Sweden: modernisation of a power supply network in demanding surroundings
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Offshore in the Gothenburg archipelago, Omexom is to manage three of the four zones in a vast modernisation project on behalf of the network operator Ellevio. The aim is to fundamentally overhaul local electrical infrastructure, enhance distribution reliability and sustainably support the region’s energy needs from 2028.
©VINCI Energies
Omexom, the energy infrastructure brand of VINCI Energies, was recently awarded a major contract relating to the Tjörn project, a huge modernisation of the operator Ellevio’s local offshore network across the Gothenburg archipelago in Sweden. The business unit will be responsible for three of the four zones (East, North and South) under a contract worth over 75 million Swedish krona (around €7 million).
This massive project will include the construction of a completely new distribution network for customers in the region, followed by the dismantling of existing overhead lines. In total, the project involves around 75 kilometres of trenches, undersea cables and overhead lines connecting the islands, and the installation of 74 onshore substations.
For Robert Lindhe, Project Lead at Omexom Sweden, this mission illustrates the network operator’s continuing confidence in his business unit. “We will be completely reconstructing the medium-voltage and mains-voltage networks in the area concerned. Design and preparation works are already under way. We hope to be able to begin work on the ground in autumn 2026. The whole contract should be completed by summer 2028.”
Pooling expertise
The project will be overseen by the Sweden Local Grid unit and managed jointly between the Karlstad and Nässjö offices. “The project organisation will combine internal and external personnel,” explains Robert Lindhe. “We are mobilising project managers, technical planners, administrators, fitters and construction workers, along with a range of machinery.”
“The current network includes obsolete transformer stations and is predominantly made up of overhead lines”
This pooling of expertise enables Omexom to effectively coordinate multiple resources for a project that is both vast and technical, ensuring quality in execution to the agreed deadlines.
Technical and environmental challenges
The Tjörn project presents a number of major challenges. “The network we will be rebuilding is not interconnected but it is split into several distinct zones, which requires meticulous planning,” says Robert Lindhe. And there are major geographical constraints to be considered: the project is located on the island of Tjörn, which is mostly mountainous with extremely steep drops making access difficult.
Works extending across multiple islands further complicate the operation. Omexom will be working not only on Tjörn, but also on several smaller islands in the archipelago, so boats will be required to transport materials, machinery and personnel each day.
Environmental requirements are also a key concern. “On coastal projects, the presence of nesting birds and the proliferation of algae can limit the periods when construction is permitted,” explains the project lead. The project will also require large quantities of cable ducts, which further intensifies the technical aspect.
Strategic lever
Notwithstanding these challenges, this project represents a strategic lever for the region. “The current network includes obsolete transformer stations and is predominantly made up of overhead lines,” says Robert Lindhe. “With this project, the network operator hopes make distribution more reliable, improve electrical quality and increase transmission capacity by replacing these old substations and removing overhead lines in favour of underground cabling wherever possible.”
By fundamentally modernising the existing infrastructure, the Tjörn project will contribute to building a more robust, more sustainable power supply network better able to meet the region’s future energy needs.
09/10/2026
