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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

#71

Post by Robotbeat »

short_sells_poo wrote: post #59
Robotbeat wrote: post #53

Earlier quoted context omitted.

A large solar field makes for a pretty diffuse target. You might be able to target the connection to the grid, but that's no worse than it is today (and would be easily repaired). And I don't think our current electrical grid has a major problem that even a slight attention to infrastructure couldn't fix.

Ok so you are saying that the new solution isn't any worse in terms of security than the current one, so it's fine? In any case, you cannot compare this to oil pipelines directly because we can stockpile oil. Even if all the pipelines are taken out, many countries stockpile oil that can bridge them over until an alternative solution is found. If a considerable part of the electricity comes from some remote site in a…

I'm the classic US-centric American. Northern Europe can solve its own problems, they have all the tools (nuclear, hydro, wind, geothermal). The rest of the world (i.e. the vast majority of people) is closer to the equator and doesn't need a cable running to the Sahara.

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

#72

Post by politicalthrow »

shaqbert wrote: post #2

Mmmh, some of the claims in that article are debunked in this neat video from MIT (though over 1h long): https://www.youtube.com/watch?v=L0KuAx1COEk

That video gives a terrific overview of the landscape of the fusion field as it exists pretty much right now. It's an extremely coherent talk.

It's long but worth the watch.

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

#73

Post by macintux »

VLM wrote: post #51
Robotbeat wrote: post #43

Earlier quoted context omitted.

There is always some impact. There's a disease in our energy discussions where if something has ANY effect or can be measured at all, it is considered a big no-no. We lack a sense of proportion. Radiation is SUPER easy to measure even tiny amounts, for instance, since you can look for the signature of a certain decay tree, so people hear that you can measure radiation from Fukushima and lose their minds. Likewise, pe…

"The sense of scale is entirely lacking." Agree and it extends to risks. Better to kill 100K people per year with coal, than possibly maybe hundreds might die (but almost certainly zero actually will) in a nuclear accident. Your diet and your car are far more likely to kill you than global warming.

> Your diet and your car are far more likely to kill you than global warming.

True for me. True for my (entirely hypothetical and never likely to exist) grandchildren? Less clear.

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

#74

Post by Robotbeat »

spdionis wrote: post #67
Robotbeat wrote: post #42

Earlier quoted context omitted.

That all looks trivial compared to the challenges of fusion power, though.

Are you sure? This is a recurring theme in your arguments but I don't necessarily agree with you. What are the reasons for you to think that?

Read the article that this conversation is attached to for a list of very good reasons. Getting fusion to work is most certainly possible, but incredibly hard. Engineering for salt water is way easier than engineering for neutron activation, achieving high neutron economy to breed the tritium, managing tritium, managing a high temperature reactor next to a very cold magnetic containment system, a high vacuum system, oh and the very basic problem that has yet to be solved (achieving even just breakeven fusion in a non-H-bomb) etc, etc. It really does look trivial to just properly seal stuff against saltwater.

We'll probably need fusion to help reach the stars, so I think it's definitely something that should be pursued, but making it an economic power source for Earth seems very unlikely to me.

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

#75

Post by antisthenes »

short_sells_poo wrote: post #63
labcomputer wrote: post #58

Earlier quoted context omitted.

> Furthermore, you need to plaster a vast area in the desert with solar plants, which brings along all sorts of concentrated security risks This sentence seems to be at odds with itself. How does needing a large area concentrate security risks? If anything it seems to disperse them. Unlike a coal or nuclear plant, you can't just walk up to a critical part of a solar farm and blow it up. Any part that you damage is re…

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…

I'm surprised to see this kind of simplistic reductionist thinking on HN.

"Just cut the cables" isn't trivial. Have you ever seen a high voltage tower? Not only are they not accessible without professional gear, it's also going to require even more expensive gear to cut multiple inch thick conductors.

