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Fusion Energy in the 21st Century: Status and the Way Forward


Max Planck Institute for Plasma Physics Scientific Director Sibylle Günter presents the most recent results from Wendelstein 7-X and the institute’s research plans. (Photo: K. Nikolic/ IAEA)

Although its potential to generate electricity at a commercial scale is several decades away, nuclear fusion can become a promising option to replace fossil fuels as the world's primary energy source and could have an important role to play in addressing climate change, participants agreed at an IAEA General Conference side event focused on the status of fusion energy research, with major players in attendance.

Despite the potential benefits to society from fusion, such as the abundance and accessibility of fuel, the carbon free footprint and the absence of high-level radioactive waste, its science remains one of the most challenging areas of experimental physics today: controlling thermonuclear fusion for energy production is a complex and challenging undertaking.

Moderating the discussion, Meera Venkatesh, Director of IAEA Division of Physical and Chemical Sciences, highlighted the difficulties facing fusion technology to make commercially-viable fusion power a reality. She pointed out that finding the right materials to construct the fusion reactor, and developing the mechanism that will be used to extract the enormous energy/heat that is emitted, are among the major tasks ahead. “The realization of fusion power reactors would be a landmark achievement, taking nuclear science and technology to a higher level,” she said.

ITER: Proving fusion technology on Earth

One major step toward reaching this goal is the ITER project, a 35-nation collaboration to design, build and operate an experimental reactor to achieve and sustain a fusion reaction for a short period of time. ITER will be the world’s largest tokamak, a donut-shaped configuration for the containment of the plasma, which is where the reaction — at temperatures hotter than the Sun — will take place.

ITER Director-General, Bernard Bigot, highlighted the extensive progress in manufacturing and construction, which is now more than 50% completed, with the first experiments scheduled by 2025.

“When we prove that fusion is a viable energy source, it will eventually replace burning fossil fuels, which are non-renewable and non-sustainable. Our mission is to provide a new option which is safe, sustainable and economically competitive. Fusion will be complementary with wind, solar and other renewable energies,” he said.

ITER is expected to produce about 500 megawatts of fusion power by the late 2030s, and will enable scientists to observe for the first time a burning plasma, the state when the energy produced by the fusion reaction is almost or completely sufficient to maintain the temperature of the plasma, so that the external heating can be strongly reduced or switched off altogether. Studying the fusion science and technology at ITER’s scale will enable optimization of the plants that follow while leading discoveries in plasma science and technology.

Wendelstein 7-X: A new twist

These efforts are complemented by the world’s largest stellarator — Wendelstein 7-X (W7-X) at Max Planck Institute for Plasma Physics (IPP) in Germany — an alternative to the tokamak as the reactor layout. It is a twisted racetrack-shaped configuration, which is inherently stable and able to operate the plasma in a steady state for greater lengths of time than the tokamak, but it is technically harder to design.

Although W7-X will not produce energy, its designers hope to prove that stellarators are also suitable for application in power plants and to demonstrate their capability to operate continuously. Such continuous mode will be essential for commercial operation of a fusion reactor.

Sibylle Günter, Scientific Director of IPP, highlighted the most recent results from the first high-performance plasma operation of W7-X, which has recently achieved the highest stellarator fusion triple product: the density, confinement time and plasma temperature used by researchers to measure the performance of a fusion plasma.

“This is an excellent value for a device of this size, and it makes us optimistic for our further work. In the future, we expect to run the machine for a longer time,” she said.

The fusion triple product has seen an increase of a factor of 100,000 in the last fifty years of fusion experimentation; another factor of five is needed to arrive at the level of performance required for a power plant. Some of the improvements in this product were the result of experimental fusion reactors becoming larger. Plasma takes longer to diffuse from the centre to the walls in a bigger reactor, and this extends the confinement time.

Günter added: “Size matters in terms of heat insulation. Based on our experience, I believe that ITER will perform even better than planned today.”

Let there be light

While large scale experiments such as ITER and W7-X continue, nearly two dozen start-ups are working on a variety of devices, fuels, and approaches, using new technologies. These start-ups are backed by venture capital funding.

Mila Aung-Thwin, director of the award-winning documentary about the quest for fusion energy, Let There Be Light, which was shown at the event, emphasized that in addition to public investments into fusion research, there is an increase in the number of new players working in the area of nuclear fusion. As an example, the movie shows fusion start-ups in Canada and the USA.

“It’s great that there are more private entities supporting innovation. Perhaps we are at the level of technology now where start-ups can compete with national labs and agencies, as they seem to be in space travel,” he said.

Bigot added: “These companies are trying to develop alternative options to ITER. Their investors want to make fusion a reality, and this demonstrates trust in fusion as a promising energy supply for the world in the middle and long term.”

A dwarf among the giants, the Costa Rica Institute of Technology (TEC) is home to the smallest stellarator in the world. “This device is the first of a kind for Latin America,” said Carlos Otárola Zúñiga, Professor at TEC, who highlighted the importance of this technology to evolve at a power plant scale and provide alternative energy to communities in the region. The small SRC-1 stellarator was planned and built by the Plasma Laboratory for Fusion Energy and Applications and went into operation in 2016. Small and medium-size fusion devices, like SRC-1, can contribute to making important improvements towards the scaling-up to larger fusion machines, by performing joint and comparative experiments, training personnel across institutions and Member States, and educating a new generation of fusion scientists in cutting-edge technologies.

Carlos Otárola Zúñiga, Professor at the Costa Rica Institute of Technology, discusses the role for small and medium-size fusion devices and their contribution towards the scaling-up to larger fusion machines at the IAEA side event on fusion held on the margins of the 62nd General Conference. (Photo: K. Nikolic/ IAEA)

Fusion Energy at the IAEA

The IAEA has been supporting the research and development work towards future nuclear fusion energy since the beginning, in the 1950s. The IAEA played an important role in the set-up of ITER, and continues to act as a central hub among Member States developing programme plans and initiating new R&D activities leading to various concepts of a demonstration fusion power plant (DEMO) through its DEMO Programme Workshop.

The IAEA is cooperating with the ITER Organization based on the IAEA-ITER Cooperation Agreement, and is playing an important bridging function between the 35 ITER members and the other IAEA Member States through its periodic series of Fusion Energy Conferences, Workshops and Technical Meetings, Coordinated Research Projects, and publishing the leading scientific journal in the field, Nuclear Fusion.

Director General of Radioprotection and Nuclear Safety Institute (IRSN), Jean-Christophe Niel, introducing the recently published Nuclear Fusion Reactors // safety and radiation protection considerations for demonstration reactors that follow the ITER facility, which underlines the importance of safety and security for future fusion facilities. (Photo: K. Nikolic/IAEA)

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