Prof.Dr. Markus Roth
| Martina RothVDE dialog: For over 70 years, nuclear fusion has been repeatedly presented as the ideal way to achieve an affordable, clean energy supply. Can we expect a breakthrough at some point?
Prof. Markus Roth: Research has really picked up speed in recent years; experiments are now regularly managing to double the energy used. Now it’s all about increasing efficiency. For example, colleagues at the National Ignition Facility (NIF) at California’s Lawrence Livermore National Laboratory (LLNL), who achieved an energy gain with ignition for the first time in 2022, want to massively increase the performance of their facility. This includes replacing the dummy slabs of the individual lasers with active laser glasses. This alone should increase the gain – the energy generation factor – to 14.
What do you think of the ITER fusion flagship in southern France? Critics describe this project as a never-ending story.
That is understandable. Work began back in 2010, and operations are not due to start until 2034 at the earliest. The costs now amount to over 20 billion euros. But we have to remember the circumstances under which the project was launched. ITER was a joint idea of Mikhail Gorbachev and Ronald Reagan. The two had decided to end the Cold War and initiate international cooperation. And since curing cancer and achieving world peace seemed a little too difficult, they agreed on nuclear fusion. Subsequently, many different countries were brought on board – from the EU to China, Japan, South Korea and India. It took time just to negotiate all the contracts with the individual countries. And then it took another ten years or so to agree on the location of the research reactor in the south of France. The biggest problem, however, is the fact that each participating country contributes individual components to the project. You can imagine that not everything always fits together. And the quality levels are also very different in some cases. These days, of course, the technology and the installed equipment are no longer quite state-of-the-art.
In contrast to the magnet technology used in ITER, JET and Wendelstein x7, you are pursuing a laser-based approach with Focused Energy, as at NIF.
Exactly. Research into magnetic fusion has been going on for much longer. That is why this technology has a certain advantage in some areas. But if you look at the progress that laser technology has made in recent years, it’s very impressive. That’s why the momentum seems to be with us at the moment. I’m also thinking of industrial applications that have emerged from laser systems – for example in chip production. And as soon as something is used in industry, extreme leaps in development occur, which then benefits research again.
What challenges are you currently working on with laser technology?
As NIF, among others, has shown, fusion itself is physically understood and stable. However, in order to turn a basic experiment into something that can be used to earn money, we need to improve the efficiency significantly. At the same time, upscaling is no longer about fundamental scientific questions, but primarily a matter of engineering. I’m thinking of the old laser systems, for example; they only had an efficiency of half a percent. However, the new ones are already at ten percent. And that’s twenty times the power.
As is so often the case, Germany is far ahead in research. And now, in addition to private investors, policymakers are also providing funding. In the past, however, it was often the case that innovative technologies were developed here, whereas the economic success was realized in Asia and the USA. Can things be different with nuclear fusion?
Germany continues to produce excellent engineering. And that is precisely why I believe that nuclear fusion offers us particularly good opportunities. Ultimately, the organization that is able to produce electricity at affordable prices will be successful. That is why we need to restructure our industrial system and adapt it to the needs of nuclear fusion. So far, we have been the world champions in the automotive industry; I could imagine something similar for the optical industry. We are already one step ahead. But we are still far from having sufficient capacity. Companies such as Heraeus and Schott would have to expand their production and build new factories in order to produce the optics for future power plants on a large scale. In terms of scale, more high-performance optics have been installed at the NIF than in all the telescopes in the world. In addition to these glasses, we also need special power electronics and laser diodes. Establishing the corresponding supply chains is both a major challenge and a huge opportunity for an industrialized country like Germany.
What does the Focused Energy roadmap look like?
As a German-American company, we are currently completing a laboratory in Darmstadt covering over 2,000 square meters for high-precision target and laser development. We will be building a facility in California where we will test new-generation laser systems from 2026. It has not yet been decided where our largest and most important project on the path to a fusion power plant will be built – the Integrated Test Facility with around 100 installed laser systems. There, we want to demonstrate the interaction of all the processes and bring them to a technology readiness level. That means raising the technologies to such a level of maturity that the first demonstration power plant with around 2,000 laser systems can then be built with a clear conscience. In addition, we are building a demonstration facility at the former site of the Biblis nuclear power plant for a testing method developed in laser fusion that works with hard X-rays and neutron beams.
Can you explain in more detail what the test procedure in Biblis is all about?
The process has nothing to do with energy generation, but it emerged from our laser research into nuclear fusion. It is a classic spin-off for which we have founded a consortium that is funded by the German government and includes RWE, TU Darmstadt, the Helmholtz Zentrum Dresden-Rossendorf, the Fraunhofer Institute ILT in Aachen and Trumpf Lasertechnik. This test method allows us to examine complex systems non-destructively. For example, we can even examine nuclear waste containers, such as the ones stored en masse at the state collection points and power plants. In addition, there are vast quantities of drums that have to be retrieved from the Asse mine. It is not known what condition they will be in after ten to twenty years of storage, nor what exactly is in them. Before these drums are finally stored somewhere, they have to be certified. We examine the structure of the containers and check for cracks. In addition to this application, we can also use the test method to examine other things, such as the condition of the reinforced concrete in bridges. Collapses like the one that occurred in Dresden on the Carola Bridge can be prevented in this way. Such spin-offs are extremely exciting – after all, they show that nuclear fusion research can be used for completely different applications. In addition, the laser systems prove themselves under industrial conditions, our partners drive forward the development of supply chains and the investments in research begin to pay off.
Do you think it’s realistic to build a reactor that can run at a profit by the end of the 2030s?
Not in my opinion. However, it is realistic that we will have a first fusion demonstration reactor capable of producing electricity – a so-called fusion pilot – by the end of the 2030s. As for a commercial fusion power plant that has to face the market and market prices, it’s not possible to say exactly when we can expect such a plant, but I expect it to be in the 2040s.
Could China also overtake us in this area?
The Chinese have the great advantage that their resources are virtually inexhaustible because they are financed by the state. They work with both magnetic and laser technology. Compared to other countries, China is relatively reticent when it comes to research results. But recently there have been some high-quality publications from China that are definitely world-class. The country is catching up in leaps and bounds in the intense global race.
What do you say to critics who claim that the money for fusion research would be better invested in solar and wind energy plants?
It is true that fusion research must not become a fig leaf to avoid investing in renewables. Renewables are available now and must be used to drive forward decarbonization. However, they alone will not be sufficient in the long term. One example: we are an exporting country and 90 percent of world trade is handled by ships. There are over 50,000 merchant ships sailing the world’s oceans, and each one burns between 100 and 200 tons of heavy fuel oil a day. If we want to decarbonize them all without equipping them with nuclear reactors, the only option is synthetic fuels. However, their production requires primary energy with a factor of 5. If this amount is to be produced with solar cells and wind turbines, I wonder where anyone is going to live. So the answer to the initial question is that we need to invest in both. We must expand renewables at full speed. But from the second half of the century onwards, we will have to make use of a high-density energy source that is safe and does not produce CO2.
Dr. Markus Roth (born 1965) is Professor of Laser and Plasma Physics at TU Darmstadt. There, he conducts basic experimental research and teaches about the interaction of intense laser beams with matter. The physicist is also co-founder and scientific director of the German-American startup “Focused Energy.”
