- Its freshwater and has to be freshwater because it goes through pipes and/or is evaporated. Corrosion, scaling and fouling are all issues.
Even if seawater was easy to use and datacenters were near the shore, it would produce very saline brine which would be difficult to safely get rid of.
- Any discussion of aurora which do not mention space tornados: https://en.wikipedia.org/wiki/Space_tornado
Is inherently incomplete. Not necessarily because they're needed to explain it, but they do need to be brought up at any time possible because they're cool.
- Pretty unlikely. Solar is built on cheap land with low demand, and if the land isn't sold then the power is free so why wouldn't you sell it? No matter how high the taxes are, free money is free money. Aside from making it totally illegal it is very hard to reduce the incentive to sell power.
On top of that the subsidies for solar installations are mostly frontloaded, since the costs are frontloaded. Annual tax breaks are transferrable, so they get sold at the beginning of the project to offset investment cost, lowering interest payments. Even removing tax breaks would not make existing installations less profitable.
- Lasers and masers are not inherently collimated or straight lines. The only thing specific to lasers/masers is that all the light is the same wavelength. Beam, parabolic and phased antennas are all very capable of making much tighter beams than your average laser.
In fact at the limits of performance lasers (and particularly masers) are quite bad at generating straight beams, because they are quite small sources of light and divergence is inversely proportional to the width of the emitter. It is a misconception that they are low-etendue.
- Cruising altitude is ~40k feet or 12 km and the range of the weapon is 2km. The system only works because of all the exposed wiring on quadcopters; everything in a plane is enclosed in a highly conductive aluminum shell and is very well protected. The windows are large enough to let in microwaves, but not very well. Some antennas might be in danger but in general planes are built to survive lighting. It would be a real freak accident for something to break.
- > Not surprisingly a very common failure mode is that if you induce currents in the coils of the brushless motors
No, that doesn't happen. Currents can be induced in the wires to the motors, but not in the motors themselves. For one thing, the outside surface of the motors is the aluminum rotor which is an extremely effective faraday cage. For another, coils don't act like antennas. Loops of wire in an electric field have the exact same voltage difference as a straight wire.
> Shielding helps of course, adds expense and adds weight, the two things that cut into how many you can make for $X and how far they can fly.
Shielding adds virtually zero weight; carrying a spool of fiber optic cable adds a lot of weight. All the drones in Ukraine right now are fiber optic but most of them are unshielded... the reason why is not that shielding is heavy, it's just that there are lots of jammers but very few truck-sized weapons intended to totally disable drones.
That's also assuming it would even work on a drone without an antenna. If these weapons are not relatively broad-spectrum then they will be very sensitive to the particulars of the circuitry, and they won't always work.
- > How much energy, how long is the pulse, how close were the drones?
1 millisecond pulses and 70 kW continuous usage[1] which is roughly equivalent to the AN/TPQ-53[2]. 2 km range.
> Regardless I think the primary challenge with these systems will be energy on site and a surge of it during waves of attacks. Charged up capacitors can only handle so many waves.
That is not how this kind of thing works. Capacitors are a terrible energy source. Their voltage drops off exponentially as they discharge and almost all electronic are very particular about the voltage they require. A railgun wants current and does not care about voltage. Radio transmitters care a lot about voltage.
Regardless, a 70 kW generator fits on a small trailer. Smaller than the weapon itself. It will run for days on a good sized tank of diesel.
[1] https://www.twz.com/land/army-puts-50m-bet-on-next-gen-leoni...
[2] https://en.wikipedia.org/wiki/AN/TPQ-53_Quick_Reaction_Capab...
- A good N52 neodymium magnet can be 1.5 tesla- MRIs are usually 1.5 tesla. The pull force is around the same too- a steel object will experience say 20g, and 100 lb fishing magnets are not hard to find.
The difference is the size. Even a large magnet only hits that 20g force over an inch or two. An MRI pulls at that force over a full foot or more; equivalent to dropping the object from 20'+. Worse, the MRI starts pulling at 5 or 10 feet away. Objects can experience a tremendous amount of uncontrolled acceleration in fractions of a second.
It's not like a black hole- unless you are trapped under something very large, the crushing force is substantial but not incredible. In fact inside the tube the gradient is actually smaller than the entrance of the tube- you are pulled in strongly, but once inside the tube you are pressed against the wall somewhat less forcefully. Instead it's like an invisible waterfall, and any metal will be swept away in it, fast enough to put holes in you.
- The switches are right next to each other and have a very short throw[1]- it would definitely be possible to do them in under a second and it looks possible to throw them together.
IMO that looks like a spot that would be pretty difficult to hit accidentally even if the ward failed. You'd have to push them down and the throttles are in the way.
