Cargo and cruise ships represent 3 percent of global emissions and could reach 17 percent by 2050.  Nearly all these ships use cheap dirty heavy oil with high sulphur content.  Open-loop scrubbers are widely used to remove sulphur from the exhausts to transfer the pollutants into the sea.  International regulations are weak and difficult to enforce.  New technological solutions are under development, but without stringent territorial waters and docking standards, technological progress will remain insufficient.

International Marine Organization (IMO) and Greenhouse Gases

Cargo and cruise ships account for 740 metric tonnes of greenhouse gas emissions (GHG)/year, 3% of global emissions.  Left unchecked, by 2050, the industry would represent 17% of global GHGs by 2050, corresponding to 90-130% of their 2008 levels of GHGs.  Nevertheless, these sectors operate in a near environmental anarchy.  It doesn’t have to be that way.

The International Marine Organization (IMO) “govern” the seas for the 60,000 ships on the planet’s waters.

But IMO regulations are lax, and it is difficult to apply their rules in international waters.

This laxity is exemplified by the extraordinary low levels of emissions targets associated with the highest CO2 polluting, least refined, high sulphur content heavy oil, consumed by both the cargo and cruise ships.  Heavy oil is the inexpensive yucky residue at the bottom of the barrel of crude oil after all the gas products are refined.

The IMO total annual CO2 emission reduction from ships for 2050 are only set to be at least halved relative to 2008 levels.

There is an IMO 2030 interim target to reduce the average carbon intensity across the shipping industry by 40% based on 2008 levels.  This is not to be confused with absolute emissions, just emissions per unit of consumption.  Hence if consumption increases significantly, so will the emissions.  This leaves the industry with plenty of wiggle room to augment emissions over the next decade.  One can’t get more timid than that.

IMO and sulphur: Cure not better than the disease

The IMO global sulphur environmental standards, effective as of January 1, 2020, call for a sulphur content reduction from 3.5 percent to 0.5 percent mass by mass (m/m).

Nitrogen oxide limits for ships built on, or after January 1, 2000, became incrementally more stringent for ships built on or after January 1, 2011 and January 1, 2016.

For The Sulphur Emission Control Areas (SECA), since 2015, the IMO sulphur limit is 0.10 percent m/m. The SECAs include the coastal waters of Canada and the U.S. (200 nautical miles out from shorelines), the North Sea and the Baltic Sea.

Similarly, beginning January 2022, South Korea will require 0.10 percent sulphur content in its control zones.

The industry response to the IMO sulphur oxide emissions standards, has mostly been to install open-loop scrubbers on about 4000 ships to remove sulphur from the smokestacks and flush them into the sea.  These ships represents 4 percent of total vessels, but 21 percent of the fleet in terms of tonnage.

In the SECA areas, scrubbers are boosted to meet the more stringent requirements.

The IMO 2020 standard is 35,000 parts per million (ppm) of sulphur into the sea for a ship with an open-loop scrubber and 5000 ppm for ships without scrubbers that emit sulphur into the air.

For every tonne of fuel burned, the open-loop scrubbers emit approximately 45 tonnes of warm, acidic, contaminated washwater containing carcinogens including polycyclic aromatic hydrocarbons (PAH) and heavy metals.

PAH has been associated with skin, lung, bladder, liver, and stomach cancers, in addition to being toxic for coral reefs and a threat to the entire sea life food chain.

Since the heavy fuel oil version of diesel has 3,500 times more sulphur than road diesel, the scrubber “solution” is like exchanging cancer for a hardening of the arteries.  Those vessels equipped with scrubbers are historically primarily the biggest polluters with big engines, such as oil tankers, container ships and bulk carriers.

At least US$12B had been spent by the industry on open-loop scrubbers by 2019.  To comply with IMO regulations, by March 2021 scrubber sales have doubled since January 2020.  Annual scrubber investments are expected to reach US$7 billion by 2026.

Surely, the US$12B could better be spent on lower emission and ultimately zero emission technologies.

Only 2 percent of ships have closed-loop scrubbers, which captures the sulphur in tanks, for disposal to unknown sites.  Another 17 percent have hybrid scrubbers which can switch from open-loop to closed loop functions.

Thus far, the only nation-specific rules concerning scrubbing discharges exist in the U.S., China, Germany, Belgium, and Ireland.  The UAE has banned the use of scrubbers in the Port of Fujairah.

A technologically simpler solution would be to use more costly low sulphur fuel.  Heavy oil is 30 percent less expensive than low sulphur fuel.

