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Spotlight

Site Characterization and the Future of Offshore Wind

By Pedro Alcalá | Thu, 10/21/2021 - 11:38

Offshore wind development is a fundamental part of Mexico’s energy future. The global and national demands of the world’s energy transition will eventually align with the country’s vast coastline and territorial waters. The methods and technologies that will define the initial success of these projects will be those concerned with site characterization. The participation of technological partners such as Fugro will prove to be essential.

When considering offshore wind development, the geological conditions of the seabed need to be favorable to the structural engineering of offshore wind turbines. The more favorable conditions are, the less risk can be assumed by contractors and underwriters. The certainty that engineers need is best secured through site characterization. 

Andrew Cooper and Elena Starchenko report in their article, Preparing for a Wind Revolution (published in the August 2020 edition of Sea Technology magazine and available here), that an integrated approach to site characterization can significantly reduce project risk in offshore wind development. The article states that this is true for coastal regions where available geological information and seabed mapping is limited. The Bureau of Ocean Energy Management (BOEM), a US agency that operates under the jurisdiction of the Department of the Interior, classifies these coastal areas as “frontier regions.” The Gulf of Mexico is not included in this category because the oil and gas industry has performed an important number of geological mapping projects that have generated a sturdy base of knowledge regarding that coastal region. However, Mexico’s Pacific and Caribbean coasts would be considered frontier regions by comparison.

Cooper and Starchenko say site characterization can “detail surface and subsurface conditions to help identify and mitigate potential geohazards in the lease area, and inform the design, construction and installation of wind turbine foundations, cabling and related infrastructure.” This makes site characterization not only essential to the establishment of wind turbines in Mexico’s frontier regions but also necessary for the laying of transmission cables and infrastructure that would not be present on site and needs to be developed from scratch given the regions’ primordial state.  

Independent Surveying Technologies 

The geological data acquisition campaigns need to successfully characterize project sites, collecting datasets that include bathymetry, side-scan sonar, high-resolution seismic and magnetometry. The resulting water depth and seafloor elevation data is used to report project design parameters that include turbine height and the design of turbine bases to account for seabed conditions, including as sand waves, geohazards, such as boulders, and anthropogenic hazards, such as shipwrecks and abandoned or otherwise decommission oil and gas infrastructure, which is very common in the GOM. Environmental concerns must be taken into account; for instance, avoiding any possible damage to coral reefs.  

Fugro has developed surveying technologies that have proven to be flexible and independent to meet the needs of these campaigns. The first is the Fugro RAMMS (Rapid Airborne Multibeam Mapping System), a next-generation airborne LiDAR mapping system that delivers industry-leading depth penetration and point densities for fast and accurate bathymetry in nearshore and coastal waters from a lightweight and compact frame that can be operated from certain drones and other similar uncrewed aerial vehicles. 

The second is the FAS-900 (Fugro Autonomous Surveyor 900), an uncrewed surface vessel that can collect multibeam echosounder data in full autonomy, semi-autonomy or by remote control in offshore and coastal waters. “In addition to improving data collection rates, these systems help improve project safety and sustainability by limiting the number of crew needed in the field and significantly reducing fuel demands,” explain Cooper and Starchenko. The unmanned nature of these technologies opens them up to be further developed into increasingly independent and automated tools that can cover a great deal of ground in terms of seabed analysis with increasingly smaller budgets. 

Commitment To Post Survey Analysis

Another success factor to site characterization is the analysis that follows surveying and data acquisition. For example, Fugro has experience in the conduction of geotechnical site studies (once a general site or possible candidate has been selected) to “ground-truth” for the ground model in the project’s time frame. If successful, these studies can be used to inform the positions and engineering designs of wind turbines and their foundations with more detail, including the choice between jackets and monopiles for such foundations, for example, along with the positioning and engineering design of inter-array cables and the optimal methods for their installation, such as the choice between jet-plowing and trenching. This can increase the efficiency with which offshore wind projects are developed in the future, which will prove essential in economically benefiting Mexico. 

As Cooper and Starchenko conclude, “high-quality data allow conservatism to be removed from the engineering design, which translates to significant material and cost savings.”

 

Fugro is the world’s leading Geo-data specialist, collecting and analyzing comprehensive information about the Earth and the structures built upon it. Adopting an integrated approach that incorporates acquisition and analysis of Geo-data and related advice, Fugro provides solutions. With expertise in site characterization and asset integrity, clients are supported in the safe, sustainable and efficient design, construction and operation of their assets throughout the full lifecycle.

Pedro Alcalá Pedro Alcalá Senior Journalist & Industry Analyst