6 ms·
Worldwide power grid with glass insulated HVDC cables
- msandford 1y agoIt's an interesting take to be sure. I suspect that the lack of flexibility is going to be the real killer. You'd probably have to build offshore platforms on either side to bring the cables up and terminate them and now that's a nightmare, saltwater/salty air and electronics don't mix well. Or you're going to have to trench very deeply for the first few miles. Either way you're stuck with something that really doesn't want to be bent. I think the "glass is great insulation" is a good insight and perhaps a composite glass fiber/polymer sheath would really increase the V/m without the brittleness.
- deleted 1y ago[deleted]
- bluerooibos 1y ago> interesting take I think that's being generous.
- kashkhan 1y agoa material that stretches 1% to failure (like steel/aluminum) can ballpark bend to a radius 100 times the thickness. so a 1 meter cable could bend 100m radius before cracking. assuming 10x margin that would be 1 km radius. large but not crazy. A tube that size can easily span 1 km trenches in water. you could also add a few meters of foam around it to make it neutrally buoyant and just barely press on the ocean floor.
- londons_explore 1y ago> meters of foam around it to make it neutrally buoyant In the deep ocean (typically 4km deep), foam collapses and doesn't float...
- philipkglass 1y agoI swoop in on something like this looking for the first obvious error in units/arithmetic/materials that renders the whole thing ludicrous, but the author has a spreadsheet and it looks like the units are about right. It's an absurdly cheap cable in terms of materials to transmit 10 GW across an ocean. The main things that render it dubious as a practical matter: - I don't know if operating at 14 million volts is achievable in terms of converter stations. Today's highest voltage HVDC projects operate at 1.1 megavolts and it took years of development to get there from 0.6 megavolts. - The mechanical practicality of thousands of kilometers of silica clad aluminum. There's a big mismatch in coefficients of thermal expansion and silica is brittle. Still, this appears to be facially valid in scientific terms if not in engineering terms. That's impressive! It's a really thin intercontinental cable carrying a lot of power. The whole thing reminded me of this discussion here from 3 years ago: https://news.ycombinator.com/item?id=31971039 https://news.ycombinator.com/item?id=31971039 It has rough numbers for a globe-spanning HVDC cable on the order of a meter in diameter (assumes voltages more like present day commercial HVDC, much thicker conductor to compensate).
- jrd79 1y agoI believe resistive losses are the primary limiting factor, not insulation.
- eru 1y agoThe higher your voltage, the lower your resistive losses.
- bob1029 1y agoBuilding a circuit breaker that can handle 14 megavolts of DC seems improbable to me.
- idiotsecant 1y ago14MV would be capable of sustaining an arc 1400 feet long in normal atmosphere. I struggle to imagine how you'd build such a thing. You could maybe have a high volume sf6 pump system that would cool and quench the arc on breaker trip with a constantly replenished sf6 supply.
- amluto 1y ago> The cable, if snagged by a ship anchor, would catastrophically fail. Not only would it snap, but the internal stresses would propagate the crack along the entire length. I can’t this writeup seriously with comments like this. There is no mention of any attempt to calculate the allowable bend radius. Also, quenching a glass tube in a continuous process? Does that work?
- londons_explore 1y agoThe bend radius doesn't actually matter - one can fairly trivially adjust the factory ship to make bends at specific places if desired. Including, if necessary, to fit the contour of the seafloor. The critical thing is the length of the longest unsupported span - and that's 64 meters, but surface hardening could possibly dramatically extend this, but it seems beyond available literature.
- amluto 1y agoThat seems wrong. If you have a cable with a literally infinite bend radius and lay it on a perfectly smooth sea floor, it will be supported in the middle and nowhere else, because the Earth is round. If you lay it on a real sea floor, the length of the longest unsupported span will depend on the shape that the installed cable takes, and whether the cable breaks in that shape will depend on the bend radius it tolerates.
- aaron695 1y ago[dead]
- bluerooibos 1y ago[flagged]
- Titan2189 1y agoCouldn't find the "downvote"-button, so I clicked "reply" instead. Nearly every argument you made is covered and explained in the article. Your points would get more traction if you would refer to the existing arguments made.
