A REVOLUTION IN MARINE FUELS: FIVE BEHAVIOUR CHARACTERISTICS OF LSFO RESPONDERS NEED TO KNOW

The topic of Low Sulphur Fuel Oil (LSFO) was thrust into the spotlight in July 2020 when the MV Wakashio vessel ran aground in Mauritius. At the time journalists noted that this fuel is relatively new to the market, some referring to it as a ‘Frankenstein fuel’ and so in this article, we look at what we know collectively about LSFOs within the oil spill response industry, and what responders need to be aware of when potentially dealing with future LSFO incidents.

Over 30 years ago, when I was serving on oil tankers in the UK Merchant Navy, we concerned ourselves with only two types of marine fuel: Fuel Oil (FO) and Marine Diesel Oil (MDO). FO represented the vast majority of fuel used for long ocean passages. It was black, syrupy-thick and required heating before being injected into a ship’s boilers or directly into the engine. These vessels also used the lower viscosity MDO at the beginning and end of ocean passages, specifically for manoeuvring in and out of port. It was essential to have the fuel system primed with MDO when the engine was stopped (i.e. in port) to guard against issues when restarting.

In the years I have been ashore, a raft of emission control regulations has been developed and implemented by the Marine Environment Protection Committee of International Maritime Organization (IMO). Through the Organization, Member States have rightly sought to reduce the atmospheric pollution associated with the use of these traditional marine fuels in operational consumption which, as we now know, have four principal detrimental components:

Sulphur Oxide (SOX), Nitrogen Oxides (NOX), Volatile Organic Compounds (VOCs), Particulate Matter (PM)

Ship-borne fuel combustion emissions may contribute to climate change. In the period 2007–2012, annual greenhouse gas emissions from shipping amounted to approximately 1000 Mt of CO2 representing about 3% of global manmade emissions (IMO, 2015). Reducing this burden is important in terms of the

Paris Agreement commitments and we canexpect further regulations in the future inthe ongoing drive to decarbonise shipping.Reducing sulphur emissions from ships,however, is primarily designed to protecthuman health from undesirable respiratoryeffects. Indeed, 40% of the world’spopulation live on or near the coast andcould be at risk from the adverse effects ofatmospheric pollution from ships.

The Global Sulphur Cap is the most recentemission control regulations introduced byIMO. The cap limits the sulphur content to0.5% and came into force on 1st January2020. Additionally, ships that trade withincertain designated coastal regions definedas Emission Control Areas (ECAs) mustfurther restrict the sulphur content of theiremission to less than 0.1%

Complying with the Global Sulphur Cap.

There are two principal ways in whichoperators of ships can comply with theregulations:

Use of compliant fuel (involving theuse of distillate fuels such as MarineDiesel and/or the use of heavierlow-sulphur petroleum fractionsor blends). Collectively these arereferred to as Low Sulphur Fuel Oil(LSFO), of which there are currentlytwo standards:

Very Low Sulphur Fuel Oil (VLSFO,sulphur content not exceeding0.5%)

Ultra-Low Sulphur Fuel Oil for usein ECA’s (ULSFO, sulphur contentnot exceeding 0.1%)

The traditional marine bunker fuel market has consequently been supplemented by a wide range of new cleaner nextgeneration fuels, designed to comply with the prescriptive specifications required under the Global Sulphur Cap. As global citizens, we can applaud these control measures that are designed to improve our atmosphere from the effects of marine operations. But what happens when one of these new fuels is accidentally spilled in the marine environment? Responders, like OSRL, are familiar with the characteristics of conventional Fuel Oil and Marine Diesel Oil together with the respective clean-up techniques that can be applied in the event of a spill, but the new generation fuels are potentially a whole different ball game. Fundamentally, whenever an unfamiliar oil type is spilt, there are five questions responders need to know:

WILL IT FLOW?

The pour point is the temperature below which the oil ceases to flow. This is determined by the chemistry of the oil including the presence (or absence) of wax and other constituent compounds.

Oil spilled into a marine environment quickly assumes the surrounding sea’s ambient temperature however if the sea temperature is below the pour point of the oil, the oil will cease flowing and behave as a semi-solid, highly viscous material.

This is typically the case with traditional high-sulphur FO, however, the newgeneration blended low-sulphur fuels have a much broader range of pour points which may well be lower than the ambient sea temperature at the time and place of a spill.

In this scenario, the oil will continue to flow and spread easily, with implications for which response techniques are most effective.

WILL IT SPREAD?

The viscosity of an oil is a measure of the internal resistance to flow, and here again, we see some wide variations in the marine fuels in use today.

A spill of MDO has a low viscosity at all ambient temperatures and will spread thinly in all directions over a wide sea area. With the new-gen blended LSFOs, however, there is no set standard for the viscosity at ambient temperatures provided the fuel meets the criteria for sulphur content and other physico-chemical parameters required for efficient operation in ships’ boilers and engines.

In the MV Wakashio incident (Mauritius, 2020) many responders and observers were surprised to see how fluid the spilled LSFO was, spreading extensively through the island’s sheltered tidal lagoons.

