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Biodiesel

Does biodiesel have a place in the marine fuel purchasing portfolio?

Tim Wilson highlights the potential for biodiesel as a marine fuel and outlines the key points to consider when using it as a blend.

As the industry looks to prove the technical feasibility and commercial viability of fuels like ammonia, hydrogen and methanol – and ensure the safe application of electro-fuels – biodiesel is another option becoming more readily available that could provide short-term emission reductions.

Energy efficiency measures are already being applied to varying degrees through innovative ship design, engine power, optimised speeds/navigation and the adoption of hybrid technologies. But a more immediate, non-fossil fuel, lower carbon emitting solution is being sought after by some well-known shipping customers who are looking to reduce the carbon footprint of their retail products. Suppliers also get credit under certain regulatory schemes for putting biodiesel into the market so with the push from the supplier and the pull from the customer, could this provide a short-term solution to reduce shipping’s emissions?

LR is conscious of the community readiness issues surrounding biofuels, however this article focuses on the technology readiness as we see more supply into the marine market and an increase in trials in the industry.

The use of biofuel in a diesel engine is nothing new, in fact the first successful diesel engine test was carried out in 1897 by Rudolph Diesel on straight peanut oil. At that time, Diesel predicted that vegetable oils would become a fuel source as important as petroleum products. Petroleum (fossil) fuels originally won out over bio-derived because of cost. The tables are now starting to turn however, as urgent climate action is needed.

Currently, bio-derived fuels are widely used in the non-marine transport and power sectors. The most widely used is FAME (fatty acid methyl ester), derived from waste cooking oil or another feedstock, generally referred to as “biodiesel”. This is mainly used as a varying percentage blend component in petroleum diesel. However, biofuels come in a variety of other forms, such as higher viscosity residue-based biofuels to the more advanced products, such as the hydrogenated vegetable oil (HVO), often referred to as “green diesel”.

Ship operators are now starting to look towards available and affordable biodiesel. This is being seen as a “drop-in” (no change requirements for fuel storage, handling system, machinery setting or supply infrastructure and distribution) interim solution for reducing carbon emissions. The degree of carbon reduction will depend on the percentage ratio of biodiesel blended into the distillate marine (DM) or residual marine (RM) fuel and the original choice of feedstock used to produce them. The sustainability credentials of biofuels are contentious and from a lifecycle perspective, some could have worse carbon credentials than the fuels they are replacing, depending on the biomass feedstock used. The Roundtable on Sustainable Biomaterials (RSB) and the International Sustainability & Carbon Certification (ISCC) organisations both offer certification against sustainability criteria for bio-derived fuels.

LR is involved in several projects following growing interest by a number of shipowners and suppliers to trial the use of biodiesel blends. This is not just at the B7 in DM fuel (i.e. 7% biodiesel blend ratio), but expanding further to higher blends ratios, ranging from B20 to B50 (20 to 50% biodiesel), in the new RM very low sulphur fuel oils (VLSFOs), and we have even had some enquiries for B100, 100% pure FAME. Some ships are also sailing with 100% other bio-derived fuels and claiming up to 90% carbon reduction benefits. Biodiesel derived from varying waste oil feedstocks are favoured for a blend combination. Despite some increase in cost, their global consumer base is seemingly more willing today to cover this increase for the benefit of the environment. This is clear evidence that biodiesels are back on the marine bunker’s options portfolio.

Sustainability credentials aside, biodiesel offers a marked reduction in hydrocarbons, particulate matter and carbon monoxide. However, because of the molecular nature of FAME, nitrogen oxides (NOx) may rise as much as 15% or more, when combusted in a diesel engine, depending on the original feedstock, the blend ratio used and the engine itself. IMO MARPOL Annex VI Reg. 18.3.2.2 specifically states however, that fuels from non-petroleum refinery methods shall not cause an engine to exceed the applicable emission limit, leaving the marine industry in a conundrum, which was raised in the IMarEST Submission to IMO MEPC 70-7-2.

