A method and system to report the environmental benefits of consumers' purchases of alternative fuels. The system tracks and stores the purchases of customers from a vendor of alternative fuels. The system calculates the environmental savings that a customer generates by using alternative fuel in place of standard fuels. Environmental savings may be calculated in terms of various metrics, including reduced carbon emissions, gasoline not consumed, or other environmental benefits. The system provides a marketplace that allows consumers to receive the benefit of the calculated environmental savings by selling, trading, or retiring the generated savings.