Renewable Energy Credits
EarthEra
EarthEra provides a powerful new way for Americans, from large organizations to individual consumers, to reduce their carbon footprint and help build a clean energy future by purchasing renewable energy credits. EarthEra energy credits are Green-e certified, and 100% of your purchase price is invested in renewable energy sources.
TerraPass
TerraPass offeres renewable energy credits, and you can calculate your carbon footprint with their online calculator.