Document 50GGGBNooyEGj0rvoOj2xjomD

USCA Case #24-1190 Document #2062093 Filed: 06/27/2024 Page 27 of 123 67. Customers rely on electricity to power their health care and other personal devices, cool their homes, heat some homes (often our lower-income customers living in mobile homes and apartments with electric baseboard heating), and power important infrastructure, including gas pumps. Natural gas appliances also rely on electricity for ignition and, in the case of forced air furnaces, fans. 68. Even when customers have generators, as some critical infrastructure customers do, there is a limit to how much fuel is stored on site at each individual location. These factors all contribute to a significant environmental justice component to reliable electrical supply. 69. NorthWestern also cannot realistically construct 444 MW of new capacity in Montana to replace our current and future (starting in 2026) interest in Colstrip by the MATS2 compliance date of July 2027. This arises from both timing and regulatory constraints. From a timing perspective, it takes several years to bring new generation on-line. As illustrated by YCGS -- the most recent significant generation project -- the YCGS development process commenced in 2019 and YCGS is only now coming on-line. 444 MW of capacity would be more than double YCGS and correspondingly more difficult to construct and permit. 70. Additional rencwables would not reliably replace Colstrip, because of the associated intermittency issues. Additional coal capacity is infeasible for the same reasons as will result in result in shutdown of Colstrip by the end of 2031 under the GHG Rule. And additional natural gas capacity is problematic, both because of the CCUS requirements on new natural capacity under the GHG Rule, and because there is insufficient natural gas supply and pipeline capacity in Montana to bring hundreds of additional MW on line by the end of 2031, much less mid-2028. 26 Sierra Club FOIA 2025-EPA-04883 ED_018388_00000310-00027 SC_EVERSPLIT0006282