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LAS VEGAS, NV - AUGUST 24: U.S. President Barack Obama delivers the keynote address at the National Clean Energy Summit 8.0 at the Mandalay Bay Convention Center on August 24, 2015 in Las Vegas, Nevada. Political and economic leaders are attending the summit to discuss a domestic policy agenda to advance alternative energy for the country's future. (Photo by Ethan Miller/Getty Images)

LAS VEGAS, NV - AUGUST 24:  U.S. President Barack Obama delivers the keynote address at the National Clean Energy Summit 8.0 at the Mandalay Bay Convention Center on August 24, 2015 in Las Vegas, Nevada. Political and economic leaders are attending the summit to discuss a domestic policy agenda to advance alternative energy for the country's future.  (Photo by Ethan Miller/Getty Images)