Sibylle Günter, Director, Max Planck Institute for Plasmaphysics, Garching/Greifswald#

“Fusion Energy - base load electricity for the second half of the century”#

Abstract:#

In a future fusion power plant, two hydrogen isotopes – deuterium (2H) and tritium (3H) – will combine to form a He atom and set free a neutron, releasing in this process 17.6 MeV of energy. The reaction is an analogue to combustion, but the burn temperature is in the 100 Million oC rather than the several 100 oC range, and the energy set free in a single reaction is correspondingly some Million times larger. Thus, like in combustion we face the need to obtain a sufficiently high temperature and to keep the reactants from cooling too much by contact to the cold surroundings.

There are in principle two ways to a fusion reactor, the so-called inertial fusion and the magnetic fusion. In inertial fusion, a small pellet with frozen deuterium and tritium is heated up so fast that a sufficient number of fusion reactions can occur before the pellet disintegrates. Research in inertial fusion energy will not be reported here as it is mainly performed outside the EURATOM framework and to a large extend driven by military applications. At the required temperatures of about 100 Mio degrees, a gas is fully ionized, and the motion of the particles of this so-called plasma can be influenced by electromagnetic fields. Only a strong and properly shaped magnetic field, in combination with a very low plasma density can provide this exceptional insulation, but even in that case a large volume is required for self-sustaining burn. As a stationary fusion power plant has to be a system with inherently low power density – only about one hundredth of that of a fission plant – the thermal insulation has to be very good.

As opposed to fission the safety of a fusion reactor is inherent. Even in the event of external catastrophes, consequences would remain limited to the immediate power-plant vicinity. The product of the fusion reaction is helium, which is not radioactive and does not produce any afterheat. As the fusion reaction is not a chain reaction, there is no possibility of loss of control. The only volatile, radioactive element in the fuel cycle is tritium, which is produced and also consumed in the reactor itself, and the needed inventory can therefore be kept very low. Radioactive isotopes are also produced due to the neutron bombardment of components in the reactor core, but the consequences strongly depend on the choice of materials used. For example, steels have been developed which could be fully recycled within a hundred years period.

The inherent safety properties, the crisis-proof availability of the fuel, and the promise of small environmental impact make fusion an attractive candidate for a source of CO2-free electricity production, suited in particular to cover base-line loads. Its development had to clarify and overcome first a set of novel physics challenges: identification of magnetic configurations that can stably confine plasmas, heating of a plasma to 10 times the temperature in the solar interior, and control of the interaction with materials at energy fluxes locally comparable to those at the surface of the sun.

After more than 50 years of research, fusion has advanced to the decisive step on the way to a power plant: the international tokamak experiment ITER is designed to demonstrate the feasibility of net energy production from nuclear fusion reactions. In a joint enterprise by 7 partners (the EU, Japan, Russia, USA, China, the Korean Republic and India) - ITER - will for the first time show energy production exceeding the heat input to the plasma by an order of magnitude.

While magnetic confinement fusion research has converged to one experiment for the demonstration of sustained thermonuclear burn, there exist, at present, still two options for the ultimate, electricity producing power plant. They differ essentially on how stationarity of power production is to be achieved. By far the most advanced confinement configuration – the tokamak – requires the continuous flow of an electric current in a donut-shaped plasma. In present devices this plasma current is driven by a transformer, and can therefore be maintained only over a certain time, which – in a reactor – could amount to some hours. A thermal storage would provide for continuity of the electric power production during the short time interval needed to recharge the transformer. There exist, however, also ways to drive the plasma current continuously, but to do this in an economic way is a subject of current R&D. Both of these distinct operating modes of a tokamak are being prepared at present day experiments such as JET (Culham, UK) and ASDEX Upgrade (Garching, Germany), and will be tested extensively in ITER. An alternative to the tokamak is the stellarator, which has a considerably more complex magnetic configuration, but is intrinsically stationary without any need of external current drive. The complex magnetic field of a stellarator requires careful optimization to ensure sufficiently good confinement properties. The first optimized stellarator of sufficient size to proof that the stellarator concept has the potential for a power plant, Wendelstein 7-X, has recently been built up in Greifswald, Germany. It will start plasma operation still in 2015.

Given the still open physics and technology issues and also the need to further develop and characterize materials, fusion can make a significant impact on the electric energy supply only in the second half of this century. However, even after 2050, electricity needs are still expected to further rise (about by a factor of 3 till 2100) and some of the shorter-term solutions to the CO2 problem, like the enhanced usages of gas or CO2-sequestration, will run out of resources or face a shortage of suitable repositories by that time. Fusion has the promise to offer a complement to renewables, being available continuously and independently of location.

The European fusion community has recently elaborated a roadmap to fusion electricity by 2050, pointing out the main missions and the milestones to be met on that way. All European fusion laboratories are working jointly to implement this roadmap. The collaboration is organized within the consortium EUROfusion, involving fusion laboratories from 26 EU member states and Switzerland.

