Even though maritime shipping is one of the most efficient way to transport goods, emissions from international shipping are around 1 billion tons of CO2 per year. This corresponds to 2-3 percent of the total global emissions. Without measures, emissions will increase by 50-250% the next 30 years was stated by International Maritime Organization (IMO) in 2014. However, IMO has a goal of halve the emissions by 2050 and then work towards zero emissions as soon as possible after that. According to SINTEF to reach the goal of 50% reduction by 2050, each individual ship must reduce emissions by almost three quarters.
One of several answers on this challenge could be implementation of subsea gliders for overseas bulk transportation. Subsea gliders are a specialized type of autonomous underwater vehicle (AUV). Rather than using a propeller to move through the water, they use fixed wings and changes in buoyancy to achieve both vertical and forward motion, moving through the water in a saw-tooth pattern. The autonomous freight glider concept is able to reduce emissions by more than 90% compared to conventional ships. Other benefits could be lower operational, less dangerous exposure for crew and the possibility for new transport systems. Through the project, a concept design has been developed for a vessel of around 50 meters in length, that can carry more than 500 m3 of CO2 in liquid form and can operate in great water depths. We have also gained increased insight into regulations for autonomous, international shipping and have had dialogue with possible users of such shipping.
A baseline design for the USFG capable of travelling at a lower speed of 1 m/s with an operating range of 400 km and a maximum operating depth of 200 m is proposed. The length of the USFG is about 50 meters which allows the vessel to carry 518 m3 of CO2 while serving the storage needs of the carbon capture and storage (CCS) ventures on the Norwegian continental shelf. The USFG is powered by battery cells, and it only consumes a little less than 8 kW of electrical power. The main details of the design are presented in the first part of the work. A torpedo-shaped shell is employed for the USFG, having a diameter to length ratio (slenderness ratio) of 1:9.7. This design reduces the manufacturing difficulty of the vessel while optimizing the slenderness of the structure to obtain maximum cargo capacity and reduced drag resistance. The external hull is reinforced by utilizing a stiffener. The stiffeners are used conferring to the calculation procedure in DNV-RU-NAVALPt4Ch1.