When I was in the generation industry we called these base and peaking plants. The 5 nuclear plants were base loaded, a portion of the fossil plants were the l

When I was in the generation industry we called these base and peaking plants. The 5 nuclear plants were base loaded, a portion of the fossil plants were the load following units then there were the required number of spinning reserve plants. These spinning reserve plants, which are running and using fuel but not producing electricity are what utilities would like to replace first.