IN Brief:
- Physical works have begun across the 82km Ventilus transmission reinforcement in West Flanders.
- The programme combines upgraded 380kV lines, new overhead infrastructure, underground cables, and substation works.
- Ventilus is intended to carry additional North Sea wind inland while strengthening Belgium’s transmission backbone.
Construction has begun on the Ventilus high-voltage reinforcement in West Flanders, moving the 82-kilometre project into physical delivery after years of planning and permitting.
Elia Transmission Belgium has started work on the existing 380kV line between Izegem and Avelgem, where conductors will be replaced with higher-capacity equipment and towers and foundations strengthened. Two existing pylons, one near the motorway at Deerlijk and another close to the Izegem high-voltage substation, will be replaced before the original structures are removed.
The Izegem–Avelgem work is one part of the wider Ventilus corridor, which runs from the coastal landing point for offshore-generated electricity to Avelgem. Elia describes the route as a missing link in Belgium’s high-voltage network, intended to reinforce the system in West Flanders and provide additional capacity for electricity brought ashore from the North Sea.
Across the full route, around 21 kilometres will consist of new overhead line, approximately 10 kilometres will be placed underground, and existing overhead infrastructure will be reinforced or reused over much of the remaining distance. Elia expects to build around 60 new high-voltage pylons as part of the programme.
The construction sequence is spread across several sections rather than concentrated on a single new-build corridor. Work on underground 380kV cables between Zedelgem-Baliebrugge and De Mol-Bosmolens, together with a new overhead 380kV line planned along the E403, is scheduled to begin in 2027. Substation extensions and transition works form part of the same programme.
The existing Izegem–Avelgem reinforcement shows how transmission operators can increase transfer capability without replacing every part of an established corridor. Higher-performance conductors can carry more power, but higher loading also changes mechanical, thermal, and electrical duties, requiring tower strengthening, foundation work, protection studies, and careful outage planning.
Ventilus also has a system role beyond the local works. Elia’s federal network planning has described the project as a 380kV corridor capable of carrying up to 6GW, closing the connection between the coastal Stevin axis and Avelgem. That capacity is intended to help move additional offshore wind output inland while reducing the risk of bottlenecks in the western part of the Belgian transmission system.
The need for stronger internal transmission is growing alongside Belgium’s offshore programme. Bringing power ashore is only one part of the connection chain; the onshore network must also have sufficient capacity to move that electricity towards demand centres and other parts of the interconnected system. Without that internal headroom, new offshore capacity can be constrained after it reaches land.
The same dependency is visible in the Princess Elisabeth Island programme, where high-voltage equipment, transformers, and AC connections are being developed to connect future offshore generation. Ventilus provides part of the inland network reinforcement needed to accommodate those additional flows once they arrive onshore.
Large grid projects also have to align several programmes with different delivery times. Offshore generation, subsea and land cables, substations, and internal transmission reinforcement can each take years to permit, procure, and build. Delays in one element can leave capacity elsewhere underused, so starting the Ventilus construction programme is a material step in synchronising the wider Belgian offshore and onshore grid build.
West Flanders also faces rising electricity demand from industrial electrification. More renewable generation does not reduce the need for a robust meshed transmission network; it increases the range and variability of flows that the network must accommodate. Industrial loads, offshore injection, interconnection, maintenance outages, and system contingencies all compete for capacity on the same high-voltage backbone.
The project’s mixed use of upgraded lines, new overhead sections, and underground cable reflects those competing requirements. Reusing existing infrastructure can limit the amount of entirely new corridor required, while underground sections can address specific planning or spatial constraints. Each approach brings different cost, maintenance, thermal, and construction characteristics, so the final route is a combination rather than a single engineering solution.
The first phase will also require extended outage and worksite coordination along an operating transmission corridor. Replacing conductors and strengthening structures cannot be treated as isolated civil works: crews must work around live-system requirements, planned outages, and restoration sequences while preserving network security. That coordination will continue as later underground and new-build sections enter construction.
Elia says the Izegem–Avelgem works will proceed in phases and continue through to the end of 2030. By then, the individual reinforcements, new lines, cables, and substation works are intended to operate as one 380kV corridor linking the coast more securely with the inland network.
