Subsea Power From Waves Works in North Sea Test

Wave power plus a subsea battery can be a reliable source for subsea operations, to a point.

A hinged design allows each side to rise and fall, spinning the electric generators.
Source: Mocean Energy.

A 4-month test off the coast of Scotland has shown a battery charged by a floating wave-energy device can reliably power subsea control and communications equipment as well as an autonomous underwater vehicle (AUV) stationed on the seabed at a site 5 km off the coast of Orkney.

The test has been extended until April 2024, which will among other things, show how reliably this system performs during winter storms.

The corporate partnership led by Mocean Energy and Verlume, suppliers of the generator and the subsea battery, respectively, described this as a “first-of-its-kind” project.

What is new is the integration of the proven parts to deliver steady flow of electricity to subsea systems using the power generated by a large, hinged floating device that generates power by moving with the waves.

The announcement included a bit of news suggesting oil companies are showing interest in the technology. The consortium recently added a third operator—PTTEP, the national oil company of Thailand.

“The test programme has given all project partners growing confidence in our system’s reliability and ability to power a range of subsea applications,” said Cameron McNatt, managing director of Mocean. Adding PTTEP to the consortium is a sign of “growing interest from a number of other major energy players,” he said.

The key objective accomplished was providing power to subsea electronics modules provided by another partner, Baker Hughes, “simulating the control and communications needed for subsea wellheads using 100% renewable energy,” according to the announcement.

The system is a step toward reducing the need for fossil-fueled generators. But the current design has its limits.

Mocean’s Blue X wave energy generator is capable of delivering 10–100 kW of power, according to its recent paper (SPE 210910). The company’s website said it is working on a much larger version of its two-part hinged design for grid-scale power generation.

A wave-power generator on the surface is connected to a battery and power-control unit on the bed, supporting communications, monitoring, and an AUV docking station.
Source: Mocean Energy.

Verlume’s Halo battery and power-control unit also was able to provide the power needed to charge an AUV 50 times.

Offshore oil and gas is the logical initial target of wave power because the cost comparisons are far more favorable than trying to compete with wind and solar to provide power to utilities.

Installing a wave power unit via an umbilical cord to the subsea power unit, all of which were tested over the past 3 years by the Renewables for Subsea Power (RSP) project, could be an affordable option to replacing a failed cable providing power and communications, which can cost more than $12 million to replace.

Having the AUV stationed near the wellheads could save the cost and risks associated with vessels delivering them to the site.

And the paper’s authors wrote that a wave-powered system over the offshore site of the planned Acorn Carbon Capture Project could save about $94 million compared to running an umbilical from shore and also eliminate 92% of the carbon emissions for the North Sea project.

For Further Reading

SPE 210910 Innovative Industry Lead Project for Renewables for Subsea Power by Ian Roger Crossland, Mocean Energy Ltd.; Paul Slorach, Verlume Ltd.; and Andrea Caio, Jay Parle, and Cameron McNatt, Mocean Energy Ltd.