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Fusion reactors: Not what they’re cracked up to be

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Re: Fusion reactors: Not what they’re cracked up to be

#141

Post by DennisP »

Recurecur wrote: post #33
_rpd wrote: post #27

Earlier quoted context omitted.

There are a whole bunch of options for aneutronic fusion ... https://en.wikipedia.org/wiki/Aneutronic_fusion

True, but there are many engineering tradeoffs. Any of the listed reactions involving deuterium produce some neutrons, so those aren't desirable (plus deuterium and tritium are rare). Of the other reactions, neither Li-6 or N-15 are readily available, plus lithium is highly chemically reactive. The proton-boron reaction requires the lowest input energy (temperature) of the desirable aneutronic reactions, so it's the…

Tritium is rare, and has to be bred from lithium, but deuterium isn't the least bit rare. There's enough deuterium in your morning shower to provide all your energy needs for a year, and enough in the oceans to last until the sun goes out.

(Plenty of boron too, though it's not so absurdly abundant as deuterium.)

Re: Fusion reactors: Not what they’re cracked up to be

#142

Post by Retric »

WalterBright wrote: post #136
opo wrote: post #103

Earlier quoted context omitted.

You are handwaving away huge issues here. As Bill Gates said in the same interview I quoted from before: >"...It’s kind of ironic: Germany, by installing so much rooftop solar, has it that both their coal plants and their rooftop solar are available in the summer, and the price of power during the day actually goes negative—they pay people to take it. Then at night the only source is the coal, and because the energy…

Nobody ever mentions varying the price of electricity to reduce demand when the sun isn't shining. We need to get past the assumption that electricity prices should be fixed. This won't solve the baseload problem, but it will reduce it.

Electric prices have never been fixed at scale. It's really only small scale consumers that get a fixed but often higher rate. See Enron for example. Changing when energy is cheap does not break the model.

Re: Fusion reactors: Not what they’re cracked up to be

#143

Post by mikeash »

sgift wrote: post #138
mikeash wrote: post #129

Earlier quoted context omitted.

An example of this which always gets me with nuclear power is the waste problem. The fact that the waste remains dangerous for tens of thousands of years is always held up as a huge problem, completely ignoring the vast quantities of extremely poisonous chemical waste produced by other industries which lasts forever . "This waste is dangerous." "OK, guess we'd better be careful with it." "This waste is dangerous for…

> "This waste is dangerous for the next 10,000 years." "Holy shit! We need to build a high-tech underground fortress to contain it!" Time is a major risk factor. Look where we were 10,000 years ago. There is relevant chance that 10,000 years in the future no one will easily understand the danger of radiation anymore, so we have to prepare for that possibility.

You seem to have missed the other half of the point I was making, which was that there's lots of non-nuclear hazardous waste which lasts forever and we don't get nearly as upset about those.

Re: Fusion reactors: Not what they’re cracked up to be

#144

Post by kpil »

Retric wrote: post #80
short_sells_poo wrote: post #63

Earlier quoted context omitted.

Sorry I worded that sentence poorly. Let's assume two scenarios: a) We create a 200 square mile solar field in the Sahara, from which cables run to Europe to supply electricity. To take this plant out, one just cuts the cables. There, you just plunged Europe into darkness. b) We create a 20x 10 square mile solar fields in the Sahara, all dispersed over a very large area. Well, this is an engineering and construction…

Renewable power is very much going to be a distributed more than our current power generation. Further, you want redundancy in power transmission so you can do maintenance anyway and many countries are already dependent on foreign sources for a significant chunk of there daily energy demand for economic reasons. Any actor that can destroy thousands of cables can cut the power systems we have now. Further, outside of…

Exactly, while Sahara is obviously sunny and the land is cheap, it might not be the best place to place solar plants, due to the logistics.

I think that roof top solar is just as viable in more or less the whole Europe - even in the Nordics, at least the southern parts.

The only thing that would make desert-sized solar plants a really good business would be really cheap low efficiency cells.

Re: Fusion reactors: Not what they’re cracked up to be

#145

Post by kpil »

logfromblammo wrote: post #140
Robotbeat wrote: post #52

Earlier quoted context omitted.

This really is not a big technical problem. You simply don't output the power. This is trivial with any kind of decent power-optimizing inverter setup commonly available today. Solar PV isn't spinning a turbine that needs to find a load. If you disconnect a solar panel, it doesn't damage itself, it just sits there. But I'm sure we'd eventually find uses for this extra energy. Like producing ammonia for agriculture.

Desalination of seawater seems a safe bet for excess solar power.

Ah! I was going to write water pump reservoirs or at some price point electrolysis + fuel cells, but making cheap water in the daytime is also good.

