Sailing towards a sustainable future

The global shipping industry rarely gets a mention in the news unless an oil tanker has been wrecked, a freighter blocks the Suez Canal or, in one memorable incident, 28,000 rubber ducks are swept overboard, prompting 30 years of headlines[1]. 

The industry’s environmental impact also seems comparatively benign.  Even though it accounts for approximately 80% of global transportation by volume, it is only responsible for only 10% of transport emissions and 3% of total greenhouse gas emissions[2]. 

Now 3% may sound small.  But growth in demand for shipping worldwide means that maritime emissions have been accelerating faster than most other sectors in recent years.  And according to some experts, without action, shipping could be responsible for 10-13% of global emissions within a few decades.[3]

There is growing pressure on the shipping industry to improve its sustainability credentials by reducing greenhouse gas emissions, pollutants such as sulfur oxides (SOx), nitrogen oxides (NOx), and particulate matter (PM), as well as fuel consumption. 

The International Maritime Organization (IMO), the UN body that oversees global shipping, has a key role in regulating this.  The IMO has set a target of achieving a 40% efficiency gain by 2030[4] and has called for a reduction in total emissions from international shipping by at least 50% by 2050 compared to 2008 levels. 

This is an ambitious target, but given the sheer scale of the sector, it is a necessary one if the net zero targets of the Paris Agreement are to be achieved.

Three segments – bulk carriers, tankers, and container ships – are responsible for around 65% of the shipping industry CO₂ output and make up around 90% of shipping volumes.   The good news is that when compared to other forms of freight transport, shipping is the cleanest – at least if measured in terms of emissions.  It produces 20 to 25 grams of CO₂ per ton-kilometer, a fraction of that produced by other freight transport.  In comparison, aviation can produce up to 600 grams of CO₂ per ton-kilometer and road-based transportation generally ranges between 50 and 150 grams.

However, recent research[5] indicates the ongoing expansion of global trade could result in a surge of emissions from shipping until 2050, despite the efforts underway to decarbonize the sector. 

The industry consumed about 300 million tons of fossil fuel in 2018, and as the global demand for traded products grows, shipping volumes are expected to climb by around 1.3% on average every year until the middle of the century.  Or, as the International Renewable Energy Agency[6] puts it, if global maritime were a country, it would be the sixth- or seventh-largest CO₂ emitter. 

Seas of change

There has been some progress in efforts to make shipping more sustainable.  Ship engines are more energy efficient, thanks to improved technology, and changes in operating practices have reduced emissions.  Slow steaming, the practice of deliberately slowing down to reduce fuel consumption, helped reduce emission intensity per ton-mile by 13% between 2008 and 2012, for example. 

But given the global scale of the shipping industry, I believe regulation is vital to drive forward meaningful improvements in sustainability.  The IMO has developed a crucial agreement, the International Convention for the Prevention of Pollution from Ships (MARPOL)[7], which is the primary convention for preventing pollution from vessels. 

The latest supplement to this agreement, Annex VI, focuses on cutting air pollution from ships.  In 2021, the maximum sulfur content in fuel oil was reduced to 0.5%.  For shipping companies, the three most viable options to reduce their sulfur exhaust to 0.5% are: switching to very low sulfur fuel oil (VLSFO), ultra-low sulfur fuel oil (ULSFO) or Marine Gas Oil (MGO); using liquid natural gas (LNG); or fitting exhaust gas cleaning systems, or ‘scrubbers’, which remove pollutants from regular (and cheaper) fuel.[8]

The economics could not be simpler.  Installing a ‘scrubber’ costs between US$ 1.5 million and US$ 5 million, while cleaner fuel can cost up to US$ 400 a ton[9].  The scrubber pays for itself within a year – which is why the number of scrubber-fitted ships nearly doubled from 2,011 ships to 3,935 in just 14 months from January 2020, according to figures from BIMCO, the world’s largest international shipping association[10].

