Sustainable Marine Coatings: Comparing the Costs, Benefits, and Impacts of Biocidal and Biocide-Free Paints

Biofouling presents a major challenge for maritime industries, leading to the widespread use of copper-based biocidal coatings that, while effective, release harmful substances into marine environments. Biocide-free alternatives, such as silicone-based, hydrogel, and natural product-derived coatings, offer more sustainable solutions. This systematic review and meta-analysis assesses the functional, economic, and environmental performance of both coating types using PRISMA guidelines and literature from Scopus and ISI Web of Knowledge (2003–2025). Data from experimental, field, and modeling studies were synthesized, covering fouling intensity, coating durability, toxicity, cost-effectiveness, and regulatory compliance. Biocidal coatings generally performed better short-term, but biocide-free options showed comparable efficacy in some cases and clear environmental benefits. Although initial costs for biocide-free coatings are higher, they may yield savings over time. The meta-analysis found no significant differences in fouling or hydrodynamic performance, though quantitative evidence is limited. Research gaps remain, particularly in long-term studies, highlighting the need for standardized testing and lifecycle assessments to guide sustainable antifouling practices. The outcome of the review also showed that some evidence was excluded due to being in non-indexed sources. This highlights the importance of combining systematic and traditional review methods to ensure a more comprehensive assessment.