difficult is it really? What does this mean? Let’s make an honest attempt to answer some questions we think you might have. Why should we care that American scientists have gotten more energy out of a fusion reaction than they put in? Because one of the really big challenges humanity is working on is access to green energy. Fusion has long been a potential solution, which in principle can provide access to almost infinite amounts of energy. Now this solution seems to be a little closer. The Lawrence Livermore National labratory, which houses the National Ignition Facility, is located in northern California, not too far from San Francisco. Photo: Damien Jemison / AP What is fusion for something? The mass-energy law, better known as e=mc2, tells us that mass can turn into energy, and that energy can turn into mass. Fusion is an example of the former, that mass can be turned into energy. You don’t need to know how fusion works to enjoy the fruits. And it is probably luck for many, because one of the fruits is that the Earth is livable. The sun is a huge fusion reactor. The Sun is a huge lump of gas, packed full of hydrogen. So packed, in fact, that the hydrogen atoms are constantly colliding with each other. If four hydrogen nuclei, each with one proton in them, slam into each other with sufficient speed, it starts a chain reaction that results in an atomic nucleus with two protons and two neutrons. Popularly called helium. The mass of the helium nucleus is less than the combined mass of the hydrogen nuclei. Where has the surplus mass gone? It has become energy, which radiates from the Sun. It is this merging of atomic nuclei that is fusion. So simple, and so difficult. Since the Sun is so massive, gravity ensures that the hydrogen atoms are pressed together and fuse into helium. Photo: NASA What exactly have they achieved at NIF? At the National Ignition Facility at Lawrence Livermore National Laboratory in California, they are working on laser-induced fusion. The recipe they have used is as follows. First, take a peppercorn-sized lump of hydrogen. It is important that you do not use ordinary hydrogen, you will have to obtain the hydrogen isotopes deuterium (known from heavy water and hydrogen bombs) and tritium (known from heavy water and hydrogen bombs). Put the lump of hydrogen in a small cylinder. Synchronize 192 extremely powerful lasers so that they are able to hit the same point at the same time. Shoot the laser beams into the cylinder with the hydrogen lump. Fingers crossed that the cylinder gets so hot that the hydrogen isotopes fuse together to form a helium nucleus that has a neutron to spare. Make use of the heat energy that the extra neutron provides. What they have now achieved at NIF is to implement this with positive energy flow. This means that they have generated more energy than what they put in. Something that is obviously necessary for the method to be viable for power production purposes – a power station that uses more energy than it generates is a bad business idea. Does this mean that the energy problem is solved? No, absolutely not. The energy that hit the hydrogen peppercorn was 2.05 megajoules, the energy generated was 3.15 megajoules. At first glance, it may look like a method that gives you 50 percent more energy out than what you put in. At second glance, however, you notice how much energy was used to drive the lasers. 322 megajoules, i.e. about a hundred times as much as the energy that was extracted at the other end. The experiment has thus succeeded in producing an energy surplus in the fusion process itself, but the slightly larger calculation is still heavily in the red. If you also take the time to take a third look, you notice that the lasers have to be cooled down for days after an experiment. In other words, it will be a while until this turns into a reactor that can buzz and go off by itself. No, the fusion breakthrough does not mean that we can immediately dismantle all wind turbines. Photo: Erlend Lånke Solbu Are there more ways to the Fusion Room? Yep! The laser variant NIF uses is one possibility. ITER, an international research collaboration that has been working with fusion-generated electricity as a goal since 2007, is betting on the tokamak variant. It is a device that, with the help of a magnetic field, closes plasma into a doughnut shape. When the plasma becomes dense enough and hot enough, fusion can occur. The reactor they are now in the process of completing is a research reactor, but in the long term the goal is to create a tokamak reactor that can actually sustain fusion, and convert the energy into electricity. The tokamak variant currently appears to be the most appropriate if the goal is to use the energy from fusion for power production. It is not as obvious how they will harvest the energy from the laser-driven fusion. Having said that: NIF has never aimed to create a commercial fusion power station. The experiment is basically designed to give scientists working with nuclear weapons the opportunity to study thermonuclear processes. The ITER experiment is located in the south of France, and is scheduled to be turned on in 2025. Photo: ITER So what is required for this to go from “interesting to those who work on it” to “wohooo, we have access on infinite amounts of green energy”? Quite a lot, to be honest. First of all, we can moderate it with infinite amounts of green energy. Fusion-based power will be much greener than most of the power we use today. It is still not completely without an imprint. The innards in the tokamaks will, for example, become radioactive, and will require waste solutions. We’re not talking waste-from-a-nuclear-power-plant scale, but still, it belongs in the equation. So does everything that is done to get to where we need to be – not necessarily bright green either. And then it’s not like everyone can eventually build themselves a small fusion reactor and not have to think about electricity anymore. Fusion reactors are large and expensive, and will probably be reserved for countries with a lot of money and solid power grids. In other words, fusion will not ensure that all people in the world have access to all the power they need. But it will definitely be able to help, a lot! We’re just not quite there yet. US Secretary of Energy Jennifer M. Granholm said that the experimental success was a big damn thing, which most experts seem to agree with. But we need a lot of similarly big damn things to be able to use fusion in power generation. Photo: DOA Currently, as was said several times at the press conference where NIF presented the breakthrough, there are many and high obstacles on the way to commercial fusion power stations. Both technological and scientific. The two most important: We must get more energy out than we put in. And then the current that drives the lasers must also be included in the calculation. We must be able to convert the energy that is created into electricity in a sensible way. Are we going to make it? We will certainly do that, from time to time. But it will take time. And times, of course. Most people in the know seem to agree that it is a few decades in the future. So it is not the case that we can now stop relating to the climate goals because fusion is going to fix everything. Does that mean that what happened in California was not really a breakthrough? Well then, this was definitely an important step on the way. But there are still many steps to go. Do you want to know more about fusion in general, and the NIF and ITER experiments in particular? Check out this lovely episode of Abel’s basement: Sources: Mentioned Abel’s basement episode Ann-Cecilie Larsen, professor of nuclear and energy physics at UiO Press release from NIF Nature: Nuclear Fusion Lab Achieves ‘Ignition’: What Does It Mean?Titan: Breakthrough in fusion energy – provides seven minutes of heating



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