Environmental views on shipping, part 2: reducing exhaust gas emissions

“In the next 20 years the maritime industry must rebuild its cargo fleet. If this is done with the radical technologies now available, it will lead to the biggest change in ship design since steam replaced sail in the 19th century”, writes Martin Stopford, the world’s most important maritime economist.

The International Maritime Organisation (IMO) adopted an initial IMO strategy on the reduction of GHG emissions from ships, setting out a vision of reducing carbon intensity from international shipping by 40% by 2030, and 70% by 2050, compared to the 2008 level. The initial GHG strategy envisages that total annual GHG emissions from international shipping should be reduced by at least 50% by 2050 compared to 2008, and phasing them out as soon as possible. At the same time, the European Union is planning a carbon emissions trading system.

To increase the fuel efficiency of ship engines, IMO has developed a tool called the Energy Efficiency Design Index (EEDI), which defines the efficiency values of new ships. The EEDI is calculated for each new ship in the design phase. It depicts the relationship between the amount of fuel consumed by the ship and the amount of cargo transported. Because the stowage factor of a ship greatly affects the efficiency values, different indexes are used for different types of ships.

To be able to achieve these carbon neutrality targets, a substantial share of the worldwide fleet has to be carbon neutral by 2050. The lifespan of the vessels is long, and they are usually in operation for 20-30 years. This means that vessels that are already built have to emit much less carbon than their predecessors.

The exhaust gas emissions of the vessels can be reduced in three ways: (i) the choice of energy, (ii) vessel design, and (iii) the choice of vessel type and speed.

Substantial efforts are put into new low-emission fuels in shipping. Shipping companies in the Baltic Sea have been forerunners in using LNG in ro-pax vessels, in particular. Research groups are working actively with new power sources, such as hydrogen and ammonia, as well as battery technology and wind power. In addition, the energy sector is moving towards so-called power-to-X solutions, in which synthetic methane, hydrogen, or fuel is made from water and carbon dioxide using electrical energy. The synthetic energy can then be used as a direct replacement for fossil fuels, for example in marine transportation.

In addition, vessels can be plugged into shore-side electricity while berthing. Ports have developed their capacity in shore-side electricity and are preparing to distribute new fuels for marine traffic.

It seems now that short-distance vessels, such as small ferries, are being replaced by electric ones, and large vessels are seeking solutions first in LNG, and later in hydrogen or ammonia. Many engine manufacturers are developing engines that can use several types of fuels.

Vessel design is constantly improving a vessel’s hull for less energy consumption. New materials will make it possible for lighter and thus less-consuming vessel constructions, like catamarans, to be more competitive compared to large vessels. IoT, AI, automation and remote control optimise vessels’ fuel consumption, increase safety, and reduce workload in ships and ports.

There are also other possibilities to reduce emissions in the supply chain, such as increasing the use of intermodal transport, or splitting cargo and passengers between the slower and less-polluting and the faster vessels. Increases in rail capacity in Europe and, in particular, Rail Baltica, ending in Estonia, will bring new solutions for combining sea and rail transport. This may also change some of the truck or trailer cargo to containers, and thus change the required vessel type.

In any case, IMO decisions have a great influence on vessel design, fuel decisions, and supply chains. The effect will be greatest in big and high-speed vessels, like car-passenger ferries. This will have an effect on all ro-ro shipping and the supply chains related to it, which should be taken into account in the strategic planning of shipping companies and ports.

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