- deepsun 1y ago> Fused silica (glass) is a really good insulator (500 MV/m, vs 150 MV/mm for XLPE plastic) 500 MV/m is 0.5 MV/mm, so it's 300x worse insulator than XLPE plastic per article. Would be a bummer if we build the worldwide insulated network, only to find out it's not insulated enough ツ)_/¯
- femto 1y ago> glass isn’t known for its ability to bend Not quite true. Glass optical fibre is reasonably flexible. More so than many coaxial cables. Just don't go below its minimum bend radius, as it is brittle and will snap. Glass insulated power cables might work, provided the glass layer is thin enough and its band radius isn't exceeded. One can imagine a cable insulated with many thin layers/strips of glass, which have some movement relative to each other. Multiple layers of insulation is normal practise with plastic insulation, as the failure mode is typically pinholes in the insulation and multiple layers reduced the probability of pin holes going all the way through. Biggest problem might be a conductor with decent diameter will put a lot of stress on the interior and exterior of a bend. Some ides: * A multi-standed conductor with each individual conductor insulated. Maybe have high voltage in the interior stands and have a radial voltage gradient (to zero) across the outer strands so no one thin layer of glass is taking the full electric field? * Could a conductor be insulated with a woven/stranded insulating layer? One can imagine many layers of extremely fine glass fibre finished off with an enclosing layer of something else to keep everything in place. Sort of like a glass insulated coaxial cable.
- D13Fd 1y agoI’m no engineer, but this is a glass tube, not a glass sheet. I thing the amount of bending it does without breaking will be very small.
- hcknwscommenter 1y agofiber optic strands are glass tubes and they bend.
- shrx 1y agoFiber optic strands are glass rods (solid interior) instead of tubes (hollow cylinder). The two shapes have different strength properties per unit mass [1, 2]. [1] https://physics.stackexchange.com/questions/12913/hollow-tube-stronger-than-solid-bar-of-same-outside-diameter-o-d https://physics.stackexchange.com/questions/12913/hollow-tub... [2] https://www.mtbiker.sk/forum/download/file.php?id=207637 https://www.mtbiker.sk/forum/download/file.php?id=207637
- kleton 1y agoOr you could build nuclear power plants and not depend on sun/weather
- ben_w 1y agoAt the prices the blog post is estimating, PV + antipodal grid is cheaper than nuclear. Or at least, could be. No reference to how long the cable would last (only the ship), which is kinda important.
- londons_explore 1y agoRealistically, most cables last until some ship's anchor destroys them and they aren't economic to repair.
- kumarvvr 1y agoContinuous melted silica coating is fine, but how does one account for all the movement, bends and vagaries of the high seas, especially for something that is so brittle?
- NooneAtAll3 1y agoimo, least believable part for me is the "a custom ship with a glass factory onboard" part as I understand it, nobody is doing cable laying this way - and this dream of 14MV cable is kinda hinges on that
- elric 1y agoThis seems like the most feasible part of the whole operation to me. International cooperation in these weird times being the least believable part.
- mousethatroared 1y agoI don't buy it 1. The technical solution relies heavily on fantasy. 2. It is not needed. We have no significant power transmission across the low lying fruit of continental America or Eurasia, and those lines are built! Why bother crossing an ocean? 3. Why not cross Greenland and the North Sea and its islands? Under sea cables are expensive. 4. Why not cross the Bearing Strait?
- pstuart 1y agoIn Peace and Harmony Land™ I could see the value of shipping excess power from sunny/windy locations to those that are without, but I don't think the present world is ready to collaborate at that level.
- colechristensen 1y agoNukes and trade are the biggest bringers of peace.
- mikeyouse 1y agoTell that to Iran tonight..
- clort 1y agoIran doesn't have nukes.. (yet, I guess)
- jahnu 1y agoAnd the case for acquiring them as quickly as possible has been strengthened.
- rozab 1y agohttps://en.wikipedia.org/wiki/United_States_withdrawal_from_the_Joint_Comprehensive_Plan_of_Action https://en.wikipedia.org/wiki/United_States_withdrawal_from_... The US abandoned trade as a means to peace
- K0balt 1y agoI wonder if the glass sheath could be replaced with bundled glass fibers in a dielectric gel? Would that cross section allow for a much greater distance for current to trace through the gel? Seems like maybe it would give a 2x advantage, or maybe glass ribbons could be made instead for a micro braided insulation?
