The ONLY way to attain a sustainable economy is to attain sustainable energy supplies entirely based on renewable energy. This 'transformation would easily provide the largest possible economic stimuli to World economies, IF done intelligently and on a massive scale. 
Historically, economic growth in America has been facilitated by increases in fossil fuel demand. The 'peak in the World's fossil fuel supply has placed us at an economic cliff and at the threshold of irreversible global warming. 
Read "Small is Beautiful" by English economist E.F. Shumacher 
Also, StopTheEnergyWaste.blogspot.com