Energy · 1954

HVDC transmission

Mercury-arc valves send DC power undersea to Gotland.

Uno Lamm's team at ASEA opened the 20 MW, 100 kV Gotland link in 1954. HVDC loses less power over long distances and undersea cables and can connect unsynchronized grids; thyristor valves replaced mercury arcs from the 1970s.

See it in the living tree Wikipedia

Arcs above join it to what it stood on, arcs below to what it led to. The bar places this stretch on the tree's whole timeline.

What it built on 2

Vacuum tube 1904
Electric power grid 1882

What it led to 2

Ultra-high-voltage DC lines 2010
Gigawatt-scale offshore wind 2019

Related measurements

The dashed line marks when it first worked.

World electricity generation Latest: 31.8k TWh (2025) Source: Our World in Data

Share of electricity from low-carbon sources Latest: 42.6 % (2025) Source: Our World in Data