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華盛頓大學團隊發表核熔合設計 - M. Ma
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UW fusion reactor concept could be cheaper than coal

 

Michelle Ma, 10/09/14

 

Fusion energy almost sounds too good to be true – zero greenhouse gas emissions, no long-lived radioactive waste, a nearly unlimited fuel supply.

 

Perhaps the biggest roadblock to adopting fusion energy is that the economics haven't penciled out. Fusion power designs aren't cheap enough to outperform systems that use fossil fuels such as coal and natural gas.

 

University of Washington engineers hope to change that. They 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.

 

"Right now, this design has the greatest potential of producing economical fusion power of any current concept," said Thomas Jarboe, a UW professor of aeronautics and astronautics and an adjunct professor in physics.

 

The UW's reactor, called the dynomak, started as a class project taught by Jarboe 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 design builds on existing technology and 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.

 

"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," Sutherland said.

 

There are several ways to create a magnetic field, which is crucial to keeping a fusion reactor going. 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.

 

Other designs, such as the experimental fusion reactor project that's currently being built in France – called Iter – have to be much larger than the UW's because they rely on superconducting coils that circle around the outside of the device to provide a similar magnetic field. When compared with the fusion reactor concept in France, the UW's is much less expensive – roughly one-tenth the cost of Iter – while producing five times the amount of energy.

 

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.

 

"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."

 

Right now, the UW's 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 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.

 

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.

Explore further: Research team uses remote control to replace the fusion reactor cassette collecting impurities

 

More information: www.sciencedirect.com/science/… ii/S0920379614002518

 

 

http://phys.org/news/2014-10-uw-fusion-reactor-concept-cheaper.html



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New Fusion Reactor Cheaper than Coal? BS.      

 

Tom Hartsfield, 10/12/14

 

Inventor: "I've just created my most perfect work: a new type of paper airplane."

Funding agency: "Wow great but what does it do?"

Inventor: "Oh, right now it's useless, but soon I'll just scale up the concept and we'll have a cheaper space shuttle!"

 

Shame on the University of Washington for hyping its research with this exact logic. Touting the "great potential" of a new cheaper-than-coal fusion plant, they see reality and choose to look the other way. Or maybe they're just incredibly naive.

 

To quote the press release: "Perhaps the biggest roadblock to adopting fusion energy is that the economics haven't been penciled out". BS! Let's talk about the real obstacle to fusion power. The report itself actually leads us to the culprit.

 

Among many statements ranging from meaningless to wrong, this is the one that dodges the heart of the matter: "They [researchers] 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." (Emphasis added.)

 

What is keeping fusion energy from reaching market? The fact we don't understand how to do it well yet. It's impossible with current science. Why? Precisely because we don't know how to scale it up. We can make little demonstration fusion reactors like the one in this report, but expanding them to become large enough to produce useful power eludes our grasp. The entire problem of current fusion devices is scaling them up.

 

The basic idea in this proposal is a magnetically confined plasma device that uses a geometrical plasma configuration called a spheromak. It's a magnetic field bottle built to trap plasma inside. It's a sibling of the tokamak, the best known and best working of the current fusion devices. The idea is quite old, dating to the 1950s. Several of these machines were built in the 1970s and 1980s, notably by the lead investigator of this work.

 

The press report claims that the spheromak device is simpler than the tokamak. This is only true to a point. There are fewer external magnets in such a device. Enormous electromagnets require very high electrical current, so the spheromak needs less power. However, part of the magnetic field confinement of the plasma is performed by the magnetic field produced within plasma itself. (Travelling charged ions produce magnetic fields calculable with the laws of electrodynamics.) While this idea sounds simpler, it's actually more difficult in many ways: you have fewer magnets for external control, and the internal plasma configuration is actually much more complicated.

 

This very difficulty is why the world's biggest and best fusion projects are tokamaks and not spheromaks. The extra control magnets and simpler plasma configuration inside the machines have allowed them to be scaled up to larger sizes much more easily.

 

So, not only is scaling up the entire problem with magenetic fusion, this device is probably much more difficult to scale up even than current tokamaks, which have not yet been economically scaled up and may not be for several decades.

 

RCS enthusiastically supports fusion research and increased funding for fusion projects. However, we do not tolerate misleading information being reported.

 

Tom Hartsfield is a physics PhD Candidate at the University of Texas.

 

http://www.realclearscience.com/blog/2014/10/new_fusion_reactor_cheaper_than_coal_bs_108895.html



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