Renewable Energy Credits Losing Luster With McDonald's, Whole Foods, PepsiCo - Businessweek
From the article in part but read the entire article yourself for context.
"For years, thousands of companies have purchased renewable energy credits, known as RECs, to say they use green power and to shrink their carbon footprints. Now, as skepticism mounts about whether RECs achieve their claimed environmental benefits, the market for these credits is slowing—and a number of companies, from Whole Foods Market (WFM) to McDonald’s (MCD), are quietly scaling back their involvement."