By Guillermo Bautista Alderete T THE CALIFORNIA INDEPENDENT SYSTEM OPERATOR (CAISO) IS ONE of nine independent system operators (ISOs) in North America. Its primary responsibility is to ensure the safe and reliable delivery of electricity on the power grid. CAISO manages the flow of electricity for about 80% of California and a small part of Nevada, which encompasses all of the investor-owned utility territories and some municipal utility service areas. The ISO wholesale energy market is comprised of day-ahead and real-time processes. The energy products and services traded in its markets allow the organization to meet reliability needs and the serve load at the least cost. The ISO is responsible for ensuring fair, nondiscriminatory, and transparent access to the transmission network and market transactions. In 2014, CAISO, together with PacificCorp and other balancing areas, designed and implemented the energy imbalance market (EIM). The EIM allows participants to buy and sell power close to the time in which electricity is consumed and gives system operators real-time visibility across neighboring grids. Figure 1 displays the footprint of the CAISO balancing area and that of the EIM. About 82% of the load in the Western Interconnection is either active in or already committed to participating in EIM by spring 2022. This real-time market improves the balancing of intrahour supply with demand at a lower cost than could otherwise be achieved by hourly or 15-min scheduling practices. In addition to the optimized balancing of supply and demand, EIM manages congestion on the transmission system to maintain grid reliability and support the integration of renewable resources. The western EIM also makes Energy Insecurity Due to Gas Supply Availability Digital Object Identifier 10.1109/MPE.2020.3043612 Date of current version: 19 February 2021 28 ieee power & energy magazine 1540-7977/21©2021IEEE march/april 2021