As for CO2 emissions, the bottom line is dubious since scrubbers increase heavy oil consumption by 2%.

Cruise Ships

Cruise ships also primarily use heavy fuel oil, but some are capable of switching to auxiliary engines for cleaner burning to enter certain U.S. and European ports.

Removing one mid-size cruise ship with an all-electric one would be equivalent to removing 1 million passenger vehicles from the roads.  Passengers on board of a cruise ship breath in 20 times the emissions than those living near a main road.

Cruise ships emit black carbon, which per unit of mass, have a warming impact 460-1500 times greater than CO2.  Co-pollutants are particulate matter, toxic air pollution.  While cruise ships only account for 1% of total ships, they represent 6% of black carbon ship emissions.

The average cruise ship consumes 227 tonnes of fuel/day.  One of the largest cruise ships, the Harmony of the Seas, at full power, consumes 55,000 imperial gallons/day.

Cruise ships with scrubbers consumed 3.6 million tonnes of fuel in 2020.

While the large cruise ships can cost up to US$1.4 billion to build, pollution remains an investment afterthought with only 34 percent of the world’s cruise ships having scrubbers installed. These “clean ships” account for 96 percent of scrubber discharges of contaminated water in 7 of the 10 ports with the highest discharges.

The world’s largest cruise ship companies, Carnival Corporation, Royal Caribbean Cruises Ltd., Norwegian Cruise Line Holdings Ltd., and MSC Cruises have installed, or will install, scrubbers for most of their ships.   Currently, 68 percent of the ships of these companies are equipped with scrubbers and 31 percent use low sulphur fuel.

In areas where scrubbers are banned, like California, cruise ship companies keep low sulphur fuel on board to make a switch in these areas.

Data from 2017 showed that vessels owned by Carnival Corporation & PLC emitted 10 times more sulphur oxide in European seas than all of Europe’s 260 million vehicles.

Solutions: Docking and Territorial Waters Regulations

Evidently, international collaboration is needed, yet currently only national legislation and enforcement offers paths for addressing these challenges.  That’s where national docking and territorial waters regulations come in.  If China, the U.S., and the European Union (EU) were to have some degree of agreement on national regulations to this effect, the entire international shipping paradigms would have to change.

Empirical evidence supports this.  Vehicle emission and plastics regulations in the EU and China are respectively globally engendering a massive and rapid transition to electric vehicles and plastics circular economy developments.

Ditto can be said for cargo and cruise ships if enough countries adopt strict regulations.

On July 14, 2021, the European Commission revealed details on its proposed climate package, European Green Deal Investment Plan (EGDIP), aka Fit for 55, which comprises new applications of the European Trading System (carbon price) to shipping and transportation at-large; and termination of fossil fuel tax exemptions for maritime transportation.  The 3,500-page Fit for 55 is a draft US$1.2 trillion game plan for 2021 to 2027 to reduce EU emissions 55 percent by 2030, based on 1990 levels.  It includes incrementally decreasing emission caps under the ETS to the tune of 4.2 percent/year.

A study undertaken by the Europe’s non-profit Transport & Environment revealed that, at worst, 7 percent of ships would evade total trip emissions by going to an intermediate port since the additional costs associated with a trip diversion render the evasion option not cost-effective.

Unfortunately, the EU measures translate into renewable and low-carbon sources to represent only 6-9 percent of the maritime energy mix by 2030.  More encouraging, that rises to 86-88 percent by 2050.

This suggests long-term solutions are possible, but the short-term is still problematic.

Electric-powered ships

Electric marine vessels are making their entry into fray for emission reductions, but for short- and medium-haul transportation only.  Battery electric vessels are gaining market share for brief trips but not for long hauls due to insufficient energy density.

Canada is among the early adaptors.

By Summer 2021, BC Ferries took possession of its third hybrid electric ferry, manufactured in Romania.  A fourth hybrid electric ferry will join the fleet in late Summer 2021 with 2 more to come shortly afterward.  These BC ferries have capacity for 47 vehicles and 400 passengers.

One other BC ferry service to undergo electrification is that of the Kootenay Lake Ferry Service, for use between the Balfour and Kootenay Lake Terminals.

In Ontario, as of August 2021, the Merilyn Bell 1, the ferry between the Island Airport and downtown Toronto, was in the final retrofit phase to become an electric ferry.

