Entergy’s large transmission system and five operating companies in Louisiana, Arkansas, Mississippi and eastern Texas have been integrated into the Midcontinent Independent System Operator (MISO).  This extends MISO’s footprint to 15 states from Canada down to the Gulf of Mexico, making MISO the largest Regional Transmission Organization (RTO) by geography.  The integration adds about 18,000 miles of transmission lines and 40,000 MW of generation to the MISO footprint.

Both MISO and Entergy have described the customer benefits that joining MISO will provide, including an estimated $1.4 billion in cost savings for customers and associated operational efficiencies.  A number of other transmission owners and market participants in the Entergy region joined MISO as well, riding the coat tails of Entergy.

RTOs such as MISO dispatch generation, operate day-ahead and real-time energy and ancillary services markets, control the transmission grid and maintain reliability over a defined region.  As a general matter, increasing the geographic scope of the RTO increases dispatch efficiencies and provides benefits to customers and other market participants.  In orders issued by FERC more than a decade ago that defined the RTO concept, FERC specified large regional scope as an important feature that would enhance the value of the RTO as a grid manager and market operator.  At FERC’s December 19 public meeting, Acting Chairman LaFleur and Commissioners congratulated MISO and Entergy on the successful integration.