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US engineers have designed a fusion reactor that they say would be up to a tenth cheaper than the current most advanced fusion reactor design in the world, the £13 billion Iter, when scaled up to commercial-size.
The team of researchers from the University of Washington are due to publish the results of a cost-analysis of its “dynomak” reactor this week at the International Atomic Energy Agency’s Fusion Energy Conference in St. Petersburg, Russia.
Thomas Jarboe, Professor of aeronautics, astronautics and physics at the University of Washington, said: “Right now, this design has the greatest potential of producing economical fusion power of any current concept.”
The dynomak would work in a similar way to current experimental magnetic fusion reactors. Super hot plasma would be held within a closed space by magnetic fields and heated until fusion occurs and becomes self-sustaining. The heat from the self-sustaining reaction would be used to drive a coolant that would spin turbines to generate electricity.
The dynomak reactor is based on a design called the spheromak, which generates most of its magnetic fields by driving electrical currents into the plasma itself. This reduces the amount of required materials and allows researchers to shrink the overall size of the reactor, the researchers said.
In contrast, a tokamak, the most advanced fusion reactor design, has a very large electromagnet in the centre, known as the central solenoid, to induce electrical current and create the main magnetic field, alongside superconducting coils that circle the outside of the device. Both act to confine the plasma.
Researcher Derek Sutherland said: “This is a much more elegant solution because the medium in which you generate fusion is the medium in which you’re also driving all the current required to confine it.”
According to the University of Washington researchers, the dynomak would be significantly smaller and around one-tenth of the cost of Iter, while capable of producing five times the amount of energy. Iter is the largest experimental tokamak in the world and is being built in the South of France. The multinational research project involves China, the European Union, India, Japan, the Russian Federation, South Korea and the USA and is planned for completion in 2022.
The team's cost analysis also compared the dynomak against the cost of building a coal power plant. According to their analysis, A dynomak-based fusion power plant producing 1 gigawatt of power would cost £1.7 billion, while a coal plant of the same output would cost £1.75 billion,.
“If we do invest in this type of fusion, we could be rewarded because the commercial reactor unit already looks economical,” Sutherland said. “It’s very exciting.”
Research into spheromak reactors started more than 30 years ago. European fusion researchers close to the Iter project said that although the research sounded promising, there was as of yet no experimental results to back them up and the design is not developed enough to be a viable alternative to the tokamak.
The University of Washington said it has developed a prototype around one tenth the size and power output of the final product which has “efficiently sustained” a plasma. The research team expects significant fusion power output as they increase the size of the reactor and achieve higher-temperature plasmas, although a commercial-scale plant is still “years away”.