On February 10, 2021, the Midcontinent Independent System Operator (MISO), an Independent System Operator (ISO) that monitors the electric grid in 15 U.S. states and the Canadian province of Manitoba, published its Renewable Integration Impact Assessment (RIIA).[1] RIIA’s purpose was to better understand the long-term impacts of renewable energy growth in the Eastern Interconnection bulk electric systems with a focus on the MISO footprint, provide examples of integration issues, and examine potential solutions to mitigate them. The report examined renewable penetration levels in 10% increments up to 50%. As of 2021, about 13% of MISO’s systemwide energy is generated from renewables, including 26 GW of wind and 1 GW of solar. There are agreements in place for an additional 6GW of wind and 10GW of solar, bringing renewables penetration up to 20% of total energy. MISO predicts that 30% renewable penetration could be achieved by 2026.

RIIA found that renewable penetration under 30% would be manageable within MISO’s existing framework. However, beyond 30%, transformative thinking and coordinated action between MISO and its stakeholders will be required to manage the challenges associated with renewable penetration such as resource adequacy and reliability. The report also notes that renewable growth is not happening uniformly and nearly 80% of renewable resources in MISO are in the northwest region of its footprint, which concentrates current integration challenges to one area. Reaching 30% penetration, though, would mean that those challenges will be system wide. The study concluded that 50% renewable penetration is achievable, but will require changes in planning, operations, and markets to accommodate more variable energy sources.

[1] https://cdn.misoenergy.org/RIIA%20Summary%20Report520051.pdf