Arguably, however, scrubbers are part of the problem, not the answer.  These devices sit in the exhaust stacks and use seawater to wash out sulfur dioxide pollutants from the engine’s exhaust. 

However, the ‘washwater’ can have negative impacts on the environment.  Research has found that the acidic wash, which is up to 100,000 times more acidic than seawater, can harm zooplankton, a major food source for fish like cod and herring, with impacts across the foodchain.

Most ships use an open-loop system, which means they discharge the waste directly overboard, rather than holding it in a tank for disposal at dedicated port facilities, which would increase costs. 

According to a report by the International Council on Clean Transportation[11], roughly 10 gigatons of scrubber washwater are discharged into oceans each year – almost the same weight as all the cargo transported by ships annually.  The toxins from scrubber washwater, which include heavy metals, can accumulate in marine food chains and have long-lasting effects on the wider environment.

Europe takes action

The IMO is not the only organization intent on cleaning up global shipping.  The European Union (EU) is recognized as a driving force in encouraging sustainable shipping and is keen to encourage more aggressive measure to deal with emissions[12].  In 2015 it adopted a new regulation (Regulation (EU) 2015/757) that aims to collect data on CO₂ emissions by ships of more than 5,000 gross tonnage calling at any EU port.  Called EU MRV, the regulation runs in parallel with the IMO Data Collection System, so there are two data reporting regimes for shipping companies to comply with.

In 2020, the EU Parliament voted in favor of a proposal to revise the EU MRV and to add affected ships to the EU Emissions Trading System (ETS)[13].  This move aims to achieve a 40% reduction in CO₂ emissions from shipping by 2030.  The MEPs (Members of European Parliament) also called for an ‘Ocean Fund’ to be created to support investment in innovative technologies and infrastructure, such as alternative fuel and green ports.  The fund would allocate 20% of its revenues to protecting, restoring, and efficiently managing marine ecosystems impacted by global warming.  Lack of agreement between EU Members States has, so far, prevented the proposal passing into legislation.[14]

Despite the efforts of the IMO and the EU, a global regulatory framework to facilitate sustainable shipping is still lacking.  The public’s demand for action on climate change and environmental sustainability has driven the shipping industry, investors, and banks to take matters into their own hands. 

The institutions that finance shipping, for instance, are now using the Poseidon Principles[15], a yardstick for measuring the greenhouse gas impact of fleets.  Fleets that do not measure up will not get finance.  Some of the industry’s larger customers, such as Amazon and Unilever, are also setting zero-carbon targets for their supply chains as part of their own sustainability commitments.

Advances in shipping technology

Much of the research into cutting carbon emissions centers around alternative fuels, biofuels in particular.  So far, progress is mixed.  The IMO 2020 Data Collection System (DCS) indicated that 99.91% of marine fuel use was of carbon-based conventional fuels[16].  Nevertheless, the potential is enormous, because biofuels offer medium and long-term marine fuel alternatives that can replace conventional fuel without substantial modifications to engines, fuel tanks, pumps, or supply systems.  

For example, bio-methanol and bio-LNG (liquefied natural gas) have the same specifications as methanol and LNG, which have been used for years, while diesel-like fuels, such as hydrotreated vegetable oil (HVO) and fatty acid methyl esters (FAME) have already been tested primarily in blends with conventional fuels.  Most makes of European trucks, for example, have engines that will run on HVO, and commercial haulers are already beginning to use it.

Perhaps some of the most exciting opportunities in sustainable shipping are being driven by technological advances. 

The search for carbon-free forms of propulsion has even taken some companies back to wind power and sails.  Back in the 1980s several ships were fitted with rigid sails to cut fuel consumption, driven by high oil prices.  These claimed savings of between 10% and 30%[17].  Now marine engineering consultancy BAR Technologies has partnered with Scandinavian marine technology company Yara Marine to develop WindWings[18], a system in which solid wing sales up to 45m high are fitted to the decks of bulk cargo ships.  Combined with route optimization, WindWings cuts fuel consumption by up to 30%.

