Chase.... it would take at least a decade as most government initiatives do.
Did you know... President Jimmy Carter proposed and got enacted by the Congress a comprehensive energy policy that would have made the U.S. completely independent of foreign oil production today, even if we only acted on just part of his energy plan. This is the same plan Brazil instituted back then and is now benefitting from. Why didn't this plan take hold here??
It would not be impossible to end our dependency as we already have the technology, resources and motivation. It would have to be done over the course of a decade... like adding taxes to oil/gas every year motivating people to make the switch to alternate energy sources.