Is Fusion the Future?
Fusion is hot, extremely hot. Not only in terms of the extreme temperature required, but also on account of the ITER project, which involves the construction of an experimental plasma fusion reactor in Cadarache, France. The stakes are high. If the project succeeds, an alternative to fossil fuels and nuclear fission will have been found, and the global energy crisis will be solved. If it fails, billions of euros in tax money will have been blown on a research dream.
“We are on a fast track to realising fusion as a commercial energy source,” says Jan Scheffel, Professor of Theoretical Fusion Plasma Physics at the School of Electrical Engineering (EE). The ITER reactor is scheduled to enter operation in 2019 and is expected to be producing 500 MW of electricity by 2026. Thousands of researchers from around the world are involved, as mandated by an international agreement entered into on 21 November 2006 by the EU, Japan, the U.S., China, India, Russia and South Korea.
“ITER is the future of fusion,” says James Drake, Professor of Fusion Plasma Physics at EE and head of the Swedish Fusion Research Unit, a partnership involving KTH, Uppsala University, Chalmers, Lund University and Studsvik Energy AB. The Swedish Research Unit is part of a broader EU-administered fusion research initiative.
“What’s so important about the ITER experiment is that it comprises the building of an actual plant,” says Professor Drake. “It will serve as proof of principle.”
The knowledge and experience acquired from ITER will set the stage for the construction of a commercial prototype by 2035, to be followed, given the success of the latter project, by large scale use of fusion energy by mid-century.
The commercialisation of fusion energy would constitute an extremely long-term alternative to fossil fuels and nuclear fission. The theoretical problems have largely been solved, and scientists have succeeded in producing energy from fusion on a very small scale. A number of major technological hurdles remain to be overcome.
Fusion requires a temperature of at least 150,000,000 °C, at which hydrogen gas is transformed into a plasma state, characterised by separation of electrons from nuclei. This temperature allows the nuclei to come close enough for the powerfully attractive strong nuclear force to come into play.
The basic fusion reaction involves the transformation of an iom of each of deuterium and tritium, two hydrogen isotopes, into an atom of helium and a free neutron. The energy liberated is primarily carried by the neutron. In the ITER reactor, the free neutrons will pass through the wall of the vacuum vessel to heat the surrounding metal blanket.
“From that point on, nothing very innovative will be involved,” says Professor Drake. “The heat will be used to boil water, producing steam to run turbines and, by extension, electrical generators. Our research focuses on two significant challenges: developing materials capable of withstanding the extreme heat and controlling the plasma inside the reactor.”
The heavy door to the EXTRAP T2R reactor facility at EE’s Fusion Plasma Physics Lab is locked. The red alarm light is on. Engineers monitor the stream of data on computer screens.
“Shoot,” says Associate Professor Per Brunsell. An engineer punches a button, activating the enormous assembly of electromagnetic coils surrounding the vacuum vessel and initiating the process of heating up the hydrogen gas to achieve a plasma state. A camera is pointed through a small window in the vacuum vessel. “There it is!” shouts Brunsell in response to a flash of light. “Did you see it?” The plasma state only lasts for a fraction of a second, but this is long enough to allow experimentation into how it behaves under a variety of magnetic-field conditions.
“The goal is to learn how to control the shape and position of the plasma,” says Associate Professor Brunsell. “Ideally, a cylindrical form should be maintained at the centre of the vacuum vessel. Any displacement towards the vessel walls means a drop in temperature and potential damage to the wall material.”
EXTRAP T2R is one of the smallest of the 14 experimental reactors in Europe. The largest, the Joint European Torus (JET), the primary prototype for ITER, is located in England.
The various research teams involved in the ITER project will be delivering different pieces of equipment that will be assembled at the Cadarache site. The technology and understanding contributed by each group will be made available to all. “Needless to say, assembling a whole from equipment developed in India, China, South Korea the U.S, Russia, Japan and the EU presents logistical challenges,” says Professor Drake.
The development of suitable materials for the reactor is regarded as the chief obstacle to realising the commercial potential of fusion.
“Structural components have to last long enough to make investments worthwhile,” explains Professor Drake. “With fusion, the most significant costs relate to plant construction, not fuel. Any need to shut down a reactor for maintenance impacts economic feasibility.”
The ITER reactor is expected to take ten years to construct and to have an operational lifetime of 20 years. Research during the first half of this operational lifetime will focus on plasma control issues. The following ten years will focus on materials development and associated problems.
“The ITER project will serve as a test bed for designing the subsequent demonstration plant,” says Professor Drake.
In Sweden, support for fusion is lukewarm at best. Although some funding is provided by the EU, KTH and the Swedish Research Council, fusion was completely overlooked in 2010 by the Swedish Energy Agency, which distributes approximately SEK 1 billion for energy research funding in Sweden each year. The Energy Agency opted to concentrate funding on research relating to energy efficiency and renewable energy sources.
“Fusion represents a great complement to renewable energy sources,” says Professor Scheffel, who, in his capacity as spokesperson for fusion research in Sweden, works to convince Swedish politicians and authorities that fusion has a future as an energy source. “Renewable energy sources like wind and solar are intermittent, and the need for a baseload energy source will remain. The wind doesn’t always blow, and the sun doesn’t always shine.”
More information, contact Jan Scheffel, 08-790 8939, email@example.com, James Drake, 08-790 7721, firstname.lastname@example.org or Per Brunsell, 08-790 6246, email@example.com.