For decades capacity and capacity reserve have been used to determine if enough generation exists to meet demand. While some de-rating of plants is done for conditions, basically the size of the facility has dominated the capacity rating.
A recent blog indicating one-third of global capacity was renewables got me to thinking – is raw facility size useful anymore? If a natural gas fired generator is denied fuel, do they have available capacity? At night does PV count? Does solar plus storage with a 4-hour battery count at 4 AM? On a stormy day does a wind farm count?
I am not arguing that capacity should only be made up of facilities with fuel on site.
I am asking if the idea of capacity useful to answer the question: “can we get thru the winter season with the energy that we have available?”
This is a more complex question than capacity. Into this energy equation would go demand response (hours contracted times megawatts), the seasonal total output of each type of power plant based on contracted fuel or historical weather. Hydro would include water is in the reservoir.
This does not answer the question of meeting peak. The next step would be – At specific times can we meet demand?