As of 2011, new evidence has shown that there are large risks associated with traditional energy sources, and that major changes to the mix of energy technologies is needed. Several mining tragedies globally have underscored the human toll of the coal supply chain. New EPA initiatives targeting air toxics, coal ash, and effluent releases highlight the environmental impacts of coal and the cost of addressing them with control technologies. Events at the Fukushima nuclear plant have renewed doubts about the ability to operate many nuclear plants safely over the long term. Cost estimates for “next generation” nuclear units continue to climb, and lenders are unwilling to finance these plants without taxpayer guarantees.