Re: Fusion reactors: Not what they’re cracked up to be

#146

Post by sbierwagen »

scriptkiddy wrote: post #60
Robotbeat wrote: post #26

There's nothing quite like trying to get fusion to work for a while to make you appreciate how awesome fission technology is. If we applied even half the cleverness needed for fusion to making better fission technology, we'd probably be way better off. ...and then there's solar. Why even bother with producing the energy, just capture it with a very thin solid state device! Just need to automate the planting of solar…

Spoken like someone who has never visited a desert. As a Southern California native, I am intimately familiar with the Mojave, Anza Borrego, and Sonora deserts. I will tell you that these deserts are far from "crappy land that nothing can grow on" as you put it. The North American deserts are areas of huge ecological and geological diversity. They are also some of the most beautiful and awe-inspiring landscapes that…

  That said, I am no way in favor of scarring any more of 
  our deserts by covering "a fifth to a tenth" of them in 
  solar panels.
Tough luck. We live in a democracy. When we run out of oil, the number of people who want electricity are going to outnumber the number of people who want to look at dirt.

Re: Fusion reactors: Not what they’re cracked up to be

#147

Post by sbierwagen »

ChuckMcM wrote: post #122
Robotbeat wrote: post #26

There's nothing quite like trying to get fusion to work for a while to make you appreciate how awesome fission technology is. If we applied even half the cleverness needed for fusion to making better fission technology, we'd probably be way better off. ...and then there's solar. Why even bother with producing the energy, just capture it with a very thin solid state device! Just need to automate the planting of solar…

Really the only reasonable world wide solar plan I've ever seen is solar power satellites. There has been a lot of work done there and they beam the energy back to the planet as microwaves where it is needed into the existing grid system. But so far the cost of getting all of that material into orbit to build them is something of a deal breaker.

https://dothemath.ucsd.edu/2012/03/space-based-solar-power/

>At this level, our 3.6 km diameter collecting area would generate about 40 GWh of energy in a day, at an assumed reception/conversion efficiency of 70%. By comparison, a flat array of 15%-efficient PV panels occupying the same area in the Mojave Desert would generate about a fourth as much energy averaged over the year. So these beaming hotspots are not terribly more concentrated than what the sunlight provides already. Again, I find myself scratching my head as to why we should go to so much trouble.

Re: Fusion reactors: Not what they’re cracked up to be

#148

Post by bduerst »

short_sells_poo wrote: post #40
Robotbeat wrote: post #26

There's nothing quite like trying to get fusion to work for a while to make you appreciate how awesome fission technology is. If we applied even half the cleverness needed for fusion to making better fission technology, we'd probably be way better off. ...and then there's solar. Why even bother with producing the energy, just capture it with a very thin solid state device! Just need to automate the planting of solar…

How exactly do you propose to get that electricity from the desert to say Finland? Furthermore, you need to plaster a vast area in the desert with solar plants, which brings along all sorts of concentrated security risks. The alternative is to have many smaller plants dispersed, which results in a big loss of efficiency. I'm all for clean energy, but you seem to be handwaving away pretty huge issues as "thought exerc…

>How exactly do you propose to get that electricity from the desert to say Finland?

Microwaves

http://www.economist.com/node/18864324

Re: Fusion reactors: Not what they’re cracked up to be

#149

Post by abalone »

ChuckMcM wrote: post #121

This is an interesting article from Dr. Jassby who has both patents and papers on Fusion going back to 1977 at least. And there are at least two things that stand out for me, the first is that he goes out of his way to craft a narrative that is negative, and the second he doesn't mention the half dozen or so fusion efforts that are on going beside the NIF and ITER projects. The interesting thing about the narrative i…

> While it is absolutely true you could design a fusion reactor whose purpose was to create fissile material for bombs, that design would look nothing like a power reactor

This directly contradicts the article:

"The open or clandestine production of plutonium 239 is possible in a fusion reactor simply by placing natural or depleted uranium oxide at any location where neutrons of any energy are flying about. The ocean of slowing-down neutrons that results from scattering of the streaming fusion neutrons on the reaction vessel permeates every nook and cranny of the reactor interior, including appendages to the reaction vessel."

Re: Fusion reactors: Not what they’re cracked up to be

#150

Post by ChuckMcM »

sbierwagen wrote: post #147
ChuckMcM wrote: post #122

Earlier quoted context omitted.

Really the only reasonable world wide solar plan I've ever seen is solar power satellites. There has been a lot of work done there and they beam the energy back to the planet as microwaves where it is needed into the existing grid system. But so far the cost of getting all of that material into orbit to build them is something of a deal breaker.

https://dothemath.ucsd.edu/2012/03/space-based-solar-power/ >At this level, our 3.6 km diameter collecting area would generate about 40 GWh of energy in a day, at an assumed reception/conversion efficiency of 70%. By comparison, a flat array of 15%-efficient PV panels occupying the same area in the Mojave Desert would generate about a fourth as much energy averaged over the year. So these beaming hotspots are not ter…

Grid delivery. You cannot easily move power from the desert into urban centers.
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