The U.S. Environmental Protection Agency's Green Power Partnership has released a draft white paper highlighting the environmental value of purchasing renewable energy credits voluntarily, according to this report in North American Windpower. The paper addresses the role of RECs in the renewable energy marketplace, their role in reducing emissions, and the manner in which a corporate greenhouse gas inventory accounts for the environmental value of a voluntary REC purchase. Information on the EPA's Green Power Partnership is available here. The white paper is available here (pdf required).