U.S. President Barack Obama arrives to speak about energy during a visit to a Wal-Mart store in Mountain View, California May 9, 2014. Walmart will double by 2020 the number of on-site solar energy ... more 
U.S. President Barack Obama arrives to speak about energy during a visit to a Wal-Mart store in Mountain View, California May 9, 2014. Walmart will double by 2020 the number of on-site solar energy projects at its U.S. outlets and distribution centers, the company announced, during an event attended by Obama on Friday. REUTERS/Kevin Lamarque (UNITED STATES - Tags: POLITICS ENERGY BUSINESS) less 
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Reuters | Photo By KEVIN LAMARQUE / REUTERS
Fri, May 9, 2014 1:10 PM EDT