The maritime industry plays a vital role in the global economy, transporting over 80% of total world trade (1). While it boasts efficiency in terms of cost and performance per distance travelled, a hidden challenge lies underneath the waves: biofouling.
What is biofouling?
By definition, “biofouling” refers to the unwanted build-up of aquatic organisms on surfaces that are submerged in water. These organisms can range from microscopic bacteria or algae to larger animals like barnacles and mussels. In the maritime industry, biofouling poses a significant problem for ships. This unwelcome accumulation of aquatic organisms creates a significant drag on a ship’s hulll. This drag, as documented by the International Maritime Organization (IMO), can cause a staggering 55% increase in fuel consumption. (2)
This additional fuel consumption has a double negative impact. While maritime shipping is considered one of the more environmentally friendly transportation methods, biofouling can contribute to a rise in greenhouse gas emissions. For example, a layer of slime as thin as 0.5 mm covering up to 50% of a hull surface could trigger an increase of GHG emissions in the range of 25% to 30%, depending on ship characteristics, its speed and other prevailing conditions. (3).
Ships are already responsible for approximately 3% of greenhouse gases. Especially in the context of International Maritime Organization (IMO)’s goal to cut greenhouse gas emissions and develop zero-emission vessels by 2030, the serious issue of biofouling – and its negative impact on sustainable solutions – is now one of the industry’s top priorities.
Additionally, biofouling can introduce invasive species to new environments, disrupting delicate local ecosystems, causing ecological and economic consequences.
Recognizing the dangers of biofouling, countries like Australia have implemented mandatory biofouling management practices. These practices address not only the environmental concerns but also the negative impact on the vessels themselves. Biofouling can shorten a ship’s lifespan and increase maintenance costs due to the need for more frequent cleaning or hull repairs.
However, tackling the challenge of this scale effectively requires a collaborative effort. While governmental bodies play a crucial role in laying the foundation by establishing regulations, a multi-stakeholder approach involving the maritime shipping industry, technology developers, and coating manufacturers is essential.
Current solutions and the need for Innovation
So how to prevent biofouling?
While mechanical approaches like hull wipers offer an environmentally friendly solution to biofouling, their effectiveness can be limited by organism type. It also requires frequent cleaning. In many cases, shipowners look into an alternative, coating to combat this challenge,
Traditionally, the industry relied on anti-fouling coatings containing biocides such as copper. These coatings are effective but come at a high environmental cost. Copper is also be toxic to most species when its concentration exceeds physiologically required levels (4). Additionally, applying these coatings is labor-intensive process that can be hazardous for workers.
Fortunately, the tide is turning towards more sustainable solutions. Non-toxic coatings are emerging as a promising alternative. These coatings employ various strategies to make the surface unappealing to organisms. Silicone-based coatings, which is a form of a Fouling Release Coatings (FCRs), offer a slick, low-friction surface that makes it difficult for organisms to latch on. These coatings also allow initial attachment but then provide a slippery surface that sloughs of organisms as the ship moves. However, it is important to note that non-toxic coatings like FCRs are most effective on ships that operate regularly or under go frequent cleaning. Stagnant vessels, or those that remain stationary for extended periods, are still susceptible to biofouling and may require additional measures.
Despite the advancements in non-toxic coatings, their application using traditional methods remain a challenge. These methods can pose environmental and worker safety risks due to overspray and difficulty in achieving consistent quality and speed of application.
