Soil Thermal Properties (STP) for subsea cable design

Guidance on how to test, interpret, and adapt offshore wind inter-array and export cable design based on the site soil thermal properties. By adopting the insights within this report, the industry can potentially save tens of millions of pounds in capital expenditure and reduce operational costs, paving the way for more efficient and sustainable offshore wind projects. 

Front cover of report


The thermal properties of soil play a pivotal role in offshore wind inter-array and export cable design. However, the lack of clear guidance on conducting and interpreting tests often leads to conservative cable design choices, resulting in potential cost overruns. To address this challenge, the Offshore Wind Accelerator (OWA) cables technical working group embarked on a comprehensive investigation.

Specifically, the project delved into pre- and post-installation soil conditions, their impact on costs, and improved testing methodologies for accurate thermal property measurements. The resulting published guidance offers valuable insights:

  • Optimal investigation strategy: It outlines the best practices for laboratory and in-situ testing of soil thermal properties.
  • Installation effects: The report highlights the effects of installation on soil properties and their implications for cable design and operation.
  • Characteristic values: It establishes a basis for determining appropriate characteristic values for cable design.
  • Measurement techniques: Recommendations for enhancing measurement techniques and result interpretation for offshore use are provided. 

This report is published under the Offshore Wind Accelerator (OWA) cables technical working group and was delivered by Cathie, ITPEnergized, and the University of Southampton. 

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