Further Reading:

• Fusion Electriciy. A roadmap to the realization of fusion energy https://www.euro-fusion.org/wpcms/wp-content/uploads/2013/01/JG12.356-web.pdf
• CM Braams and P.E. Stott: "Nuclear Fusion - Half a century of magnetic confinement fusion research" IOP 2002
• Fusion Physics, International Atomic Agency, WIen, 2012 (ISBN: 978-92-0-130410-0) Wesson Tokamaks, Oxford University Press; 2nd edition 1997

Profile:#

Prof. Dr. Sibylle Günter is scientific director of the Max Planck Institute for Plasmaphysics in Garching

• 1982 High school diploma in Rostock
• 1982-1987 Study of physics, Rostock University
• 1990 PhD in theoretical physics, Rostock University
• 1990-1996 Scientific staff member, theoretical physics Rostock University
• 1994 University of Maryland and National Institute for Standards and Technology (NIST), USA
• 1996 Habilitation in Rostock, venia legendi in theoretical physics
• 1996 - 1998 Scientific staff member, Max-Planck Institute for Plasma Physics
• 1998 Appointment to group leader position (C3)
• 2000 Appointment as scientific member of the Max-Planck Society and Director at Max-Planck Institute for Plasma Physics
• 2001 Appointment as adjunct professor at Rostock University
• 2005 Appointment as honorary professor at Technical University of Munich (TUM)
• 2007 - 2011 Member of the directorate of the Max-Planck Institute for Plasma Physics
• 2009 - Head of Research Unit of the EURATOM Association IPP
• 2010 - 2011 Deputy Chair of the Board of Scientific Directors of IPP
• 2011- Scientific director of the Max-Planck Institute for Plasma Physics, Chair of directorate and of the Board of Scientific Directors of IPP
• 2013 Federal Cross of Merit of the Federal Republic of Germany on the Ribbon

Collaborations

• Chair of the General Assembly of the EUROfusion consortium (2014), vice chair since 2015
• Chair of the Steering Committee of the European Fusion Development Agreement 2011-13
• Scientific Leader of the Max-Planck/Princeton Research Center on Plasma Physics since 2012
• Member of the Consultative Committee for the EURATOM Specific Research and Training Programme in the Field of Nuclear Energy (Fusion) 2011-2013
• Leader of the “International Tokamak Physics Advisory Committee on Energetic Particle Physics” (2008-2010)
• Deputy Task force leader MHD on JET (1999-2001)

Organisations/Editorial Boards

• Member of the National Academy of Science and Engineering of Germany since 2015
• Member of the Senate of the Max-Planck society
• Member of the Editorial Boards of New Journal of Physics since 2011
• Member of the Vorstandsrat of the German Physical Society since 2009
• Member of the board of trustees of the Max-Planck Institute for Quantum Optics since 2011
• Member of the board of trustees of the Wissenschaftspressekonferenz (WPK) since 2011
• Member of the board of trustees of the Karl Heinz Beckurts-Stiftung since 2011
• Member of the board of trustees of the Deutsche Museum since 2014
• Member of the International Fusion Research Council (IFRC) of the International Atomic Energy Agency (IAEA) since 2004
• Member (2004-2006) and Chair of the Plasma Physics Division of the German Physical Society (2006-2008)

Advisory Committees/Evaluations/Prize Committees

• Co-Chair of the Scientific Advisory Committee of the Princeton Plasma Physics Laboratory (USA) since 2013, Member since 2010
• European Research Council: Member of “starting grants panel” (2009-2011)
• Member of the Robert-Pohl Prize Committee of the German Physical Society (2009-2012)
• Chair of the “Board for high-performance computing of the European fusion com-munity (HPC board)” (2008-2010)
• Member of the Advisory Committee of the Computer Center of the Max-Planck Society (2007-2011), Cahir: 2007, 2009
• Member of the FOM Rijnhuizen Evaluation Committee 2011
• Member of the DIII-D Programme Committee (2006-2008)

Programme Committees:

• Member (2006) and Chair (2007) of the Programme Committee of the European Plasma Physics Conference (EPS)
• Member (2007-2011) and Chair (2007) of the Programme Committee of the IAEA Technical meeting on “Energetic particle physics”
• Member of the Programme Committee of the IAEA Technical meeting on “Theory of plasma instabilities” (2002-2011)
• Member of the Programme Committee of the European Fusion Theory Conference (2000-2005)
• Director Committee of the Festival de Theorie, Aix-en-Provence, France (2011-)

Research Interests:

• Theory of Magnetized Plasmas:
  • Magneto-Hydrodynamics
  • turbulent transport
  • kinetic theory
  • supra-thermal particles
• Experimental tokamak physics:
  • Performance limiting instabilities
  • Heating and current drive
  • “Advanced Tokamak Scenarios”
• Numerical Methods to describe transport in strongly anisotropy systems