- jmyeet 1y agoI watched a video recently that talked about how China is really the only country to have developed and built UHVDC power transmission. Some look at this and say how it's a failure of everyone else. My immediate thought was: "this solves aproblem only China has" and that turned out to be correct. China produces most of its power in the west of the country between solar farms, the Three Gorges Dam and so on. Most of the population is 2000 miles away in the east of the country. For over a billion people, the cost of more efficient long-distance transmission make economic sense. Someone asked "could Australia do this to transmit solar power from the West coast to the east coast in peak hours?". Technically? Yes. Practically? No. Why? It's obviously expensive with far fewer people but also all that space in between is uninhabited. So if you ever need to maintain it (which you will) you have to send people out into the wilderness to do it. China doesn't have that problem because it's not really unpopulated anywhere, at least not to the scale Australia is. My point here is that you should always ask for something like this "what problem does it solve?" And the answer for more efficient long-distance power transmission is "almost nobody". I think power grids are going to go in the other direction and become increasingly localized rather than nationalized.
- deleted 1y ago[deleted]
- idiotsecant 1y agoThis is quite definitely not just a problem China has. We desperately need more transmission in the US.
- Animats 1y agoYes. The US wind belt is from the Texas panhandle north to Canada.[1] But there's no good connectivity to anywhere with a load. Some east-west EHV lines from that area would be a big win. There's opposition from oil interests. Just trying to connect East Texas to Mississippi has been stalled for over a decade.[2] Don't need anything as exotic as the 14MV the original poster proposes. 1MV at 1000 amps, which is a gigawatt, has been done many times in China. One right of way can have several such lines. It would be best to have at least two distant rights of way, for redundancy. California's total load is around 13GW, so the number of 1GW lines needed is not large. Undergrounding high powered lines is a huge headache, but possible. Here's an overview.[3] [1] https://unitedstatesmaps.org/us-wind-map/ https://unitedstatesmaps.org/us-wind-map/ [2] https://www.texaspolicy.com/proposed-transmission-line-in-east-texas-shows-why-connecting-texas-to-other-states-wont-solve-its-electric-grid-problems/ https://www.texaspolicy.com/proposed-transmission-line-in-ea... [3] https://electrical-engineering-portal.com/res3/Undergrounding-high-voltage-electricity-transmission-lines.pdf https://electrical-engineering-portal.com/res3/Undergroundin...
- deleted 1y ago[deleted]
- roschdal 1y agoDoesn't anyone know that Glass breaks Easily ?
- tejtm 1y agoPrince Rupert's drops were mentioned in the article, plain window glass material, sufficiently stressed, is ridiculously tough. try a web search for Prince Rupert drop vs bullet https://duckduckgo.com/?q=prince+rupert+drops+vs+bullet&t=lm&ia=videos&iax=videos https://duckduckgo.com/?q=prince+rupert+drops+vs+bullet&t=lm... The article author did not say how a cable could be wrapped in pre-stressed glass but that plain glass can be pre-stressed is encouraging.
- hwillis 1y agoEver heard of fiberglass...?
- jillesvangurp 1y agoHVDC cables are kind of an often overlooked solution to net zero. Moving power over long distances, across timezones is kind of a super power. The main obstacle to scaling this from a few GW to tens/hundreds of GW is cost. Just by laying more cables can you increase capacity between regions and their ability to share excess power to each other. But each cable is a multi billion dollar project. Which means that there is only a little bit of capacity to move power around but not a lot. For example Europe can import a few GW of African solar in the middle of the winter. But it could probably need hundreds when it is dark and not windy there. Likewise cross Atlantic cables have been talked about but so far don't exist. Same with getting power from the East coast US to the West coast and vice versa. The east coast goes dark while the west coast is still producing lots of solar. And in the morning on the west coast, it's afternoon on the east coast. There is a bit of import/export between California (solar) and Canada (wind / hydro). But it could be much more. Cables have another important function: they can be used to charge batteries. Batteries allow you to timeshift demand: e.g. charge when the sun is out, discharge when people get home in the evening. And off peak, the cables aren't at full capacity anyway meaning that any excess power can easily be moved around to charge batteries locally or remotely. Renewables, cables and batteries largely remove the need for things like nuclear plants. Yes it gets dark and cloudy sometimes but those are local effects and they are somewhat predictable. And if the wind is not blowing that just means it is blowing elsewhere. Wind flows from high pressure to low pressure areas. Globally, there always are high and low pressure areas. If anything, global warming is causing there to be more wind, not less. So, global wind energy production will always maintain a high average even if it drops to next to nothing locally. Likewise, global solar production moves around with the sun rise and sun set and seasons but never drops to zero everywhere. If it's night where you are, it isn't on the other side of the planet. If it's winter where you are, it isn't at -1 * your latitude. If long distance cables get cheap and plentiful, that's a really big deal because this allows for moving around hundreds of gwh of power. HVDC allows doing that over thousands of kilometers across oceans, timezones, and continents. Cheaper HVDC lowers the cost of that power.
