Al Gore set a goal for the US to derive all its electricity from solar, wind & wave energy within 10 years (not as some have thought, to derive all its _energy_ from those sources - the latter would include vehicle fuels; the former does not).
That seems hard to do.
But suppose we set the goal of cutting electrical use substanially and then deriving that lower amount from alt. sources? That would be a LOT easier, if only we could make large cuts in elec. usage.
It now appears that we can cut our use of electricity for lighting by say 80% - and do so easily within 10 years. The article below says LED based and cheap lighting avialable in a couple of years.
http://blogs.zdnet.com/emergingtech/?p=985