But a near tripling of natural gas prices in the past seven years has idled many gas-fired plants and put a damper on new construction.

• 天然气是一种相对洁净的能源，但是近三倍的天然气价格使得许多燃气发电厂在过去七年内遭到闲置，新的电厂的建设也受到了抵制。