Over the last few years, the Midcontinent Independent System Operator (MISO) developed a new plan for a set of lines (known
as Tranche 1) in its region that would enable around 56 gigawatts (GW) of new renewables. This plan was based on scenario modeling of state and utility emissions reduction goals that showed carbon emissions falling by more than 60% in 2040 from 2005 levels. The Tranche 1 portfolio was approved by the MISO Board of Directors on July 25, 2022.
The MISO Board of Directors recently approved 18 new transmission lines, representing the largest transmission expansion to enable low-cost clean energy in U.S. history. This report authored by Rob Gramlich of Grid Strategies LLC for American Council on Renewable Energy and the Macro Grid Initiative examines how MISO’s evaluation of the benefits of transmission was critical in enabling that expansion. The report also compares the benefits MISO used with those suggested in the U.S. Federal Energy Regulatory Commission’s (FERC) Notice of Proposed Rulemaking (NOPR) on transmission planning.