Workshop on the Relationship between Energy Efficiency and Underwater Radiated Noise from Ships, 18-19 September 2023

Over two days at IMO Headquarters (18-19 September), stakeholders from across the shipping industry, including operators, port authorities and ship designers, joined academics and engineers to discuss how technical and design processes can be applied and combined to best effect. Also discussed were the trade-offs that need to be considered, what is required in terms of research and monitoring data to help inform decision-making, and how regulation can support and effect change.  

Opening the workshop, Jack Westwood-Booth, Senior Deputy Director in the IMO’s Maritime Safety Division, reminded participants why they were there:  

Michelle Sanders, Alternate Permanent Representative of Canada to IMO ran through the Organization’s work on underwater-radiated noise, including the development in 2014 of Guidelines to address the impacts of URN on marine life and their revision approved by IMO’s Marine Environment Protection Committee (MEPC) in July 2023. An intersessional Correspondence Group is due to submit proposals on suggested next steps to the Sub-Committee on Ship Design and Construction (SDC) in January 2024 which will, in turn, report to the MEPC. 

The aims of the soon-to-be launched GloNoise Partnership project were outlined by Steven Reyersen from the project team. Established by IMO’s Department for Partnerships and Projects (DPP), its aim is to establish a global stakeholders’ partnership to assist developing countries in raising awareness and building capacity to address the issue of underwater noise from shipping at national and international level. It has almost US$2 million funding from the Global Environment Facility (GEF) to operate as a pilot project for two years.  

A study on treatments to increase energy efficiency (EE) and reduce GHG and their impact on URN conducted by VARD Marine was repeatedly referenced during the workshop. The findings of the study and associated matrix were summarised by Rienk Terweij from VARD. The report can be seen here.  

The research analyzed designs and technology for improved hydrodynamics, quieter propulsion including propeller design and the effects of using alternative fuels, and other technological energy efficiency, GHG and URN treatments, as well as operational measures such as slow steaming. It found that the main URN sources were propellor noise, machinery noise and flow noise. VARD’s research found that energy efficiency and underwater-radiated noise are often closely correlated, i.e. if EE goes up, URN goes down. However, it found that in a small number of cases, a reduction in EE leads to an increase in URN.  

The study considered how much the application of mitigating operational measures and technologies can have - for example, reducing speed or the use of wind propulsion.  

Mr Terweij called for more research to be conducted into underwater radiated noise, noting that confidence in what is known about it is significantly less than confidence in knowledge about GHG emissions. 

A panel discussion on implementation of GHG and noise reduction strategies followed with perspectives from ship owners, classification societies, academics, environmentalists, and those promoting a zero-emissions shipping industry through technology.  

Points raised included existing measures that help with both energy efficiency and reducing URN, such as speed reduction and the cleaning of hulls; the need for new vessels to be designed with GHG and URN reduction measures in mind; how the industry can be incentivized to achieve better outcomes; the interrelation of the challenges of URN, GHG and the health of the oceans; and the current lack of data on how, and how far, GHG reduction technologies can also reduce underwater noise.  

Energy efficiency by design and how that could help reduce underwater noise 

Presentations were delivered by several of those researching, developing and trialling ways to optimize energy efficiency in shipping which brings with it underwater noise reduction benefits. 

Projects in this area involve actors from right across the commercial shipping sector:  

International shipping and logistics companies such as Maersk and CSL are testing systems on their ships and trying to measure the impact on URN. 

Academic institutions - for example, research by the Korea Research Institute of Ships and Ocean Engineering (KRISO), which is developing ship URN mitigation technology, shows that the greater the energy efficiency, the less the URN reduction. The University of Strathclyde is part of the GATERS project on the retrofitting of a new “Gate” style rudder system which they claim saves at least 15% on fuel and URN reductions of 15-20 decibels (dB). And the Maritime Research Institute Netherlands (MARIN) is working on four possible solutions.  

The Life PIAQUO project and a small marine engineering firm, Oscar Propulsion, are both redesigning propeller blades to reduce cavitation and thus optimize both energy efficiency and underwater noise reduction.   

Kevin Reynolds from Glosten, a naval architecture & marine engineering consultancy, said the industry is starting to understand the pay-off between energy efficiency and URN reduction. He advocated for incentives to include underwater-radiated noise reduction as a minimum requirement at the design stage.  

Several questions from the floor during this session focused on cost savings from energy efficiency and queries about the practicalities of potentially combining solutions.  

How Greenhouse Gas emissions and underwater noise impact on Indigenous communities  

Day two of the workshop began with a keynote speech from Lisa Koperqualuk, President of the Inuit Circumpolar Council (ICC) and head of delegation at IMO. The ICC, which holds consultative status at the United Nations and provisional consultative status at IMO, represents 180,000 Inuit who live in Alaska, United States; Canada; Greenland (part of the Kingdom of Denmark) and the Russian Federation. 

