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Decarbonization and the Sulfur Cap Dance

The Challenge is on for Container Ships to Comply with EEXI, CII, Decarbonization, and the Sulfur Cap Dance

Climate change is a global and urgent crisis needing efforts by all industries, including the shipping industry with the need for container ships to decarbonize and reduce the “greenhouse effect” that is thought to contribute to global warming.[I]    In February and March’s BLOGs, we looked at what the cruise and ferry industries, respectively, are doing to reduce emissions, and touched on why antifouling and anticorrosion products play a supporting role in cleaner shipping and decarbonization efforts. This month, we focus our attention on container ships, their challenge in the race of decarbonization, and the sulfur cap dance.

In 2018, the International Maritime Organization (IMO) responded to the United Nation’s 2050 net-zero emissions goal by introducing the Greenhouse Gas Strategy, setting goals of net-zero carbon emissions and a 70% carbon intensity reduction by 2050. (GHG emissions are measured using a CO2e—carbon dioxide equivalent—to reflect the number of metric tons of CO2 emissions with the same global warming potential as one tonne of another GHG.) To achieve this, the IMO has adopted a goal-based framework. In January 2020, the IMO introduced the Sulfur Cap to benchmark and achieve a limit on the sulfur content in the fuel oil used on board ships and, in June 2021, adopted the EEXI (Energy Efficiency Existing Ship Index) and CII (Carbon Intensity Indicator) goals (both enforceable from 1 January 2023) to increase fuel and energy efficiency and reduce emissions between 2023 and 2030 by 40% from 2008 levels.[ii]

Quest to Decarbonization of Container Ships

Container ships emit around a quarter of global ship CO2 emissions.[iii] Marine shipping provides linkages to and from overseas markets for a vast array of goods we depend on every day and accounts for about 90% of world trade.[iv], [v] Moreover, it is estimated that the volume of maritime trade will triple by 2050.iv There is a good reason for this: marine shipping is the cheapest and most efficient means of transporting goods around the world.[vi]

The quest to decarbonize container ships and to get to 2050 will require “a large proportion of the fleet [to be] using commercially viable zero-carbon fuels,” according to Paul Topping, Director of Regulatory and Environmental Affairs of the Canadian/U.S. bi-national Chamber of Marine Commerce.[vii] The problem is that is “some years in the future. . . The first steps towards vessel decarbonization are about energy efficiency.”[viii]

In a market review by Danish Ship Finance, it was estimated that more than 40% of the global container fleet is over ten years old and that most vessels in operation today will be in service until 2050.vii Therefore, it is reasonable to assume that the owners of these vessels are exploring the available solutions to enable compliance with EEXI, CII, and sulfur cap requirements.

What Available Solutions are Being Explored?  

Certainly, the proposal to use carbon-neutral methanol is one medium-term cleaner fuel option being explored. However, the first steps in complying with EEXI, CII, decarbonization and sulfur cap requirements appear to optimize fuel efficiency and reduce sulfur emissions.

  1. Optimizing fuel efficiency. Reducing speed and using data are two strategies for optimizing fuel efficiency. Findings from a study by CE Delft investigating how effective reducing speed is as a short-term strategy for reducing maritime GHG emissions showed that container ships could reduce their GHG emissions by about a third by reducing speed, or “slow steaming.”[ix]
  2. Using data. Using data is the talk-of-the-town as a short-term strategy for reducing emissions. That is, using data to optimize ship operations and travel routes as a way to clean up the container shipping act. This will involve vessel owners/operators using vessel data reporting and analysis systems and processes to “gain a greater understanding of emissions and fuel consumption in vessels and across fleets.”[x]
  3. Reducing sulfur emissions. Sulfur oxide (SOx) emissions are mainly due to the presence of sulfur compounds in the fuel. Known as “IMO 2020,” the IMO’s Greenhouse Gas Strategy is about limiting the sulfur content of fuel used on board ships operating outside of designated emission control areas to 0.50% m/m (mass by mass). This is a meaningful reduction from the previous 3.5% sulfur cap.ii Using Exhaust Gas Cleaning Systems (EGCS), also known as “exhaust gas abatement systems” or “scrubbers,” is proving to be a popular go-to strategy for container shipowner/operators. Scrubbers remove SOx (as well as nitrogen oxides, NOx) from ship engine exhaust by “washing” it. This allows container ships to use less expensive albeit higher sulfur fuels.[xi]

Scrubbing Sulfur Oxides from Emissions

Container ships, in fact, “lead the way” when it comes to using marine scrubber technology.[xii]

