Ulf Hansen, senior advisor maritime at Swedish company I-Tech AB, addressed the RINA Ship Energy Efficiency Conference in Athens in March 2026 with a data-driven challenge to the growing regulatory momentum towards biocide-free antifouling. His answer was unambiguous: yes, biocides remain essential, and prematurely restricting them risks making shipping’s environmental performance significantly worse, not better.

 

The scale of the problem

An estimated 200 million tonnes of greenhouse gas emissions annually are attributable to biofouling resistance, representing around 20% of total shipping emissions. A complete absence of effective antifouling protection could push that figure to 400 million tonnes. Even modest fouling carries severe consequences: coating roughness or light slime increases fuel consumption by up to 25%, heavy slime by 25-35%, and small barnacles or weed by 35-55%. By 2050, uncontrolled biofouling could be responsible for a 19% rise in total shipping CO₂ emissions. Hull fouling is also the single largest pathway for non-indigenous species entering European waters, accounting for 41% of the total. Approximately 95% of the global fleet relies on biocidal coatings, a proven, fleet-scale solution across more than 100,000 vessels worldwide.

 

In his presentation Hansen used drydock inspection data, compiled with Safinah Group, to challenge assumptions widely held in industry and regulatory circles.

Ulf Hansen, senior advisor maritime at Swedish company I-Tech AB

 

The first is that barnacle fouling primarily affects slow-steaming or low-activity vessels. The data show otherwise. Barnacle presence was recorded on 89.9% of product tanker hulls inspected, 88.4% of crude tankers, and 71.9% of containerships. Vessels reporting significant barnacle fouling across the global merchant fleet grew from 249 in 2020 to 685 in 2025, a near-tripling in five years. This data is based on 685 vessels’ in-dock data during physical inspection.

 

The key driver is trading pattern, not activity level: tankers and chemical carriers operating in warm, nutrient-rich waters with extended anchorage and frequent idle phases below 6knots are roughly twice as likely to suffer heavy fouling as high-activity vessels. As global sea temperatures rise, this pressure will intensify.

 

The second assumption is that barnacle fouling concentrates on vertical hull sides. Inspection data show the flat bottom is in fact more severely affected, with direct implications for hull cleaning strategies and coating specification.

 

The third is that fouling is primarily a consequence of coating failure. While polish-through correlates with increased barnacle levels, significant fouling is recorded even on hulls with no polish-through, confirming that operational exposure is an independent risk factor that coating selection alone cannot fully mitigate.

 

The available biocide toolbox is limited and shrinking, just when fouling pressures are increasing. Among targeted hard-fouling biocides, only two active ingredients are currently available: tralopyril and medetomidine. Hansen also notes that most commercially successful foul-release coatings still incorporate biocidal active ingredients.

 

A biocide ban, even phased, would leave self-polishing coating systems without their primary defence against barnacle settlement, while foul-release systems would become highly vulnerable in warm-water idle conditions. The result would be increased fouling, more aggressive hull cleaning, and a carbon paradox in which the regulatory measure intended to reduce environmental impact would increase fuel consumption, worsen CII ratings, raise EU ETS costs and elevate invasive species risk.

 

A call for collaboration

Hansen’s conclusion is that a biocide-free future is not yet realistic for most of the fleet. His call is for a more sophisticated response: regulators and industry should evaluate biocide policy jointly and holistically, considering emissions to both air and sea, rather than proceeding substance by substance. Rising sea temperatures and their effect on fouling pressure require proper investigation before further restrictions are imposed.

 

Looking beyond the binary framing of biocidal versus non-biocidal, he advocates collaborative innovation towards ultra-low-biocide formulations that minimise chemical load while maintaining efficacy across all vessel types and operational conditions. The goal is to ensure the path away from biocides does not inadvertently worsen the very environmental outcomes it seeks to improve.

 

This article appeared in Technical, TNA May-June 2026.