Forcing the issue

Twenty eight US states now require that a certain percentage of electricity sales come from green energy. Analysts credit this policy - called the renewable portfolio standard (RPS) - for spurring many of the new wind farms and solar panels dotting the nation's landscape and rooftops.

Given that the policy worked for renewables, the lagging nuclear and coal industries are now pushing for portfolio standards of their own.

"Imitation is the best form of flattery," says Patricia Stanton, vice-presi