Fuel from algae-based oil can gradually replace petroleum diesel as our major fuel source. (Google algae and biodiesel)
Incentives and profits can be shifted from petroleum-based fuels by citizen or government action. (Google fuel tax incentives)
Vehicle Manufacturers can produce more diesel hybrid cars and trucks, the transportation industry can use increasingly higher blends of biodiesel to petrodiesel. (Google VW, Mercedes, Daimler/Chrysler)
With less dependency on oil in general, our dependency on foreign (and I by this I mean, not in your particular geographic region irrespective of national borders) is reduced in particular.
With less dependency on foriegn oil, less international disputes over energy and oil will be required.
World Peace has more of a fighting chance to be discovered/enacted/effected by 2020.