Can p-B11 fusion deliver net power?

[Andrew Palfreyman]

A comment recently posted on NatureNews:
the maximum ideal Q is only 3 to 4 (as for p-11B), the electric power output is not much greater than the electric power input. When you include the non-plasma power drains such as vacuum pumping, coolant pumping, cryogenics, HVAC, etc., the power balance is negative.
Comments?

[Tim1]

Could you post a link to NatureNews so we can get some context. Also I don’t understand why there would be a maximum ideal Q. Wouldn’t higher Q always be better? I would expect people to talk about a minimum Q that will allow one to get back enough energy to power the next pulse in addition to provide a reasonable output. Focus Fusion has the ability to be viable at relatively low Q because it gets its energy back as electricity rather than heat so that it can avoid Carnot cycle losses.

[Andrew Palfreyman]

http://www.nature.com/news/plasma-physics-the-fusion-upstarts-1.15592

[Tim1]

Thanks. The article covers most everyone except LPP as alternatives to the over priced IETR. LPP was mentioned in the comments. There was nothing that explained why Q should be limited in p-B11 fusion. Happily, it looks like Focus Fusion works with a Q of less than 2. If we got 3 or 4 things will be great.

[Andrew Palfreyman]

That’s not much of a retort. What about the true energy balance?

[vansig]

there are so many factors.

your basic p + B11 –> 3 alpha + 8.7 MeV is a lot of energy.
the reaction needs at least 50 keV and is best at about 600 keV;
a fraction of your plasma reacts in the pulse;
you want your magnetic fields to be strong enough to inhibit bremsstrahlung losses (gigagauss fields);
you want your exit beam to be tightly focused and heading in the right direction;
you have to keep your plasma hot and your anode cool;
and you have the energy transformation.

all these things need to be optimized systematically

[Andrew Palfreyman]

vansig wrote: gigagauss fields

1 Gga = 100,000 Tesla! That wasn’t on the menu as far as I knew.

[Tulse]

You might find this chart helpful:

http://lawrencevilleplasmaphysics.com/sankey-diagram-focus-fusion-energy/

[Andrew Palfreyman]

It seems, therefore, that Focus Fusion will deliver between 200% and 300% of the input power, having discounted all sources of costs and losses in an industrial production context. Am I low or am I high with this estimate, and why? Indeed, has anyone taken the trouble to do a serious economic quantification of the cost benefits of Focus Fusion? One has to include, for example, the mundane cost of getting the boron on-site.

Does FF work better as a space drive than as a power station, and why?

[Francisl]

A lot of the economic numbers that you are asking for will be gathered during the next 1 or 2 years of fusion experiments. The numbers that you have seen so far are based on current science and best estimates.

[Andrew Palfreyman]

Yup. And clearly scale is a factor too. The higher the Q of a process, the more the absolute power margin and the smaller one can afford to scale it and still take care of the ancillaries.

[Tulse]

Andrew Palfreyman wrote: has anyone taken the trouble to do a serious economic quantification of the cost benefits of Focus Fusion? One has to include, for example, the mundane cost of getting the boron on-site.

Right, but you also get to exclude standard power plant costs for things such as turbines and generators, along with all their associated overhead (e.g., extra staff, extra space, etc.).

[Author]

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