Few involved in the bunker and shipping industries will have failed to notice the controversy surrounding the use of very low sulphur fuel oil (VLSFO) blends to comply with the 0.50% sulphur limit imposed on fuel for ships since the start of 2020. Throughout 2019 debate was raging around the potential safety implications of such fuel, both regarding the inherent quality of new blend recipes and incompatibility risk associated with co-mingling VLSFOs from different sources onboard ships. Those concerns remain with us but at least they are well understood by now. IBIA, among others, have worked hard to provide the supply and shipping industries with the tools to produce, handle and use compliant fuels safely.
But in January 2020, VLSFO came under attack amid claims these blends would cause an increase in emissions of black carbon because they are more aromatic than the high sulphur fuel oil (HSFO) they have been made to replace. If that’s true, this will be one of several examples of unintended consequences associated with MARPOL Annex VI, the International Maritime Organization (IMO) regulation dealing with air emissions from shipping.
The main goal of reducing the sulphur limit for marine fuels to 0.50% sulphur is to improve air quality to reduce shipping’s negative impact on human health. Several studies have told us so, and while estimates vary hugely regarding just how many premature deaths will be avoided thanks to the new global low-sulphur regime, the positive impact of the MARPOL Annex VI regulation is not in dispute.
IBIA has for some time, however, been pointing out the “MARPOL Annex VI paradox”: almost everything we do to improve air quality has a negative impact on efforts to stem global warming, either directly linked to what happens on ships or indirectly due increasing emissions from other sources to provide ships with cleaner, less polluting fuels. The latter forms part of the debate around lifecycle, or well to emissions of gases that contribute to global warming, such as increased CO2 emissions from refineries to produce lower sulphur fuels and methane slip during the production and distribution of LNG. I’m not going into detail on that here. Suffice it to say it’s hard to get a handle on it because numbers presented by various studies vary a lot.
Direct impacts from ships relate to how much CO2 or other greenhouse gases (GHG) they emit. On the positive side, IMO has introduced mandatory energy efficiency measures under MARPOL Annex VI aimed at making ships technically and operationally more efficient, consequently reducing CO2 emissions per tonne of cargo carried by ships. The reduction in the sulphur limit outside emission control areas (ECAs) from 3.50% to 0.50% at the start of 2020 may have a positive side effect because low sulphur fuels cost more, incentivising more efficient ships. Ships using exhaust gas cleaning systems (EGCS), or scrubbers, however, will emit slightly more CO2 due to the extra energy required to run the scrubber. They may even sail faster and hence burn even more fuel because they can continue to use cheaper high sulphur fuel oil (HSFO). These are among the most obvious direct impacts that few would dispute, although actually quantifying them is less straightforward. There are other, less obvious and even harder to quantify direct GHG impacts from ships associated with meeting sulphur emission limits. These include methane slip from ships using LNG (which depends on what type of engines and fuel systems they use), how much black carbon they emit, and just how big the impact will be from the huge reduction in shipping’s sulphate emissions, which have a cooling effect.
Black carbon – facts or speculation?
The IMO begun concrete work on how to address black carbon (BC) emissions from shipping almost a decade ago. It is not an easy subject and many aspects of it are difficult to understand, including for example how to measure it most effectively and the exact relationship between fuel types and BC emissions.
Among the many studies submitted to the IMO on the subject over the years, it has been asserted that fuel type has a significant impact with HSFO generally singled out as the worst offender. It hasn’t always been clear-cut however, as some studies pointed to engine load as a bigger factor than the fuel type and the fuel sulphur content, at least when talking about petroleum-based fuels ranging from low sulphur marine gasoil (MGO) to HSFO, and everything in between.
