Exploring the Application and Impact of Islanded Ocean Energy Systems for the Provision of Renewable Power and Communications for All-Electric Subsea Assets

Abstract This paper examines the techno-economic feasibility of using a hybrid renewable floating hinged raft—combining wave energy, solar energy, and battery storage—to provide local, uninterrupted power to a brownfield development of four all-electric subsea trees located in the North Sea. Located approximately 100 km offshore at a depth of 300 m, this innovative system would also serve as a remote communications platform. The study compares this solution with a conventional power and communication static umbilical, with the objective of estimating its cost/benefit impact. The analysis was performed using 12-year hindcast data for incident wave and solar resources from the Copernicus data set combined with the expected conversion rates from the wave energy converter and top-mounted solar panels. Considering demand and hotel loads, as well as battery storage capacity and degradation rates, a time-series state-of-charge graph was produced. This enabled the fine-tuning of system redundancy, including minimum state of charge thresholds, and the required energy storage capacity. Cost data were used as inputs, based on an assumed 7-year life of the field, leaving the potential for cost improvements in subsequent systems. Initial findings indicate that a local ocean energy system, combined with 560-kW-h onboard battery storage, can provide sufficient power to four all-electric subsea trees for the analyzed period, with a minimum state of charge of 21%. Based on the Copernicus data set, this occurs over a very short duration of a single day in 12 years. Additional power redundancy can be provided by adding subsea energy storage, further enhancing system energy management capabilities. The cost analysis indicates that the hybrid renewable system is cost competitive when compared with a conventional power and communications umbilical for distances exceeding 10 km. The study represents a significant milestone in advancing the evaluation and development of all-electric ocean energy solutions, setting a strong foundation for future innovations. It lays the groundwork for further exploration across different assets and locations, with promising potential to expand the applicability of such systems within the offshore industry.