In-air offshore vessel charging, proven from February 2023 harbour trials to offshore operation

MJR Power & Automationʼs Offshore Power & Charging system enables vessels operating around offshore wind farms to connect, receive power and recharge directly from offshore renewable energy infrastructure.

The system has been developed to support the transition from diesel-powered offshore operations to hybrid and electric vessel fleets by enabling vessels to access clean power while operating in the field, reducing the need to return to port for charging or to rely on onboard generators.

MJRʼs offshore charging journey has progressed from concept and prototype development, part funded in 2021 by the UK Government Department for Transport through its Clean Maritime Demonstration Competition (CMDC), through successful harbour trials carried out in February 2023 and first publicly posted on 13/03/2023, before advancing to successful offshore trials with Parkwind at the Nobelwind offshore wind farm.  

Harbour trial video: February 2023

Trial carried out: February 2023

‍First publicly posted: 13/03/2023

‍Location: Port of Blyth

Vessel: TIA Elizabeth Crew Transfer Vessel, owned and operated by Tidal Transit

Project partners: MJR Power & Automation, Blackfish Engineering and Tidal Transit

The harbour trial video was first publicly posted by MJR on 13/03/2023 and shows MJRʼs platform-mounted automated offshore power and charging system being tested before offshore deployment. The February 2023 harbour trials validated the safe connection, mooring and charging of a vessel battery bank using MJRʼs offshore charging system. The trial set-up replicated the installation of the system on an offshore wind turbine and/or offshore substation.

The journey

MJRʼs Offshore Power & Charging system is not a concept-only development. It has followed a clear, publicly documented route from early design through to live offshore testing.

Concept and prototype development

MJR developed the system to solve a clear operational challenge in offshore wind: how to provide clean electrical power to vessels at sea directly from offshore renewable infrastructure. The system was designed to be installed on an offshore wind turbine, offshore substation, or a dedicated monopile allowing Crew Transfer Vessels (CTVs), Service Operation Vessels (SOVs), hybrid vessels and other offshore support vessels to connect, hold position, receive power and recharge while working in the field. From the outset, the system was designed for safety, automation, vessel control, marine-grade communications, controlled cable deployment, mooring support, and practical offshore installation.

February 2023 harbour trials

In February 2023, MJR successfully carried out harbour trials of its platform-mounted automated offshore power and charging system at the Port of Blyth. The harbour trials validated the safe connection, mooring, and charging of a vessel battery bank using the TIA Elizabeth Crew Transfer Vessel. The following core functions were demonstrated and validated during the 2023 harbour trial programme:

• In-air offshore vessel connection and charging

• Automated cable and connector deployment

• Automated vessel connection, connector docking/clamping and mooring control

• Controlled reeler operation

• Vessel-side control from the bridge

• Wind farm/control-room visibility

• Real-time system monitoring

• Marine-grade wireless communication

• Charging authorisation and control

• Manual and automatic emergency disconnection based on cable tension/load measurement on vessel and overload protection

• Safe charging of the vessel battery system

• Integration of power, automation, monitoring and safety systems

These functions were present in MJRʼs 2023 harbour trials before the system progressed to offshore testing.

13/03/2023 public announcement

MJR first publicly announced the successful harbour trials on 13/03/2023 under the title: “World's first ‘in Airʼ Offshore Vessel Power & Charging System Completes Successful Harbour Trials.ˮ That announcement confirmed that MJR, together with Blackfish Engineering and Tidal Transit, had successfully completed harbour trials of its platform-mounted automated offshore power and charging system. The announcement also confirmed that, following the successful harbour trials, MJR would demobilise the equipment and prepare for installation on an operational offshore wind farm substation in the North Sea. This public announcement is an important milestone in the development of MJRʼs technology because it confirms that the core offshore charging functions had already been designed, built, tested, and publicly demonstrated by March 2023.

Offshore trials with Parkwind at Nobelwind

Following the harbour trial phase, MJR progressed the technology to offshore testing with Parkwind at the Nobelwind offshore wind farm. At Nobelwind, MJRʼs system was installed and tested offshore, enabling a vessel to access green energy directly from an operational offshore wind farm. The offshore trial demonstrated that power could be safely transferred from a fully operational, producing offshore wind farm to a Crew Transfer Vessel without disrupting the wind farm. The successful offshore testing confirmed the operational performance of MJRʼs system in a live offshore environment, including:

• Safe power transfer from the wind farm to the vessel

• Hands-free connection and disconnection

• Automatic coupling and uncoupling

• Charge management

• Free-floating vessel operation

• Effective tension control

• Catenary management

• Single-point mooring and vessel/reeler following modes

• Overload protection

• Automatic and manual emergency release

• Recovery and reconnection without damage to the connector

• No requirement to clean, dry or overhaul the connector after reconnection

This marked the transition from harbour-proven technology to offshore-proven technology.

What the system does

MJRʼs Offshore Power & Charging system is designed to transfer clean electrical power from offshore wind infrastructure to vessels operating at sea. The system can be installed on an offshore wind turbine, offshore substation, dedicated monopile or any other offshore structure whether fixed or floating, and enables hybrid and electric vessels to connect, hold position, receive power and recharge while remaining within the offshore field. It combines offshore power conversion, automated cable deployment, vessel connection, mooring support, real-time control, monitoring, safety systems, and operator visibility into a single integrated offshore charging solution.

