Smoke on the Water

Thursday, 08/03/2023Published by: Richard Pratt

Cargo ships move more than 80% of the world’s internationally traded goods, making them essential to the global economy, but they’ve traditionally been fueled by heavy fuel oil or marine gasoil, both of which are emissions-intensive. With 60,000 or so ships in service, they account for an estimated 2.8% of global greenhouse gas (GHG) emissions, a percentage the International Maritime Organization (IMO) would like to reduce. At the 80th session of the IMO’s Maritime Environment Protection Committee (MEPC) in July, the group adopted a provisional agreement to eliminate GHG emissions from shipping by a date as close to 2050 as possible, with intermediate goals for emissions reduction by 2030 and 2040. Clearly, radical innovations will be required to meet the IMO’s goals. In today’s RBN blog, we look at some of the initiatives directed at emissions reduction in shipping and the challenges to (and opportunities for) operational improvements, especially regarding LNG carriers.

The trajectory toward the IMO’s goal will largely be influenced by the shipping industry’s response to the introduction of the Carbon Intensity Index (CII) from the start of 2023. The index, expressed as grams of carbon dioxide (CO2) per deadweight ton nautical mile, is divided into five categories (A through E), whereby vessels with a CII rating below a C (that is, D or E) for a specified period must take steps to improve their efficiency via a corrective action plan. The range of allowable CII numbers reduces over time, requiring improved efficiency and serving to hasten the recycling of the least-efficient vessels.

So how can ship owners comply with the ever-tightening CII requirements? One immediate option is to reduce vessel speed. For modern LNG carriers, a reduction in speed of 1 knot (about 1.15 miles per hour) can reduce fuel consumption by up to 6%. However, many ships are designed to operate at high speeds, such that reducing speed can result in suboptimal performance of the hull. An example is the bulbous bow that protrudes forward from the vessel and is designed to create a pattern of water flow along the hull that reduces drag. This has led some shipowners, notably container ship operators, to undertake “nose jobs” on some of their vessels to revise the bow shapes (see photo below) so the ships cut through the water more efficiently at the more fuel-efficient, lower speeds.

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