[Tulse]

It also makes it much less crucial to squeeze efficiency out of the onion, which (as I understand it) is a less established way to recover energy than capturing the alphas.

[Tulse]

Of course, what counts as thermal “waste” in some contexts could be usable thermal energy in others (for example, captured for district heating or industrial applications).

[Tulse]

Wesley Bruce wrote: It should be noted that there is a way to make alcohols and sugars and even protein from the Methane ethane mix. Add Carbon monoxide in the presence of the right catalysts. Its very very energy hungry and the sugars are pretty basic but If we have fusion we can make food in theory. However simply powering a greenhouse or hydroponics unit will work better and produces much more variety.

But this process sounds like it would much faster than growing things, and would be far more tolerant of environmental conditions. It might make sense in very impoverished situations, such as interplanetary spacecraft or lunar colonies, where one could simply “recycle” food.

[Tulse]

This may have been discussed elsewhere, but why is the anode a single cylinder, rather than a set of rods like the cathodes?

[Tulse]

Rezwan wrote: Guys, could we stop short of giving directions on how to make a dirty bomb on this forum? That would be nice.

Sorry, Rezwan. (Although, in all fairness, I initially learned the basics of dirty bomb design from 24 and Castle, so I doubt this forum is providing any new info not available from broadcast television and Google.)

[Tulse]

jamesr wrote: My take on proliferation has always been that if any organisation (state, terrorist group etc) has the resources to handle spent nuclear fuel and reprocess it into a bomb, or even just handle it and package the waste into a dirty bomb, without killing themselves in the process. Probably has the resources to build a reactor buried in a mountain and do it themselves from scratch without having to steal it.

That’s probably true for building an actual nuke, but dirty bombs are very easy to make, and if you’re not worried about eventually dying from radiation poisoning, the handling techniques don’t even need to be very fancy. A very small group of relatively non-technical people could slap one together from the appropriate materials (which are basically a van full of fertilizer and fuel oil surrounded by some spent rods), much more easily than such a group could build a reactor to breed the radioactive material.

[Tulse]

zapkitty wrote: mach 8-10, which seems to be an optimal velocity to launch to orbit from…

Perhaps I’m not following, but can you clarify what you mean here? Isn’t orbital velocity ~ Mach 25?

[Tulse]

I thought the binding energy of nickel meant that it took more energy to push a nucleon into it than the fusion releases — isn’t that why the heaviest element produced by normal stellar fusion is iron?

Like all these kind of claims, I figure the ultimate proof is in a mass produced device, as if it can legitimately generate as much energy as they claim, it won’t matter to the commercial sector that the theoretical mechanism is unclear.

[Tulse]

Radioactivity is a major problem — true, it is less of one than for a fission reactor, but it is still an issue.

In addition, when the energy comes from neutrons, one has to extract usable energy from them. Typically, in order to do this, one has them heat some medium that then heats water that then generates steam that then turns a turbine that then turns a generator — the same relatively inefficient approach to generating electricity that all power plants have used for 130 years. The real elegance of aneutronic fusion is that one can extract electricity directly from the charged particles produced, without needing the standard steam generation cycle. As a result, you get a plant that is (at least in principle) much more efficient, more compact, and requires less capital to build and with lower operating costs. (By contrast, DD or DT fusion plants would for the most part look and cost very similar to a coal- or gas-fired plant, as they need generally the same equipment for doing the actual generation of power.)

[Tulse]

Is there a reason that pB11 wouldn’t be the preferred fuel? Who cares if CNO requires little external fuel — it’s not like boron is rare or expensive.

[Tulse]

Thanks very much for the clarification, Dr. Lerner.

[Tulse]

Matt M wrote: Well, more specifically, has anyone fused Boron and actually measured the charge released? Until
someone does, it’s all just an educated hypothesis.

It’s an hypothesis informed by E=MC^2 and basic particle physics. If the reaction doesn’t behave like that, there’s a lot more wrong than just the focus fusion approach.

[Tulse]

Aeronaut wrote: The higher percentage of fusion products that can be used productively leads to the greater efficiency.

So this gets us back to the appropriate use of the term “breakeven”. I was presuming that when the press release said “The fusion energy yields achieved in these experiments are still far less than the energy used to run the machines”, it meant that the total amount of energy produced, whether theoretically capturable or not, was still below input energy (especially since we don’t yet know how much energy a FoFu machine will recover in practice). Perhaps Dr. Lerner can clarify.

[Tulse]

Lerner wrote: No at high energies pB11 bunrs easier than DD.

Thanks, Dr. Lerner, but I’m still a bit confused — does this mean that the pB11 reaction gets relatively more efficient at higher energies, compared to DD? And more efficient enough to overcome the disadvantage of having to use more input energy for the pB11 reaction? I had thought that the main attraction of the pB11 reaction was that it was aneutronic, and not that it had a higher total energy of fusion products at any level of input energy (relative to DD or DT). In other words, I thought that under all conditions one would get more energy out of DD and DT than pB11.

[Tulse]

Brian H wrote: Eric has been promoting the idea of an “X-prize” -like fusion incentive for some time. […]
Such a prize would quickly (IMO) attract private support for FF

I don’t know the history of the other X-Prize contests in this regard — was that the case there? For the Ansari version, it seemed like there were a huge number of entrants that were paper-only enterprises, and never really had the funding to bend metal. The major contestants were funded by deep pockets entrepreneurs who were already space enthusiasts, so it’s not like there was typical VC money involved. Things may have been different for the auto prize, however — does anyone know?

I think prizes are an excellent motivator, but I question whether they really get investors stoked, as the prizes are by definition for very high risk enterprises, and even if won the monetary value rarely (if ever) covers the actual invested capital. They are great publicity, but I have doubts about their effectiveness for fundraising.

[Author]

Posts