Other companies are experimenting with a combination of wind power and solar power.  Japan-based Eco Marine Power[19], for instance, has developed Aquarius MRE (Marine Renewable Energy) which combines rigid but movable sails that are computer controlled for ocean-going travel while using solar energy to maneuver while in port.

Another technological contribution toward reducing emissions is likely to be “autonomous technology” – like a driverless car – where the ship’s own computer systems monitor and correct its course constantly.  A paper from marine technology provider Wärtsilä[20] estimates that autonomy solutions can yield fuel savings of 10% or more on longer voyages by optimizing vessel routing and speed.  

Meanwhile, on a two-hour voyage, a mere 60-second reduction in docking time can cut fuel consumption by 2-3% per minute.

There are strong signs that commercial shipping is taking these innovative forms of propulsion seriously.  In terms of alternative fuels, for instance, the major shipping company, Maersk^[21], has ordered 13 ocean-going ships that run solely on carbon-neutral fuels so that it can hit its net-zero goals by 2040.  It calculates that operating carbon-neutral ships will cut its CO₂ by 1 million tons or 3%, which is a significant reduction from its current CO₂ levels of 33 million tons.  Meanwhile one of the first companies to test out WindWings is Cargill[22], a leading agri-food group, which charters between 600 to 700 ships annually.  It is taking part in a pilot project to see if a dry bulk vessel fitted with two wind sail and laden with grain, is commercially viable.

Zero-emission shipping – a glimpse of the future?

Long-time Abdul Latif Jameel partner NYK, a major Japanese shipping line, is pioneering a new approach to powering large ocean-going vessels, as part of its ‘Staying Ahead 2022 with Digitalization and Green’ strategic plan.

Working with its maritime R&D arm, MTI, and Finnish engineering and consulting company, Elomatic, NYK has designed a concept ship that showcases the potential of new technologies and fuels[23].  The power needed to operate the 200-meter ‘NYK Super Ecoship 2050’ has been cut by 70% by introducing fuel cells for electric propulsion, remodeling the hull to decrease water friction, reducing the weight of the hull, and relying on other highly efficient propulsion devices.  

Instead of fossil fuels, power for the ship would come from solar energy and hydrogen produced from renewable energy sources, all of which would lead to a reduction of CO2 by 100% and create a zero-emission vessel.

This startling reduction is achieved through the cumulative contributions of these different innovations.  Hydrogen fuel cells, for instance, contribute a reduction of 18%, while the lightweight hull cuts energy consumption by 34%.  The fuel systems use waste heat recovery to achieve a power production efficiency of 69%, while the 1,900m³ hydrogen tank allows for up to 21 days at sea without refueling.  Solar power contributes another 15% of the total energy demand.

Design innovations

Onboard innovations that improve fuel economy can reduce energy demand in new ships by 40%-50%[24] and could make alternative fuels more attractive, simply by reducing the extra costs of using them. 

In terms of existing technologies, the widespread adoption of best practices and efficiency technologies to holistically optimize powering systems and fleet operations can yield significant gains. 

For instance, the implementation of air-lubrication and wind-assisted propulsion technologies on existing ships, as well as voyage optimization software to reduce fuel burn on a large scale, can produce substantial benefits.

Several promising avenues exist for new technologies that can lead to greater efficiency.  Replicating the qualities of shark skin to give hulls biomimetic surfaces that reduce drag and enhance thrust, for example, or incorporating passive air-entrapment qualities to reduce friction are other options being looked at by researchers. 

I’m optimistic that all the factors necessary are gathering in place for there to be a step-change in the emissions – of carbon and other pollutants – produced by maritime trade.  

Research and development into alternative fuels, plus the growing role of artificial intelligence and autonomous technology, are building up to a turning point, when the world’s shipping will be cleaner, faster and more efficient, helping to speed our voyage to a more sustainable future for our planet.