E3 was retained by a consortium of public and private utilities in the Pacific Northwest to evaluate regional resource adequacy under a resource mix that, for both economic and public policy reasons, is transitioning toward higher levels of renewable energy and storage and away from coal. The study used E3’s RECAP model to examine the reliability of different portfolios and reliability contributions of individual resources such as wind, solar, hydro, and energy storage. The study examined both near-term (2030) and long-term (2050) systems. The results found that the Northwest region needs new capacity in the near term to meet growing loads and compensate for planned coal retirements. In the long term, E3 found that deep decarbonization could be achieved if sufficient firm capacity was retained for reliability during times of low wind, solar, and hydro generation. While wind, solar, hydro, and battery storage could provide reliability benefits to the system, replacing all carbon-emitting firm resources with these alternatives was found to be impractical due to the large overbuild required. Study sponsors included the Public Generating Pool (PGP), a consortium of publicly owned utilities in Washington and Oregon; Avista Corporation; Puget Sound Energy; and Northwestern Energy.