Abstract

The aim of the project was to develop a method for protection of subsea offshore structures against
corrosion and scour. The method involves the production of a protective layer “Seacrete” on subsea steel
structures by electrochemical deposition. One of the goals of the project was to investigate the production
of Seacrete in the laboratory and subsequent demonstrate the technology under real conditions. Seacrete
is mainly composed of the minerals Aragonite (CaCO3) and Brucite (Mg(OH)2) and the ratio between the
constituents was found to be highly important for the material properties. In the project a model was
developed capable of predicting the composition and amount of material produced based on water temperature
and applied current density.
Field tests were conducted at two sites in Denmark (Nissum Bredning and Hanstholm) and one site in
the North of Italy (Isola di Bergeggi) representing cold and warmer water regions respectively. In both
cold and warm water locations material was deposited on the structures which was composed of a mixture
of aragonite and brucite. The cold-water location produced less material with higher aragonite fraction.
Material with high fraction of aragonite was found to have similar properties to concrete, and thus may be
implemented in some structural applications in constructions as a sustainable alternative to cementitious
materials.
A Design Concept was developed featuring Resenwaves wave energy technology coupled with mineral
deposition technology for an offshore installation at Hanstholm harbour. Using only 1-2% of the total
energy produced for a 3kW wave energy unit, it is expected to be possible to protect the subsea structure
and at the same time create an artificial reef. With a preliminary life cycle assessment, we could verify
that the potential for CO2 reduction compared to the use of concrete is significant.
Original languageEnglish
Number of pages20
Publication statusPublished - 31 Aug 2021

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