Grid infrastructure statistics show a system measured in millions of miles, thousands of substations and generators, and increasingly large queues of proposed projects. The figures below separate observed inventories from forecasts and estimates, while keeping each geography and measurement period explicit.
Key Grid Infrastructure Statistics
The most useful high-level figures are:
- In the 2015 United States inventory, more than 642,000 miles of high-voltage transmission lines were recorded.
- In the same 2015 United States inventory, 6.3 million miles of distribution lines were counted.
- The 2015 United States electrical TS&D system linked more than 19,000 generators rated at least 1 MW.
- The 2012 North American assessment counted 15,000 transmission substations and 60,000 distribution substations.
- Meeting national climate and energy goals globally requires more than 80 million km of grid additions or refurbishment by 2040.
- Wind and solar PV are forecast to provide more than 80% of global power-capacity growth over the two decades after 2023 in the IEA national-goals pathway.
- About 1,500 GW of renewable projects were in advanced development awaiting grid connection globally in 2023.
- Global annual grid investment needs to exceed USD 600 billion by 2030 in the IEA assessment.
- Adding generation and grid capacity for one TWh is estimated at USD 30–110 million in emerging economies during 2023–2030.
- The corresponding estimate for advanced economies is USD 75–150 million per TWh during 2023–2030.
- The United States had 11,841 active generator interconnection requests at the end of 2023.
- Proposed generation capacity in United States interconnection queues totaled 1,565 GW at the end of 2023.
- U.S. electricity customers experienced about 11 interruption hours on average in 2024, including major events.
- Major events accounted for 80% of U.S. hours without electricity in 2024.
- DOE’s transmission assessment estimates an average 10-year completion time for high-voltage projects.
- Estimated within-region national transmission congestion reached about USD 20 billion in the United States in 2022.
Contents
- U.S. grid infrastructure scale
- Global grid expansion and renewable trends
- Grid investment, costs and modernization funding
- Interconnection queues and new transmission
- Reliability and outage statistics
- Transmission delivery, congestion and resilience
U.S. Grid Infrastructure Scale Statistics
The 2015 Quadrennial Energy Review: First Installment provides a United States electrical transmission, storage and distribution snapshot. Its inventory counted more than 19,000 generators of at least 1 MW at more than 7,000 operational power plants, alongside a high-voltage transmission network exceeding 642,000 miles and 6.3 million miles of distribution lines.
The figures are inventory measures, not a current-year census. The DOE report’s generator threshold, line definitions and report vintage should remain attached to the numbers.
The earlier Report on the QTR Tech Assessments – August 2012 uses a broader North American scope:
- The 2012 assessment described 180,000 miles of high-voltage transmission lines and 11 million miles of distribution lines across North America.
- It described 15,000 generators owned by 3,170 utilities and a service population of more than 143 million customers.
- The assessment counted 15,000 transmission substations and 60,000 distribution substations.
- A historical 2001 United States table listed 154,503 miles of AC high-voltage lines, which is not a current network total.
These values are not directly interchangeable: the QER figures are a 2015 United States inventory, while the technology assessment combines North American scope and an earlier vintage.
Global Grid Expansion and Renewable Trends
The IEA’s Electricity Grids and Secure Energy Transitions – Executive summary frames grid infrastructure as a capacity and connection constraint. Globally, meeting national climate and energy goals requires adding or refurbishing more than 80 million km of grids by 2040, approximately equal to the entire existing global grid according to the IEA comparison.
The technology mix is also changing. Wind and solar PV represented less than 40% of global power-capacity additions over the two decades before 2023, but the IEA national-goals pathway forecasts them at more than 80% of the increase over the next two decades; its Net Zero Emissions scenario places the share at almost 90%.
The connection pipeline shows the scale of the challenge. The IEA’s Lack of ambition and attention risks making electricity grids the weak link in clean energy transitions reported about 1,500 GW of renewable projects in advanced development awaiting connection globally in 2023, equal to five times the solar PV and wind capacity added worldwide in the preceding year.
The same IEA release estimates that global annual grid investment must exceed USD 600 billion by 2030. The comparison is a requirement tied to energy-transition goals, not a record of money already spent.
Grid Investment, Costs and Modernization Funding
The IEA’s Grid investments analysis gives regional cost-intensity estimates for 2023–2030. Adding generation and grid capacity for one TWh is estimated at USD 30–110 million in emerging markets and developing economies, compared with USD 75–150 million per TWh in advanced economies; the ranges are sensitive to the cost of capital and technology mix.
| Measure | Geography and period | Supplied figure |
|---|---|---|
| Additional electricity consumption | Emerging economies, through 2030 | Nearly 80% of global additional consumption is forecast to come from emerging economies |
| Capacity and grid cost per added TWh | Emerging markets and developing economies, 2023–2030 | USD 30–110 million |
| Capacity and grid cost per added TWh | Advanced economies, 2023–2030 | USD 75–150 million |
| Demand-response value | Australia, 2042 forecast | USD 11 billion per year |
The nearly 80% figure is an IEA 2026 outlook forecast for demand growth, not grid length. Australia’s USD 11 billion annual demand-response value is likewise a scenario estimate based on demonstrated mechanisms, not realized revenue.