In all likelihood he power to Europe will be transmitted via multiple undersea cables, the effort of disrupting which would be unavailable to all but state agents, in which case the security issue is irrelevant, as you are likely already in a state of war.

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

#76

Post by scriptkiddy »

Robotbeat wrote: post #65
scriptkiddy wrote: post #60

Earlier quoted context omitted.

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…

I said a fifth or a tenth of the land in the US used for ethanol production. NOT a fifth or a tenth of our deserts. More like 1%. And my point is we can install solar on land that has no other use. Like land contaminated by industrial waste, etc.

Ah. My misunderstanding.

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

#77

Post by FiatLuxDave »

mrfusion wrote: post #7

It's weird to consider "parasitic" loss a problem. You just factor that into the total output. If it's high enough you're good.

Large parasitic losses are indeed an engineering challenge.

In theory, you are correct. However, you are making the assumption that efficiency is a static number. In reality, parts age, get dusty, out-of-alignment, etc. Let's say you are building something that makes 10 units of power, but 8 of those units are needed to keep it running (when working as designed). Say that the part that uses the 8 units of power is nominally 90% efficient, but after you've run it for a few months it drops to 80% efficiency. Now you need 9 units of power to keep running, cutting your output in half. This is not just a problem in terms of dropping output; it is also an issue from the standpoint of understanding your machine. It's hard to engineer something when small changes have large effects. Your output just dropped 30% - is something broken, or is the fan just dusty again? How long do those electrodes really last anyways? Did someone use the wrong cleaning fluid? Maybe the pressure gauge is just off by 1% again.

All those things add up, just like coding a big ball of mud can make debugging difficult.

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

#78

Post by opo »

Robotbeat wrote: post #52
short_sells_poo wrote: post #46

Earlier quoted context omitted.

I haven't ignored the part where you mentioned overprovisioning. Where do you propose to put the excess power during sunny days? Stable baseline sources like nuclear cannot just be shut down or spun up on a moment's notice to accomodate a vast number of solar energy entering or leaving the grid. At the same time, we don't have a capability to store electricity at sufficient scale so we do need the stable baseline to…

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.

No one I know is opposed to renewable energy, but advocates really do everybody a disservice when they try to argue that an intermittent power source without storage is a reasonable replacement for base load power. As Bill Gates said in an interview "…They have this statement that the cost of solar photovoltaic is the same as hydrocarbon’s. And that’s one of those misleadingly meaningless statements. What they mean is that at noon in Arizona, the cost of that kilowatt-hour is the same as a hydrocarbon kilowatt-hour. But it doesn’t come at night, it doesn’t come after the sun hasn’t shone, so the fact that in that one moment you reach parity, so what? The reading public, when they see things like that, they underestimate how hard this thing is. So false solutions like divestment or “Oh, it’s easy to do” hurt our ability to fix the problems. Distinguishing a real solution from a false solution is actually very complicated."

https://www.theatlantic.com/magazine/archive/2015/11/we-need...

(Gates is investing in 4th gen nuclear and energy storage companies so he is putting his money where his mouth is.)

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

#79

Post by mcguire »

fao_ wrote: post #47
short_sells_poo wrote: post #40

Earlier quoted context omitted.

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…

> Furthermore, you need to plaster a vast area in the desert with solar plants, which brings along all sorts of concentrated security risks. I mean, most of the same security risks appear in oil pipelines and extraction.

And fortunately, we've got those covered.

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

#80

Post by Retric »

short_sells_poo wrote: post #63
labcomputer wrote: post #58

Earlier quoted context omitted.

> Furthermore, you need to plaster a vast area in the desert with solar plants, which brings along all sorts of concentrated security risks This sentence seems to be at odds with itself. How does needing a large area concentrate security risks? If anything it seems to disperse them. Unlike a coal or nuclear plant, you can't just walk up to a critical part of a solar farm and blow it up. Any part that you damage is re…

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 city's you can generally get solar panels from a roof to provide power for the building under it making the grid a lot more redundant vs cutting cables.

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