Classification of Single Point Moorings as Offshore Battery Charging Stations

Abstract

For vessels which operate offshore for extended periods, there has been industry interest in providing means to recharge the battery systems without repeated return to port. Solutions would ideally use renewably sourced power as opposed to onboard charging from diesel engines. The electric charging buoy is a concept that has arisen based on existing technologies from the single point mooring (SPM) buoy. To support this innovation, we can draw from experience with offshore vessels, SPMs, and electrical transmission and storage systems as they relate to safety of personnel and assets at sea. The result has been the development of Classification requirements for charging buoys which address issues such as system design, operating philosophy, operations, testing and verification. Electrical safety and establishing connections in a marine environment are fundamental to deploying this technology. Key factors include the buoy structure, power sources (e.g. onshore grid connection, offshore substation, offshore wind turbines), voltage ranges, power quality, maximum allowable current, and on-buoy systems such as transformers, converters, and cables. It is also important to address risks related to vessel profiles for connection time to the buoy and the environmental conditions which may be experienced. This paper outlines the considerations for SPM-based charging and the process by which existing standards have been combined with established practice to develop criteria, including input from interested stakeholder organizations that are engaged in battery powered operations. The new Rules are presented along with their underlying goals. Readers will gain an understanding of the process and the importance of supporting innovation in the energy transition, from the design stage through construction and in-service surveys.