船体空气润滑系统研究：关于有前景技术和可持续航运替代燃料的研究

About this study: This report was commissioned by the European Maritime Safety Agency (EMSA) under framework contract, No2024/EMSA/2024/OP/0025 Authors: DNV: Hollenbach, Uwe; Sun, Jaeouk; Jordahl, Magnus; Ruth, Eivind; Rognebakke, Olav; Sekkesæter, Øyvind;Leisner, Marius EMSA Review Panel: Alda, S; Benedetti, L; Carvalho, F; Centeno, R; Friolo, M; García Horrillo, M; Hebert, F; Pereira, C; Ramalho,M; Valle, J. Recommended citation: European Maritime Safety Agency (2026), Hull Air Lubrication System Study, EMSA, Lisbon Legal notice: Neither the European Maritime Safety Agency (EMSA) nor any third party acting on behalf of the Agency isresponsible for the use that may be made of the information contained in this report. Copyright notice1: The contents of this report may be reproduced, adapted and/or distributed, totally or in part, irrespective of the meansand/or the formats used, provided that EMSA is always acknowledged as the original source of the material. Suchacknowledgement must be included in each copy of the material. Citations may be made from such material without prior permission, provided the source is always acknowledged. The above-mentioned permissions do not apply to elements within this report where the copyright lies with a thirdparty. In such cases, permission for reproduction must be obtained from the copyright holder. This report and any associated materials are available online atwww.emsa.europa.eu © European Maritime Safety Agency 2026 ISBN: 978-92-95229-47-1doi: 10.2808/0347996Catalogue number: TN-01-26-003-EN-N Cover photo: APchanel/Adobe Stock & EMSA Document History Executive Summary This study presents a comprehensive assessment of Hull Air Lubrication Systems (ALS) for maritime shipping,focusing on their technological maturity, economic viability, regulatory context, and safety implications. The studypresents ALS as an interesting yet still maturing technology. However, the Shipping Industry still needs to have aclear picture of how systems perform under service conditions. Continued research, full-scale trials, and collaborativeefforts among shipbuilders, vendors, regulators, and classification societies are essential to fully exploit the potentialof ALS in sustainable maritime operations. Overview of ALS ALS technologies aim to reduce a ship’s frictional resistance by injecting air into the turbulent water boundary layerbeneath the hull, thereby reducing frictional drag and lowering the ship's power demand, fuel consumption, and,consequently, greenhouse gas (GHG) emissions. ALS systems employ various design philosophies and technologies, and flow topologies such as air-layer, bubble,or cavity drag-reduction are employed. ALS can be active, using compressors, or passive, using venturi effects forinjecting the air. Air injection can range from microbubble to air-water mixture injection systems, each one with itsown advantages and limitations. The study includes insights from interviews and workshops with these stakeholders, providing a comprehensive viewof the technology's current state and market readiness. Sustainability ALS is an emerging technology for reducing hull resistance and improving fuel efficiency. By lowering fuelconsumption, ALS directly reduces GHG-emissions and other pollutants, including NOₓ, SOₓ, and particulate matter. Case studies were conducted on selected vessels operating in both coastal and deep-sea conditions. The findingsindicate potential fuel savings up to 4%, depending on key factors outlined in Section 2.3 Suitability. Beyondemissions reduction, ALS may also decrease underwater radiated noise, supporting marine ecosystem protectionand broader sustainability goals. Performance prediction remains complex for systems with two-phase flow (an air-water mixture next to the hull), asthe two-phase flow dynamics cannot be predicted by traditional scaled model tests and are not yet practical withstate-of-the-art computational fluid dynamics (CFD) methods, owing to the lack of reliable full-scale data forverification. It remains challenging to determine the realistic savings potential during actual vessel operations, whichdirectly influences the estimated GHG reduction. To address this uncertainty, further investigation based on long-term in-service measurements across various weather conditions and ship types is necessary to establish credibleand representative GHG reduction figures for each system. Suitability ALS reduce hull resistance through strategic air release, with key factors influencing their performance as follows: ■Lubricated area: drag reduction is most effective when air is released in hydrodynamically favourable areas,particularly the flat bottom forward (FoB).■Operational drafts: ALS performance is sensitive to the draft. Calibration must be vessel-specific and account forexpected operational drafts.■Utilization: the more frequently a vessel operates, the greater the potential cumulative fuel and emission savingsa