fwiw, on your point A, the big boys don't use a battery-style UPS. they use the kinetic energy from a flywheel rotor until the diesel kicks in.
your point B (generators) still applies.
some tree-hugger trivia (updated from 2012), courtesy of our friends at NYT and General Electric:
every year datacenters in the US consume over 120 billion watts of energy (about 10.4% of the nation's entire production), and worldwide, waste 11 billion litres of diesel fuel in tests and short-run transition events.
GLAL,
R.