Part of the rooftop photovoltaic array is seen on the roof of the U.S. National Renewable Energy Laboratory Research Support Facility (RFS) in Golden, Colorado September 4, 2013. The 800 occupants of ... more 
Part of the rooftop photovoltaic array is seen on the roof of the U.S. National Renewable Energy Laboratory Research Support Facility (RFS) in Golden, Colorado September 4, 2013. The 800 occupants of the RFS building consume only the amount of energy generated by renewable power on and near the building. REUTERS/Rick Wilking (UNITED STATES - Tags: ENVIRONMENT ENERGY) less 
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Reuters | Photo By RICK WILKING / REUTERS
Mon, Sep 9, 2013 12:46 PM EDT