Transmission & Distribution

late 19th century · 226 years ago

Nikola Tesla and Hidetsugu Yagi attempted large-scale wireless power transmission

Both inventors devised systems for transmitting power without conductors in the late 1800s and early 1900s. Neither achieved commercial success, leaving wired transmission dominant.

late 1880s–early 1890s · 146 years ago

Smaller electric companies merged into Ganz, AEG, General Electric and Westinghouse

Consolidation created corporations able to develop AC systems at scale in Europe and the United States. Bridging DC and AC legacy equipment required rotary converters and motor-generators until a universal system emerged.

1881 · 145 years ago

Lucien Gaulard and John Dixon Gibbs built the secondary generator, an early 1:1 transformer

The pair constructed an open-magnetic-circuit transformer they called the secondary generator. It made transmission of alternating current practical by allowing voltage to be changed, which direct-current systems could not easily do.

1884 · 142 years ago

The International Exhibition of Electricity in Turin hosted the first long-distance AC line, 34 km long

A 2 kV, 130 Hz Siemens and Halske alternator fed several Gaulard transformers with series-connected primaries supplying incandescent lamps over 34 kilometres. The demonstration proved the feasibility of transmitting alternating current power over long distances.

1885 · 141 years ago

Rome's via dei Cerchi installation opened the first commercial AC distribution system for public lighting

Two Siemens and Halske alternators at 2 kV, 120 Hz supplied 19 km of cable and 200 parallel-connected step-down transformers with closed magnetic circuits, one per lamp. It marked the transition of alternating current from exhibition demonstration to commercial distribution service.

1885 · 141 years ago

The Grosvenor Gallery system became the first British AC system

Following the Rome installation by a few months, the London scheme used Siemens alternators and 2.4 kV to 100 V step-down transformers with shunt-connected primaries, one per user. It spread the AC distribution model beyond Italy.

1885 · 141 years ago

William Stanley, Jr. developed the first practical series AC transformer

Working to improve the Gaulard-Gibbs design he considered impractical, Stanley produced a transformer suited to real distribution service. It became the technical basis for the Westinghouse approach to alternating current supply.

1886 · 140 years ago

William Stanley, Jr. with George Westinghouse demonstrated a transformer-based AC lighting system in Great Barrington

A steam-driven 500 V Siemens generator was stepped down to 100 volts to light lamps at 23 businesses over 4,000 feet. The success led Westinghouse to begin installing AC systems later that year.

1888 · 138 years ago

Galileo Ferraris and Nikola Tesla independently invented the polyphase induction motor

The first designs for an AC motor appeared, running on polyphase current, with Westinghouse licensing Tesla's design. Practical three-phase machines followed from Dolivo-Dobrovolsky and Brown, though uptake was delayed by the scarcity of polyphase supply systems.

1890 · 136 years ago

The Willamette Falls hydroelectric plant made the first high-voltage single-phase AC transmission to Portland

Power was delivered 14 miles down river from the plant to the city of Portland, Oregon. It was the first use of high voltage for single-phase alternating current transmission.

1891 · 135 years ago

Engineers in Germany transmitted alternating current 175 kilometres from Lauffen to Frankfurt

Built for the international electricity exhibition in Frankfurt, the 15 kV line connected Lauffen on the Neckar to Frankfurt, a distance of 175 kilometres. It showed for the first time that three-phase alternating current could carry power over long distances with acceptable losses, settling a technical argument and establishing three-phase high-voltage transmission as the model for bulk power movement in every grid built afterwards.

1895 · 131 years ago

Tokyo and Osaka began building grids on incompatible electrical frequencies

Osaka imported German generating equipment running at 50 hertz while Tokyo bought American equipment running at 60 hertz, an early procurement choice that split Japan into two frequency zones and left the country needing costly converter stations to move power between them ever since.

1914 · 112 years ago

Transmission systems worldwide reached fifty-five systems above 70 kV, topping out at 150 kV

Voltages rose steadily through the early 20th century as interconnection of multiple generating plants over wide areas cut costs. Shared standby capacity improved reliability and allowed exploitation of remote hydroelectric and mine-mouth coal resources.

1914–18 · 112 years ago

Wartime governments spurred interconnection of local generating plants for munitions production

World War I saw large electrical generating plants built by governments to power munitions factories. This drove the linking of local generation and small distribution networks into wider grids, making transmission critical infrastructure.

