In the second in a series from Kongsberg Maritime, Oskar Levander explains how a research project has devised a ship concept using conventional fuels, that can meet future compliance targets, with the addition of energy saving technologies including wind.
There are many ways in which ship owners can tackle the prospect of tighter regulation. The easy part is agreeing that all of these new technologies have something to offer, but the difficulty lies in how to apply this to your vessel, knowing that your investment choice will need to remain relevant for decades. The fundamental target here was to design a vessel, that could comply with the predicted CII regulations throughout its lifetime.
For this study, we decided to look at a vessel, with global operations. We settled on a bulker as the basis of a new concept. To represent a vessel size that is very common, we selected a kamsarmax bulker of 82,000 dwt. It also represents a vessel type for which a switch to an alternative fuel, could become restrictive, in terms of global availability of low-carbon bunker fuels.
Central to our study was the development of a ‘super-efficient bulker’, a kamsarmax-sized vessel equipped with a range of energy-saving technologies. By combining wind propulsion, air lubrication, hull optimisation, and advanced energy management systems, this concept vessel demonstrated significant fuel cost savings of between 40% and 55% compared to conventional designs.
One of the key innovations explored in the study was the use of a hybrid wind propulsion system. All manufacturers, be that those making wing sails or rotors, only offer their own solution, and each works well in specific conditions. For example, a prevailing headwind gives better results with a wing sail, while rotor sails give maximum benefit in sidewinds.
What we chose to do was equip this vessel with two types of wind-assist technology, in order to get the best of both. So, instead of installing five of one type, we have opted for three rotor sails and two suction wing sails. The combined wind propulsor setup results in larger savings compared to either wind technology being used on its own. The three rotors in the middle are also tiltable to aid cargo handling.
Air lubrication, injecting air bubbles into the water surrounding a ship’s hull to reduce frictional resistance, has also gained prominence. While this technology has shown promise, its effectiveness can be limited by the dissipation of air bubbles. The Super-Efficient Bulker addresses this challenge through a novel, one-degree sloping hull design that traps air bubbles – with vertical bilge keels – more efficiently, enhancing the benefits of air lubrication.
Slow steaming, reducing vessel speed to lower fuel consumption and emissions, was integrated into the operating profile. Additionally, advanced energy management systems were employed to optimise the allocation and utilisation of the energy resources onboard.
This project has been a real eye-opener for us. While each element makes a difference, it’s the combination of these technologies, where the real difference is made. The fuel saving calculations were determined through comparison with latest bulker designs, rather than an old vessel as the benchmark. The opportunity to reduce fuel costs by half, compared to state-of-the-art conventional vessels, without the need to blend low-carbon fuels, is something I believe will be attractive to ship owners, particularly for the vessel type we examined.
Wind and air lubrication are great technologies, but at Kongsberg, with our experience as an integrator, it means we can pull together the best technologies out there, along with our own, and offer something that could offer an alternative destination on the journey to cleaner, more efficient shipping.
