Most of the existing fleet of bulk carriers, tankers and containerships should focus attention on seeking “tangible technical and operational measures” to reduce greenhouse gas emissions. An analysis on the Energy Transition in Shipping concludes that the best way to reduce energy and fuel consumption is by reducing speed, investing in technical modifications, and imposing operational measures including the use of drop-in biofuel/eFuel, when it becomes available. The study focuses on the three largest sectors of the industry accountable for 80% of total GHG emissions, where most ships (85%) have not been fitted with electronically controlled main engines suitable to being converted to the use of alternative fuels. This fleet should search for other emission reduction means and measures, “of which few exist, and whose utilization is uncertain based on their limited availability, small capacity, and low technological maturity”.

The authors stress that shipowners should not be expected to shoulder the burden of this investment alone. They say the consequences of the additional cost of decarbonizing shipping are considerable. “The new transformation structure of costs should enable fair pricing among the value chain stakeholders and cover owners’ front-loaded charges,” according to the analysis carried out by the Maritime Oslofjord Alliance and funded by Oslo Maritime Foundation and Oslo Shipowners’ Association. However, until the criteria for carbon pricing are more certain, investment funds and banks’ interest and eagerness to enable such value chain transformation of costs will be limited. Further, given the constraints on shipbuilding capacity to renew the target fleet, “it will take a long time to deliver vessels that will outcompete and overtake the great number of existing and conventionally fueled vessels currently in operation”.

The analysis aims to offer support to decision makers when considering emission abatement of existing ships within the next three to five years. It observes that emission abatement technology is currently in its early stages, and it is hoped that for many existing ships such technology will become available and economically feasible. “If so,” the analysis adds, “the existing vessels will be able to contribute more to the future reduction of GHG emissions than is currently possible.”

At the end of the day, reducing ship speed is the most powerful way to cut emissions, the study says, although this solution would mean an increase in the number of vessels needed to meet anticipated demand. The analysis shows that for a generic ship, a 10% reduction in speed would reduce power, fuel, and CO2 emissions by 27%. For a 14,000 teu containership, cutting speed from 15 knots to 12 knots would reduce fuel consumption and emissions by about 50%.

There is a cautionary note: there is a lower limit to how much speed can be reduced before the engine, hull, bow, and propeller are no longer operating at their optimum, and technical measures must be applied. However, the cost of technical measures is reasonable compared to retrofitting for alternative fuels and the effect of reduced emissions comes immediately.