University of Washington engineers have designed a concept for a fusion reactor that, when scaled up to the size of a large electrical power plant, would rival costs for a new coal-fired plant with similar electrical output.
The team published its reactor design and cost-analysis findings last spring and will present results Oct. 17 at the International Atomic Energy Agency’s Fusion Energy Conference in St. Petersburg, Russia.
The UW’s design is known as a spheromak, meaning it generates the majority of magnetic fields by driving electrical currents into the plasma itself. This reduces the amount of required materials and actually allows researchers to shrink the overall size of the reactor.
New Energy and Fuel reports the concept entails a recently discovered imposed-dynamo current drive (IDCD) and a molten salt (FLiBe) blanket system for first wall cooling, neutron moderation and tritium breeding. The feasibility of the energy generating system is made possible from newly available materials and an ITER-developed cryogenic pumping system – See more at:
The Dynomak will have very high neutron wall loading and FLiBe blanket which offers most attractive blanket power density, which is also an economic metric for power plant considerations. Imposed-Dynamo Current Drive (IDCD) perturbs and sustains a stable spheromak equilibrium, avoiding severe confinement quality limitations apparent in previous dynamo-driven experiments. IDCD enables energy efficient current drive when compared to conventional current drive methods, further reducing the recirculating power fraction
The UW researchers factored the cost of building a fusion reactor power plant using their design and compared that with building a coal power plant. They used a metric called “overnight capital costs,” which includes all costs, particularly startup infrastructure fees. A fusion power plant producing 1 gigawatt (1 billion watts) of power would cost $2.7 billion, while a coal plant of the same output would cost $2.8 billion, according to their analysis.
A high-β spheromak reactor concept has been formulated with an estimated overnight capital cost that is competitive with conventional power sources. This reactor concept utilizes recently discovered imposed-dynamo current drive (IDCD) and a molten salt (FLiBe) blanket system for first wall cooling, neutron moderation and tritium breeding. Currently available materials and ITER-developed cryogenic pumping systems were implemented in this concept from the basis of technological feasibility. A tritium breeding ratio (TBR) of greater than 1.1 has been calculated using a Monte Carlo N-Particle (MCNP5) neutron transport simulation. High temperature superconducting tapes (YBCO) were used for the equilibrium coil set, substantially reducing the recirculating power fraction when compared to previous spheromak reactor studies. Using zirconium hydride for neutron shielding, a limiting equilibrium coil lifetime of at least thirty full-power years has been achieved. The primary FLiBe loop was coupled to a supercritical carbon dioxide Brayton cycle due to attractive economics and high thermal efficiencies. With these advancements, an electrical output of 1000 MW from a thermal output of 2486 MW was achieved, yielding an overall plant efficiency of approximately 40%.
The ITER tokomak project has an estimated $50 billion-plus price tag with a target date of 2027 for the first experiments. The National Ignition Facility has a cost of $3.5 billion cost and has yet to achieve true break-even with its laser-blaster fusion experiment. The unorthodox Polywell fusion reactors proposed by EMC2 Fusion are projected to cost in the range of $30 million to $200 million.
The University of Washington team, led by physicist Thomas Jarboe, has generated tens of electron volts’ worth of fusion power in a small-scale reactor known as HIT-Si3, thanks to U.S. Department of Energy funding. Now the researchers are looking for $8 million to $10 million to build a test reactor that’s roughly twice as big. If the computer models are correct, that reactor, dubbed HIT-SiX, would produce temperatures in the range of hundreds of electron volts.
“HIT-SiX will serve as the key risk-reduction experiment,” Sutherland said. It wouldn’t come anywhere near the break-even point, but it would provide additional data points to show whether the team is really on the right track.
A different team of researchers from the University of Washington has been working on yet another approach to fusion power, and some members of that original team have started up a commercial venture called Helion Energy. Helion recently received venture backing from Mithril Capital and YCombinator, and it’s made technical progress as well. “We have increased our demonstrated plasma temperatures to over 5 KeV [5,000 electron volts] and continue work on the engineering hardware of our next, break-even machine,” Helion CEO David Kirtley told NBC News in an email. Kirtley told The Wall Street Journal that break-even could come in three years, and Xconomy.com quoted him as saying the company could be generating electricity and earning revenue after six years.
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