With hindsight, we can see that this is just a symptom of the variability of the fluid characteristics that accompany new-gen marine fuels.

CAN IT BE DISPERSED?

Dispersants applied from aircraft, surfacevessels or subsea are sometimes used totreat spills of crude oils.

Typically, this technique is normally ruledout for spills of Fuel Oil on account of thehigher viscosity quickly rendering thistechnique ineffective. However, the lowerviscosity of some blends of LSFO mayenable a longer window-of-opportunityduring which dispersant may be effective.

In real-world spill conditions, thereare many variables relating to theenvironmental conditions and theproperties of spilt oil that make it difficultto predict the window of opportunity.

Although dispersant use was notappropriate in the recent Mauritius oil spilldue to the proximity to the shoreline andsensitive shallow water coastal lagoonenvironment, it would be interesting tounderstand if, given different scenarios,the same oil could be dispersed effectively.The possibility that new-gen blendedfuels may offer greater opportunities fordispersant treatment is an interestingprospect for responders and is worthy ofmore research.

CAN IT BE PICKED UP?

Heavy viscous oils may have limitedspreading characteristics but they areproblematic to recover, in part becausethese semi-solid materials are very difficultto pump. Skimmer manufacturers have

developed several innovative methods to overcome this hurdle, but this makes equipment selection critical when building stockpiles for preparedness and at the time of a response.

Furthermore, conventional Fuel Oil (FO) can be very sticky, adhering to any substrate or material that it encounters. These properties again have implications for response that are already well understood by responders.

For example, improvised booms made from straw or bagasse, which have a high contact surface area, can be an effective defence of sensitive areas that could be impacted by a spill of heavy viscous oil.

Reports from responders in Mauritius,however, indicate the LSFO spilt in the MVWakashio incident was more fluid and lesssticky than traditional FO and subsequentlypenetrated some of the improviseddefences.

HOW CAN PLANNING FOR RESPONSE TO A MARINE FUEL SPILL

I have referred already to the recent spillof LSFO in Mauritius but beyond this, thereis very little case-history evidence relatingto spills of new-gen LSFO. Scientificinstitutes such as SINTEF and CEDRE arenow undertaking studies supported bythe oil industry and response communityto better understand response challengesand other knowledge gaps relating toLSFO. Perhaps the most important are theIMAROS and EPPR-PAME projects, bothof which are being coordinated by theNorwegian Coastal Administration.

One of the problems responders face isthat the physico-chemical parametersthat are provided on Safety Data Sheetsand other specifications that accompanymarine fuel, typically relate to refinerybasedcomposition or operationalcombustion characteristics rather than“real-world” fate and behaviour when spiltinto a marine environment.

The challenge is not just restricted tonew-gen LSFO but applies across allmarine fuels including new technologiesnow being used to power ships such asMSAR®, Liquefied Natural Gas (LNG) and,of course, traditional high sulphur Fuel Oilwhich is still used widely.

The response community is adaptable andresourceful in finding solutions to practicalissues of combatting spilt oil in ways that are sympathetic to the environment. “Oil is still oil” and it is probably the case that many of the components of the existing responder’s toolbox of response options will remain relevant in LSFO scenarios.

But responders need more detailed information relating to the fate and behaviour of an ever-widening range of products, when accidentally spilled. Due to the potentially wide variation in product characteristics, without knowing the actual characteristics of the oil that has been spilled, response efforts could be hampered with potentially detrimental consequences on impacted resources.

In 2013 the oil and gas industry produced guidelines on oil characterization to inform spill planning and decision making but further work is required now to apply these guidelines to the ever-broadening range of marine fuels at the point of supply.

THE WIDER CONVERSATION

In this article, I have focussed on the response challenges in the transition from conventional marine fuels to a broad range of low-sulphur variations that are now in use in ships across the world.

This is just one aspect, however, of a much broader transition taking place to make shipping cleaner and more efficient. In the

race towards decarbonisation, some ships are already powered by Liquified Natural Gas (LNG).

Other fuels that have the potential for contributing to this revolution include Liquified Petroleum Gas (LPG), methanol, bio-fuels, synthetic methane, hydrogen, ammonia, and no doubt others.

As new fuels are developed and brought to market, we would do well to be mindful of the MV Wakashio experience. Planning and preparedness remain key for effective response and in this regard, consideration should be given to the potential response challenges that might be faced before something actually goes wrong.

ABOUT THE AUTHOR ANDY NICOLL

Andy has over 30 years of experiencein oil spill preparedness and response inGovernment and Industry. He trained atthe College of Maritime Studies, Warsashwhere he qualified with a TEC Diplomain Nautical Science and a DOT Class 3Certificate of Competency (Deck Officer).Andy has fulfilled several roles at OSRLincluding Response Technician, PrincipalTrainer, Incident Manager and IndustryOutreach Manager. He joined IPIECA in2018 on secondment from OSRL, providinggeneral technical support to the IPIECAsecretariat and managing the IPIECA OilSpill Group (OSG).