Robert Allan unveils design for methanol-fueled CTV

Methanol-fueled WITV approaching offshore wind turbine. [Image: Robert Allan Ltd.]

With support from the U.K. based Carbon Trust and its Offshore Wind Accelerator program, Vancouver, B.C., based naval architecture firm Robert Allan Ltd. has developed a design for a methanol-fueled RAptor 2400 Crew Transfer Vessel (CTV).

The new design is aimed at bringing the offshore wind industry closer to eliminating carbon emissions from the supply chain.

As a marine fuel, says the firm, methanol provides emissions benefits that are similar to natural gas when it comes to reducing CO2, NOx, SOx, and particulates, but without the need for cryogenic or pressurized fuel tanks. This reduces capital cost, saves space and allows more fuel to be carried. With the advent of green methanol—produced from sustainable low carbon sources including renewable electricity with carbon capture—well-to-wake carbon emissions can be reduced to net zero by switching to green methanol as it becomes more widely available in the years to come; a seamless transition requiring no changes to the vessel.

“The possibility of using green methanol marks a shift from the current linear fuel cycle to a circular fuel cycle, where harmful combustion waste products are converted back into useful fuels. This will have great benefits for generations to come,” said Erik Johnston, P.Eng., Project Manager for Robert Allan Ltd.

The particulars of the RAptor 2400 are:

• Length Overall: 23.8 m
• Molded Beam: 8.0 m
• Molded Draft: 1.1 m
• Methanol Capacity: 12 cubic meters
• Installed Power: 1800 kW
• Speed: >25 knots

Cabins for the master and two crew are in the demi-hull accommodations. A spacious and comfortable technician seating area with large forward and side windows on the main deck accommodates up to 12 wind farm service personnel.

Four Scania DI16 main engines, each rated at 450 kW at 2100 rpm, provide propulsion. Converted to run on methanol by ScandiNAOS AB, they meet IMO Tier III emissions limits without any additional aftertreatment. Two engines in each demi-hull are connected to a dual-input gearbox driving a Servogear controllable pitch propeller system that caters to both maximizing sprint speed and bollard push performance. Extensive in-house CFD analysis was used to achieve a speed in excess of 25 knots at full load displacement.