- cyberax 1y agoWhy not just use a thicker plastic sheaf? It's a cable, it doesn't have to be thin.
- ZiiS 1y ago9 times the volumn adds up.
- hwillis 1y agoIt does have to be thin. You need to fit as much as possible on a boat and volume increases quadratically with thickness- so if glass is 500 MV/m and XLPE is 150 MV/m you would need to carry 11x more of it. Refilling means hundreds of miles back to shore.
- hyperionplays 1y agoModern cable layers can carry thousands of kilometers of cable. they have massive tanks.
- ansgri 1y agoThe importance of repairability is underestimated here. All new infrastructure must be built under assumption that there will be multiple attempts at sabotaging it by actors of various level, and multi-megavolt unrepairable cables that can be fully disabled by one smallish unmanned sub don’t win here at all.
- notepad0x90 1y agoDon't forget ships and their anchors.
- londons_explore 1y agoThe original version of this post did have a repair plan. Basically, every few kilometres you turn off the surface hardening of the cable for a yard or two. That spot won't propagate cracks - which means that if someone destroys part of the cable, the rest will be fine. Those spots of cable have no tensile strength, so you wrap just those spots in a post tensioned steel sheath. Then, you also make a few spare kilometers of cable that you lay in the ocean floor. When an incident happens, tow a new cable into position and connect it up. Underwater glass forming is a silly idea - but you can simply crack away the glass at the ends, reconnect the aluminium, then encase the whole thing in a couple of yards of epoxy. The above plan I considered probably was of similar cost to simply laying a new cable across the entire ocean ahead of time in preparation though.
- TheEnder8 1y agoIt’s interesting. I think the real way to do this is gradually scale up. Crossing the ocean is hard mode. Instead start by something much shorter and land based. Then you at least have a stable platform to work on and can focus on the other hard problems
- testing22321 1y agoIt seems like every landmass should at least have a huge east/west power line to lengthen the daylight hours as much as possible
- londons_explore 1y agoIn 1st world countries, land based cables often cost more because you have thousands of people along the route who all don't want a power line through their small village.
- lightedman 1y agoEverything looks nice but something very important was not considered in all of this. High voltage and high current means Z-pinch - the conductor itself is going to compress itself, thus resulting in basically delaminating from the glass sheathing. This is why we have rubber/petroleum-based flexible sticky insulators on cabling like that, it can somewhat flex/shrink with the conductor and is more likely to stay attached and less likely to get damaged. Just transmit laser power down fiber optics at that point. Either way you're going to need semiconductor switching (it's IGBTs all the way down baby!) nothing electromechanical is going to handle that kind of load.
- Dylan16807 1y ago> Just transmit laser power down fiber optics at that point. How does that work? You can only get the glass so clear, so you're going to lose all the energy. There's no equivalent to cranking the voltage to increase range.
- lightedman 1y agohttps://www.darpa.mil/news/2025/darpa-program-distance-record-power-beaming https://www.darpa.mil/news/2025/darpa-program-distance-recor... It works like that, and I was sending 10w down fiber optics back when I worked in solar panel manufacturing.
- Dylan16807 1y ago10w going a small distance, sure. This page doesn't say how much light was lost over the 5 miles. So I'll put it this way: If you lose just 1% every 5 miles, then by the time you go 2000 miles across an ocean you've lost 98% of your power.
- hwillis 1y agoHigh voltage does not induce pinch, only current. High voltage is used to create bursts of high current in can-crushing demonstrations. The cable is solid and the current is not concentrated in a thin cylindrical shell. The pinch is negligible, certainly in comparison to eg thermal expansion from changing load conditions.
- ACCount36 1y agoThis is the kind of transmission line design I've seen proposed for use on the Moon - where hydrocarbons are basically nonexistent, but aluminium and silicon are abundant. Glass insulated cable sounds like a tech that should be prototyped on smaller scales - and could be somewhat useful on those smaller scales.
