this is a great article to supplement this discussion...for those who might think that a megawatt is a megawatt regardless of source I encourage you to digest what they are saying when they state.....
The EPA didn’t consider the grid operators’ need for various grid services and attributes needed to maintain reliability, such as inertia, primary frequency response, reactive power support, system stability, system strength, frequency regulation, ramping, flexibility, dispatchability, black start capability, fuel and energy assurance, and extreme weather performance. Currently, those attributes are generally supplied by thermal power plants, according to the grid operators.
PJM, MISO, others warn of ‘significant power shortages’ from EPA’s power plant carbon rule