# HVDC links

Direct-current lines with lower losses over long distances, under the sea and between unsynchronised grids.

Source page: https://www.materialinsights.org/energy/e_hvdc/

Transport · Electricity · No. 51

- Transport
- Form: Electricity
 Transport · Electricity · Foundation · Energy

China's Changji to Guquan line sends 12,000 MW of direct current 3,293 km at ±1,100 kV, the highest voltage in service.

Chart: Illustration: HVDC links

##### Where it comes from

Chart: Map of where it comes from

A converter station turns AC into DC with thyristor or transistor valves. The DC runs on two poles, overhead or in cable, and a second station turns it back into AC.

##### Three things to know

1. Each converter station loses only about 0.7-1% of the power, so DC wins once routes pass about 480 km overhead or 50 km of cable.
2. A ship's anchor damaged the EstLink 2 link between Finland and Estonia on 25 December 2024; it returned to the market in June 2025.
3. Viking Link between the UK and Denmark was expected to save about 600,000 t of CO2 in its first year.

##### The journey

1. 1 **AC grid**Power from grids or offshore wind
2. 2 **Rectifier**Valves convert AC into DC
3. 3 **DC line**Two poles, overhead or subsea cable
4. 4 **Inverter**Second station rebuilds AC in step
5. 5 **Receiving grid**Exact megawatts delivered where operators choose
 Covered in [Power density: why land and space matterEnergy](https://www.materialinsights.org/learn/energy/power-density/)[Moving energy: wires, pipes and shipsEnergy](https://www.materialinsights.org/learn/energy/moving-energy/)

##### Go deeper pick a tab to open it in full

## Other sections

- [Overview](https://www.materialinsights.org/energy/e_hvdc/overview/index.md)
- [Correlation](https://www.materialinsights.org/energy/e_hvdc/correlation/index.md)
- [How it works](https://www.materialinsights.org/energy/e_hvdc/explain/index.md)
- [Efficiency and losses](https://www.materialinsights.org/energy/e_hvdc/efficiency/index.md)
- [Technology advances](https://www.materialinsights.org/energy/e_hvdc/advances/index.md)
- [Value chain](https://www.materialinsights.org/energy/e_hvdc/valuechain/index.md)
- [Geopolitics and regulation](https://www.materialinsights.org/energy/e_hvdc/geopolitics/index.md)
- [Unit economics](https://www.materialinsights.org/energy/e_hvdc/economics/index.md)
- [Impact on the biosphere](https://www.materialinsights.org/energy/e_hvdc/biosphere/index.md)
- [Relationships](https://www.materialinsights.org/energy/e_hvdc/links/index.md)