PEI submarine transmission line energized

On August 29, 2017, a Canadian utility energized a new $142.5 million (CAD) undersea electric transmission system connecting Canada's Prince Edward Island to mainland New Brunswick. 

The Northumberland Strait Submarine Transmission System includes two 180-megawatt underwater cables, running 17 kilometers from Cape Tormentine, New Brunswick, to Borden-Carleton, Prince Edward Island.  They replace aging cables with a more limited transfer capability.  The project also includes new overhead transmission lines on land and an expanded substation. The cost was split by the federal Government of Canada (contributing up to $68.9 million from the Green Infrastructure Fund) and the Province of Prince Edward Island (contributing up to $73.6 million). 

The new submarine cables supply approximately 75% of the Island's electricity.  The cables are buried under the seabed in separate trenches. The project including the use of a marine excavator called a "Starfish" as well as a trenching remotely operated vehicle with a saw cutter.

They replace cables installed in 1977, when the island's electricity load was 95 megawatts.  In addition to the old cables' age, they were also insufficient -- PEI's load has grown to 262 megawatts by 2015.  While the island does have significant wind energy supply, utility Maritime Electric noted the need for firm power to back up wind's intermittent supply.  A press release announcing the Canadian government's 2015 decision to support the project describes it as the most significant on Prince Edward Island since the Confederation Bridge. 

Interest in submarine transmission cables is growing.  Improved marine technology, the difficulty of siting major linear infrastructure on land, and the growth of offshore wind and other remote renewable resources are all driving this trend, as is the need to provide reliable, affordable, clean power to consumers in island communities.