Let’s take a dive into the innovative anti-fouling technologies designed to make our ships cleaner and greener.
When at sea, ships’ hulls start to get covered by a build-up of marine organisms such as seaweeds and shellfish. This reduces hydrodynamic performance, causing fuel consumption to increase massively which can land you in dire straits, both ecologically and economically. But ensuring that ships remain free from this biofouling is not plain sailing.
Traditional methods such as coating with copper-, zinc-, or tin-based paints, which have long been a mainstay of the maritime industry, produce lasting toxic effects on the aquatic ecosystems and should be given a wide berth. Today, there are more regulations against the use of these metal-based biocides to ensure that anti-fouling techniques are all above board.
WHICH ANTI-FOULING INNOVATIONS COULD HELP SHIPPING BECOME MORE ENVIRONMENTALLY FRIENDLY?
With these increased regulations, there has been a swell in the number of anti-fouling inventions to keep hulls, and seas, spick and span. Let’s take a look at some of these:
Self-polishing copolymer coatings
Traditional anti-fouling paints work by flaking off to release copper-based biocides into the water which deter organisms from latching onto the hull. These paint flakes are eaten by small marine species leading to the bioaccumulation of copper in fish.
Self-polishing copolymer coatings, however, undergo a hydrolysis reaction with sea water to form an acid polymer layer. This layer then dissolves in water and releases a biocide in much more controlled amounts. The dissolution of the acid polymer then exposes a new copolymer surface beneath which can undergo a further hydrolysis reaction. This system minimises the amount of biocide being released into the oceans.
Biological anti-foulants
It’s not just transition metals that can prevent marine organisms from taking over. For example, enzymes that catalyse the breakdown of chitin can weaken the outer layers of many early-stage biofouling microorganisms.
Immobilising these enzymes onto a surface coating can therefore prevent the adhesion of various plants, animals and fungi onto a ship’s hull. Alternatively, specific biochemicals can be used which interfere with protein pathways in small marine creatures such as barnacles, to stop them from being able to attach to the underside of boats. These antifoulants can be released without the damaging effects associated with transition metal-based biocides.
Hydrogels
This anti-fouling method does not rely on the release of antifoulants at all. Instead, the hull is coated with a hydrogel which absorbs water, thus creating a barrier layer which barnacles and other similar organisms are unable to cling onto.
Hydrogels have a high water content and do not contain any toxic components, making them a suitable material for marine use. However, hydrogel coatings struggle with short lifespans leading to a need for frequent re-application. There is more work to be done in this area of anti-fouling technology…
Nanomaterials
There are a wide range of nanomaterials which exhibit anti-fouling properties, some metal-based, some polymer-based, some composites. In particular, graphene has been shown to have similar anti-fouling efficacy to copper, but without the downsides of cupric bioaccumulation.
Graphene is also very light which allows it to coat the underside of a boat without adding much excess weight, and it is very chemically stable giving graphene coatings good longevity. Could this be a long-term solution to biofouling?
Biomimetics
Unlike boats, many sea creatures spend all their lives in the water without weeds and algae growing on them. This has served as inspiration for several anti-fouling innovations. Some new anti-fouling coatings use nylon microfibres which mimic the spiky surface of sea urchins. These needle-like hairs prevent organisms from growing on the hull.
Similarly, other coatings consist of tiny overlapping scales which mimic the ridged surface of shark skin. This texture prevents biofouling, even at slow speeds. By observing nature, we can learn new methods of keeping our hulls clean.
Ultrasonic anti-fouling
This method of anti-fouling steers away from using coatings entirely. Transducers can be attached to the underside of boats which emit high frequency waves. These waves cause vibrations in the hull which result in algae cells being removed from the boat’s exterior. These transducers can even be solar-powered, further reducing the environmental impact of this anti-fouling technique.
These are just some of the first-rate technologies with new patents in the offing, each balancing efficacy, environmental impact, longevity and cost in different ways. But there is always room for further improvements - could your invention turn the tide on biofouling and marine pollution?
All at sea with how to identify, protect, exploit and enforce your inventions? Contact our dedicated cleantech team today.
