Power management needed to prevent vessel blackouts

Power management becomes critical to vessel operations and safety when batteries and fuel cells are installed to drive propulsion. Some shipping sectors, such as offshore support and port service vessels, have installed batteries and are testing hydrogen fuel cells.

Owners are using this technology to cut emissions and reduce fuel costs in the long term, without affecting onboard safety.

These energy storage and propulsion systems can help shipping to meet IMO’s target of cutting emissions by up to 50% by 2050, but this needs to be done without risking blackouts.

GE Power Conversion senior sales manager for passenger vessels Renaud Cornu said ships with hydrogen fuel cells and batteries will be built in the future with advanced automation and energy management systems.

“Power management systems need to guarantee lifetime and efficiency,” he said during Riviera Maritime Media’s ‘Fuel cells: addressing the key technical challenges’ webinar on 3 June.

GE can already build fuel cell installations of around 2 MW capacity with power drivetrain, transformer and power management systems. It has a 3-MW cell under development, and a range of hybrid solutions, said Mr Cornu.

Complete installations will need resilience and back-up power to prevent blackouts if there is a fault. “We would need to tackle the power requirements with redundancy,” he said. There will be an “emphasis on fuel cells’ protection and solutions to protect against current ripple and short circuits,” Mr Cornu explained, and “safe operations and resilience under fault conditions”.

A hybrid system could be used on vessels with conventional propulsion and power generating unit either running alongside the fuel cells or ready to take over where required for resilience and redundancy. Or the fuel cell and batteries could be installed to augment power generation. Mr Cornu said a fuel cell can be used to provide power when a ship is in port. Having a hybrid system “improves control and efficiency and extends fuel cell total product life,” he said.

GE’s fuel cell system includes variable frequency drives and a dedicated power management system engineered to limit the switch-on and -off frequency of the fuel cells.

GE has an exclusive partnership with Nedstack for applying hydrogen fuel cell technology in the maritime sector. Nedstack chief commercial officer Roel Van de Pas also anticipates future ships will have hybrid systems on board with hydrogen fuel cells operating alongside batteries or conventional diesel-electric systems.

Full installations would require systems for fuel cell control, safety, auxiliaries and power conversion and a condition monitoring unit. “Fuel cells have to be maritime fit and robust,” said Mr Van de Pas. “They need to be swapped during drydocking and refuellable.”

Fuel cells also need to meet tough maritime safety criteria. “Strong safety concepts have been developed and class accepted [by DNV GL in 2012],” Mr Van de Pas said. “They need to run for thousands of hours before overhaul.” Fuel cells may need overhauls when they begin to degrade and power generating capacity starts declining.

Ulstein has developed a ship design for a zero-emissions offshore vessel as a case study with hydrogen propulsion technology on board. Ulstein SX190 is a 99-m, 5,000-dwt offshore vessel equipped to support hydrocarbon and renewable energy projects.

When it originally unveiled the design for the dynamic positioning class 2-capable Ulstein SX190 design in January, Ulstein Design said it would have a total installed power of 7.5 MW, of which 2 MW would be generated by a fuel-cell power system, typically Nedstack proton exchange membrane (PEM) fuel cells, which are located in a separate, second engineroom.

PEM fuel cells convert hydrogen and air into electric power, heat and water and produce no harmful emissions in the process.

Thruster energy management

Once power is generated it is conducted into the thruster or propeller package for vessel propulsion. Thruster manufacturers have developed advanced monitoring, control and power management systems to enable more optimised energy use, reducing fuel consumption and maximising power output. It also avoids unnecessary part exchanges and overhauls, said Schottel vice president for sales Roland Schwandt. “These systems are the cornerstone of preventive maintenance and can improve service planning,” he said. The condition of propulsion systems can be monitored remotely from the bridge or shore office.

“These modern solutions allow owners of vessels of all types and sizes to reduce costs, increase efficiency and ensure onboard safety,” said Mr Schwandt. “Digital services such as remote monitoring are gaining importance.”

All Schottel propulsion units come with control systems. It also offers PowerControl power management systems, AutoControl integrated automation systems and AlarMon alarm monitoring systems. Schottel has also developed MariHub, a gateway for internet of things (IoT) data. “MariHub contains remote monitoring, data acquisition and even condition monitoring systems,” said Mr Schwandt.

It also offers 24/7 onboard surveillance of the propulsion system and can significantly improve service and maintenance scheduling. “There is a trend towards remote monitoring or remote-controlled and autonomous functions,” he said. “In the long run, this will likely ultimately result in autonomous vessels.” This is where computer-driven power management will be vital, while IoT and machine learning will be required by intelligent autonomous systems.

“We will focus even more on the development of intelligent systems for marine automation and digitalisation,” said Mr Schwandt.

Schottel took an important step in that direction in 2019 when it acquired a 50% stake in Blue CTRL. “These systems will not only enable us to offer our customers smarter as well as integrated controls for both newbuilds and existing vessels, but also provide a solid basis for offering hybrid and electric solutions,” said Mr Schwandt.