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Low carbon innovations for maritime freight

Can we reduce the carbon footprint of maritime freight?

On May 4th, 2022 |
4 min reading time
Eric Foulquier
Lecturer in Geography at Université Bretagne Occidentale
Key takeaways
  • In 2018, shipping released just over 1 million tonnes of CO2 into the atmosphere. This represents 2.89% of global anthropogenic CO2 emissions.
  • Maritime freight is a major part of global trade and economic development. In 2020, the world's maritime fleet included 99,800 ships, of which nearly 54,000 are merchant ships carrying more than 80% of the goods traded worldwide.
  • The volume of CO2 emitted per tonne of cargo per kilometre has already been reduced by 20-30% between 2008 and 2019 thanks, among other things, to the modernisation of ships.
  • However, GHG emissions from maritime transport have increased by 30% since 1990. The capacity of maritime freight has increased from 1 to 2 billion between 2006 and today 8 and is expected to reach 3 billion by 2030.

In 2018, the ship­ping sec­tor emit­ted just over one bil­lion tonnes of CO2 into the atmos­phere. This rep­re­sents 2.89% of glob­al anthro­pogenic CO2 emis­sions accord­ing to the lat­est glob­al esti­mate 1. The main con­trib­u­tor to these cli­mate change emis­sions? Sea freight. It includes the trans­port of vehi­cles, pas­sen­gers or refrig­er­at­ed goods, but also sec­tors of activ­i­ty that weigh more heav­i­ly in the car­bon foot­print by their num­ber of units and the ton­nages involved. Con­tain­er ships, bulk car­ri­ers, oil tankers, chem­i­cal tankers, car­go ships and gas tankers account for 86.5% of emis­sions from inter­na­tion­al mar­itime trans­port. “It should be not­ed that these fig­ures only rep­re­sent fuel con­sump­tion: they do not take into account all emis­sions, from the man­u­fac­ture of ships to the post-trans­porta­tion of goods,” empha­sis­es Éric Foulquier. 

The total green­house gas­es (GHG) emit­ted by mar­itime trans­port – CO2, methane (CH4) and nitrous oxide (N2O) – amount­ed to 1,076 mil­lion tonnes in 2018, up by almost 10% com­pared to 2012. The sector’s car­bon foot­print is pre­dom­i­nant­ly due to CO2, but in recent years some changes have been observed. Because of a decrease in sul­phur con­tent lim­it in fuels, the pro­por­tion of heavy fuel oil con­sumed is falling (-7% between 2012 and 2018), to the ben­e­fit of mar­itime diesel (+6%) and liq­ue­fied nat­ur­al gas (+0.9%). As a result, CO2 emis­sions are sta­bil­is­ing while CH4 emis­sions are increas­ing (see arti­cle 2).

Maritime freight, a busy circuit 

Mar­itime freight plays a major role in world trade and eco­nom­ic devel­op­ment. In 2020, the world’s mar­itime fleet num­bered 99,800 ships, includ­ing almost 54,000 mer­chant ships 2 car­ry­ing more than 80% – or even more for the most devel­oped coun­tries – of the goods trad­ed around the world 3. “As of 2015, at least 10 bil­lion tonnes of goods are loaded annu­al­ly in the world’s ports. It is inter­est­ing to note that since 2013, coun­tries con­sid­ered to be devel­op­ing have been unload­ing more than they load,” adds Éric Foulquier. “This undoubt­ed­ly cor­re­sponds to the emer­gence of a mid­dle class in these coun­tries, in line with the devel­op­ment tra­jec­to­ry they are on.” 

In terms of its cli­mate foot­print, is mar­itime freight an effi­cient mode of trans­port? A con­tain­er ship emits 3 grams of CO2 equiv­a­lent per tonne per kilo­me­tre, com­pared to 80 for a truck or 437 for a car­go plane 4. “Com­par­ing modes of trans­port accord­ing to this indi­ca­tor min­imis­es the impact of mar­itime freight, but it is more real­is­tic to express it in absolute terms,” says Éric Foulquier. “It makes no sense to com­pare these modes of trans­port: the sec­tors are dif­fer­ent, and they often com­ple­ment each oth­er in terms of glob­al eco­nom­ic circulation.”

Par­ti­cles also emit­ted into the atmosphere

Since 2005, when the MARPOL Con­ven­tion was adopt­ed, sul­phur oxide emis­sions from ships have been reg­u­lat­ed and the thresh­olds reg­u­lar­ly reviewed (fuels are now lim­it­ed to 0.5% sul­phur con­tent). Four Emis­sion Con­trol Areas (ECAs) – sea areas where the lim­it is raised to 0.1% sul­phur con­tent – have been estab­lished. Despite these mea­sures, the IMO notes [1] an increase in emis­sions of sul­phur oxides and atmos­pher­ic par­ti­cles. This pol­lu­tion has harm­ful effects on human health, caus­ing lung dis­ease, but also on the envi­ron­ment by caus­ing acid rain.