Like all particulate matter resulting from burning stuff, including fuels, BC is bad for human health. It has one other key attribute; it is light-absorbing and therefore BC, or soot in layman’s terms, is associated with global warning. Suspended in the atmosphere it warms by absorbing sunlight, while soot deposits make ice and snow melt faster. This is why IMO’s work has been focusing on reducing BC emission from shipping in the Arctic, where its impact is most severe. LNG is a clear winner for reducing all PM, including BC, but there’s no near-term plan to require ships in the Arctic to stop using oil-based fuels. There is, however, parallel work underway at the IMO to develop measures to reduce risks of use and carriage of heavy fuel oil (HFO) as fuel by ships in Arctic waters. The outcome will likely be a ban on carrying and using HFO in the Arctic, subject to an assessment of the impacts on the region to ensure the positives (reduced pollution risk) outweigh the negatives (increasing cost of shipping activities in the region).
Work relating to BC emissions, and the development of an HFO ban in the Arctic, are both on the agenda at the 7th session of the IMO’s Sub-Committee on Pollution Prevention and Response in mid-February. Among the papers submitted to PPR 7 is a study which claims new blends of marine fuels with 0.50% sulphur content increase BC emissions by 10% to 85% compared to HFO with a 2.5% sulphur content and by 67% to 145% compared to DMA-grade MGO with 0.1% sulphur.
The reason for this increase is that fuels with 0.5% sulphur content used in the study contained a high proportion of aromatic compounds in a range of 70% to 95%, compared to 50% in the 2.5% sulphur HFO reference sample and 20% in the DMA reference sample. The study, submitted to the IMO on 15 November 2019, was followed by submissions from FOEI, WWF, Pacific Environment and CSC calling for urgent action to prevent the use of 0.50% sulphur fuel blends in the Arctic and ensure only distillates are used.
In January, the Clean Arctic Alliance sent a letter addressed to the co-authors of the Joint Industry Guidance (JIG) on “The supply and use of 0.50%-sulphur marine fuel”, including IBIA. In the letter, which was widely publicised, the Joint Industry Guidance (JIG) was criticised for making “no mention of low sulphur fuel blends containing high levels of aromatic compounds nor of an increase of black carbon emissions of potentially up to 2.45 times that of the distillate DMA.” The letter also insinuated that the industry associations behind the JIG should have been aware of this and should have immediately sought to halt the production of these fuels and alert the IMO.
BIA was surprised by the study’s assertion that the 0.50% sulphur fuel oil blends are expected to have higher aromatic content than traditional HSFO, especially as the expectation prior to 2020 was that many of the new marine fuel blends would be more paraffinic in nature. The shift to 0.50% sulphur fuels is still in its early days but early indications from several fuel testing agencies have indicated that 0.50% sulphur fuels seen so far tend to be more paraffinic and less aromatic than the HSFOs they have replaced. As such, it seems premature to draw any valid and meaningful conclusions on the level of black carbon emissions associated with the use of 0.50% sulphur fuels.
When the IMO’s Marine Environment Protection Committee decided, at its 70th session (MEPC 70) in October 2016, to implement the 0.50% sulphur limit in 2020, the availability study used as the basis for the decision said blended fuels with between 0.10% and 0.50% sulphur would account for 73% of global consumption from international shipping. As industry prepared, fuel producers began formulating VLSFO blends intended to replace HSFO as economically as possible for use by the global fleet. The focus was not on producing fuels specifically for use in the Arctic, although concerns about the cold flow properties of distillates for use in cold regions was taken into account to ensure ships don’t end up with solidified fuel, like candlewax, in their tanks. The primary focus during 2018 and 2019 was on whether the VLSFO blends would be safe, with a particular focus on stability and compatibility because more paraffinic blend components were expected to be used and might create issues when mixed with fuel components that have traditionally been more aromatic in nature. The JIG, which was published in August 2019, was developed to support suppliers, ship managers and seafarers prepare and implement the use of 0.50% sulphur fuels as safely as possible. The document was entirely focused on the safe handling and use of compliant fuels and did not investigate or comment on any other issue.
