Windship Technology: Triple-wing rig can unlock EEXI reduction benefits

Three-wing rigs for ships can successfully tackle the problem of Energy Efficiency eXisting ship Index (EEXI) and Engine Power Limitation (EPL), extending the life of current and newbuild vessels, research conducted by London-based auxiliary power system company Windship Technology found.

The new regulatory framework around CO2 emissions for existing shipping come into force in January 2023 and many ship owners are now considering how to meet these through either operational changes or technical alterations.

On 24 May, Windship Technology published proprietary research that allows ship operators, owners and charterers the ability to easily see the positive operational effect that installing just one 36-metre rig can have on their vessel going forward.

These regulations seek to measure the efficiency of ships through the amount of CO2 emitted per tonne per mile of freight carried in a year. Ships will be rated annually, from A, the highest performing, to E the lowest and the results will be recorded in the Ship Energy Efficiency Management Plan (SEEMP). Ships rated D for three consecutive years or E for a single year need to develop an approved corrective action plan as part of the SEEMP.

The International Maritime Organisation (IMO) has currently set a 2% reduction per year on Carbon Intensity Index (CII) requirements until 2025, at which point the reduction will need to increase to get towards the overall IMO CO2 reduction goals of 2050.

Wärtsilä has reported the results of its CII Insight tool, which has predicted that when CII comes into force, about 45% of the fleet is forecast to be in category D, with a further 16% in category E. The company further predicts that, if nothing is done and assuming the IMO trajectory stays constant, by 2030, 81% of the bulker fleet, 57% of tankers and 80% of container ships will be in category E.

The most common approach to achieving compliance as of 2023 is to reduce the speed of the vessel through engine power limitation (EPL), which will reduce the amount of fuel per tonne per mile used, as ship resistance is proportional to the cube of the speed of the vessel. For some vessels this will be a short-term solution, for others the EPL required may be significant, potentially meaning the engine will be operating well outside of its ideal parameters.

Apart from operational changes such as EPL, owners can implement technical efficiency improvements such as Windship’s rigs.

The performance of the Windship 36-metre rig has been calculated using computational fluid dynamics (CFD). This performance data can then be combined with the EEXI wind matrix to enable the reduction in EEXI for a given vessel to be assessed.

Windship Technology said it had conducted this assessment for a range of vessel dwt to provide owners with a guide as to the powerful effect a single 36-metre rig could have on their ship. This technology can be used in conjunction with EPL if required to achieve compliance.

A further benefit of this approach would be to consider adding a second rig if in due course the CII required further reductions.

Clearly, the final EEXI reduction will be dependent on actual ship performance characteristics, however, the graph provides a good indication of the potential, according to Windship.

“This is a known issue that is fast coming down the track and one that ship operators must start addressing. What we have developed with our … rig design is a solution that works in tandem with existing EPL measures but greatly enhances performance. Our assessment is an EPL reduction of some 20-25% depending on the size of the vessel and not only are we extending the operational life of the ships that install Windship Technology rigs but we are making global shipping compliant and faster,” Simon Rogers, Technical Director of Windship Technology, said.

In February last year, Windship unveiled its zero-emission ship design that features a patented triple-wing rig as well as a new diesel-electric ship drive system that eliminates CO₂, NO_X, SO_X and particulate matter. The True Zero design also incorporates large solar arrays, carbon capture, optimised hull shapes and specialised weather routing software. 

Several months later, the company secured approval in principle (AiP) from classification society DNV GL for its solution.

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