Elsewhere in Ontario, terminal work is underway in 2021 to accommodate two electric ferries between Kingston and the Wolfe and Amherst islands.

Halifax is another to embark on an electric ferry project, scheduled to begin operation in 2024.

Electric ferry service operations elsewhere include Stena Line plans for its car ferries between Sweden and Denmark, beginning with one ferry and subsequently installing battery systems incrementally.

Regarding electric cargo ships, Norway’s Yara International launched a short-haul autonomous electric cargo ship in September 2021.  It’s maiden voyage between the Norway’s Herøya and Brevikv municipalities will take place in late 2021.  Humans are currently required for loading and unloading, but the plans call for autonomous technology for this as well.  Just this baby step to a transition to green shipping will displace 40,000 truck trips/year.

In November 2017, China launched its first all-electric cargo ship with a carrying capacity of 2000 tonnes and an autonomy of 80 km.  Ironically, it was tasked with transporting coal.  In April 2020, trial runs were undertaken on the Yangtze River for this all-electric cargo ship capable of transporting 900 tonnes.

For short distance tasks too, Asahi Tanker, based in Tokyo, has developed a 60-metre-long lithium battery-powered ship, the e5, to be launched in 2022 to deliver diesel to fuel other cargo ships.

For long-haul shipping, electric power has potential if applied in a hybrid concept.   This would improve energy efficiency while requiring less generators.  One could alternately use the battery power rather than the generator and use the generator continuously with battery power as a back-up, if needed  This approach would be comparable to a plug-in hybrid vehicle which can be charged overnight for exclusive use of electric power for part of the next day.  As well, electric power can reduce emissions associated with acceleration.


While cheap electricity suggests that hydrogen cannot compete, a 2020 study by the International Council on Clean Transportation (ICCT) concludes that hydrogen could power all cargo ships traversing the Pacific Ocean.  This study indicates that only 5% of cargo space would need to be sacrificed for hydrogen storage, or by requiring one extra port to refuel.

However, 98% of hydrogen stems from steam reformation of natural gas and coal gasification, known as black and grey hydrogen, depending on the source.  Methane emissions from shale gas extraction, production and transportation can render this source as bad as coal.  Black hydrogen is 30 percent blacker per unit of energy than the fossil fuel it was derived from.

Not surprisingly, the oil and gas industry majors (Big Oil) are lobbying hard for hydrogen transportation applications.

The now in vogue blue hydrogen is produced by combining natural gas with carbon capture and storage (CCS) technologies.  But blue hydrogen net emissions reduction are marginal, carbon-neutral or may even increase emissions, when taking into account the large amounts of natural gas required to power CCS processes and the upstream methane “leaks” referred to above.  Regarding natural gas, up to 10 kg of CO2 is generated for every kg of hydrogen.  The upstream methane emissions are 86 times worse than CO2.

To be entirely clean, the hydrogen would have to be green hydrogen produced via electrolysis.  Notwithstanding green hydrogen benefits, it is presently too expensive and may not be competitive until 2030.  Of the global 109 million metric tonnes of hydrogen produced annually, only 0.1 percent is presently green hydrogen.

Though hydrogen net environmental benefits are questionable, research continues on its potential for long-haul freight.  This is so despite the largest fuel cell remains far from the scale needed for freight shipping.  Scaling up fuel cells for the long-haul vessels may be financially viable, but the economics do not work for the short- and medium-haul ships.

Canada’s Ballard Power Systems has conceived the FCwave fuel cell products for the marine sector, but it has limited market applications.  Applications comprise ferries, river push boats, and fishing boats plus stationary power to support hotel and auxiliary loads for cruise ships and other vessels when docked at ports.

Also in Canada, in Fall 2020, Transport Canada has awarded a 3-year contract to Canadian Nuclear Laboratories (CNL) to explore the potential of hydrogen and other alternatives to replace fossil fuels for powering marine vessels.  Specifically, the project will focus on the development of the CNL Marine-Zero Fuel (MaZeF) Assessment Tool to analyze different energy options.

Further on fuel cells, a joint venture initiative of Samsung Heavy Industries and Bloom Energy to design and develop fuel cell ships is targeting 2022 for the introduction of these ships to clients.  The design has acquired approval in principle from DNV GL, the internationally accredited marine shipping registrar and classification society.