Ms Koperqualuk made the case for the shipping sector to access and use Inuit communities’ knowledge of ocean and coastal patterns, tide patterns, ice movements, and mammals which have been built up over generations. Doing so, she argued, improves outcomes and policy recommendations.  

“Our communities are supplied by ships coming from the south. We are also ship owners. Our vision is to generate the knowledge to support safe and sustainable Arctic shipping which cannot be successfully completed without Inuit, industry and government partners,” Ms Koperqualuk told the meeting.  

Relationships between energy transition, operational optimizations and underwater noise 

In a session titled “Energy transition, operational optimizations and related solutions: What do we know about URN relationships?”, the workshop heard about the kinds of efforts some companies, such as ferry operators and port authorities, are doing to better understand the harm their operations can cause regarding underwater-radiated noise, and mitigations they are putting in place as a result.  

The Port of Vancouver’s Derek White described the “clear benefits” shown by a trial in 2017 of slowing down marine traffic. As a result, seasonal slowdowns have been expanded. In 2022, he said, results of voluntary slowdowns produced a 2.2-3 dB reduction in underwater noise. 

BC Ferries operates 39 ferries on 25 routes along the western coast of Canada. Their aim is to reduce noise levels emitted from their operations from a current baseline of 185 dB to 175 dB. Their research on propeller design has shown the quieter the propeller, the less energy efficiency can be achieved. They have also measured the benefits of using a new coating to help keep their hulls clean – this produced a reduction in fuel use of 2% and a slight reduction in noise.   

Washington State Ferries operate 21 ferries on 10 routes in the north-west Pacific’s Salish Sea. The company’s Chief Sustainability Officer, Kevin Bartoy, explained the three plans the company has in place to tackle sustainability and decarbonization which have resulted in fuel efficiencies. Their Operational Efficiency Work Group encourages suggestions from the fleet, commits to quickly “truthing” measures, and to quickly implementing those deemed to have potential.  

The workshop heard from companies producing novel energy efficient technologies:  

GRAPHITE produces coatings for vessels’ underwater surfaces which help to maximize energy efficiency. The company has also developed a coating which acts as a primer to insulate and reduce URN. Silverstream Technologies, a newcomer to the area of underwater-radiated noise and keen to collaborate on tackling it, has an air lubrication system which they claim, through the deployment of a uniform “carpet” of air bubbles, produces 5-10% net fuel and emissions savings.  

PowerCell Group produces hydrogen fuel cells which, they said, were selected for ferry projects and in which the private yacht market has shown much interest. 

The International Windship Association told workshop participants about a very old technology which is making a comeback: wind propulsion. In particular, the potential for combining wind propulsion with other technologies was highlighted.  

Practical measures as part of a strategic approach to GHG and URN reduction 

The final session of the workshop focused on practical measures that shipping industry stakeholders can take to put in place strategies that achieve reductions in GHG and URN emissions. 

Quiet Oceans’ Ocean Planner is a tool that can be fitted to ships to enable assessments of the benefits and costs induced by maritime spatial planning regulation measures, such as areas where a vessel’s speed is limited or where navigation is prohibited - or restricted to ships that comply with a given noise level limit. 

Research by the SATURN project on how noise from shipping affects the marine environment, involving 20 partners from 10 countries, claims that travelling at slower speed brings not only significant benefits in terms of noise levels, but also the duration of animals’ exposure to it and the size of footprint in which they are exposed.  

Starcrest Consulting Group’s Bruce Anderson gave examples of what some ports are doing. For example, some have in place speed restrictions: the Port of Los Angeles and Port of Long Beach operates a 12 knots speed limit; the Port of New York and New Jersey’s limit is 10 knots. The Protecting Blue Whales and Blue Skies project involves 23 global shipping companies and studies URN, whale strike survivability and emissions reductions. It found that ocean noise reduced by 6 dB on average, the risk of whale strikes reduced by 44%, and regional GHG emissions decreased by 32%.  

Charlotte Runzel from SailPlan, which measures and models outputs of the entire combustion process explained that with the right data, the system can send alerts to vessel operators to suggest real-time measures to increase efficiency - for instance, that they change speed or reduce the number of engines. Direct measurement is, she said, simpler and more accurate than calculating emissions via fuel consumption, and, therefore, it is easier to be regulation compliant. 

Research by Rene Taudal Poulson from the Copenhagen Business School focused on the human element by observing whose decisions on a daily basis influence a ship’s energy efficiency. The study found that voyage planning decisions were made by ship owners, cargo owners, port stakeholders and Governments based on commercial factors which, he argued, may undermine energy efficiency.  

Links to all the workshop presentations and photographs of the workshop can be found here.