Box-coolers are essential for a ship’s functioning. However, when unprotected, they quickly lose their effectiveness due to marine growth. Unprotected box-coolers quickly look like this:
The pipe bundle of the box-cooler is a very attractive surface for all kinds of marine life:
– It has an attractive temperature (normally between 25 and 35 Celsius)
– Because of the constant, forced flow of seawater, there is abundant oxygen and there are abundant nutrients.
There are different systems to prevent this marine growth. For box coolers almost universally used is the Impressed Current Anti Fouling system (ICAF). An ICAF consists of a set of copper bars (anodes) and steel plates (cathodes), which are placed in the sea-chest below the tube-bundle of the box-cooler. Once a current is applied, the copper anodes start dissolving, releasing copper ions into the sea-chest to poison all marine growth there.
While an ICAF might keep your box cooler clean, there is a major hitch: a sea-chest is per necessity an open system, hence all released copper ions end up in the sea.
Pollution by international shipping is already under strong scrutiny. CO2 emissions of all international shipping equals that of Germany! Recently an accord was reached to start curbing greenhouse emissions.
Given this increased scrutiny of the environmental footprint of the maritime sector, it just seems a matter of time before the ICAF systems will also become a topic of discussion.