10.12.21 Nuclear fusion will be a public service” Interview with Dr. Klaus Hesch • Reading time: 3 min.

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Dr. Klaus Hesch is carrying out research into new technologies for fusion reactors together with around 200 colleagues at the Karlsruhe Institute of Technology (KIT). He believes that nuclear fusion will be an essential source of energy in the long term.

Why will we need to rely on nuclear fusion as a source of energy in the future? 

Dr. Klaus Hesch, Fusion expert, Karlsruhe Institute of Technology

Nuclear fusion is essential because the demand for electricity is growing. Germany is decarbonizing its entire economy, including its transport systems, with the help of electric vehicles. It is also important for us to look beyond our borders. Although we can restrict our own consumption in Germany by increasing our energy efficiency, other regions of the world still have a lot of catching up to do. Where will all the electricity that we will need in the future come from? Solar and wind power alone will not be able to meet the demand. Nuclear fission is not a sustainable solution because the fuel supplies are limited and the need for ultimate storage and the possibility of accidents remain a problem. That is why I am convinced that nuclear fusion will provide an essential public service. 

A lot of people are concerned about conventional nuclear power plants. Are fusion reactors safer?

Dr. Klaus Hesch, Fusion expert, Karlsruhe Institute of Technology

Yes, because nuclear fission and nuclear fusion are two completely different things. They are based on different physics and different technologies. For example, there are no chain reactions in fusion reactors that could get out of control as happened in Fukushima. If a fault causes the magnetic field inside the reactor to collapse, the reaction simply stops. And nuclear fusion also produces no long-term waste if it is managed correctly. The remaining radioactive material is safe after around 200 years. This means that there is no need for repositories where hazardous nuclear waste can be stored safely for 300,000 years. 

Is there enough fuel available for fusion reactors?

A variety of fuels can be used for nuclear fusion. The simplest solution is to fuse the hydrogen isotopes deuterium and tritium. Plentiful supplies of deuterium are available, because it is found in water, and fusion reactors can breed radioactive tritium themselves using lithium-6. Lithium is, of course, also used for other purposes, but lithium-6 makes up only around eight percent of the natural deposits. However, using existing mineral reserves of this isotope it would be possible to operate 1,000 fusion reactors for more than 1,000 years and that does not include the much larger amounts available in brine and seawater. In my view there is enough fuel available. 

Dr. Klaus Hesch, Fusion expert, Karlsruhe Institute of Technology

Nuclear fusion is often described as the eternal promise. What is the current status of the development process?

We need to make a distinction here between two areas of research: the plasma and the materials. Let’s look first at the plasma. To produce energy from nuclear fusion, we have to enclose the fuels in a reactor and heat them to a temperature between 100 and 200 million degrees, which is ten times as hot as the sun’s core. To do this, we need magnetic fields. We have learned a huge amount about this over recent decades, for example in research facilities like ASDEX Upgrade in Germany and JET in the United Kingdom. The ITER experimental reactor in France will provide us with more information and will be producing surplus energy for the first time by the mid 2030s. 

And what is the status of the material research?

The material for the reactor presents us with a major challenge. It becomes radioactive because it is constantly bombarded with neutrons, and this damages its interior structure. We are working closely on this at KIT. We take our findings from simulations and from neutron experiments in nuclear fission reactors. In the future, information will also come from the planned DONES accelerator in Spain, which will be completed by 2030. On the basis of the results of the research into the plasma and the materials, the EU plans to build a demonstration reactor that will be able to produce 300 to 500 megawatts of electrical energy by around 2050. 

Several countries are involved in ITER. Are other state-funded projects also underway?

Yes, in the United Kingdom for example. It is one of the participants in ITER, but it also has its own ambitious plans. The British government intends to complete its first fusion reactor by 2040. China, which is also a member of the ITER consortium, is also working on its own projects and has already built some test facilities. Alongside its involvement in ITER, the USA is funding a series of start-ups in the field of nuclear fusion. 

When do you think the first commercial fusion reactor will come into operation? And how much power will it produce?

Once the demonstration reactors are up and running, it is likely to be another 10 or 20 years before the first commercial plant is completed, so this will be sometime between 2060 and 2070. A fusion reactor of this kind will probably produce a similar amount of power to a current nuclear fission power plant. It should be able to supply around one gigawatts of electricity and three gigawatts of heat, with no CO2 emissions. 

Dr. Klaus Hesch, Karlsruhe Institute of Technology


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