United States programs illustrate the difference between authorization, availability and awards. DOE’s Grid Innovation Program has USD 10.5 billion authorized for fiscal years 2022–2026; DOE announced up to USD 3.46 billion for 58 projects across 44 states in 2023 and USD 2.2 billion for eight projects across 18 states in 2024.
The GDO Fact Sheet reports USD 2.3 billion available through the Grid Resilience State and Tribal Formula Grant Program, with more than USD 800 million awarded during the first two funding years to 48 states, over 170 tribal entities, three territories and Washington, D.C. It also identifies the Puerto Rico Energy Resilience Fund as a USD 1 billion program.
Interconnection Queues and New Transmission Statistics
The FERC State of the Market Report: The Need for Transmission cites preliminary LBNL queue data showing 11,841 active generator interconnection requests in the United States at the end of 2023. That was a 16% increase from the end of 2022 and about four times the 2019 level, although queue definitions can change over time.
| United States queue measure | Period | Figure |
|---|---|---|
| Active generator interconnection requests | End of 2023 | 11,841 |
| Proposed generation capacity in active queues | End of 2023 | 1,565 GW |
| Storage capacity in hybrid-storage and generation requests | End of 2023 | 299 GW |
| Standalone storage capacity | End of 2023 | 503 GW |
| Solar, wind and battery share of queue capacity | End of 2023 | About 95% |
The 1,565 GW represents proposed capacity, not operating assets. FERC also compared it with 1,268 GW of installed United States electricity-generation capacity, stating that the queue exceeded installed capacity by more than 20%; that comparison should not be read as a buildout forecast.
More than 500 new transmission projects entered service in the United States in 2023, producing more than 4,000 miles of new lines and upgrades, mostly at 138 kV. These counts include line upgrades and come from the FERC release’s cited C3 Group data.
Electric Grid Reliability and Outage Statistics
The EIA analysis, Hurricanes in 2024 led to the most hours without power in the United States in 10 years, reports about 11 interruption hours per United States electricity customer in 2024 when major events are included. Major events accounted for 80% of those hours, with nearly nine major-event interruption hours per customer in 2024 versus nearly four hours per year during 2014–2023.
Hurricane Beryl left 2.6 million Texas customers without power in July 2024. That is an event-specific customer count, not an annual reliability measure.
The EIA’s Electric Power Annual Table 11.3: Reliability Metrics Using Any Method of U.S. Distribution System by State, 2024 and 2023 shows how results vary across New England states and the census division:
| Area | 2024 all-event SAIDI | 2024 all-event SAIFI |
|---|---|---|
| New England | 419.6 minutes per customer | 1.382 interruptions per customer |
| Connecticut | 153.6 minutes per customer | 0.876 interruptions per customer |
| Maine | 1,748.6 minutes per customer | 3.636 interruptions per customer |
SAIDI measures interruption minutes and SAIFI measures interruption frequency. EIA combines utilities using IEEE and non-IEEE methods, major-event definitions differ, and reported-customer percentages can exceed 100% because of denominators.
Transmission Delivery, Congestion and Grid Resilience
DOE’s Transmission Impact Assessment: Power Sector Infrastructure Deployment to Reduce Costs, Improve Reliability, and Lower Pollution gives an average high-voltage project completion time of about 10 years. Its project-duration figure shows a 5–17 year 10th-to-90th-percentile range, indicating that a single average conceals substantial variation.
The same assessment’s chart shows new 345-kV-and-higher line completions falling from roughly 4,000 miles in 2013 to near zero in 2022. Its estimate of within-region national transmission congestion reached about USD 20 billion in 2022, representing congestion costs rather than utility capital spending.
DOE identifies several United States financing authorities in the 2024 assessment:
- The Transmission Facilitation Program received USD 2.5 billion for loans, capacity contracts and public-private partnerships.
- The Transmission Facility Financing Program received USD 2 billion in loan authority.
- The Grid Resilience and Innovation Partnerships program received USD 10.5 billion for transmission, storage and distribution infrastructure using innovative approaches.
These are funding authorities or program amounts, not necessarily deployed funds or completed projects.
Finally, NERC’s 2024 Long-Term Reliability Assessment identified 1,160 transmission projects under construction or in planning for the next 10 years across the North American bulk power system. More than 110 had been delayed from expected in-service dates, and siting and permitting issues affected 68 delayed projects totaling 1,230 miles of new transmission.
NERC’s inventory is a planning assessment, not a guarantee that every listed project will be completed. Across the dataset, grid length, queue capacity, reliability and funding use different geographies, definitions and vintages, so each measure should be interpreted within its stated population and period.