Sustainability of corrosion protection for offshore wind turbine towers

When coatings industries have ambitions to develop more sustainable products it is important to know what path to follow. Quantitative evaluations in the form of Life Cycle Assessment (LCA) offers guidance for sustainability directions. The direction will depend on the type of coating. This work analyses sustainability performance of protective coatings, using the coating of an offshore wind turbine tower as a case. All steps in the manufacturing are assessed and the relevant environmental impacts are evaluated along the life cycle of the turbine tower. The assessment shows that the vast majority of the impacts, including climate change, originate from manufacturing of the steel. Therefore the durability of the coating system to protect the steel and prolong the lifetime, mini-mizing the need for repair, etc. should be the main priority for a sustainable direction. The coating system must keep the steel structures corrosion free for at least as long as the designed lifetime, as it is much more costly in terms of environmental impacts to repair or replace steel than to protect it properly from the start. When the protection is secured, the sustainable development path from the present situation where thermal sprayed metal (TSM) is used for galvanic protection of the wind turbine tower, will be to develop: -Coating systems where toxic substances are substituted by less toxic or non-toxic substances.-Coating systems where the thermal sprayed metal (TSM) layer is substituted by zinc-rich epoxy or Zinc silicate coatings.-Coating systems where the organic solvents are substituted by water.-Coating systems which would make it possible to reduce the amount of steel used.-Coating systems where the organic binder material is substituted with alternatives with lower carbon footprint-Ease of recycling the structure material for reuse in new structures.