Economic and Environmental Impact Trade-Offs Related to In-Water Hull Cleanings of Merchant Vessels

Merchant vessels are equipped with antifouling systems to prevent accumulation of marine organisms on the hull—a phenomenon known as fouling. In many cases, however, fouling accumulates and in-water hull cleaning is required. Hull cleanings are part of a hull management scheme, and although they are an established practice, their associated environmental and economic trade-offs and conflicts have remained largely unexplored. The purpose of this article is to quantitatively assess both economic and environmental impacts of hull management schemes on the operation of tanker vessels. After identifying induced and avoided costs and environmental impacts from the hull management system, we used both temporally and spatially distributed models to capture the degradation of the antifouling system as well as the global sailing profile of the vessels. Last, we analyzed how each of the modeled impacts varied with the frequency of hull cleanings within the hull management scheme. Our analysis revealed a convex relationship between the frequency of hull cleanings and fuel savings. The higher the frequency of hull cleanings, the less fuel savings can be achieved per cleaning. In terms of costs, from some point on the costs of the service are likely to offset the savings—especially if fuel prices are low. In regards to climate change, avoided emissions due to fuel savings are likely to outweigh the limited impacts from the service itself. Last, while ecosystem impacts from marine, terrestrial, and freshwater eco-toxicity are likely to increase from hull cleanings, they are subject to high uncertainties.