271–280 of 375 posts
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Cheaper and more plentiful resources means less reason to go to war.
Unlimited free energy means we eventually global-warm our planet through waste heat. Works out at about 10% the potency of greenhouse gasses per MW.
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I don't believe this is the case. I'm pretty sure there have been "hard" limits so far on what can be achieved. I'm not a physicist, not even close but as I understand it two issues remain. One is that sustaining the fusion reaction has been problematic. I believe the longest sustained reactions have been less than one second. Two is that currently we have to put more energy into creating and sustaining the reaction…
JT-60 in Japan has done about half a minute, actually. There is less of an issue with sustaining reactions (since there has been steady progress over the years) than with coming up with materials that would stand up under a commercial fusion reactor's duty cycle. http://iopscience.iop.org/0029-5515/48/8/085002
> U.S. submarines and aircraft carriers run on nuclear power, but they have large fusion reactors on board that have to be replaced on a regular cycle. sigh To the extent this is true I suspect those "large fusion reactors" are tuned not so much for generating electricity and a great deal for annihilating whatever the carrying missile is pointed at. But never mind fuzzy thinking at Reuters right now. This is amazing…
Looks like they issued the correction > U.S. submarines and aircraft carriers run on nuclear power, but they have large fission reactors on board that have to be replaced on a regular cycle.
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That's hardly ever true. In my experience, Hacker News is full of people from the software field; folks whose professions are often unconstrained by physics,[1] and who have a generally optimistic "this can happen" mentality. That's why everyone here believes we'll have fully self-driving cars in 5-6 years. In the rest of the engineering world, the answer to any question is: it'll be harder than you think it'll be (p…
> Did you know that coal plants, which still make up the majority of U.S. energy production, are only about twice as efficient today than they were a century ago? Did you know that wind and solar are already at grid parity in over half the world? And that in many large first-world countries (Germany, Australia) the price of energy goes negative during daylight hours because of the amount of energy produced by renewab…
http://cleantechnica.com/2014/07/05/queensland-solar-negativ...
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That's hardly ever true. In my experience, Hacker News is full of people from the software field; folks whose professions are often unconstrained by physics,[1] and who have a generally optimistic "this can happen" mentality. That's why everyone here believes we'll have fully self-driving cars in 5-6 years. In the rest of the engineering world, the answer to any question is: it'll be harder than you think it'll be (p…
> Did you know that coal plants, which still make up the majority of U.S. energy production, are only about twice as efficient today than they were a century ago? Did you know that wind and solar are already at grid parity in over half the world? And that in many large first-world countries (Germany, Australia) the price of energy goes negative during daylight hours because of the amount of energy produced by renewab…
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The majority of those suppliers provide boron-impregnated plastic, which is fine for e.g. shielding spallation neutrons from a medical linac head. Reactor shielding is orders of magnitude higher, so material damage is a real concern. Not to say that people can't or don't use that material, but it is not the most cost effective stuff. Frankly, the best neutron shielding in the world, on a per-cost basis, is water with…
So in this reactor design, the neutron shield would be quite thin, if that drawing is to scale I'd say like 30-50cm? in that case water in borax wouldn't be dense enough right? A cool thing about the shield being liquid is that you could theoretically replace it while it's running. It could make the neuron shield double as the heat transfer medium too. Of course I'm a total layman so this is just highlevel blabbering…
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> I suspect this effect means that, for reactors, the wear and tear is more localized, but of a larger amplitude. Not exactly. The initial collisions do indeed cause localised damage cascades, but the overall effect of a large neutron flux is embrittlement of the material. This is a problem already in fission reactor vessels, but the neutron fluxes are a whole order of magnitude larger in fusion reactors, and it's a…
Do the neutrons necessarily come off in all directions, or can the reactor be designed so that the neutrons tend toward specific directions?
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Betting on a math error from Skunkworks? Highly unlikely. If anything, scalability will be the issue, as it always is
It's a very safe bet. Well, probably not a math error as they are quite a fine institution, but what he says is probably the case. The challenges of fusion power are largely fundamental nitty gritty engineering issues. We know fairly well how to design most of a fusion reactor; in a lot of ways they are conceptually easier than fission reactors. The two main hurdles are the materials problems and how to keep the reac…
I'm not saying they've done it and extraordinary claims require extraordinary proof but this is the place that made a Mach 3.5 jet with wings that leaked out of titanium in the 60's.
Nitty-gritty engineering is something they are fairly good at.
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> Did you know that coal plants, which still make up the majority of U.S. energy production, are only about twice as efficient today than they were a century ago? Did you know that wind and solar are already at grid parity in over half the world? And that in many large first-world countries (Germany, Australia) the price of energy goes negative during daylight hours because of the amount of energy produced by renewab…
You make that sound like it is a daily phenomenon. It has happened infrequently (in Australia). http://cleantechnica.com/2014/07/05/queensland-solar-negativ...
Many companies have tried to set up a skunkworks since, but didn't have the guts to run it like Kelly did, and didn't get the results, either.