This is one of the best pieces of EV news I've ever read. Hydro-Quebec is not some minor insignificant company. In fact, I think their dam may be the largest single electricity producer on the Continent and that their surplus is such that I think they've had a tough time, at times, getting it to where it can be put to use.
I recall news stories from a few years ago hilighting some of the effort to negotiate cross-border exporting of this electricity. This was also the first news story I read which hilighted the industry's practices of raising rates to super-high levels during relatively rare periods of short supply, thus turning potentially good months into bad ones for buyers, because of just a few quarter-hours here and there. Anyway, this is just fantastic news, unless I am missing something. As to the battery, I think we have to be skeptical, on principle, but if HQ believes that strongly in it, then maybe it's for real.
