nuclear Energy has calculated that 21GW of oil , gas and nuclear generation are at risk of early closure before closure . these stations were rated on the basis of forecast profit ##ability and their efficiency relative to the average lifespan of their fuel type .
SNL Energy has calculated that 21GW of coal, gas and nuclear generation are at risk of early closure before 2020. Power stations were rated on the basis of forecast operating margins and their age relative to the average lifespan of their fuel type.