Emissions can be reduced

So how can we decar­bonise this vital sec­tor? The car­bon inten­si­ty of ships – the amount of CO2 emit­ted per tonne of car­go per kilo­me­tre – has already been reduced by 20–30% between 2008 and 2019 5. This has been achieved through the replace­ment of old­er ships, the pur­chase of larg­er ships, but also through tech­ni­cal and oper­a­tional mea­sures. Since the finan­cial cri­sis of 2008, a major­i­ty of shipown­ers have adopt­ed slow steam­ing, reduc­ing their speed by 20–30% between 2008 and 2015 6. A sta­ble fig­ure since then. While it was not con­sid­ered at all before 2009, ener­gy con­sump­tion is now the sec­ond envi­ron­men­tal pri­or­i­ty of the Euro­pean Sea Ports Organ­i­sa­tion 7, behind air qual­i­ty. It is also a finan­cial con­cern: if you dou­ble the speed of a ship, its fuel con­sump­tion quadruples. 

How­ev­er, these efforts are being under­mined by the increase in freight flows: GHG emis­sions from mar­itime trans­port have increased by 30% since 1990 8. The capac­i­ty of mar­itime freight has increased from 1 to 2 bil­lion between 2006 and today 9 and is expect­ed to reach 3 bil­lion by 2030 10. “Mar­itime trans­port is only one response to the needs of our soci­ety, we must act on the flows”, states Éric Foulquier. By 2050, the Inter­na­tion­al Ener­gy Agency esti­mates that CO2 emis­sions linked to freight should increase by 135% com­pared to 2018 lev­els 11, while the Inter­na­tion­al Mar­itime Organ­i­sa­tion (IMO) esti­mates this at +250% by 2035. “The mas­si­fi­ca­tion in which we find our­selves must be pro­found­ly recon­sid­ered in favour of the demas­si­fi­ca­tion of the com­mer­cial world, which is nec­es­sary if we are to imple­ment a tran­si­tion,” the researcher argues. It implies short­er cir­cuits, the mobil­i­sa­tion of small ports organ­ised around medi­um-sized urban centres.

Targets have been set

Dri­ven by the glob­al objec­tives of car­bon neu­tral­i­ty, the reg­u­la­to­ry con­text is also chang­ing.  By 2050, the IMO is aim­ing for a 50% reduc­tion in the sector’s GHG emis­sions com­pared to 2008. The Euro­pean Union has a much stronger com­mit­ment to achiev­ing car­bon neu­tral­i­ty by 2050, after an ini­tial 50% reduc­tion in emis­sions by 2040 com­pared to 1990. In 2020, the Euro­pean Par­lia­ment vot­ed to include mar­itime trans­port in the EU’s emis­sions trad­ing scheme. The mea­sure should be effec­tive by the end of 2022. How­ev­er, the Inter­na­tion­al Mon­e­tary Fund esti­mates that “a tax of US$75/tonne by 2030 would pro­mote a reduc­tion of only 15% of cur­rent emissions.”

The ship­ping sec­tor can choose to rely on many levers to reduce its CO2 emis­sions. Oper­a­tional mea­sures – speed reduc­tion in the first instance, but also weath­er rout­ing or over­all ener­gy effi­cien­cy mea­sures – have the poten­tial to reduce GHG emis­sions by up to a third [4]. Final­ly, a sig­nif­i­cant poten­tial for decar­bon­i­sa­tion lies in tech­no­log­i­cal solu­tions: mod­i­fi­ca­tion of ship design, improve­ment of machin­ery, but also the inte­gra­tion of renew­able ener­gies (alter­na­tive fuels or propul­sion) into the ener­gy mix.

Interview by Anaïs Marechal 
1 Inter­na­tion­al mar­itime orga­ni­za­tion, Fourth IMO green­house gas study 2020, 2021
2UNCTAD Stat, Flotte marchande par pays de pro­priété effec­tive en 2021, con­sulté le 28 avril 2022 : https://​unc​tad​stat​.unc​tad​.org/
3Unit­ed nations con­fer­ence on trade and devel­op­ment, Review of mar­itime trans­port 2021
4Eric Foulquier, 2019, Trans­port mar­itime et change­ments cli­ma­tiques, mise en per­spec­tive en géo­gra­phie, Lamy le droit mar­itime français, DMF n°815
5D’après l’OMI dans le livre blanc « La propul­sion des navires par le vent » par l’association Wind­Ship (2020)
6Eric Foulquier, 2019, Trans­port mar­itime et change­ments cli­ma­tiques, mise en per­spec­tive en géo­gra­phie, Lamy le droit mar­itime français, DMF n°815
7SPO Envi­ron­men­tal report 2020, Eco­portsin­sights 2020
8Fourth IMO Green­house gas study, IMO ; Emis­sions de CO2 des avions et des navires, faits & chiffres, Par­lement Européen.
9The 2020 World Mer­chant Fleet, Equa­sis Sta­tis­tics, EMSA.
10Selon des scé­nar­ios con­cor­dants étab­lis dans plusieurs études du BIMCO, de Clark­son Research et du rap­port établi par l’Université de Glas­gow et le Lloyd’s Reg­is­ter, Glob­al Marine Trade 2030.
11 ITF, 2020, Nav­i­gat­ing towards clean­er mar­itime ship­ping : lessons from the Nord Region, Inter­na­tion­al trans­port forum pol­i­cy papers, n°80, OECD pub­lish­ing, Paris

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