Capacity vs energy: a primer

Next week, ISO New England will run the 13th Forward Capacity Auction to secure the power system resources needed to meet peak demand in 2022-2023. The auction is run annually to ensure the region has the necessary resource capacity three years into the future. But what is capacity, and how does it differ from the energy markets the ISO runs on a day-ahead and real-time basis? ISO New England has put together a primer on these two measurements of energy, and how the two types of markets play into running the New England power system.