Sustainability Starts at the Bottom

February 6, 2023

Sustainability starts at the bottom. Or more specifically, sustainability in the maritime industry starts on the bottom of ships.

Over the past year, I have attended a number of maritime industry events that have either entirely focused on sustainability and decarbonization, or have included sessions and panels focusing on the same. VPs of ESG and Directors of Sustainability have presented on a myriad of initiatives intended to drive towards a better future for the planet and (of course) the industry.  These are good initiatives, reducing single use plastics, installing shore power at ports, using alternative fuel sources, to name a few.  But through those presentations and follow-on questions and discussions, it’s evident they are overlooking something critical. And that is maximizing hydrodynamic efficiency through biofouling management. Or in simpler terms, actively keeping the hull clean.

These companies all include hull cleaning in their maintenance plans, and do recognize that severe biofouling needs to be addressed. Current practices typically result in cleanings once a year or so, and budgets are built to account for that schedule. Cleaning technology is advancing, and new best practices are waiting to be adopted.

In the fall of 2022, the IMO recently released its report on the Impacts of Biofouling on Greenhouse Gas Emissions, and the report clearly indicates that taking on a proactive approach to maintaining a clean hull goes a long way to reducing greenhouse gas emissions through reduced fuel consumption.  

We can debate the precise definition of proactive cleaning, and I’ve seen different definitions used throughout the industry.  I’ll save the detailed debate for another time, but in terms of the IMO report, they take it to mean to clean before any hard fouling is established on the hull. Reactive cleaning is done to remove established hard fouling. Fair enough – we’re talking about removing slime and light microfouling. 

In their comparison studies, they opted to use a 6 month frequency for proactive cleaning. That might mean there was no hard fouling present at the 6 month mark, but their study ship in equatorial waters still experienced a 20% power penalty by the time a cleaning was completed. That’s a big penalty.  Even in Mediterranean waters with a slower growth rate, there was a 10% penalty experienced.  This quickly adds up to real money.  And significant quantities of excess greenhouse gasses (GHG) being released.  

A vessel experiencing a 20% power penalty, that normally consumes 20MT of fuel a day, is burning an extra 4MT of fuel, at an extra daily cost of ~$4000 (at 1 Feb 2023 MGO prices).  And releasing an extra 5.4 tons of GHGs.  And it’s just not necessary.

Two weeks of fouling growth from sitting in port in Florida

There is no reason for a vessel to experience that big of a penalty due to fouling. Proactively managing fouling through a regimen of frequent and gentle cleaning can keep the penalty to a minimum.  And advancing technology can make it possible to clean gently and frequently without negatively impacting operations.  And it pays for itself, quickly.  It’s almost like they can put cheaper, cleaner fuel in their vessel. 

But this needs to be pushed from the sustainability office, because the maintenance budget probably doesn’t have the room to pay a higher annual cleaning cost. And the shipowner, who is responsible for maintenance and sustainability, might not be the one paying for fuel, and thus isn’t the one recognizing the savings.  EEXI and CII rules may help influence this, but that remains to be seen. 

Keep your hull clean. Burn less fuel. Release fewer emissions. Help meet your sustainability goals by starting at the bottom.