- ben_w 1y agoWhen you're on the moon, why bother with glass? You're surrounded by vacuum and dry rock. I mean, sure, you can't go over 1022 kV or you get positron-electron pair production from free electrons, but that's still true on your outer surface even with insulation. Would coaxial HVDC let you go further, because there's no external voltage gradient? I assume so, but mega-scale high-voltage engineering in space combines three hard engineering challenges, so I wouldn't want to speak with confidence. That said, vacuum is also a fantastic thermal insulator, so perhaps you could do superconducting cables more easily. I've heard of ballistic conductors*, I wonder if that would scale up… basically the same as the current flowing around a magnetosphere at that scale? https://en.wikipedia.org/wiki/Ring_current https://en.wikipedia.org/wiki/Ring_current On the other hand, you'd have to make the magnetosphere on the moon first, and "let's use the sky as a wire" sounds like the kind of nonsense you get in the "[Nicola] Tesla: The Lost Inventions" booklet that my mum liked, and therefore I want to discount it preemptively even if I can't say why exactly. * Not superconducting in the quantum sense, but still no resistance because there's nothing to hit: https://en.wikipedia.org/wiki/Ballistic_conduction https://en.wikipedia.org/wiki/Ballistic_conduction
- ACCount36 1y ago"Just burying your wires in lunar regolith" is another proposed option for long range transmission lines, yes! We don't know how well that would work in practice though, because there's still a few unknowns about how properties of lunar regolith change across distance. Some wire applications do require isolation though. For example, motor wiring and other coils. It would be extremely challenging to make usable coils out of glass coated magnet wire - but it's not like there's oil on the Moon waiting to be made into polymer coatings.
- jauntywundrkind 1y agoA stack of optically powered 15kV mosfets, to get to 14MV, sounds absurdly awesome. 933+ mosfets that you're trying to drive in series, egads. But neat weird idea. > A 15 kV SiC MOSFET gate drive with power over fiber based isolated power supply and comprehensive protection functions https://ieeexplore.ieee.org/document/7468138 https://ieeexplore.ieee.org/document/7468138 I distantly remember reading about someone stress testing a submarine drone tether at higher than rated voltages, seeing what practical voltage they could get out of it. I distantly recall there being a lot of concern about like corona arching or something with the sea water? That was a fun paper. I don't ever if it was only because they exceeded the insulation value, but I feel like there were some notable challenges to running high voltages in salt water that I'm not quite remembering.
- aitchnyu 1y agoThe Moore-like fall of solar+battery costs took away solar satellites, solar convection plants, submarine power cables and (widely deployed though) sun tracking hardware. Labour costs are becoming a bigger proportion so some installations plop panels on the ground than slant them to south (in northern hemisphere).
- ben_w 1y ago> Labour costs are becoming a bigger proportion so some installations plop panels on the ground than slant them to south (in northern hemisphere). Even more than that: I was recently at GITEX Europe, and one of the startups* was pitching "they're so cheap, we should lay them flat for cheaper installation and maintenance". * Their name was something like "slant solar" or "tilt solar", as they had initially thought of doing exactly what you say, but I can't exactly recall the name.
- dcanelhas 1y agoDoes molten glass solidified in contaminated salt water have good insulating properties?
- hwillis 1y agoThe quenching is done on the boat with presumably purified water. That's a pretty small amount of heat to manage, so its not like you will run out of water.
- perihelions 1y agoRecent and related, https://news.ycombinator.com/item?id=42513761 https://news.ycombinator.com/item?id=42513761 ("Undersea power cable linking Finland and Estonia suffers damage", 112 comments) It's been half a year and it still[0] hasn't been fixed yet. How does anyone, really, imagine building planetary infrastructure where a trivial amount of asymmetric warfare can take the whole thing down? [0] https://yle.fi/a/74-20164957 https://yle.fi/a/74-20164957 ("Fingrid said that the EstLink 2 connection should be back online on June 25, earlier than expected")
- ben_w 1y agoThe blog is suggesting 10 GW, which is well short of "the entire thing", and they also suggest a lot of redundancy. If you were to use a single cable for everything, that would be silly because no redundancy, e.g. "A volcano? On the mid-Atlantic ridge? Who could have foreseen this?" But at the same time, a cable big enough to carry the world's power is pretty big. I've done similar ballpark calculations, and to get the electrical resistance all the way around the planet and back down to 1Ω, you'd need almost exactly one square meter cross section of aluminium (so any anchor cable breaks first), and that would have so much current flowing through it that spinning metal cutting tools can't operate nearby thanks to eddy currents from the magnetic field.
