Worldwide power grid with glass insulated HVDC cables

Summary

Worldwide power grid with glass insulated HVDC cables. Moving electricity around the world has huge financial and environmental benefits. Unfortunately, current power transmission systems are both lossy and expensive to build. This post explores an alternative design for cables to make undersea power transmission substantially cheaper. Idea Fused silica (glass) is a really good insulator (500 MV/m, vs 150 MV/mm for XLPE plastic), and is very cheap. By using it as cable insulation, cables can be made substantially thinner and cheaper. Unfortunately, glass isn’t known for its ability to bend, which introduces logistical challenges. I propose these be solved by manufacturing the cable onboard a boat in a continuous process and directly laying it. The cable would consist of an aluminium conductor surrounded by a silica insulator. There would be no outer protection - instead, the silica would be surface hardened, rather like a prince ruperts drop. The extreme internal tensions should be sufficient to allow the cable to be laid on the ocean floor and span lengthy crevasses without breaking, removing the need to bury the cable - more costs saved. What voltage?? HVDC cable voltages are chosen to trade off the cost of the conductor (thicker=more amps!) with the cost of the insulator (thicker=more volts!). Assume that we want our cable to transmit 10 Gigawatts across the Atlantic ocean - which would make it on par with the biggest existing links. Do a bit of math, and it turns out 14 megavolts is the sweet spot. That’s way higher than existing projects (typically 0.5 megavolts), but inverters based on MOSFETs scale with cost proportional to power (one can just stack the mosfets and optically control them), so this shouldn’t matter. The convertor stations could use air as an insulator (you need 5 meters of dry air on all sides), but it might be better to do the whole thing in transformer oil (500mm on all sides), and/or encase the circuits in moulded silica glass (25mm case th...