Navigating Large Load Interconnections in the Western U.S.

The demand for large load interconnections across the Western Electricity Coordinating Council (WECC) region is accelerating.  Several forces are driving this shift – ambitious decarbonization targets, rapid electrification of buildings and transportation,  and the exponential growth of data centers and AI infrastructure.  

What’s Driving Load Growth? 

States across the West are taking bold steps to reduce carbon emissions. On the generation side, the transition to cleaner energy sources requires significant additional renewable resources to supply load demand. On the load side, we’re seeing substantial electrification of everything from fleets and freight operations to warehouses and logistics centers. Charging infrastructure for electric trucks, forklifts, and delivery vehicles is expanding – creating entirely new load profiles.  

Compounding this shift is the explosive growth in data centers, fueled by AI, that require high-density, high-reliability power. The load demand forecast simply cannot be properly served by the existing transmission system with the existing resources in place. The result: utility load forecasts are outpacing existing transmission capacity and resource availability in many parts of the WECC region. 

Not Uniformized Utility Interconnection Processes  

The processes in place for new large load interconnections vary from utility to utility – and they are evolving.  Outside of CAISO, most WECC utilities require a new Transmission Service Request (TSR) to connect large loads. Unlike generation interconnection requests, these are not currently subject to open window processes. However, they still require in-depth study to evaluate: 

• The capability of the grid to serve the new load 
• Potential system impacts and limitations 
• Necessary transmission upgrades or mitigations 

These requirements vary from utility to utility and will likely evolve over time. For investor-owned utilities (IOUs) in the state of California and under the operational control of the CAISO, several tariffs exist for new load interconnection requests.  Specifically, Rule 2, Rule 15/16, Rule 21, Wholesale Distribution Access Tariff, and the utilities’ Transmission Owner Tariffs. New tariffs are being developed, such as PG&E’s proposed Rule 30, geared for interconnecting large data center loads. 

Transmission Upgrades Are Often Required 

Unless located in a “sweet spot” with available transmission headroom, new large load interconnection requests will likely need costly and time-consuming transmission- level upgrades. That’s why proactive planning and site evaluation are essential to avoid delays and costly surprises. 

How EPE Can Help  

EPE helps clients navigate the complexities of large load interconnections across the WECC region. Our services include: 

• Navigating interconnection processes for both load and generation across WECC utilities  
• Evaluating available transmission capacity across major utilities to identify optimal interconnection locations  
• Conducting due diligence and feasibility assessments to minimize risk and maximize speed-to-power 
• Stay ahead of shifting regulatory requirements to guide your strategy with foresight and precision 

Whether you’re planning a large-scale electrification project or a mission-critical data center, EPE helps you to ensure your interconnection path is smart, strategic, and future-ready.