The Western Electricity Coordinating Council (WECC) has notified NorthWestern Energy that the Mountain States Transmission Intertie (MSTI), a proposed project in Montana, has been approved to carry up to 1.5 GW of electricity north to south and up to 1.1 GW south to north.
Energy carried on the MSTI line will be generated primarily from renewable electric generating facilities located in Montana. This electricity will be sold by those generators to customers to help fulfill new energy demand and renewable portfolio standards established by western states.
WECC's three-phase rating process is a comprehensive technical planning study that defines the transfer limit a new transmission line (or lines) can achieve without interfering with the reliability or stability of other lines in the Western Interconnection. In addition to technical modeling, the path-rating process requires a peer review by all interested transmission providers and other stakeholders.
NorthWestern was recently notified that the project has received ‘Phase 3’ status, which means that the study has been concluded, the path rating has been established and MSTI can be constructed with the approved rating. Phase 3 concludes when the project is placed into service.
‘This is an important project milestone that has been several years in the making,’ says Mike Cashell, NorthWestern's vice president of transmission. ‘We still have much work to do before MSTI is in operation, but this and other recent studies affirm the regional benefit of this project to spur new energy development and alleviate congestion on the existing system.’
MSTI is still working its way through provisions with the Bureau of Land Management and Montana Department of Environmental Quality, as the path rating is independent of the siting process.