Storage as a Transmission Alternative (SATA) refers to the deployment of grid-scale battery storage systems that provide specific services that would otherwise require new or upgraded transmission infrastructure. When environmental, permitting or siting constraints delay or prevent transmission expansion, strategically placed batteries can supply local capacity, relieve congestion, support peak-load management and strengthen stability at constrained network nodes. These services are validated through standard power-system studies – including alternating current (AC) load-flow, N-1 / N-k contingency and thermal-rating analyses – to confirm that storage can reliably resolve the specific grid constraints addressed by the planned reinforcement.  

Modern SATA deployments use inverter-based controls capable of fast active and reactive power response, voltage support and the provision of grid-forming or grid-following services. Real-time telemetry, grid-modelling tools and advanced dispatch algorithms ensure that batteries act on the timescales required for contingency support and thermal-overload mitigation. Unlike traditional transmission assets, SATA solutions can be deployed rapidly, configured modularly and operated flexibly to address local constraints, while recognizing that they do not substitute for long-distance bulk transfer capacity. As non-wires alternatives become more sophisticated, they increasingly offer utilities a viable option for maintaining system adequacy, integrating renewables and optimizing capital expenditure in regulatory environments where storage may not yet be formally recognized as a transmission asset. 

Main outcomes of the solution 

• Reliability & Flexibility: Provides transmission-level services – such as local capacity, congestion relief, voltage support and peak-load management – at the specific points where the grid is constrained. Batteries can respond within milliseconds through power-electronics interfaces, offering fast flexibility when traditional lines cannot be built or expanded. 
• Affordability: Can avoid or defer selected transmission upgrades by relieving bottlenecks with targeted storage deployments. Reduces congestion-related expenditures and improves the utilization of existing grid assets, supporting more efficient capital allocation. 
• System Resilience: Strengthens resilience during outages, contingencies and extreme-weather events by placing flexible capacity directly at vulnerable nodes. Storage can maintain service, support emergency operations and stabilize the grid when conventional infrastructure is stressed. 

Key Deployment & Scaling Factors 

1. Identify grid corridors where new transmission lines cannot be built or expanded due to permitting, environmental or urban-density constraints. 
2. Use load-flow, congestion and hosting-capacity analysis to determine optimal battery locations and confirm that storage can reliably deliver the required transmission functions. 
3. Integrate SATA assets into existing operational processes — including contingency analysis, congestion management and real-time dispatch — so batteries operate as part of the transmission system. 
4. Establish mechanisms that allow storage to be procured, compensated and included in the rate base for providing transmission-equivalent services, even if it is not yet formally defined as a transmission asset. 
5. Combine utility-owned storage with contracted third-party assets (via RFPs or service agreements) to speed deployment and ensure reliable performance in regulated utility environments. 
6. Ensure accurate telemetry, model integration and data quality, as transmission-related services require precise real-time visibility and reliable control signals 

Case Study

Portland General Electric (PGE) and Eolian (2022), USA

In Portland, Oregon, additional energy supplies from renewable resource-rich regions in the eastern part of the state were constrained by a lack of transmission capacity crossing the volcanic Cascade Mountains. In 2009, local utility PGE proposed a new set of 500 kV lines called Cascade Crossing but ultimately abandoned the project in 2013 due to environmental and permitting constraints. Meanwhile, load growth and datacenter deployment was accelerating in the ‘Silicon Forest’ of northwest Portland, adjacent to the landing point of multiple transpacific fiberoptic cables and a massive Intel microchip fabrication facility. To address growing bottlenecks and enable the delivery of additional energy to the urban core, Eolian partnered with Portland General Electric (PGE) to construct large-scale battery storage as a transmission alternative, providing rapidly-deployed capacity and congestion relief without building new lines. The solution was envisioned by PGE in their IRP process and then procured through a 2022 RFP. Contracts were executed in mid-2003 and construction began almost immediately, and the solution now operates through a mix of utility-owned and contracted storage facilities. Eolian began the development and permitting of the projects in 2017, anticipating the growing mismatch between load growth, transmission utilization and regions of viable clean energy development. The projects were intentionally located at critical flowgate substations inside the load pocket that allowed for charging with low-cost energy using spare transmission capacity during off-peak hours and then direct delivery into the region’s primary bulk transmission network during hours of maximum congestion and peak demand hours.  

According to PGE, 475 MW of battery energy storage has been energized – representing 1.9 GWh of installed capacity – to enhance grid reliability, manage peak load and reduce congestion across critical network nodes. Strategically-sited assets deliver the functional equivalent of planned transmission upgrades within Oregon’s regulated-utility framework, where SATA is not yet formally defined in regulation. This project demonstrates how grid-scale storage can serve as a rapid, non-wires alternative in dense urban environments or locations where traditional transmission expansion is constrained.[1,2]

References:

1. Portland General energizes 1.9 GWh of lithium batteries in major storage expansion I Utility Dive (August 2025) 
2. PGE Energizes 475 MW of Battery Energy Storage to Boost Grid Reliability and Keep Costs Low for Oregonians I PR Newswire (August 2025)