Wave Energy Converters Hold Key to Using Renewables for Subsea Power
Authors: Carpenter Chris 
Published: August 2023

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This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 210910, “Innovative Industry Lead Project for Renewables for Subsea Power,” by Ian R. Crossland, SPE, Mocean Energy; Paul Slorach, Verlume; and Andrea Caio, Mocean Energy, et al. The paper has not been peer reviewed.

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The levels of power required to operate an offshore oil and gas field with 100% renewable energy are such that even offshore wind is unlikely to cost-effectively provide the levels of uptime needed to maintain reliable production without some form of energy storage. Providing a combination of technologies to maintain a balanced renewable energy supply system is key. In the complete paper, the authors focus on the use of wave energy converters (WECs), in combination with energy storage, to deliver benefits when powering offshore assets in situ, especially when continuous power requirements are in the 10–100 kW range.

Introduction
In 2020, a UK industry collaborative project, Renewables for Subsea Power (RSP), was launched and co-funded by the Net Zero Technology Centre. RSP is a phased demonstration project involving three technology developers (Mocean Energy, Verlume, and Modus), a first-tier international services company (Baker Hughes), and a major North Sea operator (Harbour Energy). Given the focus on ramping up the energy transition, in 2022 another major North Sea operator (Serica Energy) and an autonomous resident vehicle supplier (Transmark Subsea), who replaced Modus, also joined the project as part of the final phase (Phase 3) of activities.
RSP aims to develop a complete, fully integrated system for the provision of the following:
- Low-carbon remote power and communications using a WEC as the effective power source
- A subsea energy-storage system for power conditioning
- Smooth and uninterruptable power delivery to subsea production control systems
- Residential underwater vehicles for a variety of monitoring or maintenance activities
Throughout the three phases of RSP, project partners will design, build, and test all elements of the combined system. Phase 1 consisted of a front-end engineering design (FEED) successfully completed in 2021. Phase 2 involved the building and onshore commissioning of various subsystems. Phase 3 is planned to culminate in offshore full-system deployment and trials during 2023.

Benefits of Wave Energy
At a macro level, ocean waves are a highly abundant source of energy. Technically extractable wave energy resources amounted to 5–23% of 2017 global electricity demand, for instance, and approximately seven times that of available tidal resources worldwide. With approximately 40% of the world’s population inhabiting coastal regions, waves also provide a relatively local source of power for many coastal communities and densely populated areas. As well as being energy-dense and abundant, wave resource is predictable, often days in advance compared with solar and wind. In addition, its daily and seasonal complementarity with other renewables is crucial to achieving a more-balanced grid.