Material Feasibility and Mechanical Challenges
Several commenters express concerns about the mechanical properties of the proposed cable design, especially given the brittleness of glass and the stresses involved in underwater deployment. The core issue is whether the cable can withstand bending and potential damage from external factors like ship anchors.
- "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 canโt 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?" - amluto highlighting concerns about damage propagation.
- "A 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." - kashkhan providing a thought experiment on material properties and bending radius.
- "Iโm 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." - D13Fd questioning the flexibility of a glass tube
- "Continuous 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?" - kumarvvr expressing doubt in the face of real world conditions.
Some users countered that glass can be more flexible than commonly thought and offered potential design solutions:
- "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" - femto suggests the use of thin layers.
- "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." - msandford suggesting a composite material.
- "There's more to glass than simple silica soda lime formulations. Glass chemistry is still a dark arcane art on the fringes with discoveries made all the time...but they are more flexible than what many think of as glass" - defrost mentioning advanced glass types.
Voltage and Insulation Challenges
The proposed 14 MV operating voltage raises significant concerns regarding insulation and circuit breaker technology. The discussion highlights the difficulty of building components that can reliably handle such high voltages, especially in DC systems. Doubts were cast on whether using glass would even work, citing incorrect units in the original post: * "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 ใ)" - deepsun originally highlighting a discrepancy, later corrected. * "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." - philipkglass pointing out the gap relative to currently available technology. * "Building a circuit breaker that can handle 14 megavolts of DC seems improbable to me." - bob1029 direct statement on circuit breaker feasibility. * "14MV would be capable of sustaining an arc 1400 feet long in normal atmosphere. I struggle to imagine how you'd build such a thing." - idiotsecant discussing the arc potential of such extreme voltages. * "Even 1.1GV systems use semiconductor breakers. Basically, stacks and stacks of transistors. The actual physical breakers are only operated when the voltage is safely off." - cyberax discussing current solutions for high-voltage systems. * "An insulator made of multiple materials will have the breakdown voltage of the weakest material. So, glass fibers in some sort of resin will break down at the resin's voltage, not the glass's." - dtgriscom regarding composite insulation.
Practicality and Economic Justification
Beyond the technical challenges, some commenters question the overall practicality and economic justification for such a global-scale, undersea power transmission project. They suggest alternative solutions and question the demand for such a system.
- "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?" - mousethatroared doubting the need based on existing infrastructure.
- "Why not cross Greenland and the North Sea and its islands? Under sea cables are expensive." - mousethatroared suggesting alternative routes.
- "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." - msandford mentioning practical challenges around coastal regions.
- "imo, 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" - NooneAtAll3 calling out a specific dubious aspect.
- "Or you could build nuclear power plants and not depend on sun/weather" - kleton proposing an alternative energy solution.
Political and Logistical Hurdles
A few commenters also raised concerns about the political and logistical obstacles to implementing such a project, particularly with regards to international cooperation and the sheer scale of the undertaking.
- "In Peace and Harmony Landโข 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." - pstuart doubting the political feasibility.
- "International cooperation in these weird times being the least believable part." - elric highlighting international cooperation difficulties.
Assessment of the Original Post
There was also direct and blunt assessment of the original post, doubting its validity. * "interesting take / I think that's being generous." - bluerooibos making a terse assertion. * "I don't buy it" - mousethatroared even more direct. * "I 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. Still, this appears to be facially valid in scientific terms if not in engineering terms. That's impressive!" - philipkglass cautiously validating, but also highlighting the gap between scientific validity and engineering viability.