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| Fig. 1: Energy losses for selected years from U.S. EIA. [1] (Image Source: M. Eliades). |
Electrical energy produced at generators must traverse high-voltage transmission lines, transformers, substations, and lower-voltage distribution circuits before reaching end-use customers. Energy dissipated in conductors and equipment, together with metering and balancing adjustments, is recorded by the U.S. Energy Information Administration as transmission and distribution loss. [1] Engineering literature attributes these losses primarily to resistive heating, transformer load and no-load losses, reactive power flows, and operational constraints such as congestion; contemporary policy analyses emphasize that targeted transmission and substation upgrades can materially reduce losses where currents are persistently high. [2,3]
To state a defensible national figure in physical units, we use the latest EIA figures. For 2023, the EIA reports 4,183 billion kWh of net generation and 191 billion kWh of T&D losses (including unaccounted for), corresponding to ≃ 4.6% of net generation. [1] I deem this statistic to be the most defensible single-year estimate of electrical energy losses in transmission and distribution for 2023; the publishing agency is statutorily mandated to collect, analyze and publish impartial and independent energy statistics in the United States, often being responsible for performing analyses at the request of Congress. [4]
Absolute T&D losses scale with system size, loading patterns, and infrastructure vintage. MER Table 7.1 values indicate that U.S. losses (including unaccounted for) were on the order of a quarter-trillion kilowatthours in the early 1990s and have remained in the 200-260 TWh band in subsequent decades, even as total generation increased and operational practices improved. [1] In the most recent interval, totals near 190-210 TWh are common (see Fig. 1 for selected years, 1990-2023). [1] The long-run tendency is that the fraction of electricity lost has converged toward the mid-single digits, a pattern consistent with widespread use of higher-voltage backbones, improved transformer fleets, and more sophisticated system operations. [2,3]
A simple revenue cross-check, multiplying the 2023 loss energy by typical all-sector average retail prices, yields an order-of-magnitude dollar value in the tens of billions, although prices vary materially by sector and region and are not the focus here. Utility-level engineering assessments show that the dominant share of transmission and distribution losses arise from I2R dissipation in conductors and transformer windings, and that these can be mitigated by targeted measures such as voltage optimization, reconductoring with higher-ampacity conductors, and transformer upgrades. [3] Federal scenario analyses likewise find that expanding transmission capacity reduces congestion and associated efficiency losses, improving reliability and enabling greater access to low-cost generation, particularly under high-transfer conditions where thermal limits would otherwise constrain flows. [2] Peer-reviewed market studies further emphasize that relieving transmission constraints yields substantial cost and resilience benefits, of which lower technical losses form one component. [5]
Using finalized federal statistics, U.S. transmission and distribution systems dissipated approximately 4.6% of net-generated electrical energy in 2023. [1] This magnitude is large in absolute energy terms yet represents a relatively small fraction of national generation, consistent with a mature grid. [1] Because resistive losses are primarily driven by current and concentrated in specific network elements such as conductors and transformers, incremental reductions are most effectively achieved through selective, data-driven upgrades rather than uniform material replacement. [3] Broader modernization of the transmission system, as evaluated in recent national studies, is expected to deliver additional efficiency gains alongside its primary reliability, cost, and integration benefits. [5]
© Marinos Eliades. The author warrants that the work is the author's own. The author grants permission to copy, distribute and display this work in unaltered form, with attribution to the author, for noncommercial purposes only. All other rights, including commercial rights, are reserved to the author.
[1] "Monthly Energy Review, September 2025," U.S. Energy Information Administration, DOE/EIA-0035(2025/9), September 2025, Table 7.1.
[2] R. Wiser et al. "Transmission Impact Assessment," U.S. Department of Energy, October 2024.
[3] "Assessment of Transmission and Distribution Losses in New York," Electric Power Research Institute, November 2012.
[4] "The U.S. Energy Information Administration," Congressional Research Service, R46524, September 2020.
[5] J. M. Kemp et al., "Electric Transmission Value and Its Drivers in United States Power Markets," Nat. Commun. 16, 8055 (2025).