Large Loads and System-Wide Transmission

This policy brief by RMI argues that system-wide transmission planning is a more efficient and lower-risk method for integrating large loads, such as data centers, into the electric grid compared to the site-specific load interconnection process. The document outlines how comprehensive planning—which typically looks 5 to 20 years ahead—can reduce piecemeal network upgrades and deliver higher benefit-to-cost ratios through scenario planning and phased investment triggers.

• System-wide transmission planning is more efficient and provides greater value than the customer-by-customer load interconnection process. Analysis of seven system-wide projects in the United States showed benefit-to-cost ratios ranging from 1.1 to 3.9. Specifically, the Valley–Colorado River project near Los Angeles has provided annual benefits approximately 3.3 times its cost since 2013.
• While system-wide planning cycles are slower (taking one to three years), the overall timeline for transmission development is dominated by downstream approval, permitting, and construction. In PJM, system-wide planning takes 1.5 to 2 years, whereas upgrades identified via the interconnection process since 2015 have required an additional 2.3 to 4.8 years on average to become in-service after approval.
• Scenario planning can mitigate the financial risks of load growth uncertainty by identifying 'least-regrets' projects. The Southwest Power Pool's (SPP) 2025 Integrated Transmission Plan, which includes $19 billion in projects and over 2,000 miles of 765 kV backbone transmission, demonstrated benefit-to-cost ratios of 9.4 in a high-growth future and 5.7 in a lower-growth future.
• Phased or modular planning allows utilities to scale investments based on actual demand triggers rather than 'all or nothing' strategies. ERCOT's Delaware Basin Load Integration study identified five trigger stages based on peak demands between 3.1 and 5.4 GW. Similarly, NV Energy's master plans for Western Nevada and Apex use phased investments aligned with projected load percentages (30%, 60%, 100%) to avoid piecemeal expansion.

APA

RMI (2026). Large Loads and System-Wide Transmission. https://rmi.org/resources/large-loads-and-system-wide-transmission/

Chicago

RMI. Large Loads and System-Wide Transmission. 2026. https://rmi.org/resources/large-loads-and-system-wide-transmission/.

Wikipedia

{{cite report |author=RMI |title=Large Loads and System-Wide Transmission |date=14 April 2026 |url=https://rmi.org/resources/large-loads-and-system-wide-transmission/ |access-date=17 August 2026 |via=Climate Insights Directory}}

BibTeX

@techreport{rmi2026large, author = {{RMI}}, title = {{Large Loads and System-Wide Transmission}}, institution = {RMI}, year = {2026}, month = apr, url = {https://rmi.org/resources/large-loads-and-system-wide-transmission/}, urldate = {2026-08-17}, note = {Indexed by Climate Insights Directory} }