Send it through the earth, you can reduce it theoretically to 42.5ms
This isn’t as ridiculous as it sounds and you just need a neutrino-beam… which has a horrible bandwidth (of 0.1 bits/s) plus the ridiculous upfront cost of running two particle-accelerators for a full-duplex link. (Google it up, this exists.)
I’ll just comment about one thing that keeps popping up in the discussions: grid-level storage. There is no such thing yet really that would last a full day cycle, and the 100MW or so units we are building are mostly for frequency stabilization and for buying enough time to turn on a base-load plant when the renewables drop out. I’m not arguing against storage - it is absolutely needed.
The problem is the scale, which people don’t seem to get. Largest amount of energy we can currently repeatedly store and release is with pumped hydro, and the locations where this is possible are few and far between. Once the batteries reach this level-of-capacity, then we have a possibility to use them as grid-level storage that lasts a few days instead of hours.