Another hydrogen stakeholder, the Norwegian ship designer, the Havyard Group, has created a new division, Havyard Hydrogen which believes it will have a complete hydrogen propulsion system of up to 3.2 megawatts of fuel cells, available for ships sometime in 2021. The Havyard Group has the know how for fully integrating hydrogen propulsion systems in designs for new ships, from the bridge to the propeller.  As for existing vessels, the Havyard concept is scalable rendering it possible for flexible placement of the hydrogen storage tank in the hull of the ship.

LNG, methanol and ammonia

Other potential fuels are liquified natural gas (LNG), methanol and ammonia.

Volkswagen has two ships powered by LNG.  While LNG net emissions are greater than hydrogen, they are an improvement over heavy oil.

The marine industry itself is working on solutions.

Maersk A/S, the world’s largest container ship company, said that half of the 200 largest customers have zero-emission targets for their supply chains by 2050.

In February 2021, Maersk A/S, announced that all future new vessels would be carbon-neutral.  This was followed up in August 2021 US$1.4 billion order of 8 vessels, with a capacity of 16,000 containers, to be powered by methanol for delivery in 2024.   The price tag includes a premium of 10-12 percent/ship. Green methanol is twice as costly as low-sulphur fossil fuel which translates into a 15 percent increase in shipping costs.  And that’s with methanol only being useful for half of most trips.

These ships will be manufactured by Hyundai Heavy Industries Co. and will account for 3 percent of Maersk capacity.  Maersk has an option for 4 more ships for 2025.

According to the hype, the 8 ships will save one million tons of CO2 annually.  This is misleading. Methanol is derived from steam reformation of natural gas, meaning there are upstream emissions.  Thus, it may solve the problem with sulphur, but not necessarily resolve net greenhouse gas emissions.

Euronav NV has put in an order for ships powered by ammonia or LNG.

The drawbacks of ammonia are that the fuel is dangerous if not handled correctly.  Its vapors being reactive and corrosive, can cause poisoning that can burn the respiratory system if inhaled.  If swallowed, it can burn and damage the digestive system.

Wind in the sails: Back to the future

Wind-powered ships may not be that far-fetched as some would think.

Wallenius Marine of Sweden is developing the wind-powered Ocean Bird which the company claims can reduce emissions by 90 percent.  The remaining 10 percent of energy pertains to onboard energy requirements and assistance for certain maneuvers.  Ocean Bird is projected to set sail in 2024.

A novel windpower ship concept is that of Norsepower with tiltable Rotorsails.  The idea is to make it possible for ships equipped with sails to go under bridges.  This concept involves rotating cylinders, rather than cloth sails, that rotate to best take advantage of the wind and, in turn, reduce demand on heavy oil engines.  The Rotorsail’s computers ensure the sails only work when sailing conditions can help reduce fuel consumption.  Studies have shown Rotorsails can reduce fuel consumption from 5 to 25 percent.  Existing ships can be retrofitted to have the Norsepower system installed.  The first ship to operate with these tilting sails will be the SC Connector to operate in the waters of Norway, Denmark, Sweden, the Netherlands and Poland.

Cargill intends to add wing sails for some of its fleet.


Biofuels are a better option than scrubbers since they no longer displace food-based agriculture.

Volkswagen is using a biofuels for one of its ships.  These biofuels consist of a variety of certified feedstocks sourced from waste or residue.  No changes in ship hardware are required.  GoodFuels, the biofuels supplier, claims its products are scalable, affordable, technically compliant and ready for the market.

The upshot

Regulations for ships travelling in international waters are difficult to enforce and an international consensus on effective environmental standards are hard to come by.

The European Union’s Fit for 55 is the first major political initiative to address the regulatory playing field in international waters as it applies to emissions/trip for ships docked in European ports.  But at present, Fit for 55 emission reduction projections remain too little, too late.  On the other hand, Fit for 55, being a draft document, leaves open possibilities for legislative and policy innovations.

It would be nice if other developed jurisdictions collaborated with the EU on the formulation of final Fit for 55 proposals on shipping for implementation in SECA zones, South Korea, China and possibly other countries.

On technological solutions, all of the preceding clean technology solutions are nascent.  As with the vehicle legislation in the EU and China leading to global investments in electric vehicles (EVs) and a worldwide electrification massive and rapid industrial revolution in the vehicle sector in which all vehicle manufacturers must compete, it appears that the regulatory framework must come first, and the technological innovation will follow.  The EU and China are on track for EVs to represent 50 percent of new vehicle sales by 2025.

Few, if any, of the major international shipping companies can afford to be barred from the ports and territorial waters in the globe’s most important areas of international commerce.



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