Shipping is by far the most efficient way of moving goods around the world and, as this sector grows, it can become a good deal cleaner and more efficient yet

Global shipping is in the paradoxical position of being both vital to more sustainable transport systems and yet lightly regulated as a polluter.

This means that the industry – which like aviation is not a signatory to the Kyoto protocol on carbon emissions – faces a double challenge in the coming years: how to expand and make major progress on the technological front.

More than 90% of all trade between countries is transported by ship, which in terms of energy expended per tonne-kilometre is far more efficient than air or road freight.

Big shipping lines scent the prospect of further growth in the next decade and beyond, driven partly by this inherent environmental edge. They argue that the more shipping expands at the expense of road and air cargo, the better the CO₂ emissions cuts.

However, the industry also knows it has room for improvement, with engineers and scientists striving to develop technologies to increase efficiency and cut pollution.

Lately several major companies have taken a more proactive stance after years of perceived complacency about what the sector could get away with on the oceans.

Jacob Sterling, head of climate and environment at Maersk Line, one of the world’s largest shipping companies, with more than 500 container vessels, says: “In the absence of global CO₂ regulation for shipping, the sector risks being seen as a laggard, even though it has a real potential to facilitate the development of a low-carbon economy through its transportation services.”

Toxic cocktail

And CO₂ is not the only undesirable byproduct of shipping. Most ship diesel engines burn comparatively cheap heavy fuel oil that contains a rich mix of pollutants. This low-quality viscous substance is a residual waste product of petroleum distillation.

In addition to CO₂, the heavy fuel produces nitrogen oxides. These react with hydrocarbons in sunlight to form ozone and can lead to smog. Ozone causes respiratory problems in humans and damages plant life. Another shipping pollutant, sulphur dioxide, can also exacerbate respiratory disorders and is considered one of the contributing causes of acid rain.

Global shipping traffic is responsible for about 7% of all sulphur dioxide and 11% to 12% of all nitrogen dioxide emissions, according to the German Advisory Council on Global Change.

Then there is the release of oil and chemicals through accidental spills and operational discharges; release of biocides via toxic chemicals used in anti-fouling paints; dumping of waste; and physical and other damage to marine life from the dropping of anchors – including the striking of whales.

On top of all that, alien species that can prove harmful to new habitats are often imported unwittingly in ballast water.

Light touch

Yet international law severely limits the ability of coastal nations to impose and enforce their own regulations on foreign vessels passing through their waters. Countries must instead apply international conventions established by the International Maritime Organisation (IMO) and the UN Convention on the Law of the Sea (Unclos).

In November 2011 an alliance of shipping lines, banks, insurers and shipping customers launched a sustainability drive aimed at making the global industry more energy efficient and environmentally friendly in the long term.

Sustainable Shipping Initiative/Vision 2040 (SSI) includes BP Shipping, Cargill, Rio Tinto Marine, Maersk Line, Daewoo Shipbuilding & Marine Engineering, ABN Amro, Lloyd’s Register and Unilever – the latter representing shipping customers.

Among SSI’s goals are to pioneer and implement “aggressive improvements in ship design, retrofits and operation while shifting to a diverse mix of renewable and other energy sources, using resources more efficiently and responsibly, and dramatically reducing greenhouse gas intensity”.

The mission statement also mentions “exploring ways to put a financial value on ecosystems, goods and services to ensure responsible resource use and reduce ecosystem impacts”.

It calls for development of financial solutions that reward sustainable performance and enable large-scale implementation of innovation, technology, design and operational efficiencies.

SSI admits that it is a broad framework for action with not much detail so far, but insists it is serious about meeting the objectives.

Self-starters

In the meantime, some players have taken unilateral steps towards the goals. Maersk has set a voluntary target of cutting CO₂ emissions by 25% per container by 2020 (compared with 2007). The company is also demanding measurable environmental standards for the whole industry, vessel by vessel.

In the past four or five years several liners have introduced “slow steaming”, where fuel consumption is reduced by up to 40% when speed is reduced by 20%. Though extra vessels are added to ensure the same service frequency, overall fuel consumption, and therefore CO₂ emissions, fall.

New vessels are also typically about 20% more fuel efficient than their predecessors of 20 or 30 years ago.

Academics and engineers are also exploring radical methods of improving the carbon footprint of vessels.

A team at Newcastle University is heading a £3m European scheme to harness energy from renewable sources such as wind turbines and solar cells, as well as waste heat recovery systems, waste gas recycling and new battery technology.

The aim is to combine these with conventional hydrocarbon fuels, with various energy sources selected according to a ship’s operational needs and the others staying in standby mode to be used on demand.

Professor Tony Roskilly, who is leading the project at the Sir Joseph Swan Centre for Energy Research at Newcastle University, says: “At present there are no energy management systems mixing conventional and renewable energy sources on cargo vessels. The development and deployment of such a system would be a breakthrough for increasing the energy efficiency of ships.”

The team is also involved in two other projects: one looking at reducing emissions from shipping in port and the Ulysses project to investigate vessels operating at ultra-slow speeds.

Energy boost

Meanwhile, a German company, SkySails, has pioneered the use of large, dynamically controlled towing kites for auxiliary propulsion. These generate up to 25 times more energy per square metre than conventional sails, and are attached to cargo ships via fibre cables up to 300m long.

The output equals up to 2,000KW of power in good wind conditions, potentially cutting fuel consumption by an average of 10% to 15%, according to Geerd Wessels, managing partner of the Wessels shipping company, which is a longstanding partner of SkySails and supported development of its technology with funding and expertise.

Wessels became the first shipping company worldwide to retrofit a cargo ship with a SkySails system and has ordered further units.

Gert-Jan van den Akker, energy, transportation and industrial platform leader at Cargill, says: “In addition to lowering greenhouse gas emissions, the SkySails technology aims to significantly reduce fuel consumption and costs. We are very impressed with the technology and see its installation on one of our chartered ships as the first part of an ongoing, long-term partnership.”

Looking to distant horizons, shipping is set to grow as a means of global freight and is showing some encouraging signs of change. But how far the industry chooses – or is ultimately forced – to innovate and tighten standards remains to be seen.

Shipping facts

• Shipping worldwide produces over 1bn tonnes of CO₂ a year, about 4% of the global total.
• CO₂ emissions are usually at least 90% less for shipping freight than transporting it by air.
• Global shipping emissions are growing by about 4% a year.
• To ship a pair of shoes from China to northern Europe emits the same amount of CO₂ as driving 2km in a regular car.
• About 50,000 merchant ships ply the world’s oceans.