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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

#201

Post by Recurecur »

DennisP wrote: post #141
Recurecur wrote: post #33

Earlier quoted context omitted.

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.)

Interesting, I'd never really looked into that...perhaps someday we'll figure out a good solution for thermal neutrons.

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

#202

Post by Arizhel »

cletus wrote: post #82

I've been hearing about and hoping for fusion power since probably the 1980s. The more I think about it the more I think it's probably a pipe dream. The idea appears so simple an elusive: combine Hydrogen into Helium (and there are variations that use Helium, particularly He-3 as a fuel), which releases energy. Hydrogen is essentially limitless (He, particularly He-3, less so). Stars do it all the time. The two big p…

>I don't want to discount the rising importance of wind and solar. I do believe that with the ever decreasing costs these will become even more important, even critical, in the future. They simply won't completely replace some kind of combusted fuel.

I completely disagree. There's no shortage of solar power hitting the earth at any given moment. The problem with these renewable sources is that they're non-constant. The solution is simple: storage. Obviously, that's easier said than done, but it is something that's being worked on. Once really good energy storage is in place, then the variable nature of solar/wind isn't too much of a problem any more. It's not here yet (we do have some battery storage, and for some time now we've had stuff like pumped hydroelectric), but it's coming.

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

#203

Post by Retric »

Retric wrote: post #194
opo wrote: post #191

Earlier quoted context omitted.

>100,000 tons of methane with a half life of less than 10 years. The math is complex and 1 ton of methane becomes more than one ton of CO2, You are downplaying the impact of methane. As I quoted in the last post, the IPCC estimate is that over 100 years a given amount of methane is 34 times more potent as a heat-trapping gas compared to CO2. Over a 20 year period (which is probably more relevant considering where we…

That's just lying with numbers. 86 / 5 = 17.5 so average from year 20 to year 100 is 34 - 17.5 = 16.5x. And again the majority of that 16.5 is over years 20-40. Further, because of this decay increases in release rate don't stack at 86x year over year. You get a magnified increase in the first year and a smaller net increase every year after that until your down to the carbon content of methane. Under 10% total gen f…

Ed: Make that 5/4 * 16.5x or 20.6 However, again it becomes more than 1 CO2 by weight because the 2 O's in CO2 make up a larger fraction of total weight than 4 H's.

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

#204

Post by cowardlydragon »

High energy neutrons makes LFTR's issues with volatile chemicals degrading its pipes a child's task ...

At least LFTR can be scaled down to "cell" sizes (the Oak Ridge reactor was slated as an perpetually flying aircraft powerplant) that can be regularly replaced/recycled. Fusion reactor designs of any practicality are HUGE and can't be rebuilt on a regular basis...

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

#205

Post by logfromblammo »

TheSpiceIsLife wrote: post #183
kpil wrote: post #145

Earlier quoted context omitted.

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.

By no measure is reverse osmosis or flash distillation of water cheap even if the energy is free. Imagine building a huge water desalination plant and only running it when there is excess power available on the grid. I can't see anyone wanting to invest in that, except maybe a financially myopic government, and they tend not to last very long.

If the energy is free, you could just do electrolysis with huge carbon electrodes and immediately ignite the gases, bubbling the exhaust through your freshwater reservoir. You can knock together a setup like that in your own backyard from junkyard parts.

How you do it depends on whether you prioritize capital costs or operating costs.

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

#206

Post by TheSpiceIsLife »

extrapickles wrote: post #195
TheSpiceIsLife wrote: post #184

Earlier quoted context omitted.

You can't just do those things when the weather is good. Not without huge tax breaks to incentivise load following, because intermittent production of large scale industrial processes is hard and not cheap.

They already do this without any gov intervention. The local steel recycling plant only operates when power is cheap. While they do need some advance notice to make sure they have enough people to run, they probably can get a good enough idea from a weather forecast (power here is mostly hydro with a dollop of wind and fossil). Some processes are better fits than others. If you have 2-5x extra capacity that is sold c…

Do we have any numbers on what it means that they run only when the power is cheap?

Does that mean they can operate in 4hr windows? Or do they run have to run the furnace for a minimum period? A large quantity of steel takes a large amount of energy to melt.

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

#207

Post by maxerickson »

TheSpiceIsLife wrote: post #206
extrapickles wrote: post #195

Earlier quoted context omitted.

They already do this without any gov intervention. The local steel recycling plant only operates when power is cheap. While they do need some advance notice to make sure they have enough people to run, they probably can get a good enough idea from a weather forecast (power here is mostly hydro with a dollop of wind and fossil). Some processes are better fits than others. If you have 2-5x extra capacity that is sold c…

Do we have any numbers on what it means that they run only when the power is cheap ? Does that mean they can operate in 4hr windows? Or do they run have to run the furnace for a minimum period? A large quantity of steel takes a large amount of energy to melt.

Interesting question. Brief research says the cycle time is ~1 hour (or less):

http://www.steel.org/making-steel/how-its-made/processes/pro...

It could also be a plant for shredding scrap, where I guess it wouldn't be a time issue so much (and if it doesn't have the material inflows to run full time, timing cheap power would make sense).

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

#208

Post by Arizhel »

jandrese wrote: post #123
Arizhel wrote: post #113

Earlier quoted context omitted.

Yeah, I'm sure it'll look just great that Germany or whoever is stationing the Wehrmacht in northern Africa, and no one will complain about that... /s You really think that's a viable way to maintain the electric power supply for all of Europe? "What could possibly go wrong?!"

It won't be uniformed European troops. It will be Blackwater type mercenaries. They'll have an implicit license to kill and/or abuse any locals. That's how you do security for European companies in Africa.

You really think you should put the entire welfare and existence of the European continent in the favor of some hired Blackwater mercenaries? Are you f'in serious?

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

#209

Post by WalterBright »

Retric wrote: post #180
WalterBright wrote: post #174

Earlier quoted context omitted.

My electric rates have been fixed rates 24/7 for decades.

Are you using KW, MW, or GW of power? So yea, residential customers get a fixed rate but that's because there is no point in demand based pricing. They simply charge you enough that it makes little difference what time of day you use slightly more power. In the future the same is likely to be true.

My own usage is inconsequential, but not the aggregate of all the consumers.

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

#210

Post by TheSpiceIsLife »

maxerickson wrote: post #207
TheSpiceIsLife wrote: post #206

Earlier quoted context omitted.

Do we have any numbers on what it means that they run only when the power is cheap ? Does that mean they can operate in 4hr windows? Or do they run have to run the furnace for a minimum period? A large quantity of steel takes a large amount of energy to melt.

Interesting question. Brief research says the cycle time is ~1 hour (or less): http://www.steel.org/making-steel/how-its-made/processes/pro... It could also be a plant for shredding scrap, where I guess it wouldn't be a time issue so much (and if it doesn't have the material inflows to run full time, timing cheap power would make sense).

Thanks for the link, looks pretty detailed. I work in steel fabrication, so it'll make interesting reading for me.
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