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Central Maine Power outlines two‑phase plan to bolster Portland electric grid
Summary
Central Maine Power presented a two‑phase plan to add 115 kV capacity into Portland, including a new Bayside substation and an eventual submarine or underground route to the peninsula; CMP said phase 1 will be filed with regulators this summer and could take about six years to construct.
Central Maine Power officials told the Sustainability and Transportation Committee Wednesday that CMP plans a two‑phase transmission and substation program to relieve capacity and reliability constraints in greater Portland and to support electrification goals.
CMP Senior Director of Integrated System Planning Chris Moore said the utility has identified capacity, asset health and reliability shortfalls across a study area that spans Cumberland to Scarborough and includes the Portland peninsula. Officials said the system currently relies heavily on 34 kV and limited underground transmission into the peninsula; losing a key element in the southern loop could affect tens of thousands of customers.
CMP proposes closing a 115 kV gap by building a new 115 kV line and a new Bayside substation near the Water District wastewater plant on the East End. Phase 1 focuses on using existing rights‑of‑way where possible, rebuilding some 34 kV lines to higher capacity, decommissioning Elm Street substation assets by moving them to Raven Farm, and rebuilding East Deering substation to accept 115 kV supply. CMP said the new Bayside substation would add roughly 100 MVA of capacity and would allow load to be redistributed from two heavily loaded peninsula substations.
Phase 2 addresses routing transmission from the Bayside substation into the Portland peninsula. CMP showed possible underground routing coordinated with the Franklin Arterial reconstruction and an option that would use a submarine cable across the harbor into South Portland. The utility said sea‑level rise and flood‑plain exposure at existing substations (for example, Cape Substation) are part of the reason CMP is exploring relocation or alternate routing.
Schedule and next steps: CMP plans to file the phase 1 proposal with the Maine Public Utilities Commission this summer and expects a roughly one‑year regulatory process; construction would follow and is estimated at about five years after approval (about six years total). Phase 2 will be developed with more city coordination and CMP aims to file later next year so both phases can meet the same service date. CMP representatives said they are coordinating with city planning and public‑works staff and with stakeholders including the Port, South Portland and the Greater Portland Council of Governments.
City sustainability staff said the project is important to reach local decarbonization goals because electrification will more than double expected demand in some parts of the peninsula. CMP officials noted the project will include formal public outreach as part of the certificate process; they plan mailed notices to abutters, an FAQ/fact sheet and media outreach timed with the formal PUC filing. CMP and city staff said they had already met several times with municipal departments to coordinate routes, dredging and other timing considerations.
Ending: CMP will file phase 1 with the Maine PUC this summer; the city will continue coordinating routing decisions for phase 2 and CMP said it will engage publicly when the filing goes live.
