Eesti Energia AS Oil Shale Production [Getty Images]

Vapor drifts from chimneys at Eesti Energia AS's Enefit 280 oil shale processing plant and energy production facility in Narva, Estonia, on Wednesday, Nov. 19. 2014. Eesti Energia is one of the world's largest oil shale to energy companies with an annual production of around 1.3 million barrels of shale oil. Photographer: Peter Kollanyi/Bloomberg via Getty Images

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