A passenger ship owner presented the successes and challenges of operating a hybrid-electric propelled, sightseeing vessel in California at Riviera’s Maritime Hybrid & Electric Conference
In a case study, sightseeing passenger ferry owner Red and White Fleet revealed the vessel had achieved fuel savings of around 35% over a steel ship with conventional propulsion by using an aluminium-hulled, hybrid-electric vessel.
The savings were the biggest highlight from a year’s operation of newbuild passenger vessel Enhydra in San Francisco harbour, in California. The 39m vessel carries up to 600 passengers on an hour voyage around San Francisco, several times a day. And its Cummins generators and Corvus 160-kWh energy storage system give Enhydra nearly 600 kW of power for the trips.
Red and White Fleet president Captain Joe Burgard said the company wanted to build an inspirational vessel with forward-looking technology, and that the end product had to be more economical than typical vessels performing similar services.
“The hybrid-electric propulsion represents around 10% of the capital we needed to see a return on that investment,” Captain Burghard said at Riviera Maritime Media’s Maritime Hybrid & Electric Conference in Bergen, Norway on 5 September.
“Our primary saving is in the fuel costs and we are seeing 30-35% fuel savings” versus a conventional steel-hulled vessel, he said.
“A lot of the fuel savings is from the aluminium hull design as it is a light material," Captain Burghard said. Aluminium displaces only a third of the water volume of steel.
The battery system made up the rest of the savings, he explained. "During operating hours, the vessel’s internal combustion engine works only around 50% of the time,” based on the vessel’s operational profile.
Enhydra’s batteries are charged from a shore facility overnight and charged during idle periods by the diesel generators throughout the day. “Enhydra can do an all-electric cruise for one hour,” said Captain Burgard. The generators use diesel sourced from renewables to minimise the emissions and environmental footprint of vessel operations.
Captain Burgard said another benefit of electric propulsion was how quiet the onboard systems are, adding to passenger comfort. Quiet operations generate challenges for crew, however.
"On the rest of our vessels, operators will use auditory input for the engine controls, but Enhydra is quiet so they need to have indication from the motion and instruments," he explained.
Training & operation
The low-volume engine operations mean telemetric information is particularly useful for crew operating this electric-hybrid vessel, informing sailing decisions that assist the vessel in operating on optimal battery power consumption.
Captain Burgard said additional crew retraining was needed when the vessel launched as operations and failure-mode processes are different with hybrid-electric compared with conventional propulsion.
“Crew needed to be trained on which sequences and processes to go through and on becoming familiar with the checklists,” said Captain Burgard.
“We worked with the US Coast Guard to ensure we did not need more crew and with the system integrator so the system was not too complex and the crew could be trained on the system,” he said. Red and White Fleet selected BAE Systems as the system integrator and the shipyard for its willingness to work in partnership.
“We looked at the processes of the shipyard as they would be taking on something as new as we were,” said Capt Burgard.
“It was important that the yard had a direct line with the US Coast Guard to resolve technical issues quickly. It was important that the shipyard had a sense of ownership and was a partner.”
Construction of hybrid-electric Enhydra was a significant milestone in technical shipbuilding in the US, he said. “We all wanted this to be a success."