The Clean Hull Initiative (CHI) aims to develop and work towards implementation of an industry-wide recognized and accepted standard for proactive hull cleaning in international shipping.  Biofouling on ship’s hulls pose a risk to the environment. Not only does biofouling serve as a vector for the spread of aquatic invasive species, it also increases the hull resistance and decreases the propeller efficiency, leading to higher fuel consumption and increased air emissions.

According to the Third IMO Greenhouse Gas Study, as much as 2,5 % of the world’s GHG emissions stems from marine shipping activities. 9 % of these emissions is the direct result of biofouling on vessel hulls causing increased drag through water. Thus, combating biofouling on hulls can potentially save 9 % of the global fuel consumption and thereby GHG emissions from shipping. This amounts to about 79 million tons of CO₂-equivalents per year.

The most common way of combating biofouling is through use of anti-fouling coatings containing biocides. As coatings alone are not able to prevent all biofouling, accumulated fouling needs to be physically removed. Fouling removal (or cleaning) can be done in-water (known as in-water cleaning (IWC)) or in dry dock. IWC can generally be classified as either proactive or reactive. Proactive cleaning is carried out on microfouling only (fouling at early stages of development), where hull grooming is performed at frequent intervals with gentle force without causing damage or erosion to the coating. Reactive cleaning is performed on macrofouling (fouling at later stages of development), which has heavier attachment to the hull and coating. Reactive cleaning has a higher risk of damaging the coating and can further cause release of aquatic invasive species to the local marine environment. Therefore, reactive cleaning is often performed with technology that captures the organic debris removed from the hull.

There is currently no international regulation or standard for hull cleaning of biofouling. Some guidelines have been published, such as IMO’s Biofouling Guidelines from 2011 (currently under review in 2021), and the industry associations BIMCO’s guidelines on IWC with capture. With the increasing awareness on biosecurity worldwide, some port authorities are introducing their own preventative measures, including legislation which arriving ships have to comply with. The competence in port authorities to set regulations and assess arriving ship’s biosecurity risk is varying. Furthermore, varying local regulations create a complex regulatory landscape for ship owners to operate in.

We believe that combating the biofouling issue in shipping is a “problem worth solving”. Solving this issue will lead to less transfer of invasive species, significantly reduced GHG emissions from the global shipping fleet and increased energy efficiency and fuel savings to ship owners and operators. However, solving the biofouling issue requires a holistic approach to hull cleaning, and the “biofouling management toolbox” should comprise several methods to combat hull fouling. IWC should be performed both proactively and reactively, in a safe and controlled manner. The technological development of in-water cleaning has now matured to at a stage where proactive hull cleaning should be utilized as a part of ship owner’s biofouling management plan. As guidelines has been developed for reactive cleaning, we believe the time has come to also develop guidelines and standards for proactive cleaning.

The solution

Bellona, together with industry partner Jotun, launched the Clean Hull Initiative (CHI) in 2021. The objective of the CHI is to work towards development and implementation of an industry-wide recognized and accepted standard for proactive hull cleaning. We are well aware of the complexity of making this vision a reality, and we consider partnering with stakeholders during this process as critical. Therefore, the CHI aims to bring together key stakeholders from the industry, public sector and civil society with a goal to reach consensus on an industry-standard for proactive hull cleaning.

Key success factors for this ambition will be to ensure collaboration and consensus in the industry, and communication and awareness raising of the importance of proactive hull cleaning from both an environmental and a financial perspective.

Contact person

The Clean Hull Initiative (CHI) is led by Bellona Norway.

CHI project manager: Irene Øvstebø Tvedten, irene.tvedten@bellona.no, Senior Advisor Maritime.