Fusion reactors: Not what they’re cracked up to be • Hacker News Board

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

#101

Post by jandrese » Wed, Apr 26, 2017, 5:15 PM UTC

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…

Seems a lot easier to fix a cable cut than a sabotaged nuclear power plant. I mean if you are the point where a nation-state is detonating fuel-air explosives over solar farms then there's probably no power plant design that is going to survive.

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

#102

Post by dkirtley » Wed, Apr 26, 2017, 5:16 PM UTC

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.

1% of all deserts is only correct if you are talking about only today's electricity use. Even moderate growth and actually solving energy, not just the electricity subset drives these percentages much higher. To get US centric again, NREL published an optimistic 2016 report suggesting that the maximum rooftop solar capability could ever meet is 40% of electricity. That's 15% of today's energy use in an electricity heavy country.

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

#103

Post by opo » Wed, Apr 26, 2017, 5:18 PM UTC

Retric wrote: post #91

opo wrote: post #78

Earlier quoted context omitted.

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 i…

The term Baseload power is not a goal, it's a Problem with some types of power not being flexible. In that context, soar is closer to Baseload power than peaking power plants. Yes, it currently better matches demand than Baseload power, but as you ramp it up the supply / demand miss mach will simply shift around the day. Turning on some peaking power plants at night vs the day is not a significant issue. Further, the…

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 companies have to recover their capital costs, they either raise the price because they’re not getting any return for the day, or they slowly go bankrupt. There are many people working on storage—batteries are a form of storage, and there’s a few others, like compressed air, hot metals. But it’s not at all clear that we will get grid-scale economic storage. We’re more than a factor of 10 away from the economics to get that."

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

#104

Post by theptip » Wed, Apr 26, 2017, 5:18 PM UTC

I think the four objections here can really be summarized as two:

1) there are energy/fuel losses involved in operating a fusion reactor which aren't present in other types of power source.

This doesn't seem fatal to me; either we get the losses down low enough that this system is cost-competitive, or we don't. There's no way to know in advance where this tech will end up, and it doesn't seem like a reason to stop investing in R&D now.

2) Fusion as currently designed produces lots of neutrons, so there is the same sort of waste and proliferation concern as a normal (or fast breeder) fission reactor.

I think this is actually the interesting one; the international community will not permit this tech to spread beyond the current nuclear powers if there's a strong proliferation risk. I hadn't realized that the current design of fusion plants were basically breeder reactors, and that's very significant; look at how the theoretically-appealing fast breeder fission reactors have been hamstrung for a prequel to this fight.

Of course, if fusion gets to an integer factor cheaper than the next-best source, then it will be hard to keep a lid on this tech, but development is currently relying on many billions of dollars of research funding from the very countries that could be turning away from it out of political/security concerns.

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

#105

Post by jandrese » Wed, Apr 26, 2017, 5:18 PM UTC

Arizhel wrote: post #97

theptip wrote: post #81

Earlier quoted context omitted.

> How exactly do you propose to get that electricity from the desert to say Finland? High voltage DC transmission works fine for this problem. All of the engineering challenges have been credibly worked out and priced ( https://en.wikipedia.org/wiki/Desertec ). The main problems with this approach are political, in that it requires massive cooperation between many countries over very long time scales (decades). Why i…

So you think northern African nations are going to let European nations station troops there and take over a big chunk of their land? That doesn't seem realistic, and seems rather imperialistic actually. Letting the northern African nations provide the security is just plain folly, and also makes Europe completely dependent on these economically backwards and frequently hostile nations.

Why wouldn't an African nation want to charge rent to some European country for vast amounts of land that are otherwise literally worthless[1]? It's not like they're strangers to private company security forces that are basically just extrajudicial mercenaries. History says any company that wants to do this just needs to apply some bribes to the appropriate officials.

[1] In the sense that nobody is willing to buy it so it has no price.

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

#106

Post by jandrese » Wed, Apr 26, 2017, 5:23 PM UTC

erikgrinaker wrote: post #23

Much of the (valid) criticism in this article relates to the deuterium-tritium fuel cycle. This is the easiest reaction to accomplish on Earth, so most experimental reactors are designed with this fuel in mind, and we're certainly having a hard enough time making even this work. However, I've always considered D-T fusion an intermediate step on the path to aneutronic fusion, such as Helium-3 or proton-Boron reactions…

Billion Kelvin operating temperatures make me super skeptical about the practicality of that solution in my lifetime. It's just so many orders of magnitude beyond where our materials science is.

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

#107

Post by Retric » Wed, Apr 26, 2017, 5:25 PM UTC

opo wrote: post #103

Retric wrote: post #91

Earlier quoted context omitted.

The term Baseload power is not a goal, it's a Problem with some types of power not being flexible. In that context, soar is closer to Baseload power than peaking power plants. Yes, it currently better matches demand than Baseload power, but as you ramp it up the supply / demand miss mach will simply shift around the day. Turning on some peaking power plants at night vs the day is not a significant issue. Further, the…

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…

Coal and nuclear are huge steam engines. They cool down when you turn them off which causes thermal stress and you then need to heat them up again before they can generate power. Thus Germany's problem is they have coal power plants in the first place.

Gas turbines also have thermal stress, but they are designed for this and they loose vastly less power when you turn them off. With enough of them you can have zero storage and zero problems. Because storage is simply one solution to production / demand mismatch not the only one.

Now yes, peaking power costs more but energy costing more at night is rational behavior and without subsidies you will minimize overall costs.

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

#108

Post by philipkglass » Wed, Apr 26, 2017, 5:27 PM UTC

c517402 wrote: post #87

hencq wrote: post #22

Earlier quoted context omitted.

The 'reporter' "was a principal research physicist at the Princeton Plasma Physics Lab until 1999. For 25 years he worked in areas of plasma physics and neutron production related to fusion energy research and development. He holds a PhD in astrophysical sciences from Princeton University." Do you think it's perhaps possible that the author knows what he's talking about? If you'd continued reading after that second s…

I don't understand why the OP considers sneaky Pu239 production a proliferation problem, but doesn't consider unaccounted for tritium in the fuel cycle and the general availability of Li6 to bread more tritium a proliferation problem. Anyone?

Tritium is useful only if you can manufacture a fission weapon in the first place. The vast majority of anti-proliferation efforts are aimed at preventing fission weapons capability. Preventing a nuclear weapons state from graduating from fission weapons to boosted-fission or full two stage thermonuclear is a much lower priority.

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

#109

Post by _rpd » Wed, Apr 26, 2017, 5:31 PM UTC

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…

I agree about focusing on the proton-boron reaction. I meant to refer to other fusion technologies that can sustain the reaction. As well as dense plasma focus (the Lawrenceville group that you linked), there is Polywell, Tri Alpha, the Z-machine, and some interesting laser-accelerated proton beam experiments.

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

#110

Post by cucucfudud » Wed, Apr 26, 2017, 5:34 PM UTC

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…

i read an article that the nordics actually gets as much sun as southern europe, if you count the whole year. Its as good a place for solar as anywhere else.

The summers are sunny all day and night. The problem becomes how to store the energy until the dark winter months.

(There are solar panels that doesnt need heat just light)

Edit: http://www.nordicenergy.org/article/solar-power-at-the-arcti...