- KaiserPro 1y agoSo the initial premise is the bit that gets me. For the glass to be the insulator we need, I'm assuming the author envisions a solid tube, with no airgaps (can't do fibre braid as that would allow gaps which means loss of insulation, or you'd need oil to fill the gaps.) This means huge bend radius in the order of hundreds of meters. Not only that but laying it on the ocean bed would require trenching and full support to stop localised bending. Now to the manufacture: > The cable is then quenched in water to surface harden it, before it moves out of the back of the ship and falls to the ocean floor over a length of many kilometers (due to very low curve radius). So that'll cause the tube to break. Glass builds up hige amounts of stresses when it cools down quickly (see prince ruperts drop) so needs an annealing step. ( https://en.wikipedia.org/wiki/Annealing_(glass) https://en.wikipedia.org/wiki/Annealing_(glass) ) Moreover changes in temperature mean that using aluminum is probably going to cause the glass to shatter when the temperature changes. which means that you either need https://en.wikipedia.org/wiki/Kovar https://en.wikipedia.org/wiki/Kovar or somehow make expansion joints every n meters. Finally that cable is going to be heavy, so unless you make it around the same densisty as salt water, it'll have so much weight it'll snap as soon as you try and dump it into the sea. apart from that, looks good. well apart from the units are wrong to start with. TLDR: you'd need 5x the width of Polyethylene to achieve the same level of insulation at high voltages. but as silica tube doesn't bend and shatters really easily, cant be transported and has a slow extrusion rate, it seems logical to just use PE.
- londons_explore 1y agoPE doesn't work as well as you imagine. As well as needing waaaay more of it, due to the power of 2 in the volume of a cylinder formula, and it being much more expensive, it also can't withstand high temperatures, which means the current carrying capacity of the core is lowered.
- hwillis 1y ago> As well as needing waaaay more of it Have you done an accounting of how many kilometers you can fit on a 200,000+ tonne boat? Seems to me you could cost-effectively carry nearly 20x as much cable weight as current cable layers. You need 25x the volume of polyethylene, but that's only 10x the weight and it isn't even counting the weight of the conductor.
- tomthe 1y agoIf I (and only I) owned such a cable from Europe to the US, how much money could I make by buying cheap solar energy from the bright side and selling it to the dark side of the Atlantic? First thought: 10 GW * $0.03/kWh 4 hours/day = $1.2Mio per day [0] I am not sure about my assumptions... [0]: https://www.wolframalpha.com/input?i=10+GW+*+%24+0.03%2FkWh+*4+hours%2Fday https://www.wolframalpha.com/input?i=10+GW+*+%24+0.03%2FkWh+...
- eru 1y agoExploiting the pricing difference would probably diminish it?
- tomthe 1y agoTo some degree, yes. I just looked it up and the EU produced ~2500GWh in 2023, which is around 280 GW on average.
- ben_w 1y agoProbably more like 8 hours: you can sell in both directions, to US before sunrise in US, to EU after sunset in EU. How much you can charge probably also depends on storage, but it seems plausible (same magnitude as current transmission/distribution costs?) to my amateur understanding.
- drtgh 1y agoYou are ignoring many variables, ranging from cable resistance losses and maintenance costs to signal re-synchronisation systems. Not to mention environmental factors such as seabed warming and subsequent changes in ocean currents, over time.
- tomthe 1y agoYes, of course I do ignore a lot in that calculation. I just wanted to calculate the biggest possible usefulness of this cable. Especially the resistance losses could be quite disastrous.
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- tlb 1y agoIt's true that you can switch very high voltages with MOSFETs in series. But the next step after switching is a transformer that needs to handle 14 MV between the primary and lower-voltage secondary winding. I don't think anyone has built something like that before. Given the dielectric strength of transformer oil, the primary windings need to be 500mm away from both the secondary windings and the core, which seems like it'd be hard to do while getting good inductive coupling.
- londons_explore 1y ago35mm of silica glass would do the trick. Since the ferrite core isn't a good insulator, the glass would need to fully encase either the primary or secondary winding. At the sort of scales this transformer would likely be built, an extra 35mm would make the whole thing a little bigger and more expensive, but not massively so. The glass tank could also double up as an oil bath for cooling the coil - the first 500 millimeters or so of the piping needs to be glass, but after that you can use a typical cooling radiator with no extra concerns.