1926 · 100 years ago

The United Kingdom created a national transmission grid

The Electricity (Supply) Act established a Central Electricity Board to build a national network of high-voltage lines linking the country's many separate local power stations, replacing a fragmented patchwork with an integrated system for moving power to where it was needed.

1936 · 90 years ago

The United States passed the Rural Electrification Act

The law created low-cost federal loans for rural electric cooperatives to build distribution lines into farming areas that private utilities had judged unprofitable to serve, extending mains electricity to most of rural America within about two decades.

1951 · 75 years ago

Western European utilities founded a body to synchronise their national grids

The Union for the Coordination of Production and Transmission of Electricity linked the transmission systems of several countries into one synchronised network operating at the same frequency, the forerunner of today's continent-wide European grid coordination.

1954 · 72 years ago

ASEA completed the Gotland HVDC link

The Swedish company built the world's first commercial high-voltage direct current transmission line, running under the sea to the island of Gotland, proving a technology that decades later became the standard for very long-distance and undersea power links.

1965 · 61 years ago

The Great Northeast Blackout cut power to 30 million people in the US and Canada

A single misconfigured protective relay near Niagara Falls cascaded into a failure that darkened most of the north-eastern United States and Ontario within minutes, exposing how tightly interconnected grids could turn a local fault into a continental emergency.

• North American utilities created a formal reliability body in response

1965–2011 · 61 years ago

The United States grid suffered major regional blackouts in the Northeast and elsewhere

The US Northeast faced blackouts in 1965, 1977 and 2003, with further large failures in other regions in 1996 and 2011. These events exposed the reliability risks inherent in wide-area synchronous interconnection.

1982 · 44 years ago

The Inga–Shaba line carried power 1,700 kilometres across Zaire

One of the longest high-voltage direct current transmission lines built up to that time linked the Inga hydropower complex on the Congo River to copper mines in Shaba province, an early demonstration that HVDC could move bulk power across a whole continent's width.

1990s · 36 years ago

Many countries liberalized electricity markets, splitting transmission from distribution

Historically transmission and distribution lines were often owned by the same company. Regulatory liberalisation from the 1990s led to separate companies handling each function, restructuring the industry around network access.

2026 to date · this year

China commissioned further ultra-high-voltage transmission lines linking western generation to eastern demand

State Grid Corporation continued a decades-long programme of building direct current lines operating at 800 kilovolts and above, moving hydropower, wind and solar generated in the west and north of the country to industrial demand centres on the coast.

April 2025 · last year

Spain and Portugal suffered a near-total blackout across the Iberian grid

A sudden, unexplained loss of generation and voltage oscillations brought down most of the interconnected Spanish and Portuguese grid within seconds, cutting power to tens of millions of people for most of a day and prompting investigations into the resilience of a grid running on very high shares of solar and wind.

• Investigators had not identified a single confirmed cause months later

Early 2025 · last year

Nigeria suffered repeated collapses of its national grid

The interconnected transmission grid went down entirely on several occasions, plunging much of the country into blackout at once, a recurring failure blamed on an ageing, thinly meshed network that leaves the system with little redundancy when a single line or plant trips.

• The blackouts renewed pressure for grid reform

Mid-2025 · last year

Australia saw major transmission projects face delays and steep cost increases

Lines intended to connect new renewable energy zones to the grid, including links between New South Wales and Victoria, ran behind schedule and over budget amid landowner opposition and construction cost inflation, slowing the pace at which new wind and solar capacity could be connected.

• HumeLink and VNI West were among the most delayed projects

Mid-2025 · last year

Saudi Arabia and Egypt advanced construction of a high-voltage interconnector linking their grids

The direct current link, designed to allow large volumes of electricity to flow between the two countries at times of surplus or shortage, moved further through construction, part of a broader push toward a more connected Middle Eastern and North African grid.

Late 2025 · last year

India continued building transmission corridors dedicated to renewable energy zones

The Green Energy Corridor programme added new high-capacity lines linking wind and solar-rich states such as Rajasthan and Gujarat to the national grid, addressing a persistent bottleneck in which renewable capacity had been built faster than the lines needed to evacuate its power.

2024 · 2 years ago

A report on grid-enhancing techniques found the United States behind Belgium and the Netherlands in adoption

The assessment concerned techniques for increasing capacity of existing lines to accommodate electrification and renewable energy. It highlighted a lag in deployment relative to European leaders.

