The University of Southampton has initiated a study, commissioned by the International Chamber of Shipping (ICS), to evaluate the relationship between measures designed to improve ship energy efficiency and the emission of underwater radiated noise (URN).
his study underscores the significant synergy between efforts to enhance energy efficiency in shipping and the unintentional noise generated by vessels as they move through the water. ICS commissioned the comprehensive study to explore the synergies between energy efficiency measures and URN reduction. The report highlights the opportunity to reverse the upward trends in URN, simply be leveraging these synergies.
Chris Waddington, Technical Director of the International Chamber of Shipping, commented:
“At ICS we welcome this report. It recognises that most energy efficiency measures will also reduce URN, and therefore presents a win-win situation for shipowners. For safe and cost-effective operation, it is important that shipowners retain discretion on the selection of measures. But for example, modest speed reduction, such as we have seen as a consequence of the EEXI regulation can improve both efficiency and reduce URN for vessels fitted with fixed pitch propellers.”
Similarly, both wind-assisted propulsion and air lubrication improve efficiency and can each provide around 10 dB URN reduction.
…Chris Waddington added.
Considering the aging fleet of vessels, the forthcoming, more stringent Carbon Intensity Indicator (CII) requirements, and the likely high cost of the alternative fuels, the study anticipates a growing trend of vessels implementing energy-efficiency measures to align with the IMO’s revised GHG strategy targets.
”There is no one size fits all solution for the challenge we have ahead but we recognise that by improving energy efficiency, URN can also be reduced and our oceans can be healthier.”, he further said.
Also, Professor of Maritime Fluid Dynamics -part of the University of Southampton’s Marine and Maritime Institute (SMMI) – Stephen Turnock added that the ”report should help in choices being made for future ship design and operation that reduce the overall environmental impact of shipping.”
Among other findings, the report notes that:
- Innovative energy efficiency measures, such as air lubrication systems and wind-assisted propulsion systems, represent promising solutions with positive impacts on URN reduction and the enhancement of energy efficiency.
- As the maritime industry undergoes a transition towards vessel electrification, employing fuel cell, battery, or hybrid technologies, the incorporation of azimuth propulsion and podded propulsors, along with their related machinery, can significantly reduce URN emissions from vessels.
- Enhancing URN reduction in commercial vessels can be achieved through various means, including the improvement of machinery design, the utilization of quieter machinery, the strategic design of engine rooms and machinery placement, and the implementation of resilient mounting systems
- In addition to evaluating the noise generated by individual machinery components, a comprehensive assessment must account for the interaction and collective contribution of these machineries as an integrated system.
It is imperative to recognize that compliance with GHG regulations could indeed lead to
a reduction in URN from commercial vessels, contingent upon the chosen pathway and strategy for
meeting the IMO’s revised GHG strategy