Doesn't mean the switch couldn't have failed in some other way- eg the switch got stuck on the ward but was still able to activate with a half-throw, and spring pressure pushed it back into off during a bump. But switches generally only activate when fully thrown, and failing suddenly at the exact same time is not really what you would expect.
[1]: https://www.reddit.com/r/indianaviation/comments/1lxra3g/b78...
- You're massively misrepresenting what I'm saying. I am not dismissing nuclear or suggesting overbuilding solar by 5x. I am responding to someone who is dismissing solar now for the fantastical idea that nuclear is cheaper now. Nuclear is good. Nuclear should replace coal. Shutting down reactors that are not unsafe is ridiculous. We should build breeder reactors. Personally I think even many countries that have reactors should build more, and retrofit existing reactors to have much higher ramp rates a la French nuclear. Countries with no nuclear or hydro or geo base like Poland should definitely build nuclear plants.
But many countries have large amounts of nuclear- many enough to supply most nighttime power. And in almost all countries, solar is by far the best and cheapest immediate option, and those countries should be building as much solar as possible until the marginal return of nuclear or storage or infrastructure for imports are cheaper than just building more and more solar.
> I am not aware of any large scale operating exports of solar energy from equatorial regions to Northern Europe, or similar distance.
No country is even close to a solar oversupply, much less a 2x or 5x. If there is no margin, why would those projects exist?
- That's just not true, unless you mean resource reserves. Taiwan has the largest NG strategic reserve I know of (11 days) and the US has the largest petroleum reserve in the world at 19 days: https://en.wikipedia.org/wiki/Strategic_Petroleum_Reserve_(U...
Resource reserves are unextracted and not replenished. They are not the same as storage.
- > You still need enough power to cover that, especially if it has been a cloudy/rainy day, or week, or month.
That's besides the point! The window of highest demand completely covers the window of solar. You can build a LOT of solar before storage starts becoming cheaper than just building more solar. You only need storage if it's ALL solar- you can have a majority of your power supplied by solar with hardly any storage! There this idea that if you overbuild solar that power will have nowhere to go, or something- you can just turn it off. You use backup power for the non-shining hours and you're totally fine.
> And this is so easy and foolproof to do, just check out the Iberian power outage.
In fact I did[1]. Page 117: "In fact, in most of the network nodes analyzed, there is no correlation between voltage stability and the amount of solar generation or the amount of coupled synchronous generation"
They had 2.3 seconds of inertia, more than the regulated 2 seconds. Power sloshing through interconnects caused plant ramp rates to be overwhelmed one-by-one, causing the cascading failure, because they had no buffering. If they were all solar or wind plants, the failure would not have happened!
[1]: https://media.licdn.com/dms/document/media/v2/D4D1FAQGcyyYYr...
- Numbers: In poland the solar output in December is 1/5th of July output while demand is ~10% higher. Insolation drops off quickly at higher latitudes so it dominates much more strongly than heating demand even if heating were electrical.
At the global scale this would ideally balance out- more equatorial solar is cheaper in the winter since they don't need air conditioning, so you just send it up north. That's the only really feasible solution to seasonal variation in individual countries- it's totally unreasonable to store 3 months worth of power. Its also important to note that even with 2x or 3x oversupply, solar is cheaper than nuclear currently is.
[1]: https://re.jrc.ec.europa.eu/pvg_tools/en/#PVP [2]: https://www.pse.pl/web/pse-eng/data/polish-power-system-oper...
- A 747 burns ~9 tonnes of kerosene per hour, creating ~29.6 tonnes CO2. The Monroe Power Plant produces 3400 MWe at ~1 kg CO2 per kWh, so ~3400 tonnes CO2 per hour.
It's a little complicated to weigh stratospheric emissions- the CO2 has a larger impact, and while the water droplets and contrails left by planes somewhat counteracts it (by reflecting incoming infrared) it's harder to compare intangibles like mercury emissions from coal. If you just say its all a wash, that plant is equivalent to 120 747s running full speed.
Private jets consume more like .9-1.5 tonnes per hour, so that's equivalent to ~900 billionaires. That's a bit less than half of them which is probably a lot more than were at the wedding. They also probably parked them instead of leaving them circling in the air.
If there were 90 billionaires who flew 12 hours each way in their private jets, then they probably released around 2.5 hours worth of Monroe Power Plant time over those 90 days- 8458 tonnes. Fun fact, the pilots and flight attendants probably used ~1000 tonnes of CO2 worth of energy etc and exhaled ~25 tonnes of CO2 in that time. 25 tonnes is small compared to the planes (>.3%), but in those 90 days the planes released just .11% as much as the coal plant.
Coal really truly sucks and it's unfair that I can't eat tuna without getting mad hatter disease.
