The title reads “EPA” but I wonder if it was the DOE actually.
It is the EPA. They do not set limits on power capacity of a electric plant. They set the limits for the emissions that plant can produce per unit of energy. In this gas grams per kilowatts hour. NOx , SOx, lead,mercury, arsenic, particulates as well. There is a fundamental physics limit based on combustion conditions for a given mass of air flow of how much NOx will be produced. Higher temps equals more NOx emissions that’s a function of physics. The plants have a limit as to how much they can make per kWh so the operator has to choose who to meet that limit. They could run high temps max output limited by the plastic melting temp of the high pressure turbines first stages they would have to install SCR catalysts to destroy the high levels of NOx such combustion would create. The other choice is to not run that hot and keep the NOx levels inside the legal limits by reduced combustion temperature this of course due to the rules of thermodynamics means lower total power output. Again within the legal limits of the amount produced per kWh in this case less kWh for equal emissions to stay under the legal limits. The third choice is to modify the combustion parameters from lean or rich to a staged combustion process Georgia tech has a combustion that uses lean burn to drop the O2 level in the first stage and then rich burn to.raise the temps and this power output without the NOx of a pure high O2 burn. Both the scr and stage combustion cost $$$$ so most plants run right up to the NOx limits with out control technologies it is the emissions limits that set max power for a given set of combustion parameters.
Abbot asked for a waiver of the emissions limits so that plants who have not out in SCR or staged combustion could run way WAY over the NOx limits and burn the turbines right up to the plastic melting temps of the turbines it’s like adding nitrous to a drag racing car once you add in the extra fuel and nitrous power output jumps but you are now well outside normal and permitted operating conditions. In the gas turbines case upwards of a hundred times the emissions limits. The reason the high price per mwh was to discourage the whole.scale use of rich burning and saving thousands of tons of toxic nitric oxide emissions which cause smog, acid rain, and if inhaled respiratory distress syndrome. These plants could have already installed SCR or staged combustion and they would have been able to operate at max combustion temperature full time within the existing EPA pollution limits.