Researchers are working on a system that uses ultra-voilet (UV) light to prevent biofouling on ships' hulls.
The novel approach involving a UV light-emitting layer applied on exposed underwater surfaces is being trialled by researchers from Philips Research in the Netherlands and Defence Science and Technology Group in Australia.
The researchers say their concept could solve the common drawbacks of existing coating technologies which are either not fully effective or, like TBT, have negative environmental effects. Biofouling agents either provide surface conditions that are repellent or toxic to settling organisms or they cause settled organisms to be released easily from a moving vessel. However, solutions that rely on a moving vessel are by definition not very effective for vessels that are stationary for prolonged periods.
UV light is known to harm or kill many species and is currently being used in some ballast water treatment systems as well as land-based applications such as water sterilization.
The researchers are using short-wavelength UV LEDs in a thin coating-like structure with properties that enable the light to escape uniformly. Where a typical ballast water treatment system might use tens of kilowatts of power, the system under trial uses only milliwatts to treat a surface. The system can also be fitted to curved surfaces, so it offers a solution to niche area biofouling by being suitable for areas such as sea chests.
Several prototypes are currently undergoing long-term testing in a number of locations around the world.
A 30 to 30 cm test sample after a year underneath a small vessel in Zeeland (Netherlands).