- > and the fact that cycles of power generation in most cases do not align with usage.
This is false. Power usage everywhere is highest when the sun is shining. There are also very very few places where solar power ever causes the market to bottom out with any regularity. Note that there is no technical problem with this- you can always just disconnect renewables from the grid.
The phenomenon you are thinking of -the duck curve- refers to the power demand after subtracting solar. The daily peak consumption of power in many places is wider than solar generation, so if there is enough solar you end up getting new smaller peaks just after dawn and around sunset. This is minorly inconvenient for non-renewable sources, which prefer to have more predictable demands.
> Usually most analysis ignore costs of having a buffer in the system
Correctly! Non-renewable plants are the ones that need buffer. Solar, wind, hydro etc can all be connected to a grid with zero instability- you just unplug them if nobody wants the power. Non-renewable plants have slow ramp speeds- they need the buffer in order to follow a changing load.
> Not to mention less land required, which is another of ignored costs.
This is incorrect; I don't know of any analyses which don't include land and interconnection costs which are obviously substantial. If you mean more intangibly... that's very silly. The US Interstate system is 3.9 million miles of road, with 60' medians, 16' of shoulder, and 48' of lanes. 237,250 square kilometers. The "blue square"[1] is 10,000 square km. The amount of land we spend on parking lots absolutely dwarfs it.
> Because nuclear is superior by every metric
Nuclear has not gotten cheaper- why would it? It's a big clockwork. We are not better at building pipes than we were 80 years ago. Solar has and will continue to: plants get more productive, panels get thinner, efficiencies go up. There is no grounding principle that indicates nuclear can be cheaper, and it certainly is not in practice. Solar is far cheaper than coal by capacity much less kWh, and nuclear plants are more complex than coal. What indicates that a 500 MW nuclear plant should be cheaper than a 500 MW coal plant, not counting running costs?
> Are they?
Demonstrably yes, absent weird conspiracy theories. Renewable installations keep opening at much lower costs than traditional plants.
[1]: https://blogs.ucl.ac.uk/energy/2015/05/21/fact-checking-elon...
- Same, hah. The similarity between gridwall and powerwall in another comment also snagged me. "Perfboard" has also gotten me before- both are perforated board, but one is used for quick circuit boards and the other (more commonly called pegboard) is a wall-mounted modular hook system for storage.
- Yeah, fair to say its feasible. ROSA on the ISS produces 240 W/m^2 and weighs 4 kg/m^2.
The S6W reactor in the seawolf submarines run at ~300 C and produce 177 MW waste heat for 43 MWe. If the radiators are 12 kg/m^2 and reject 16x as much heat (call it 3600 W/m^2) then you can produce 875 watts of electricity per m^2 and 290 watts at the same weight as the solar panels. Water coolant at 300 C also needs to be pressurized to 2000+ PSI, which would require a much heavier radiator, and the weight of the reactor, shielding, turbines and coolant makes it very hard to believe it could ever be better than solar panels, but it isn't infeasible.
Plus, liquid metal reactors can run at ~600 C and reject 5x as much heat per unit area. They have their own problems: it would be extremely difficult to re-liquify a lead-bismuth mix if the reactor is ever shut off. I'm also not particularly convinced that radiators running at higher temperatures wouldn't be far heavier, but for a sufficiently large station it would be an obvious choice.
- > If you wanted to have a very-long eva spacesuit you'd have to have radiators much bigger than your body hanging off of it.
I was curious about this! The Extravehicular Mobility Units on the ISS have 8 hours of life support running on 1.42 kg of LiOH. That releases ~2 kJ per gram used, so .092 watts.
The 390 Wh battery puts out an average of 50 watts.
And the human is putting out at minimum 100 watts with bursts of 200+.
Long term it's probably reasonable to need at least 200 watts of heat rejection. That's about a square meter of most radiator, but it needs to be facing away from the station. You could put zones on the front/back and swap them depending on direction, as long as you aren't inside an enclosed but evacuated area, like between the Hubble and the Shuttle. The human body has a surface area of roughly 2 m^2 so its definitely not enough to handle it- half of that area is on your arms or between your legs and will just be radiating onto itself.
It's also not very feasible to have a sail-sized radiator floating around you. You'd definitely need a more effective radiator- something that absorbs all your heat and glows red hot to dump all that energy.
- Per wiki: radiators reject 100-350 watts per m^2 and weigh ~12 kg per m^2. Not unlikely you would need 10x as much radiator as server. You need about as much area for radiators as you do for solar panels, but radiators are much heavier.
That also makes nuclear totally infeasible- since turbines are inefficient you'd need 2.5x as many radiators to reject waste heat. Solar would be much lighter.
https://en.wikipedia.org/wiki/Spacecraft_thermal_control#Rad...
