The U.S. Energy Information Administration (EIA) has estimated the potential savings from a nationwide 25% renewable electricity standard, a goal included in the Waxman-Markey energy bill that narrowly passed the House last year. Best-case scenario: about 306 million tons less CO2 by 2030. Given that the agency expects annual U.S. carbon emissions to be about 6.2 billion tons in 2030, that expected reduction will only equal about 4.9% of emissions nationwide. That's not much when you consider that the Obama administration wants to cut CO2 emissions 80% by 2050.