IBIA, along with co-authors of the JIG, supports a thorough scientific debate of the black carbon issue at the IMO. Furthermore, IBIA believes IMO decisions should be based on solid evidence and science that stands up to scrutiny, and it is important that all interested parties retain open and inquisitive minds when examining potentially conflicting information.
The work underway to develop a ban on the use and carriage of HFO in the Arctic could offer a way forward. PPR has been tasked with developing a definition of HFO, taking into account regulation 43 of MARPOL Annex I which gives a definition of heavy grade oil (HGO). All carriage of HGO, as fuel and as cargo, is banned in the Antarctic. HGO is defined as all oil with a density at 15°C higher than 900 kg/m3 or a kinematic viscosity at 50°C higher than 180 mm2/s. This definition means all the marine fuel grades meeting current ISO 8217 marine distillate (DM) specifications would be allowed for carriage and use in the Antarctic. Residual grades (RM), although several of them have a kinematic viscosity at 50°C below 180 cSt, all have a maximum density limit in excess of 900 kg/m3, which would not be allowed. Although many of the VLSFO blends seen so far have viscosity below 180 cSt, most have tested above 900 kg/m3 threshold used in the HGO definition and as such would be eliminated by using this definition. To help reduce BC emissions in the Arctic further in the future, investigations could be made into including a limit on aromatic content in HFO. If so, we need to understand how it can measured and tested by a recognised test method, and whether we need a new ISO 8217 specification parameter to do so.
The SOx paradox
Sulphur oxide (SOx) emissions form sulphate aerosols and while these
increase human health risks, they have another less discussed side-effect: sulphates formed by ships burning HSFO contribute a cooling effect, both directly by reflecting energy back into space, and indirectly by interacting with clouds and making them brighter so they reflect more sunlight away from the Earth. A paper published in the journal Nature in February 2018 estimated that implementation of the 2020 sulphur limit for ships would result in approximately 75% reduction in shipping SOx emissions globally. This meant policymakers “face trade-offs whereby achieving human health benefits may be associated with climate change,” the paper said. Its authors included several renowned academics from the US and the Finnish Meteorological Institute.
A more recently released study into this phenomenon, led by researchers from Imperial College London, together with University College London and the University of Oxford concluded that sulphate aerosols have the most significant impact on cloud formation compared to other components of ship exhaust. The team studied more than 17,000 ship tracks from satellite observations and matched them to the movements of individual ships using their onboard GPS. The study was able to assess the impact of the introduction of the 0.10% sulphur limit in emission control areas (ECAs) where the researchers found that “ship tracks nearly completely disappeared compared to before the restrictions, under similar weather conditions.”
The most publicised part of the study’s finding was the observation that it might be possible to monitor compliance with the 0.50% sulphur limit because ships burning HSFO “create a measurable difference in the satellite-observed cloud properties.” This could indeed be a useful tool on the high seas where compliance monitoring is tricky.
The study notes that the impact of aerosols on cloud properties “is one of the leading uncertainties in the human forcing of the climate” and the team behind it want to find out how to predict more accurately the influence of sulphur aerosols on cloud formation on a larger scale to feed into climate models.
Does this mean that the IMO will reconsider the global sulphur cap because of the climate change impact? At MEPC 70, IBIA proposed that a “global ECA” covering all countries’ shores could improve coastal air quality to a similar extent as a global cap and also reduce overall global warming by allowing continued use of HSFO out on the high seas. It wasn’t the first time this idea has been mooted, and it might not be the last, but it would require a major revision of MARPOL Annex VI which is complex and time-consuming. There was no time for that at MEPC 70, which was under huge political pressure to ensure the 0.50% sulphur limit would enter into force in 2020. The key concern was to improve the life expectancy of populations affected by air pollution from ships. Sometimes medicine comes with undesirable side effects, but as long as the benefits outweigh them, the prescription won’t change.
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