Qualla: HVDC Vancouver Island

HVDC Vancouver Island: Introduction

Wed, 16 Sep 2026 00:00:00 GMT

Photo credit Gah4, CC BY-SA 4.0. Look west across Sansum Narrows from the Salt Spring Island shore and you will see something that should not be possible. Two conductors leave the last tower on the island side and simply keep going, sagging in long catenary curves across 1,900 metres of open saltwater before landing on Vancouver Island. No tower in between. No pier, no island, nothing. There is a second span like it further east, 880 metres from Galiano Island to Parker Island. These crossings are the visible portion of a power link that spent nearly half a century pushing mainland electricity onto Vancouver Island, most of it out of sight under the Strait of Georgia.

Read more: HVDC Vancouver Island on Qualla

Image: Gah4 | CC BY-SA 4.0

HVDC Vancouver Island: The Island Problem

Wed, 16 Sep 2026 00:00:00 GMT

Photo credit Gah4, CC BY-SA 4.0. Vancouver Island has never generated all the power it consumes, and the water between it and the mainland is deep, busy, and unhelpfully wide. Alternating current behaves poorly in long submarine cables, where the cable's own capacitance wastes an increasing share of the capacity...

Read more: HVDC Vancouver Island on Qualla

Image: Gah4 | CC BY-SA 4.0

HVDC Vancouver Island: Seventy-Five Kilometres of Improvisation

Wed, 16 Sep 2026 00:00:00 GMT

Photo credit Gah4, CC BY-SA 4.0. The route is a peculiar hybrid, 42 kilometres of overhead line in three separate sections and 33 kilometres of submarine cable in two. Leaving Arnott, the overhead line splits, one branch heading for the Canoe Pass Terminal and the other for Tsawwassen Beach Terminal, where the f...

Read more: HVDC Vancouver Island on Qualla

Image: Gah4 | CC BY-SA 4.0

HVDC Vancouver Island: Mercury Vapour

Wed, 16 Sep 2026 00:00:00 GMT

Photo credit Gah4, CC BY-SA 4.0. The converters for the first pole belonged to an earlier technological era. They were mercury-arc valves, which rectify current by sustaining an electric arc through mercury vapour inside a sealed vessel, and they were not small. Each rectifier stood 6.10 metres high, 3.35 metres...

Read more: HVDC Vancouver Island on Qualla

Image: Gah4 | CC BY-SA 4.0

HVDC Vancouver Island: The Second Pole

Wed, 16 Sep 2026 00:00:00 GMT

Photo credit Gah4, CC BY-SA 4.0. By 1977, when BC Hydro added a second pole under Gunnar Ahgren's Swedish team, the technology underneath had changed completely. The new pole used thyristor valves, solid-state semiconductors with no mercury, no arc, and no moving parts, operating at 280 kilovolts and rated at 37...

Read more: HVDC Vancouver Island on Qualla

Image: Gah4 | CC BY-SA 4.0

HVDC Vancouver Island: Switched Off, Left Standing

Wed, 16 Sep 2026 00:00:00 GMT

Photo credit Gah4, CC BY-SA 4.0. During regulatory hearings in 2005 over a new 230-kilovolt alternating-current submarine cable, the HVDC system was reported to be at the end of its service life and no longer considered reliable. The new AC cable was built, parallel to the old DC route, replacing one of the two ...

Read more: HVDC Vancouver Island on Qualla

Image: Gah4 | CC BY-SA 4.0