Fusion energy from 2038? “The nuclear power plants are already being investigated as fusion sites,” says Markus Roth in the “climate laboratory”

Fusion energy is the holy grail of all energy systems, promising endless clean energy like the sun. But the research is time-consuming and expensive. For decades, progress has been rather sluggish – until Californian researchers announced a breakthrough six months ago. In the meantime, intensive plans for the first fusion power plants are also being made in Germany. The first locations are already being checked, says Markus Roth in ntv.de’s “Climate Laboratory”. The physicist wants to work with his company Focused Energy connect a demonstration power plant to the German power grid as early as 2037 or 2038. In an interview, Roth explains why laser technology is a promising approach and why BASF in particular would be a possible customer. But there are still obstacles: “Bringing a star to earth and milking it is much more complicated than rocket science.”

ntv.de: You want to connect a demonstration power plant to the German power grid in 15 years. Will it be as big as the giant ITER being assembled in Cadarache, France?

Markus Roth: ITER is a fusion power plant with magnetic fusion. We are pursuing an approach in which fusion is initiated using high-power lasers. Our power plant will not be any smaller, but it will be a bit more modular than the system in southern France.

Can you be more specific?

We are already assuming that we will need an area of ​​one to two football pitches for the power plant. Because the actual chamber in which the reaction takes place and where the energy is generated must have a certain minimum diameter. Because no matter what material we use, if you want to fuse atomic nuclei together, extremely high temperatures are required. We’re talking about a few hundred million degrees. Because you can only send a certain amount of megawatts per square meter of energy through a surface and expect that surface to last a long time. So if you want to build a gigawatt power plant, you need a reactor surface of a certain size.

How exactly is the energy created?

Fusion is the opposite of nuclear fission. In nuclear fission, a large and heavy atomic nucleus is chopped up. In nuclear fusion, on the other hand, small and light atomic nuclei are fused together at extremely high temperatures. We use hydrogen for this. Helium is produced as “ash”. Large amounts of energy are released in this reaction. I look at it from the accounting side: In the beginning I have to invest a lot, put energy into it to heat the whole thing up. Energy is only supplied when the reactions begin.

This has always been one of the big problems with fusion energy.

A power plant that mostly uses energy but doesn’t provide any would be pretty silly. That’s why you have to confine this extremely hot gas, we call it plasma, in the reactor. There are two possibilities: In magnetic confinement, an attempt is made to hold a very thin gas together for a very long time using very strong magnetic fields. The other variant is laser fusion. In our case, we are attempting to compress frozen hydrogen incredibly quickly and powerfully using high-power lasers. Then the distances between the atoms are so small that they can no longer escape when the reaction starts.

And the big advantage in the end is that you create endless energy, but no nuclear waste?

The reaction itself produces no radioactive waste. The waste product is just helium. However, any reaction with such high energy densities produces radioactive radiation while the reactor is running. As a result, components from the reactor itself become radioactive. So when the reactor reaches the end of its life, what remains is radioactive waste. It doesn’t work without it. But if I use materials that quickly decompose, I can use them again after 10, 20 or maybe 50 years, for example as steel for the next power plant. I don’t need a repository, as with conventional nuclear power.

Nuclear power plants are often located on rivers for cooling purposes. Could the decommissioned nuclear power plants be converted into fusion power plants?

In fact, the nuclear power plant sites are being studied as future sites for fusion power plants. Because, as you rightly said, rivers are great for cooling. It should also not be forgotten that the line infrastructure already exists in the area, because the nuclear power plant has also fed electricity in the gigawatt range into the grid. Personally, however, I would prefer to replace coal-fired power plants with fusion power plants. Then you would also keep CO2 out of the atmosphere.

In France, however, one can see that nuclear power plants have to be shut down regularly because the rivers carry too little water or become too hot to cool the reactors due to climate change. Wouldn’t that also be a problem for your power plant?

Basically, this is a problem for all thermal power plants that generate electricity in some way via a thermal process and a steam turbine. The charm of a fusion power plant is that the reactor itself operates at a temperature of around 900 degrees. This is significantly hotter than in nuclear power plants, but means that electricity is generated very efficiently via heat exchangers and steam turbines. In addition, you can actually switch to pure air cooling at such high temperatures. You don’t have to cool it down with water.

So how realistic is your schedule? It is always jokingly said that the breakthrough is still 30 years away. Has this breakthrough in California really happened yet?

In the beginning you called nuclear fusion the Holy Grail. That’s correct. Fusion is the most difficult experiment that humans have ever done. We always joke that it’s not rocket science. Because if it were rocket science, we would have had it back in the ’60s. Bringing a star down to earth and milking it is much more complicated. That’s why this joke was valid for decades. You had to learn a lot. But that learning curve has increased significantly in recent years. And actually the big breakthrough did not happen in December 2022, but on August 8, 2021: At that time, burning, self-sustaining plasma was produced in the reactor in California for the first time. Since then it has been clear to scientists that fusion works. The candle was lit and burned. Just not long enough to get more energy out than you put in.

But what is there still to do?

We as an industry have been able to return about one percent of electrical energy as fusion energy. That’s the general problem: no energy comes out yet. This requires a fusion reaction that provides an amplification factor of at least 100. But you have to remember that the laser systems in California are 1980’s state of the art. If you think about what mobile phones and computers looked like back then, you get an idea of ​​the advances that are still possible.

So can we stop arguing about wind turbines in the landscape and actually sit back and relax?

That would be the completely wrong approach. First of all, we have green technologies that work. We have to expand these as quickly as possible in order to become energy self-sufficient and reduce our carbon footprint. That is why I am an absolute supporter of expanding renewable energies as quickly as possible. Second, I am opposed to the idea that one technology makes everyone happy. We will also need an energy mix in the future. A decentralized energy supply via solar and wind is a great thing for houses and cities. Why do we still need fusion power plants with an output of up to five gigawatts? I can imagine that BASF in Ludwigshafen would be very interested. Because they have the energy consumption of Denmark on an area of ​​eleven square kilometers.

But we still have to achieve production prices in the range of two to four cents, maybe four to six cents per kilowatt hour. Then we will be able to compete worldwide, especially since the energy will always be available. And we have to find the transition from scientific breakthrough to power plant.

Clara Pfeffer and Christian Herrmann spoke to Markus Roth. The conversation has been shortened and smoothed for better understanding.