System overview

The charging system integrates a range of technologies to enable safe and efficient offshore vessel charging. Key components include:

• Turbine or offshore substation power converter

• Automated deployment system, known as the Reeler

• Mooring and charging cable

• Vessel connection and mooring system

• Real-time control and safety system

• Vessel-side operator controls

• Wind farm control-room monitoring and management systems

• Web portal for booking, authorisation, monitoring and reporting

The turbine or offshore substation power converter converts wind farm medium-voltage AC power into DC power compatible with the Crew Transfer Vessel propulsion and battery system. The Reeler manages the charging cable and connector, enabling controlled deployment and recovery during charging operations. Together with the vessel connection and mooring system, these technologies create a complete offshore charging infrastructure capable of supporting safe power transfer between offshore renewable energy assets and vessels operating at sea.

Key proven functionality present from the 2023 trial programme

MJRʼs offshore charging system was developed around practical offshore operations, not laboratory demonstrations alone. The following functions were part of MJRʼs development and trial programme and were demonstrated through the harbour and offshore testing route:

In-air connection and charging

The system is designed around an in-air connection approach, reducing exposure of sensitive charging equipment to the harsh splash-zone and subsea environment. This supports reliability, maintainability, and safe offshore operations.

Hands-free connection and disconnection

The system supports safe and efficient vessel connection and disconnection, reducing manual handling and improving operational safety. This functionality was present in MJRʼs development programme and was later proven through offshore testing.

Automated deployment and Reeler control

The automated Reeler system controls the deployment and recovery of the charging cable and connector. Once authorised, the vessel can take control of the deployment process, allowing the cable and connector to be lowered safely into the vessel connection system.

Vessel-side operator control

Vessel personnel have visibility of the charging and deployment systems from an operator control station located on the bridge. This allows the crew to monitor system status, connection status, and charging performance throughout the operation.

Real-time control and safety system

The real-time control system enables safe operation of the charging system from both the vessel and the wind farm control room. The control and safety system has been developed in accordance with marine classification society rules and standards, drawing on MJR Power & Automation's experience designing and delivering safety-critical and mission-critical systems for the commercial marine and offshore energy sectors. The control software supports:

• Fully automatic operation

• Semi-automatic operation

• Manual operation

High-level control modes include:

• Manual Control

• Follow Mode

• Mooring Mode

• Positioning Mode

Throughout the charging process, vessel personnel maintain full visibility of the charging system status from the operator control station on the vessel bridge.

Wireless communication and authorisation

The system uses secure marine-grade wireless communication between the vessel and the offshore charging infrastructure. This supports vessel identification, charging authorisation and safe operation before the charging process begins.

Emergency release and recovery

Safety is embedded throughout the system. MJRʼs trial programme validated the emergency disconnection, overload protection, and recovery functions, supporting safe release and reconnection without damaging the connector.

Web portal and operational management

The web portal supplements the real-time control system on both the vessel and the turbine or offshore substation, providing asset owners and operators with access to live operational data and analytics. The portal supports:

• Booking and management of charging operations

• Charging authorisation

• Remote real-time monitoring

• Energy usage metering

• Carbon savings and emissions reduction reporting

• Billing and operational reporting

• Vessel traffic and position monitoring

• Wind farm charger status visibility

• Historical operational data and analytics

The secure web-based platform can be accessed by authorised users on desktop computers and mobile devices. While many offshore operators may prefer to book, authorise, and communicate operationally via VHF radio between the vessel and the wind farm control room, the portal remains a valuable operational tool by providing access to real-time and historical data, analytics, and reporting.

Booking system

The booking system provides functionality similar to familiar online reservation platforms. Using the web portal or application interface, a vessel operator can identify an available charging slot and submit a booking request. Under the current operating model, the booking is authorised by the wind farm control room before the vessel can connect to the charger. The platform has been designed with flexibility in mind and can support alternative operational models as industry requirements evolve, including approaches similar to land-based EV charging, where vessels may be automatically authorised on arrival, subject to account status and operational permissions.

Charging operations and monitoring

During charging operations, operators have access to a dedicated charging interface displaying the vessels position relative to the turbine charger in real time. The charging screen provides visibility of:

• Vessel position and movement

• Charging status

• Power transfer information

• Battery charging performance

• System health and operational status

• Key charging and performance parameters

This information supports safe and efficient charging operations while providing operators with continuous visibility of system performance.

Offshore power supply for standby vessels

In addition to charging CTVs, the system can provide offshore power to support vessels, allowing diesel generators to be reduced or shut down while the vessels are standing by. This creates a practical route to reducing offshore emissions even before full vessel electrification is complete. The system supports CTV charging and is being developed for higher-power offshore charging and power supply applications for larger vessels, including Service Operation Vessels.

Designed for offshore wind operations

The Offshore Power & Charging system has been developed for the practical operating requirements of offshore wind farms and marine assets. It supports:

• Crew Transfer Vessels

• Hybrid and electric offshore support vessels

• Service Operation Vessels

• Platform Supply Vessels

• Offshore wind operations and maintenance fleets

• Vessels on standby near offshore assets

• Wind farm operators seeking to reduce operational emissions

Reducing offshore emissions

Offshore wind farms already generate clean electricity at sea. MJRʼs Offshore Power & Charging system enables vessels operating around those assets to use that energy directly. By allowing vessels to charge or receive power offshore, the system can reduce fuel use, cut emissions, reduce unnecessary transit time, and support the wider deployment of hybrid and electric offshore vessel fleets. The integrated monitoring and reporting capabilities also provide visibility of energy consumption, carbon savings and emissions reductions, helping operators quantify the environmental benefits of offshore charging.