Biofouling — the accumulation of barnacles, plants and algae on ship hulls — is only getting worse as waters warm and as port congestion increases idle time, according to a recent I-Tech study.
As it builds up, the biological material adds drag and reduces fuel efficiency, costing shippers money and releasing greenhouse gases unnecessarily. The study found that the risk of biofouling accumulation increases significantly when a vessel idles or is in warmer water.
“Fouling takes place significantly faster in warm, tropical waters. Ships exposed to longer periods at anchor waiting for cargo or access to port face a larger risk of fouling than those that are moving,” stated the study by I-Tech, a Swedish company that developed an antifouling paint ingredient. “It is known that vessels at idle for 14 days or more are highly exposed to the risk of barnacle growth.”
Given the increase in port congestion in areas such as the West Coast of the U.S. and the East Coast of China, biofouling is accelerating. The average wait time for vessels from anchorage to berth in Los Angeles was at an all-time high of 13 days on Wednesday, according to FreightWaves’ most recent congestion update for the area.
Biofouling can begin within the first few hours a ship enters the water, according to the International Maritime Organization.
“On average, barnacles can grow around 0.1 mm per day, but this can be even more under the proper conditions,” Markus Hoffmann, technical director of I-Tech AB, told FreightWaves. “When a vessel’s hull first begins to foul, its full impact is not fully realized until after weeks of growth have passed. Initially, after their first week of adhesion, smaller barnacles can be removed relatively easily. However, we can only see the full extent of the fouling impact of idling after weeks or even months, when the fouling organisms start to grow.”
Before recent congestion reached critical levels, the study estimated the number of vessels idling had already roughly doubled in the past decade.
The study highlighted a negative feedback loop. More biofouling can lead to more fuel use and higher emissions, which increases the carbon footprint. More GHG emissions can lead to higher water temperatures, which increase the risk of biofouling.
Cost and ecosystem considerations
“A vessel with just 10% barnacle coverage requires an increase in shaft power of 36% to maintain the same speed through the water,” said the I-Tech study.
Since fuel usage is such a large portion of shipping costs, this increase in drag can cut deep into profits. Each hull cleaning related to biofouling can cost $15,000 to $45,000, according to the study. ECOsubasea, a Storebø, Norway-based robotic biofouling cleaner and collector, estimates that shippers can save up to 20% on fuel costs when friction from biofouling is removed.
But fuel efficiency, profit and emissions aren’t the only reasons biofouling is an enemy of the shipping industry. It also brings invasive aquatic species around the world to unique marine environments where the species can damage local ecosystems.
“The spread of invasive species is now recognized as one of the greatest threats to the ecological and the economic well-being of the planet. These species are causing enormous damage to biodiversity and the valuable natural riches of the earth upon which we depend. … Significant economic impact occurs to industries that depend on the coastal and marine environment, such as tourism, aquaculture and fisheries, as well as costly damage to infrastructure,” the IMO said.
The organization recommends routine biofouling management to reduce ship resistance and lessen threats to biodiversity. There are several anti-fouling coatings for different conditions and various cleaning techniques in the industry, though most such techniques damage coatings meant to prevent accumulation.
I-Tech developed Selektope, a metal-free, organic marine antifouling paint ingredient designed to keep barnacle larvae from attaching to ship hulls.
ECOsubasea’s robotic biofouling removal solution collects what is removed from ship hulls, including any invasive aquatic species, and brings it to land to be used as a feedstock for biofuels. This gentler removal technique can be performed in the water, removes more than 97% of fouling material and does not damage the hull’s antifouling coating, according to the company.
“The savings from effective antifouling systems are estimated at more than 100 million [metric tons] of carbon dioxide for the entire shipping industry annually,” the study said.