The transmission network is the high-voltage backbone of Great Britain’s electricity system. Its pylons, overhead lines, underground and subsea cables and substations move large amounts of power over long distances, from big power stations and offshore wind farms to the points where local networks take over.
Voltages and owners
According to NESO, transmission in Great Britain generally means equipment operating at 400 kV and 275 kV, and in Scotland also at 132 kV. Running at very high voltage cuts the energy lost as heat over long distances.
| Area | Transmission owner |
|---|---|
| England and Wales | National Grid Electricity Transmission |
| Southern and central Scotland | SP Energy Networks |
| Northern Scotland and the islands | SSEN Transmission |
The owners are funded through energy bills under price controls set by Ofgem. The National Energy System Operator (NESO) runs and plans the system but does not own it. Cables linking offshore wind farms to shore are run under a separate offshore transmission regime.
Transmission versus distribution
| Transmission | Distribution | |
|---|---|---|
| Voltage | 400 kV and 275 kV (plus 132 kV in Scotland) | 132 kV and below in England and Wales; below 132 kV in Scotland |
| Job | Bulk power over long distances | Local delivery to homes and businesses |
| Who runs it | Three transmission owners, with NESO as operator | Distribution network operators |
Very large users and generators can connect directly to transmission. Most homes and businesses are supplied through distribution.
Building more of it
Ofgem has said the network needs to grow at more than four times the rate of the last decade. Its accelerated scheme for strategic transmission projects covers 26 projects that could help connect up to 50 GW of offshore wind by 2030. Getting projects onto the network is also being reformed: the old first-come, first-served queue is being replaced by the Gate 2 process, which favours projects that are ready to build and needed for Clean Power 2030.
Read more: Ofgem proposes letting developers build their own grid connections.