Shipping is coming under pressure to adopt more sustainable measures.Shipping plays an increasingly vital role in the exchange of goods in a globalised world. In fact, in the past decade, the demand for global shipping has steadily risen as international trade has increased.
However, like any other means of transport, shipping is coming under pressure to turn a greener shade and adopt more sustainable measures.
According to the Centre for Climate and Energy Solutions, the global marine shipping sector is responsible for approximately 1.5 per cent of global greenhouse gas emissions. These are expected to double by 2050.
To reduce these emissions, the shipping sector is being encouraged to research, develop and implement more effective technology, change operational practices, burn lower-carbon fuels and improve the fuel efficiency of ships. Combined together, it is estimated that these changes could reduce shipping emissions by 62 per cent by 2015. This means that roughly, emissions would remain as they are presently, despite large increases in shipping volume.
Such measures will not be easy to implement. This is especially because marine shipping is a complex sector, due to ownership of the international shipping fleet – just consider that a company based in Greece could have a ship that, while registered in Panama, is used to move goods from Asia to North America.
Until a few years ago, electric cars seemed futuristic – now they are actually on our roads. In much the same way, these technological advances in shipping could be nearer than we think.
Increasing efficiency
In recent years, ships have become more efficient thanks to hull and propeller optimisation and advanced low-resistance hull coatings. Engines are also more efficient.
Ships are also getting larger – while the idea of building larger ships may sound counterproductive, it actually contributes to increased efficiency. For instance, a single large ship with the same cargo capacity as two smaller ships weighs less in total and has less hull-area contact with water, thus lowering the energy required for propulsion. However, this necessitates massive changes in port infrastructure, especially in cargo handling equipment, canal sizes and harbour depths.
Operational changes help greener shipping
It is not just technology which can make shipping greener – operational changes can also lead to a reduction in fuel consumption. One of the more effective ways of achieving immediate reductions in greenhouse gas emissions is slow steaming, that is, decreasing a ship’s speed. For instance, decreasing speed by three knots for a typical container ship at average speed reduces the resistance of the ship’s hull against the water by 50 per cent – therefore, the ship would consume less fuel. The downside is that reducing a ship’s speed would also reduce shipping capacity as it would cover fewer miles in a given period of time.
Alternative fuels
Currently, most ships burn heavy fuel oil. While research is currently being carried out to improve the refinement of bunker fuel, other and greener alternatives exist. These include marine diesel oil which is less carbon intensive, and liquefied natural gas. Longer-term opportunities could include wind power, biofuels, and even hydrogen fuel cells.
Even when at berth, ships can also use less fuel thanks to measures such as cold ironing. Also known as alternative marine power, this process involves plugging a ship when in port directly into shore-based power. This means that a ship can shut down all its engines, thus reducing fuel consumption and port pollution levels. Some ports have already adopted this practice. The State of California requires a percentage of ships calling in its ports to use shore power, while the Port of Oakland has implemented a high voltage shore connection.
Better design
Improved ship design can also lead to greener operations. More streamlined hull design and propeller redesign are being incorporated into new ship design to reduce water resistance. A number of cargo ships are also using sky sails. Manufactured by Hamburg-based SkySails GmbH, sky sails are large foil kites which cover an area of around 320m2. These are attached to the bow of a vessel and flown at altitudes of 100 to 300 metres. By using high altitude wind power, these kites help a ship receive higher thrust per unit area – in fact, it is calculated that a ship equipped with sky sails consumes from 10 to 35 per cent less fuel.