- > Another unrelated point, a significant number of Iranian civil engineering graduates are women. A somewhat dichotomous economy, when you consider the theocratic restrictions on costume and behaviour.
Iran does not have the same degree of sexist restrictions as eg Saudi Arabia. It's a very different climate from places where salafism is more common. Female education in particular is highly supported eg: https://x.com/khamenei_ir/status/1869369086142296490
- > His install would have a net negative value to the Texas grid without it.
Absolutely untrue. Solar and wind can always just be disconnected at any moment. Wind resources are also a huge inertia source- windmill blades are massive grid stabilizers.
Renewable tech does not have a big coal fire they need to keep at a constant temperature. How about instead of requiring batteries with solar, we require coal plants to have sufficient bypass cooling that they don't need the load of a grid connection to stay cool.
Renewables are a boogeyman. The reality is simply that they are always able to undercut any fossil plant and they don't like that. It has fuck all to do with grid stability.
- Iran is one of the top producers or radiopharmaceuticals from highly enriched materials including uranium. This should be unsurprising because Iran has a natural abundance of radioactive isotopes- the background radiation of spots in Iran is extremely high: https://en.wikipedia.org/wiki/Ramsar,_Iran
https://www.presstv.ir/Detail/2024/04/08/723301/Iran-among-t...
https://www.energy.gov/science/ip/articles/harnessing-power-...
- Radiopharmaceuticals are enriched to 60%. Iran is one of the top producers in the world. Iran has a natural abundance of radioactive isotopes- the background radiation of spots in Iran is extremely high: https://en.wikipedia.org/wiki/Ramsar,_Iran
https://www.energy.gov/science/ip/articles/harnessing-power-...
https://www.presstv.ir/Detail/2024/04/08/723301/Iran-among-t...
- There is some improvement in vehicle control, but the biggest impact was inside the engine. Controlling the vehicle at transonic speeds benefits a lot from simulation- control inversion is an example. When grid find pass the sound barrier, the flow through the holes of the grid becomes choked off by shockwaves, and the fin starts acting like it was solid and sideways. Since it's effectively pointed 90 degrees off, it acts like its reversed. Knowing when, how intensely, and how turning affects that is important. Simulation also helps you find unexpected places where flows may unexpectedly become super/subsonic and cause torque. Experimenting at these speeds is... hard.
Simulation inside the engine can find resonances, show where shockwaves propagate, and show you how to build injectors (pressure, spray etc) so they are less affected by the path of reflections. Optimizing things like that smoothly along a range of velocities and pressures without a computer is not very feasible, and you need a minimum of computing power before you start converging to accurate results. The unpredictability of turbulence means low-resolution simulations will behave very differently.
- Electrical engineer: motors and sensors are not really any better- motors have gotten more efficient and sensors have gotten cheaper, but gold standard sensors like ring laser gyroscopes have existed since the 60s.
> Launch-thrust engines that throttle down low enough and preciesly enough for landing
In large part this is due to improved simulation- spaceX made their own software: https://www.youtube.com/watch?v=ozrvfRHvYHA&t=119s
Experimentation was also a large factor- pintle injectors have been around for a long time, but were not used in production rockets until SpaceX (who moved from a single pintle to an annular ring). Pintle injectors are very good for throttling.
> Better materials to handle stress for flip over manover etc without added weight
We're still using the same materials- good ol inconel and aluminum. However 3d printing has made a pretty big difference in engines.
More rockets use carbon fiber, but that isn't new exactly and the main parts are still the same variety of aluminum etc. Titanium has become more common, but is still pretty specialized- the increased availability was probably the biggest factor but improved cutting toolings (alloys and coatings) and tools (bigger, faster, less vibration) have also made a big difference.
Motors need to be made of laminated steel sheets to reduce parasitic eddy currents. The laminations need to be thin in the direction of the direction of the flux. For radial flux motors you just punch out a shape and stack a bunch of sheets up. For axial flux you have to wind a strip: https://15658757.s21i.faiusr.com/2/ABUIABACGAAgmviFqAYozvPw-...
Each layer of that strip has a different cut in it, so its much more complicated to make. The shape and manufacturing method typically impacts efficiency; YASA avoids that by spending more money. Efficiency is an unavoidable requirement of high power density- heat is the limiting factor, and going from 98% to 96% efficient means double the heat.
The mechanical demands on the motor are also much higher- radial flux is balanced since the magnetic force pulls the rotor from opposite sides. Axial flux motors are usually one-sided, so the magnets are trying to pull the rotor and stator together with incredible force. That also makes vibrations worse. Extremely strong, expensive bearings are required to handle it. With permanent magnet rotors you need a jig to lower the rotor into place; they can't be assembled by hand. That also makes maintenance more difficult and expensive.