Scrubbers come in various designs with two different classifications of scrubbers, dry and wet scrubbers: dry scrubbers use solid lime and wet scrubbers use sea or freshwater (with, for example, added pellets of hydrated lime) to remove—or “scrub”—SOx from exhaust gasses. Wet scrubbers break down into three types:

  • Open-loop scrubbers simply take in seawater for the cleaning process; provided the seawater has sufficient alkalinity, no other chemicals are needed for removing SOx from exhaust emissions. The big plus of open-loop scrubbers is that wash water can be discharged into the ocean while the ship is underway.
  • Closed-loop scrubbers use freshwater treated with alkaline chemicals to scrub emissions. Wash water then goes through a process tank where it is cleaned and then recirculated for use or discharged into the ocean. The inconvenience of closed-loop scrubbers is when wash water is not allowed to be discharged into the ocean, or ports, and must be held for disposal on land.
  • Hybrid scrubbers can operate on either or both sea or freshwater at the same time or are readily switched between the two. The plus of hybrid scrubbers is the flexibility of mode depending on ocean zone and port conditions and regulations.[xiii]

However, the thing about open-loop and hybrid wet scrubbers is that both fall foul of biofouling accumulation. Biofouling comes with the turf of seawater. It just is. And this is even though seawater spends only a brief period within the internal systems of open-loop and hybrid wet scrubbers. The economic cost of biofouling in open-loop and hybrid scrubbers is that it impairs the function and integrity of the systems. Open-loop and hybrid wet scrubbers, therefore, require defouling. xiii

EMCS Industries Ltd. Partner With Containerships in Scrubber System Sulfur Cap Dance + Decarbonization

EMCS’s out-of-the-box Marelco™ Liberator system helps prevent biofouling and corrosion of internal seawater systems, including wet open-loop and hybrid scrubber systems. The Marelco™ Liberator is an above-deck system that can be accessed while vessels are underway. The system includes a control panel, tank, two pumps, copper marine growth, and aluminum trap corrosion anodes. EMCS Industries Ltd. is keen and ready to partner in a vessel-by-vessel way with containerships using wet open-loop and hybrid scrubbers as one step in cleaner shipping and sulfur cap efforts.

Wrapping Up

Love them or hate them, given where we are and with cleaner fuel still on the horizon, scrubber systems are playing a large role in reducing emissions and cleaning up the containership industry’s act in lessening its emissions footprint. As innovators in marine growth protection systems and dominating this space for over 66 years, EMCS is ready, and proudly so, to partner with container ship owners/operators currently using, or exploring using, an EGCS to scrub SOx from exhaust emissions.

Let’s not forget about biosecurity

A second, but not secondary, environmental issue, is biofouling in internal seawater systems, such as wet open-loop or hybrid scrubber systems, is a vector for invasive aquatic species transfer. Managing biofouling and corrosion is of environmental concern for local biosecurity and is another reason why we at EMCS Industries Ltd. are invested in what we do.

[i] Andersen, S. (2017, November 29). NOx and SOx—What’s it all about? Dixon.,major%20contributor%20to%20acid%20rain

[ii] IMO (2019). IMO 2020: cutting sulfur oxide emissions. Media Centre Hot Topics.,were%20already%20stricter%20(0.10%25).

[iii] Transport & Environment. (2017, October 30). Almost three-quarters of new containerships already meet the 2025 energy efficiency requirements.

[iv] Stone, M. (2021, November 12). The shipping industry faces a climate crisis reckoning: will it decarbonize? The Guardian

[v] OECD (n.d.). Ocean shipping and shipbuilding. The Ocean. OECD.

[vi] OECD (2021). Navigating towards cleaner maritime shipping: Lessons from the Nordic Region. International Transport Forum. OECD, p12.

[vii] Gedeon, J. (2021). Decarbonization route. Green Marine Magazine, (2021, Summer), p.8.

[viii] Danish Ship Finance (2021, November). Shipping Market review – November 2021., p.5.

[ix] CE Delft (2017, October). Regulating speed: a short-term measure to reduce maritime GHG emissions.

[x] Wingrove, M. (2022, January 28). Data will drive shipping’s decarbonization voyage. Riviera Maritime Media’s Data-driven routes to decarbonization webinar.

[xi] S&P Global.

[xii] The Maritime Executive. (2020, August 14). Scrubber installations continue with containerships leading the way.

[xiii] Sethi, S. (2021, December 30). A guide to scrubber systems on ship. Marine Technology. Marine Insight.





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