NOx emissions can only be determined by measurement from the combustion of the biofuel in service. To this extent any ship running a biofuel trial are best to consider direct measurement of the NOx emissions and seek their flag state guidance as to the exemption required for Annex VI Reg 18.3.2.2. under Reg 3.2 (Trials for ship emissions reduction…) against which they may unknowingly exceed the NOx restrictions.

Reduction of CO2 emissions from waste cooking oil of up to 88% for B100 can be expected, dropping proportionally according to the % blend ratio with conventional diesel, when accounting for the full lifecycle GHG analysis of the fuel. The actual decarbonisation benefit is dependent on the sustainability of the feedstock used, the energy to produce it and its impact on land use.

Scalability of production is a huge issue and availability of supply is limited, compared to the conventional fuel quantities consumed by the marine sector today. Although it is readily produced in most countries from wide-ranging oil seed crops, with waste cooking oil being derived from their use, it is suited mostly for a percentage blend offering. However, there are also ambitious reduction targets on crops in some countries which could lead to price increases due to the supply constraints. Some governments require between 5% and 20% of biodiesel to be used in fuels for land-based usage, and in a few cases marine also. So, although it may have a role in taking short-term action today, biodiesel’s mid- to long-term use has uncertainties over price, availability and sustainability.

Due to the storage and handling challenges in the use of FAME, addressed in the International Council on Combustion Engines (CIMAC) guidance document, and considering the harsh ambient conditions for storage and handling onboard a ship, the marine industry has taken a more cautious approach for the use of biodiesel. Back in 2010, during the revision of the ISO 8217:2010 standard, a de minimis level for FAME was included in marine fuels purchased against both the RM and DM tabled standards, due to limited in-service performance experience at that time into the use of biodiesel blends in the marine sector. References to the FAME national standards to be met of EN 14214 and the ASTM D6751 were included to provide some initial quality measures on the FAME being supplied.

The ISO 8217:2017 revision amended its initial cautious approach to the presence of FAME based on further performance experience; thus included that some hydrocarbons from synthetic or renewable sources might be blended into the predominant component of petroleum-derived hydrocarbons fuel that the standard represents. The first biodiesel blended grading was introduced as the distillate FAME (DF) grades for up to 7% (B7), which was very much in line with the automotive industry at the time. The otherwise FAME free categorisation was redefined as not to exceed a de minimis level of approximately 0.50%.

Important points to note when considering using a biodiesel blend:

  1. The use of blends up to B50 in VLSFO-RM or DM are still very much on trial. Ships should initially take a precautionary approach, applying similar practices to that applied in the VLSFO Ship Implementation Plan (SIP) for the transition into 2020. It is important to understand the characteristics of FAME, monitor its impact on ship machinery performance and handling characteristics. You should take into account CIMAC and ISO guidance documents, along with seeking Class, original equipment manufacturer and SME guidance, as offered by LR advisory services.
  2. NOx emissions from biodiesel combustion may rise, the degree of which cannot be predicted without direct measurement in service (taking into account measurement methodologies defined in the NTC, which require the results to be in grams per kilowatt-hour (g/kWh) not in parts per million (ppm)); flag state guidance for exemptions to Annex VI reg 18.3.2.2 under Reg 3.2 should be sought for a trial and specialist guidance on the specifics and challenges of in-service exhaust emission measurement should be sought, LR’s technical team are well placed to support with this.
  3. Determining the sustainability of a biodiesel product is a complex path. Suppliers should ensure their product is certified to recognised sustainability standards and customers should request access to verify such certification, obtainable from independent bodies such as the Roundtable on Sustainable Biomaterials (RSB) or the International Sustainability & Carbon Certification (ISCC);
  4. There are carbon accounting issues. Under EU and California fuel standards all biofuels are accounted for as being zero. The International Civil Aviation Organization framework does not have a blanket approach and has CO2 for different pathways. The IMO Data Collection System (DCS) scheme currently accounts for operational CO2 emissions and not lifecycle carbon emissions of the fuel being used. The IMO has committed to producing lifecycle guidelines for low-zero carbon fuels but there is uncertainty around how these will be used in future regulations.
Horizons September 2021

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