I'm just shooting from the hip here but I think an unconventional and very Austin idea for how to remedy the substation issue would be to make the station itself into a sculptural landmark of the city. By which I mean, what if an artist could come in and create a redesign of the substation utilizing sculptural elements that doubled as the actual functioning parts of the substation? Instead of form following function or vice versa, both could go hand in hand. I'm picturing something out of, say, Meet the Robinsons or Robots. It could be rebuilt in phases so as to never actually cut the power to the city but you end up with one of the world's most unusual pieces of public sculpture...artwork that doubles as a power station. I feel like why hide the station with art when the station could BE the art.
A less expensive solution could also be to drench the thing in LEDs, or have it shoot fireworks or fire like that praying mantis in Vegas.
Just food for thought.