According to this Wall Street Jounal article of June 15, a study conducted earlier this year compared the cost of eliminating one ton of CO2 emissions using different means: Wind power cost about $38 per ton of CO2 saved; solar cost about $30. But replacing incandescent lights in a home with light-emitting diodes saved about $159 per ton of CO2, and using energy-efficient appliances saved about $108 per ton.

http://www.efficiencyfirst.org/blog/2009/06/15/the-u-s-government-o...