What's old is new again.
There is a movement to distribute power within a datacenter as DC instead of AC. The concept is that the small power supplies in the servers/computers are sooooo inefficient, that we might as well provide the power directly from the output of the large rectifier within the UPS.
BTW: many DC applications like elevators use local rectifiers rather than getting it from the utility. The subways in NYC use 600vDC too, through rectifiers.