Early 2024 · 2 years ago

Brazil held further auctions for new high-voltage transmission concessions

The regulator awarded contracts to build and operate additional lines extending the country's already extensive direct current network, which carries hydropower more than two thousand kilometres from Amazon basin dams to the industrial south-east.

Mid-2024 · 2 years ago

Laos, Thailand, Malaysia and Singapore expanded a multilateral electricity trading arrangement across their grids

The power integration scheme linking the four countries increased the volume of hydropower traded across borders, a step towards the long-discussed ambition of a single ASEAN power grid that would let members trade surplus generation instead of building it all themselves.

Mid-2024 · 2 years ago

The Xlinks Morocco–UK project continued seeking financing for a subsea cable to carry Moroccan solar and wind power to Britain

The proposed link, which would run several thousand kilometres of high-voltage direct current cable under the Atlantic and the Bay of Biscay, remained one of the most ambitious cross-border transmission schemes under development anywhere, though it had yet to reach a final investment decision.

Late 2024 · 2 years ago

US regulators pushed through reforms aimed at clearing a large backlog of grid connection requests

The Federal Energy Regulatory Commission moved to a first-ready, first-served process for reviewing new generation and storage projects seeking to connect to the grid, responding to queues in which thousands of projects, many of them renewable, had waited years for an interconnection study.

December 2023 · 3 years ago

Viking Link became the longest operational HVDC interconnector at 765 km

The land-and-subsea link between the United Kingdom and Denmark surpassed the 720 km North Sea Link. It marked a new distance record for cross-border high-voltage direct current transmission.

2022 · 4 years ago

The Biden Administration streamlined environmental reviews and grants for transmission projects

In April 2022 the administration streamlined environmental reviews for transmission projects, and in May 2022 announced competitive grants funded by the 2021 Bipartisan Infrastructure Law and the 2022 Inflation Reduction Act. The measures targeted the interconnection backlog holding back new generation.

2012 · 14 years ago

Northern India's grid collapsed and cut power to roughly 620 million people

A cascading failure across three regional grids left more than half the country's population without electricity for up to two days, the largest blackout in history by number of people affected and a stark demonstration of the risks of a thinly interconnected transmission system.

August 2010 · 16 years ago

NASA contracted firms to design laser power beaming systems

The agency engaged private companies to develop laser power beaming to supply low earth orbit satellites and to launch rockets. It extended power transmission concepts beyond terrestrial conductors.

2010 · 16 years ago

The US Federal Energy Regulatory Commission issued Order 1000 to open transmission to third-party investment

The order attempted to reduce barriers to third-party investment and to the creation of merchant transmission lines where a public policy need is found. It extended the market-opening approach begun by Order 888.

November 2009 · 17 years ago

LaserMotive won the NASA Power Beaming Challenge with a laser-powered climber

The company powered a cable climber one kilometre vertically using a ground-based laser transmitter. The result revived interest in beamed power as a specialised transmission method.

2007 · 19 years ago

Consolidated Edison and American Superconductor began commercial production of superconducting cable systems

The companies moved specialised high-capacity transmission technology from demonstration into commercial supply. It offered an option for dense urban corridors where conventional conductors are constrained.

2003 · 23 years ago

A cascading failure blacked out the north-eastern United States and Ontario

A software fault that let operators lose track of a sagging line in Ohio triggered a chain reaction that cut power to around 50 million people across eight US states and one Canadian province, prompting a decade of work on mandatory reliability standards for the grid.

1997 · 29 years ago

A health study of transmission corridors reported no increased cancer risk near transmission lines

The study measured electric field strength at the edge of an existing right-of-way on a 765 kV line and found no increased risk of cancer or illness from living nearby. Such findings shaped siting and exposure policy for high-voltage corridors.

1996 · 30 years ago

The US Federal Energy Regulatory Commission issued Order 888 on open access transmission service

The order promoted wholesale competition through open access non-discriminatory transmission services by public utilities and addressed recovery of stranded costs. It spurred the establishment of regional transmission organisations in the United States.

1990 · 36 years ago

The New York State Public Service Commission issued an Interim Policy Statement on Magnetic Fields

Following a study of magnetic field strengths, the commission set a standard of 200 mG at the edge of the right-of-way using the winter-normal conductor rating. Related rulings also limited new New York transmission lines to 345 kV.