NorthWestern Energy All Source RFP 2025

NorthWestern Energy Public Service Corporation is issuing an all-source request for proposals for capacity resources to serve its South Dakota system. The RFP seeks qualified bidders to submit technical and commercial proposals for supply-side capacity resources with availability for delivery by the end of 2029 or latest by June 2030. NorthWestern has identified a near-term accredited capacity need ranging from 50 MW to 100 MW, with certain planning scenarios indicating potential needs up to 250 MW.

Eligible technologies include storage, renewable, thermal, and combinations thereof. Contract structures may include asset purchase agreements (APA), build-transfer (B-T) agreements, power purchase agreements (PPA)/energy storage agreements (ESA), or other structures satisfying RFP requirements. Capacity accreditation shall be based on Southwest Power Pool (SPP) methodology. Resources must be located in South Dakota service territory and SPP Upper Missouri Zone preferably, with site control requirements. Bidders must demonstrate adequate progression of key development activities including federal, state and local permitting; stakeholder outreach; design; project execution planning; and financing. Resources must adhere to detailed technical requirements including utility-grade system design, equipment redundancy, and operational capabilities. For energy storage, a maximum of 50 MW of accredited capacity will be considered. Standalone resources should have a minimum accredited capacity of 20 MW unless paired with other resources, though smaller offerings may be proposed as alternates.

The RFP contemplates two submission tracks: intermediate ERAS offers due September 12, 2025, and firm capacity proposals due November 12, 2025. Intermediate ERAS offers represent expedited proposals for inclusion in SPP's Expedited Resource Adequacy Study (ERAS), with interconnection requests to SPP required no later than October 2, 2025. Firm capacity proposals follow traditional solicitation sequence with evaluation and negotiations expected through Q2 2026. Bidders must submit notice of intent to respond by August 29, 2025, along with safety forms and executed nondisclosure agreements. Two pre-bid meetings are scheduled: August 26, 2025 and October 8, 2025, both virtual at 1:00 p.m. CDT. Questions must be submitted by September 5, 2025 (for ERAS window) and November 3, 2025 (for general proposals).

Proposals will be evaluated on levelized costs over a 30-year period, commercial attributes including performance guarantees and credit quality, development status and timeline, and technical attributes including dispatchability and reliability. All proposals must include executive summaries, completed proposal forms, marked-up form agreements, and detailed supplemental information. Bidders must provide financial statements for the two most recent years, credit ratings if available, insurance coverage details, and safety history including OSHA records. Proposals must remain valid for minimum 180 days from submission deadline. All pricing must be in U.S. dollars including applicable taxes and fees, and must account for all electrical interconnection costs, network upgrades, and firm transmission service requirements.