Reply To: turn heat into electricity

[zapkitty]

Maya wrote: Yep, you did. The discussion is about fusion. Which costs more to build and run? Savannah River Site or ITER?

Pretty much irrelevant since ITER and its costs are in no way a design paradigm for a commercial fusion reactor… even a tokamak 🙂

Tokamak-style power reactors such as ITER are problematic in and of themselves and may not turn out to be workable power sources but if ITER does work out then the researchers intend to continue with DEMO, a demonstration power plant with at least 4 times the power output at 1/4 the cost.

And then they’ll try to segue the DEMO facility into PROTO, a prototype power plant… if they can.

And of course there are several current non-ITER fusion projects that operate by different rules altogether. Focus Fusion, Tri-Alpha, Polywell, Helion, General Fusion and whatever it is that Lockheed Martin calls the project that the Skunk Works is working on to name some of them.

And all of these are different projects with different designs (assuming that the lockmart design isn’t a polywell variant) and they all involve relatively small (12 to 100 MW) and inexpensive reactors that can be used to add to a distributed power grid to provide as much power as needed where it is needed.

As for your ideas about fusion economics some background on your figures would help. First you speak of single reactors providing hundreds of gigawatts at a minimum to be “viable” and then you speak of one (1) reactor that would supply all the worlds power and half again that much… how many such 21 terawatt reactors were you envisioning to be built?

Maya wrote:

The pB11 reaction is aneutronic in nature and units built along the lines envisioned by Focus Fusion, Tri-Alpha and the Polywell concept would be in the scale of a few megawatts to a gigawatt or so and their neutron flux would be pretty damn small.

It seems that you’ve set impossible-to-meet criteria and I look forward to learning what you envision as the solution to them 🙂

I don’t think so. I think the criteria are grounded in hard reality. I don’t believe that megawatt class fusion reactors will ever be economical in any foreseeable future. On this particular point the issue isn’t technical. It’s economic. Why would anyone build a megawatt class reactor that would be such a colossal construction for a single one-off?

… again, you seem to have confused ITER with actual commercial fusion power proposals.

Much of what you say is not applicable to commercial tokamak concepts and even less of it applies to non-tok designs… and none of it would seem to apply to aneutronic designs.

Maya wrote:
And the four key issues I described are part of the reason why I don’t think they’ll be economical. Even if you lower the power output you will still have phenomenal pressures to deal with. Have you looked at the structural loading on ITER

… again, you seem to have confused ITER with actual commercial fusion power plant proposals 🙂

Patient “Doctor it hurts when I do this.”
Doctor: “Then don’t do that.”

All of the non-ITER fusion startup concepts avoid the problem by handling much smaller fuel masses more efficiently than ITER. Their individual methods are different but none of them are trying to hold ITER’s 840 cubic meters of plasma at fusion temperatures.

In fact the Focus Fusion dense plasma focus design goes one step further by allowing an unstable collapsing magnetic field to do the fuel compression… no external compression required. This is one of several neat ways that the FF concept takes advantage of natural instabilities 🙂