University of Washington (UW) engineers believe their new fusion reactor design has the greatest potential of producing economical fusion power of any current concept. The team’s analysis shows their reactor scaled up to the size of a large electrical power plant would rival costs for a new coal-fired plant with a similar electrical output.

Experimental Fusion Reactor at U of Washington. The UW’s current fusion experiment, HIT-SI3. It is about one-tenth the size of the power-producing dynomak concept. Image Credit: University of Washington.

Experimental Fusion Reactor at U of Washington. The UW’s current fusion experiment, HIT-SI3. It is about one-tenth the size of the power-producing dynomak concept.  Image Credit: University of Washington.

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.

The UW’s reactor, called the dynomak, started as a class project taught by Thomas Jarboe, a UW professor of aeronautics and astronautics and an adjunct professor in physics, two years ago. After the class ended, Jarboe and doctoral student Derek Sutherland, who previously worked on a reactor design at the Massachusetts Institute of Technology, continued to develop and refine the concept.

The team’s research paper, “The Dynomak: An Advanced Spheromak Reactor Concept with Imposed-Dynamo Current Drive and Next Generation Nuclear Power Technologies” has been published in Science Direct’s journal Fusion Engineering and Design.

Building on existing technology the new design called the “dynomak” creates a magnetic field within a closed space to hold plasma in place long enough for fusion to occur, allowing the hot plasma to react and burn. The reactor itself would be largely self-sustaining, meaning it would continuously heat the plasma to maintain thermonuclear conditions. Heat generated from the reactor would heat up a coolant that is used to spin a turbine and generate electricity, similar to how a typical power reactor works.

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.”

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. A spheromak is one of several ways to create a magnetic field, which may prove crucial to keeping a fusion reactor going.

The UW team is thinking big. Compared to other designs like the ITER being built in France that are much larger because they rely on superconducting coils that circle around the outside of the device to provide a similar magnetic field, the UW design is thought to be much less expensive – roughly one-tenth the cost of ITER – while producing five times the amount of energy.

Using the ICDC and FliBe changes the cost picture dramatically. The UW team used a metric called “overnight capital costs,” which includes all costs, particularly startup infrastructure fees. The estimated cost of building a Dynomak fusion reactor power plant using their design producing 1 gigawatt (1 billion watts) of power would cost $2.7 billion compared with building a coal power plant of similar electrical output costing $2.8 billion.

Perhaps the biggest roadblock to developing fusion energy, aside from the technical issue of getting more energy out than going in, is that the economics for large reactors hasn’t penciled out. Fusion power designs aren’t cheap enough by far to outperform systems that use fossil fuels such as coal and natural gas.

“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.”

For now the UW’s reactor concept is about one-tenth the size and power output of a final product, which is still years away. The researchers have successfully tested the proof of concept pre-prototype’s ability to sustain a plasma efficiently, and as they further develop and expand the size of the device they can ramp up to higher-temperature plasma and get significant fusion power output.

To date the tested proof of concept pre-prototype can generate an electrical output of 1000 MW from a thermal output of 2486 MW, yielding an overall plant efficiency of approximately 40 percent. The team’s press release isn’t saying how much energy went in to get that done.

The current research does show the imposed-dynamo current drive and a molten salt blanket system do in fact work. The team is already using high temperature superconducting tapes for the equilibrium coil set, substantially reducing the recirculating power fraction in comparison to previous spheromak reactor studies. For the equilibrium coil the team uses zirconium hydride for neutron shielding projecting a full power coil lifetime of at least thirty years.

The researchers have successfully tested the prototype’s ability to sustain a plasma efficiently, and as they further develop and expand the size of the device they can ramp up to higher-temperature plasma and expect to get significant fusion power output.

Other members of the UW design team include Kyle Morgan of physics; Eric Lavine, Michal Hughes, George Marklin, Chris Hansen, Brian Victor, Michael Pfaff, and Aaron Hossack of aeronautics and astronautics; Brian Nelson of electrical engineering; and, Yu Kamikawa and Phillip Andrist formerly of the UW.

This is a serious effort with impressive results for a first device. This group is one to watch especially as they have funding by the U.S. Department of Energy.

There is getting to be a lot of fusion efforts getting very serious with step by step closer results to the breakeven line. This group is interesting because they have a means to get the energy out. The task may be to get the fuel in and run a steady state.

Jarboe said, “Right now, this design has the greatest potential of producing economical fusion power of any current concept.”

Meanwhile, the team has filed patents on the reactor concept with the UW’s Center for Commercialization and plans to continue developing and scaling up its prototypes.

Go Washington!


Comments

2 Comments so far

  1. MattMusson on October 10, 2014 7:48 AM

    At least it is proposed as a workable commercial model. The ITER models are 30 years away from commercial use – and always will be.

    In a rational world, this model would be funded and the ITER folks would have to go back to work.

  2. Marc on October 12, 2014 3:39 PM

    Interesting that, no matter which team of scientists you ask, theirs is always the design with the most potential for net-power LOL. With one exception: the EMC2 team has been exceptionally disciplined about what they say vs. what they can PROVE. Kudos to discipline.

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