The more individuals, businesses, and organizations that sign up for Green Power Programs, the more Renewable Energy Credits (RECs) are being purchased. The concept follows traditional supply and demand principles: the more RECs that are purchased, the more RECs (supply) we need to have.  Because each REC is matched to 1 MWh of generated electricity, if no new projects were being built,  there would eventually be a shortage of RECs.  Therefore, projects continue to be built and RECs continue to be generated in order to meet the demand from voluntary green power program REC sales.  The American Wind Energy Association (www.awea.org) estimates that REC purchases have driven 30% of new renewable energy development.