Coal fired power plants have essentially been regulated out of existence in the US.  Dirt cheap natural gas has hastened the process.  Mileage rules for automobiles have reduced their use of petroleum significantly and that regulation is extending into light trucks and commercial trucks.  Most new regulation has occurred under Democratic administrations.  A counter trend is the petroleum glut which has pulled the stops out on driving.  I would like to see the return of 100$/bbl crude petroleum, in part because that would speed the transition to cleaner energy sources.