With shrinking demand and limited long-term contracts from energy majors, Corvus Energy senior vice president sales Christian Søvik said low- and zero-emissions OSVs are the future of the offshore support sector
Speaking at Riviera’s Annual Offshore Support Journal Conference, held virtually in 2021, Mr Søvik described some of the work Corvus is doing to assist OSV owners grappling with making idle tonnage more attractive.
The company has delivered batteries for more than 60 hybrid OSVs with the Orca ESS its most popular offering. The company also launched the battery-on-board (BOB) application, a "plug and play battery room" to simplify integration into a system integrator’s power management system on board a ship which incorporates the Orca ESS.
Mr Søvik said conversions present owners with an option to keep their fleet competitive, but owners must also contend with return on investment. At present, Mr Søvik believes the hybrid OSV is the industry’s best return on investment “with a payback time of two to four years dependent on government funding”, and with more vessels switching to all-electric, the company believes the day of the all-electric platform supply vessel (PSV) is near.
Such vessels will require high-capacity batteries. A typical PSV operating in the North Sea requires 60 MWh to complete a round trip of 50 hours. Opting for battery-only propulsion will require enormous storage capacity. Corvus is offering its Blue Whale ESS to meet the need for large-capacity batteries.
Alternatively, future vessels can reduce emissions via offshore charging which reduces the need for high-capacity batteries. When this is achieved, Mr Søvik said zero-emissions can be achieved with an installed battery of less than 30 MWh, while low-emissions transits, done at efficient engine loads with LNG or other existing carbon fuels, can be achieved with less than 15 MWh.
Finally, batteries can be combined with fuel cells. In January, Corvus announced a new fuel-cell division to design and certify the marine fuel-cell system using Toyota fuel-cell technology as a building block for larger systems. The project is backed by shipowners including Norsk Hydro, Equinor, Shell and BW Group.
However, battery fuel cells may not be suitable for all OSVs in all operational environments. Mr Søvik said the lifetime of a fuel cell is dependant on how it is run.
“It is more sensitive than a diesel engine. Rapid load changes substantially reduce the fuel-cell lifetime. The higher the load, the less efficient it is,” he said.
As operational costs drive change, Corvus expects the cost of hydrogen to remain more expensive than electricity for some years to come. To facilitate conversions, the company is also offering options to lease batteries. By leasing batteries, the BOB application or an entire system, Corvus can offer a performance warranty and buyback options.
The lease option is tailored to attract vessel owners by offering no upfront capital investment and the equipment acquisition cost is distributed over the period of use. Owners will also be granted full rights of use.
Mr Søvik said Corvus Energy foresees change in the offshore support vessel (OSV) sector to be driven partly by forthcoming regulation. The EU is mulling a carbon tax in shipping and in January, the Norwegian Government revealed plans to hike the CO2 tax by €200 (US$235) per tonne by 2030, which drew the ire of the country’s oil industry.
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