Microbially induced corrosion of iron and possible corrosion protection measures in monopiles of offshore wind turbines

Kiel University of Applied Sciences - Department of Mechanical Engineering, Institute for Materials and Surfaces
Prof. Dr.-Ing. Jana Schloesser

The aim of the project is to find economic solutions to reduce microbially induced corrosion inside a monopile of offshore wind turbines and thus extend their service lifetime. For this purpose, the vulnerabilities of the currently used monopile steel as well as economic modifications to MIC in the monopile are to be tested exemplarily on the FINO3 research platform.

In the subproject "Corrosion analysis and material choice impacting microbially induced corrosion on offshore structures", the corrosion and surface analysis of in situ and laboratory experiments takes place. This, complemented by the project partner's microbiological analyses, creates the basis for understanding the corrosive behaviour of different materials in the special corrosive environment inside the monopile. The corrosion phenomena of the samples incubated in situ are investigated macroscopically and microscopically, and the corrosive environment is simulated electrochemically to enable further experiments in the laboratory. The experiments enable a selection of alternative materials and Inhibition Hotspots, which in turn will be investigated in situ and ex situ for corrosion behaviour. Overall, a corrosion model will be developed that predicts the corrosive behaviour of different materials and corrosion protection measures and thus enables targeted use to minimise microbially induced corrosion.

The Federal Ministry for Economic Affairs and Climate Protection is funding sub-project 03EE3082A with funds from the federal budget amounting to EUR 347,009.13. The grant is valid for the period from 01.07.2023 to 30.06.2026. The project is part of the joint project "MiCorFe - Microbial Fe corrosion and possible corrosion protection measures in the monopile of offshore wind turbines".

Activities and goals

The collaborative partners will define the corrosion mechanisms of microbial corrosion inside the monopile of offshore wind turbines in an overall understanding by closely integrating materials engineering and microbiology. Furthermore, MiCorFe ensures knowledge and technology transfer to interested companies.

In the sub-project of the FH Kiel, samples incubated in situ are examined with regard to the corrosion phenomena. The mass loss of the incubated samples is determined gravimetrically and the corrosion rate is determined. The surface of the samples is examined for pitting corrosion by means of confocal 3D microscopy; in this way, a three-dimensional model is generated for the simulation of the project partner. In the scanning electron microscope, both the corrosion products and the surface of the steel are analysed in terms of microtopography and corrosion layer thickness, and chemical changes are investigated using energy dispersive X-ray analysis. In this way, the corrosion phenomena present are evaluated quantitatively and qualitatively. Furthermore, the structure and chemical composition of the corrosion products will be investigated using X-ray diffraction in order to draw conclusions about the corrosion mechanism and, together with the project partner, about the active microorganisms.

In the laboratory, the microbial corrosion system is simulated together with the project partner and thus material alternatives and corrosion protection measures of the partner Krebs as well as self-made Inhibition HotSpots are evaluated. The corrosion process itself will also be electrochemically investigated and the biofilm that forms will be characterised using atomic force microscopy and nanoindentation. All laboratory experiments will be verified by in situ experiments and thus a corrosion model will be synthesised together with the project partners.