Damian Carrington - MIT nuclear fusion record marks latest step towards unlimited clean energy
A nuclear fusion world
record has been set in the US, marking another step on the long road towards
the unlocking of limitless clean energy.
A team at the
Massachusetts Institute of Technology (MIT) created the highest
plasma pressure ever recorded, using its Alcator C-Mod tokamak reactor.
High pressures and extreme temperatures are vital in forcing atoms together to
release huge amounts of energy. Nuclear fusion powers
the sun and has long been touted as the ultimate solution to powering the world
while halting climate change. But, as fusion sceptics often say, the reality
has stubbornly remained a decade or two away for many years.
Now MIT scientists
have increased the record plasma pressure to more than two atmospheres, a 16%
increase on the previous record set in 2005, at a temperature of 35mC and
lasting for two seconds. The breakthrough was presented at theInternational
Atomic Energy Agency’s fusion summit in Japan on Monday. Successful fusion
means getting more energy out than is put in and this requires the combination
of pressure, temperature and time to pass a critical value at which point the
reaction becomes self-sustaining. This remains elusive but the MIT record shows
that using very high magnetic fields to contain the plasma may be the most
promising route to practical nuclear fusion reactors.
“This is a remarkable
achievement,” said Dale Meade, former deputy director at the Princeton Plasma Physics Laboratory.
“The record plasma pressure validates the high-magnetic-field approach as an
attractive path to practical fusion energy.” Prof Riccardo Betti,
at the University of Rochester, New York, said: “This result confirms that the
high pressures required for a burning plasma can be best achieved with
high-magnetic-field tokamaks such as Alcator C-Mod.”
However, the world
record was achieved on the last day of the MIT tokamak’s operation, because
funding from the US Department of Energy has now ended. The US, along with the
EU, China, India, South Korea, Russia and Japan, are now ploughing their fusion
funding into a huge fusion reactor called
ITER. The giant,
seven-storey-high tokamak is being built in southern France, with magnets weighing
about the same as a Boeing 747. The volume of ITER’s tokamak will be 800
times bigger than the MIT vessel. ITER should be completed in 15-20 years and
aims to deliver 500MW of power, about the same as today’s large fission
reactors. But the project has been hampered by delays.
In the meantime, there
are numerous private companies hoping to develop small scale nuclear fusion
reactors. One is Tokamak Energy,
a spin-off from theUK’s national fusion lab,
which uses high-temperature superconductors to create the magnetic field to
contain the fusion plasma. The MIT tokamak used copper magnets, which require
use more power. Dr David Kingham,
chief executive of Tokamak Energy, said the important aspect of the MIT world
record was that it showed extreme conditions can be created in small tokamaks:
the volume of the MIT device is just one cubic metre. “The conventional view is
that tokamaks have to be huge [like ITER] to be powerful,” he said. “The MIT
people disagree with that view, as do we.” Kingham’s target is for his
company’s compact reactors to produce
their first electricity by 2025.
Rival companies also
backing small fusion reactors include Lockheed
Martin’s famous Skunk Works team. In 2014 said they would produce a
truck-sized fusion plant in a decade but attracted criticism for providing few
details. Others in the field
include Tri Alpha Energy,
which harnesses particle accelerator technology and is backed by Paul Allen,
Microsoft’s co-founder. General
Fusion, which uses a vortex of molten lead and lithium to contain the
plasma, is backed by Amazon’s Jeff Bezos. Helion Energy, First Light Fusion and the University
of Washington’s Dynomak are all also chasing the fusion dream.
Prof Dennis Whyte,
director of MIT’s Plasma Science and Fusion Center, said small, non-tokamak
approaches, though less familiar, could be promising: “Compact, high-field
tokamaks provide an exciting opportunity for accelerating fusion energy
development, so that it’s available soon enough to make a difference to
problems like climate change and the future of clean energy, goals I think we
all share.”
https://www.theguardian.com/environment/2016/oct/17/mit-nuclear-fusion-record-marks-latest-step-towards-unlimited-clean-energy