The power use is not limited to the stadiums ... the problem is much more apparent in England during a big game. At half time, millions across the country do two things at half time. They put the kettle on for a cup of tea and they go to the toilet an flush. Literally everyone doing it during a 15 minute period. Kettles use power and the surge in power usage is hard to handle. The flushing drains reservoirs more quickly than usual ... and pumps start up to fill reservoirs agains. All a knock on effect. Whilst the stadium power use is limited, it's what happens around that is more important.
Anyway ... we live in SA. We drink beer and not tea ... and we "pee in the garden" and not the toilet. What else can you do to save energy ... come on, it's earth day!