French Offshore Wind Developer Thinks Decommissioning Before Final Investment Decision

Danish consulting engineering company Niras has won a contract to set up a plan for decommissioning of two offshore wind projects in France with a combined capacity of nearly 1GW which are still awaiting respective final investment decisions.

Les Eoliennes en Mer Services (LEMS), a joint venture partnership between Engie, EDP Renewables and La Caisse des Dépôts, is developing the 496MW Dieppe et le Tréport and the 496MW Iles d’Yeu et de Noirmoutier offshore wind farms.

Each wind farm comprises 62 Siemens Gamesa 8MW  wind turbines and an offshore substation.

Niras has assisted LEMS in the phase of de-risking regarding the issue of future dismantling and has used the ODIN (Offshore, Decommissioning of Installations Niras) tool to create the decommissioning plan for the two projects.

“LEMS takes their job seriously and has chosen to think years ahead when they include the full life cycle of the turbines, from birth to last breath, and thus also wish for help with the retirement and clever dismantling,” said Johan Finsteen Gjødvad, project manager in Niras, who will help to make the final strategy for decommissioning.

Niras used the experience gained while assiting on the dismantling of the world’s first offshore wind farm, the Vindeby wind farm off Lolland, Denmark, to set up the decommissioning strategy for the two French projects.

“By using known methods and actual data, we are able to think backwards,” Gjødvad said, adding that the decommissioning market is traditionally operating with an uncertainty of up to 50% when it comes to calculate what it would cost to take down a wind turbine down.

“But we can reduce the uncertainty to 15% because we base our knowledge on what things have actually costed and which methods have already been tested earlier regarding installing, maintenance and dismantling. We have specific knowledge about what can be sold, which metal parts and cables can be recycled, and which stones from the foundation around the mills that can be used elsewhere. So not only is it about optimal waste management and a reduced environmental impact, but we also reduce costs in relation to the dismantling,” Gjødvad said.