Stolt Tankers: To Correct CII Ratings We Consume More fuel and Produce More Carbon Emissions

Stolt Tankers' Managing Director, Maren Schroeder. Image Credit: Stolt Tankers

The International Maritime Organization's (IMO) Carbon Intensity Calculator (CII) rules are flawed and cause ships to consume more fuel and produce more carbon emissions, the opposite of IMO's intention, according to Stolt Tankers' Managing Director, Maren Schroeder.

"CII has some pros and many cons, but there must be a better and easier solution," they wrote in a post on the firm's website

The CII rules came into effect on January 1, 2023 and give ships an annual efficiency rating on a scale of A (best) to E (worst). Ships with D and E ratings must improve to at least a C rating.

However, Schroeder says that taking the steps needed to improve ratings actually produces more emissions.

"The biggest improvement is supposedly achieved by optimising the ship's speed and route, and this is one of the problems with CII that many owners are now experiencing," writes Schroeder.

"Route optimisation also involves managing your port-time-to-sea ratio and, on average, ships that spend more time at sea have a better CII, while ships with longer port stays typically have a worse CII rating.

"Many factors can contribute to longer port stays – including the type of ship and the cargoes it is carrying, port congestion and weather, as well as terminal, customer or ship operator delays – and most of these delays are beyond the control of ship owners in terms of implementing preventative and corrective actions."

To highlight the issue in practice, Schroeder says that rerouting their ships to avoid the Red Sea and instead go via the Cape means ratings will automatically improve due to longer voyages, despite higher emissions.

Further, the rules incentivize the placement of older, less fuel efficient ships on longer voyages with long ballast legs, meaning more fuel-efficient ships then have to take the trades with the longer port stays.

"These examples show that by trying to correct the CII we inherently consume more fuel and produce more carbon emissions. This is the opposite of what the IMO intended when it introduced the CII to improve a ship's carbon efficiency," she says.

Schroeder suggests this problem can be addressed with a 'pilot station to pilot station CII' approach that comprises both a 'sea' and 'port' assessment.

"This would also allow for a more accurate measurement of a ship's energy efficiency performance when transiting under normal working conditions at sea. And this is what CII should be measuring in terms of efficiency," says Schroeder.

A further issue with the current rules is that efficiency considerations are made on a per-ship basis, rather than a per-fleet basis.

"Assume you have an E-rated ship and want to use biofuel to correct that rating. However, the ship is in a part of the world where compliant biofuel is not readily available. The current regulation does not allow ship owners to consume a matching amount on a different ship and allocate the abated emissions to the E-rated ship," she says.

Schroeder suggests this could be addressed with a 'book-and-claim system' whereby biofuel could be burned on one vessel but allocated to another.

"Why consume biofuel on an A-rated ship and pay extra? But what if the abated emissions could be allocated to an E-rated ship? The planet would be happy in terms of overall emission reductions, and at the end of the day, this is what matters most. But at this point, operators do not have any incentives to further improve ships with better ratings," says Schroeder.

Schroeder's comments can be read in full by clicking here.