Seabed survey unlocks insights for floating offshore projects in Portugal

A geophysical and geotechnical survey conducted offshore Viana do Castelo by Portugal’s WavEC Offshore Renewables has provided data on the seabed’s characteristics, supporting the development of floating offshore renewable energy projects. 

The study, carried out within the Technological Free Zone (ZLT), is part of the EU-SCORES initiative and was commissioned by WavEC to Instituto Hidrográfico – Marinha Portuguesa.

According to WavEC, the survey, executed in two phases, aims to enhance understanding of the seabed’s physical and geotechnical properties to inform engineering and deployment strategies for floating offshore wind, wave energy, and offshore solar technologies. 

The first phase focused on seabed geomorphology, sedimentary layer composition, and overall seafloor characteristics.

“The findings reveal a sedimentary morphology and structure shaped by the unique geological setting and dominant oceanographic conditions,” said WavEC. 

“The unconsolidated sedimentary cover is largely uniform, comprising two main sedimentary units resting on a rocky substrate that outcrops intermittently in the southwest corner of the survey area. This composition illustrates the dynamic interaction between sediment deposition and geological formations, offering essential insights for offshore engineering applications.”

The data was gathered through oceanographic surveys aboard the NRP “D. Carlos I” in March 2023 and the NRP “Andrómeda” in October 2023, utilizing acoustic data collection and physical sampling techniques.

Key findings from the first phase indicate a predominantly stable seabed with a gentle slope of 0.34°, except for a localized rocky outcrop and small geological depressions. The sedimentary cover ranges from fine silt to very coarse sand, with three distinct subsurface layers identified, WavEC said. The top layer averages around 13 meters in thickness.

In August 2024, WavEC conducted a fish population survey to provide relevant information for the currently installed HiWave-5 project and future installations. With the support of local fishermen, WavEC researchers surveyed the Aguçadoura and adjacent control areas using mobile and fixed fishing techniques to characterize fish populations and associated invertebrate communities preliminarily.

In April 2023, the EU-SCORES project, focused on developing energy multi-use parks incorporating different offshore renewable energy sources at one site, received an official go-ahead from the European Climate, Infrastructure and Environment Executive Agency (CINEA).