Opinion: Offshore charging is the missing piece for decarbonized offshore wind projects
Key Highlights
- Electrification of O&M vessels offers operational savings of up to £1 million annually and is becoming increasingly cost-competitive as battery technology advances.
- Embedding charging points directly on turbines and substations enables vessels to recharge at sea, eliminating the need for port visits and reducing emissions.
- The Nobelwind trial demonstrated the technical feasibility and safety of offshore charging systems, reaching Technology Readiness Level 8 and paving the way for commercial deployment.
By Dimitri de Gunzbourg, Charge Offshore
With the global offshore wind industry entering a record period of growth, marine fleet electrification is being explored as a primary route for decarbonizing the sector as it expands. Two out of three puzzle pieces for achieving electrification are already in place, and a rapid rollout of offshore charging infrastructure will help successfully complete the transition.
The Global Wind Report 2025 confirms a landmark moment for clean energy: a record 28 gigawatts (GW) of offshore wind capacity is under construction worldwide, 94% of which is from China, the UK, Taiwan, Germany and France. This unprecedented build-out marks a pivotal opportunity to accelerate global decarbonization, but only if the offshore industry tackles a constant challenge that remains hidden in plain sight: the emissions of its operations and maintenance (O&M) fleets.
Operational, fuel and maintenance savings
While the world focuses on deploying new offshore wind turbines at scale, too little attention has been paid to how those assets are serviced and sustained once they are in the water. O&M vessels, essential for inspection, repair and logistics, are still overwhelmingly powered by marine gas oil. This contradiction is not only environmental but economic.
Marine fuel prices are volatile, and diesel-powered vessels are costly to maintain. However, a clean, cost-effective alternative—electrification of the O&M fleet—is ready to be implemented. With advances in vessel design and battery technology, electric service operation vessels (E-SOVs) and crew transfer vessels (E-CTVs) are commercially viable, and as the market matures, the capital cost gap between electric and diesel vessels is shrinking fast.
In 2024, E-CTV and E-SOV construction was just 12-14% higher than diesel-powered, which is a cost expected to fall considerably as the technology evolves and energy storage becomes markedly cheaper, according to a 2024 report by BloombergNEF.
As for operational savings, an E-SOV under long-term charter can achieve fuel and maintenance savings of up to £1 million (US$1.3 million) per year, while E-CTVs are expected to hit breakeven opex by 2027.
O&M electrification is gaining momentum, with two pieces of the puzzle already firmly in place:
- Battery costs are falling rapidly as commercial uptake grows; and
- Electric vessel manufacturing is accelerating in parallel, with a number of E-CTVs and E-SOVs now commercially available.
Embedded charging points offshore
Electric vessels must return to shore for recharging, limiting their operational efficiency and feasibility. As the third and final piece of the puzzle, the solution lies offshore, integrated into the very wind farms the vessels serve. By embedding charging points on turbines, substations, dedicated monopiles or floating platforms, developers can enable vessels to recharge at sea, eliminating the need to travel back to port and slashing Scope 1 emissions from fleet operations entirely.
This offshore charging infrastructure is the final enabler that can unlock the full potential of electric fleets. It allows offshore wind developers to decouple operations from oil markets, deliver long-term opex reductions and dramatically lower the carbon footprint of the industry’s service fleet backbone.
Electrification in practice during E-CTV trials at Nobelwind Offshore Wind Farm
In July 2024, MJR Power & Automation successfully completed a landmark offshore charging trial at the Nobelwind Offshore Wind Farm, operated by Parkwind and JERA.
The project involved the installation of the Aquarius ECO, a charging system from MJR spinout Charge Offshore, on a live offshore substation, enabling real-time power transfer to an E-CTV without disrupting field operations. The modular system was installed and commissioned in 2.5 days using only the existing offshore substation crane and a CTV, demonstrating ease of deployment and minimal operational impact.
During the trial, the system performed multiple safe and fully automated charging cycles, validating its functionality in real-world offshore conditions, including hands-free connection and disconnection, weather-compensated cable handling and real-time energy monitoring.
Demonstrating maximum operational safety standards (a critical factor in offshore electrification), the project also successfully completed emergency release, recovery and reconnection, and the immediate resumption of power transfer without any intervention or maintenance required. No mechanical or electrical failures were recorded, and the trial confirmed the charger’s compatibility with field infrastructure and its readiness for broader deployment.
The trial reached Technology Readiness Level 8 (on a 9-point scale), marking a major step toward commercial rollout. It proved that offshore charging is technically and operationally viable and scalable, and it offers the highest levels of safety, speed and reliability for crew in all-weather operating conditions.
This successful trial at Nobelwind provides a foundation for the electrification of offshore wind O&M fleets.
Prioritizing electrification from the start
To fully transition to electrification, original equipment manufacturers, port authorities, grid operators and policymakers must align to define standards, incentivize infrastructure and support innovation. Developers should also prioritize moving pilot electrification projects, like the Nobelwind trial, to standard practice by designing offshore charging into new wind farm projects from the outset.
Many wind farm operators are already signaling their intent to electrify. Charge Offshore has collaborated with several operators to complete front-end engineering design (FEED) studies to evaluate the technical requirements, costs and risks of implementing offshore charging infrastructure, and several further FEED studies are in the pipeline.
As the offshore wind sector sets new construction records, it must also set new standards for sustainability. The future of clean energy does not stop at the turbine blade, but extends far beyond to the critical O&M fleets supporting offshore wind expansion.
About the Author
Dimitri de Gunzbourg
Dimitri de Gunzbourg is CTO at Charge Offshore.
With degrees in mathematics and physics, he worked as a scientist before switching to engineering, actively participating to the development and operations of new technologies for ultradeepwater energy infrastructure installation.
He then acted, for the following 25 years, as engineering lead and manager as well as operation manager for major offshore energy subsea contractors like Comex/Seaway, McDermott, Subsea7 and Technip.
Since 2021, he has been fully focusing on the development and bringing to market of Charge Offshore’s offshore charging solutions for both e-CTVs and e-SOVs.