An increasing number of utilities in the U.S. offer renewable energy purchasing options. These special programs, called green tariffs, allow a class of customers to source up to 100% of their electricity from renewable resources. A green tariff customer purchases the renewable energy and associated renewable energy certificates (RECs) and the utility adds an additional line item on the electric bill. For more information, see the American Cities Climate Challenge Cities Renewables Accelerator’s Green Procurement Foundation webinar, which describes Green Tariffs in more detail.