Lighting can account for 15-20% of your monthly electric bill. With recent advances in LED technology we are able to reproduce the same level of brightness for 1/5- 1/10th the power. This is a huge savings. If we all work together we can reduce this country’s electrical draw by 10%! That equates to a lot of CO2!
Here is some helpful information from the USgov Department of Energy.
http://www1.eere.energy.gov/buildings/ssl/using_leds.html