261–270 of 322 posts
This is an incredible achievement but there are strong reasons to suspect that stellarators are not and will never be plausible candidates for energy generation. For some more experimental or perhaps military tasks, it's viable.
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In motion. Yes it is perpetual motion. The same thing can be observed in superfluids.
It is my understanding that electrons on a curved trajectory will lose energy to electromagnetic radiation. Is that not the with electrons in a superconductor?
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Possibly the poster is from a country like America where "turnover" is not a preferred term to refer to gross receipts of a business. (Americans typically use "revenue" instead.)
I am indeed from the US and had never heard "turnover" to mean gross receipts.
I lost money on the endeavor, though.
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Doing CAD design is really interesting. A lot of stuff is just 2.5D, extrusions of 2D sketches sitting on other 2D sketches. Then you accidentally make something truly 3D by intersecting things and realize you have no idea what you're looking at, couldn't imagine it if you closed your eyes, couldn't replicate it if you had a picture of the result and didn't know the 2D inputs that made it... and then you realize ther…
Coming from 3d sculpting to CAD was...eye opening. It really makes you realize how much of design constrained by the CAD tools, which are mostly constrained by manufacturability. If true 3d printing* ever gets cheap, it'll be interesting to see how much form will be able follow function, rather than manufacturing cost. * true 3d, as in overhang are allowed. Something like a cheap FDM is more 2.5d, since overhangs are…
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The reason just that this is a simple process for which a steam turbine can achieves 90% of the thermodynamic optimum. To my knowledge, the only reason people consider alternatives is to reduce capital costs. You're still capped by thermodynamics though.
That's what I was wondering: if heat -> steam -> turbine is close enough to the theoretical upper limit and you get diminishing returns by other means. Still, it seems very indirect. Like generating solar power by using a parabolic mirror to heat water instead of photovoltaic panels... but of course I just found an example of doing that too: https://en.wikipedia.org/wiki/Parabolic_trough
Usually the liquid is some sort of oil that csn reach higher temperature and then the oil is used to heat water
Another design uses hundreds of mirror centered around a high tower with molten salts as the heat medium
The really good part of this design is that the molted salts can produce energy for 3-4h after the sun is set.
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Which doesn't make sense for power generation since there will always be some percentage of neutrons produced by any type of fusion reaction that can only be useful for generating steam. To entirely skip the steam cycle portion is to intentionally make a much less efficient design. For space-constrained, high-value, applications where economics don't matter that much, such as a submarine, that would make sense, but o…
Helion's fuel mix produces just 6% of its energy as neutron radiation, and if you harvest it you'll lose a third of that. As long as you have enough net energy, collecting that 4% might not make financial sense. With fuel costs insignificant, your cost per kWh is mainly capital cost. Let's say it's all capital just to keep it simple. I don't know how much the input energy will be but if your choice is between, say, g…
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'Theoretically' is the right word for sure. iirc, the predecessor of the Wendelstein led to the bankruptcy of the engineering firms building the parts, because tolerances were so tight and they failed multiple times to land within the constraints.
W7-X is a new stellarator design. It’s magnet arrangement was optimized using a lot of compute time and is designed to overcome the faults of previous more naive designs.
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No. Right now there is no reasonable way to have a 100% renewable and reliable grid in Northern Europe, excepting classic hydro. I specifically studied the German grid, and it needs about a MONTH of storage to compensate for a once-in-a-century Dunkelflaute (a period with little wind, no sun, and cold temperatures).
> Right now there is no reasonable way to have a 100% renewable and reliable grid [...] and it needs about a MONTH of storage to compensate for a once-in-a-century Dunkelflaute If you accept slightly less than 100% renewables, you could use diesel or gas backup for these once-in-a-century events.
That's a lot. Even cheap gas turbine power plants will cost around $100B to build.
And while the one-month Dunkelflaute is exceptional, the shorter versions lasting a couple of days happen basically every year. As a result, you probably need about 2-3 weeks a year of various levels of backup utilization every year.
This is how it looks in practice: https://energy-charts.info/charts/power/chart.htm?l=de&c=DE&... - look at the period from 18th Jan to 25th Jan. The renewable generation fell to around 8% of the nameplate capacity during that period.
I have not seen any real plans to fix this. My prediction is that Germany will just continue to burn gas and coal well into 2030-s.
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No. Right now there is no reasonable way to have a 100% renewable and reliable grid in Northern Europe, excepting classic hydro. I specifically studied the German grid, and it needs about a MONTH of storage to compensate for a once-in-a-century Dunkelflaute (a period with little wind, no sun, and cold temperatures).
You're wrong about that. Back up with green hydrogen is quite plausible. Europe has enormous salt formations in which cavities can be solution mined for gas storage (this is one of the chief ways natural gas is stored). Storing hydrogen, the cost of these caverns per unit of storage capacity in these would be about $1/kWh. The total potential capacity there is in the petawatt hours, far more than would be needed. A c…
I have not seen any real plan to achieve this. Right now, it's basically a giant asterisk with a footnote saying: "Magic happens here".
One plan I've seen where authors went totally wild and actually tried to compute what's needed, required converting 80% of housing to district heating with molten salt storage, all kinds of energy storage, and 2x price electricity increase.
I've seen estimates that simply building out hydrogen backup will cost on the order of $300B in power line and pipeline upgrades (because hydrogen can't just be piped through natural gas pipes). And it will still require expanding the renewable fleet.
I'm not at all optimistic about that.
FWIW, I think power-to-natural-gas has the biggest chance, because it can re-use the natural gas infrastructure. But it's still going to be too expensive.
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Makes sense. I would love to see a blog post with some progress pics, but I understand that building a fusion reactor is simply a slow process!
I expect they'd happily give access to anyone who wanted to cover it. Say, if someone wanted to do quarterly update videos, and had the appropriate skills, they'd only have to find the right person to ask, on the academic side. Hint.