- namibj 1y agoNah, just do a few divide-by-2 capacitive converter stages to tame it. Basically just a FC-3L buck running at exactly half to not need meaningful amounts of inductance. Feed the radiation to adjacent phases of a radially symmetric setup, and it shouldn't be an issue anymore. These classic HVDC transformers only exist because those lines plug directly into the AC grid; it's easier to just tame the HVDC and keep it DC for a bit, though, at these extreme facility sizes.
- timerol 1y ago> The cable, if snagged by a ship anchor, would catastrophically fail. Not only would it snap, but the internal stresses would propagate the crack along the entire length. I admire that the author wrote this sentence and continued with the thought experiment anyway
- Workaccount2 1y agoOK, my day job is doing HV engineering, not transmission, but high energy stuff. The author did something kind of equivalent to: "If we scale a GPU clock to 75 Petahertz, we can make datacenters that fit in bed rooms! Here are the FLOPS calculations to prove it!" This whole thing is so crazy I don't know where to begin. I applaud the author for jumping into a new subject, but there is _way_ more complexity here than laid out. HV is very difficult to penetrate too because there really isn't much info available online about it. Those initial dielectric strength numbers are definitely off (maybe they used Wikipedia, which references a value from a 1920 physics book). As from what I can find fused silica has a dielectric strength around 50-100MV/m, which is taken from the AC figure and doubled to get the DC figure (which is fairly typical). Also these numbers are extrapolated, and dielectrics often have non-linear properties. The testers used to get these figures can be a little fickle, and HV is always fickle. On top of that, in actual HV system design, you really need to be using 25% of the actual dielectric strength for any kind of reliability. So the practical strength of fused silica would ultimately be around ~20MV/m. Which pretty much kills the whole idea right there. Never mind that a single fracture or dielectric breakdown anywhere in the whole glass sheath would require the entire thing to be replaced. Spoiler: You cannot patch HV dielectrics. Trust me, I and many others have tried. Some other hurdles would be dealing with the insane parasitics, which the author didn't even mention, but are one of if not the most limiting factor in transmission. HVDC lines can have up to 10% ripple, which for the author would be 1.4MV of high frequency ripple. And sea water is conductive! You are basically building a massive capacitor with sea water! The losses would be enormous. And I don't even want to think about the electronics...14MV is so insane I cannot fathom anything that would be able to reliably handle it. 1MV is already nuts. 800kV is the highest in the world, and that is kinda just a flex.
- bilsbie 1y agoThanks for the analysis! I’m curious if there are any exotic materials that would be way better dielectrics? Also are there ways to step down really high voltages? I can’t picture how the electronics would work without shorting?
- Workaccount2 1y ago
- janalsncm 1y agoStepping back from the technical question of how to lay HVDC undersea, a globally connected power grid seems like a major win for renewable energy. There are a lot of places you’d like to put power plants, and having the infrastructure in place to be able to sell that energy makes it immediately more feasible. We could put nuclear plants anywhere. Solar plants across the Sahara. It would increase the energy available to developing countries without tempting them with dirty fossil fuel plants.
- roomey 1y agoIt sounds like they need to lay the cable with a submarine not a boat, to avoid waves etc
- Out_of_Characte 1y agoI like the article for brainstorming possible technological solutions. Though whats missed is the cost of maintaining and repairing seafloor cables. This is what makes or breaks your idea after its already built and broken in a couple days rather than its rated lifespan of decades.
- Bjartr 1y agoIt's an interesting thought experiment at least. Feels like one of those ideas that could work out number-wise on paper, but reality ends up making way, way harder than it first appears. Would be cool to see the continuous wire machine on a smaller scale. How much additional volume does the fuel to run the glass & aluminum furnaces take up, and how does that compare to the volume of insulation saved? It's hard not to be cynical these days about AI, and so this comes off as a shower thought that someone proposed to an AI and got into a "what a great idea!" feedback loop.
- kaliszad 1y agoPerhaps we don't need to transport electrical current in the form of electricity but rather some kind of media, perhaps sodium metal could be a good choice. We could pump liquid sodium through pipelines or just transport it by ships. Salt (NaCl) is abundant in oceans. If you react sodium with water in a fuel cell you get NaOH, which you can again electrolytically split into sodium metal, oxygen, and hydrogen. There are ways how to extract sodium metal more efficiently than using the 130 year old basic Castner process though and there are better approaches to the fuel cell than what Lockheed imagined originally in the 1970s.