Nuclear fusion, the Holy Grail of clean, safe and virtually never-ending energy is a step closer to becoming a reality, say German scientists at the Max-Planck-Institut für Plasmaphysik (IPP). They will heat a very small amount of hydrogen until it becomes an ultra-hot gas (plasma), mimicking what occurs within our Sun.
Nuclear fusion (a thermonuclear reaction) is a process in which two light atomic nuclei join together and form a larger nucleus, in doing so giving off a huge amount of energy. It is the energy source that causes hydrogen bombs to explode and stars to ‘shine’.
For the reaction to succeed, the positively-charge nuclei have to collide at super-high speed to give the short-range gravitational forces that pull nuclear particles together the opportunity to overcome the electrostatic forces that are trying to push the positive-charged particles away from each other.
In the example above, the two nuclei of hydrogen are two isotopes called deuterium and tritium. (Image adapted from MBN ‘What is Nuclear Fusion’ article)
The Max-Planck-Institut für Plasmaphysik says the following about nuclear fusion:
“Nuclear fusion is the fusing of light atomic nuclei to form heavier nuclei. Of all pairs of light atomic nuclei capable of fusing it is the reaction between the two heavy hydrogen isotopes, deuterium and tritium, that affords the greatest energy yield at the lowest temperature.”
“One deuterium and one tritium nucleus fuse here to form a helium nucleus. A fast neutron is then released that carries eighty per cent of the energy gained (17.5 MeV).
Nuclear fusion – an almost inexhaustible supply of energy
In terms of the natural resources available here on Earth, fusion power offers the prospect of a nearly inexhaustible supply of energy for future generations. Put simply, it would solve all our energy problems forever and reduce the amount of greenhouse gases we emit considerably.
Although the technology is probably some decades away, advocates say when we have it, fossil fuels and conventional nuclear fission reactors will be replaced entirely. The world would literally become a better and cleaner place.
The eminent British theoretical physicist, cosmologist, author and Director of Research at Cambridge University’s Centre for Theoretical Cosmology, Prof. Stephen Hawking, once said: “I would like nuclear fusion to become a practical power source. It would provide an inexhaustible supply of energy, without pollution or global warming.” (Image: hawking.org.uk)
ITER international experimental reactor
The ITER international experimental reactor, which will put fusion research on the way to demonstrating an energy-yielding plasma, is bieng built at Cadarache in France. It forms part of an international project involving scientists and centres in the USA, Europe, Russia, Japan, China, India and South Korea.
ITER uses a powerful electric current to trap plasma with a doughnut-shaped device – a tokamak – long enough for nuclear fusion to occur. The tokamak, which was conceived in the 1950s by Soviet physicists, is fairly straightforward to construct but extremely hard to operate.
The Max Planck scientists in Griefswald, a city on Germany’s Baltic coast, are working on a rival technology called a stellarator, invented in 1950 by Lyman Spitzer (1914-1997), an American theoretical physicist and astronomer.
The stellarator looks just like the doughnut-shaped tokamak. Unlike the tokamak, however, the stellarator can operate in continuous mode from the outset.
Stellarator has more complex coils than tokamak
It functions without a plasma current, using a field generated exclusively with external coils – which holds the plasma. However, this calls for magnet coils of considerably more complex shape than those used in a tokamak.
According to project leader Thomas Klinger, the stellarator should be able to hold the plasma in place for considerably longer than a tokamak can.
In a telephone interview with the Independent, Dr. Klinger said:
“The stellarator is much calmer. It’s far harder to build, but easier to operate.”
Schema of the Wendelstein 7-X stellarator coil system (blue) and plasma (yellow). A magnetic field line is highlighted in green on the yellow plasma surface. (Image: ipp.mpg.de)
Called the Wendelstein 7-X stellarator (W7-X), the €400 million ($435m, £304m) device was first switched on in December, when it used helium, which is much easier to heat. Helium can also ‘clean’ any tiny dirt particles left behind while the device was being built.
Experts said the results obtained when the W7-X was fired up were remarkable. It became operational much faster than people had expected.
Germany funded nuclear fusion research for decades
Critics say the quest for nuclear fusion is a waste of money and other resources that could be put to better use on alternative energy projects. However, Germany has continued funding the Greifswald project – more than €1 billion over the past two decades.
Chancellor Angela Merkel worked and studied at the Central Institute for Physical Chemistry of the Academy of Sciences in Berlin-Adlershof, where she was awarded a doctorate for her thesis on quantum chemistry. She had previously graduated in physics at the University of Leipzig. She is expected to attend today’s event, which happens to be in her constituency.
View into the experimentation hall: The main installation of Wendelstein 7-X is completed. (Image: mpg.de. Credit: IPP/Bernhard Ludewig)
In the years to come, W7-X will test several of the extreme conditions stellarators will be subjected to when power-generation is achieved one day.
The Max-Planck-Institut für Plasmaphysik wrote:
“A study on the development of the European energy market as of 2050 shows that fusion as a new and comparatively capital-intensive technology can penetrate the European market if the emission of carbon dioxide is to be appreciably reduced. In 2100 fusion could then cover about 20 to 30 per cent of Europe’s power requirements.”
“The importance of the fusion option becomes obvious primarily in the global perspective, in view of the world’s growing population: In countries with rapidly increasing economic activity such as India and China it is almost only coal-fired power plants that are being planned for the next few decades. Power plants and infrastructure are being designed for lifetimes of about forty years, by which time the DEMO fusion demonstration power plant is to start power production.”
Video – Nuclear Fusion: Wndelstein 7-X
What is the concept underlying the W7-X? This video illustrates how the device is configured and what objectives are being pursued by fusion research carried out at the Greifswald branch of Max Planck Institute for Plasma Physics with W7-X.