First featured on Marine Professional (The official IMarEST magazine and newsletter)
Evaluating the impact of long-term use of an alternative fuel.
Biodiesel products have gained increasing attention in shipping as an immediate measure to comply with greenhouse gas (GHG) emissions reduction regulations. This is due to their compatibility with conventional marine fuels and interoperability with existing bunkering infrastructure and shipboard systems, in addition to their environmental benefits for reducing GHG emissions.
However, there are distinctive differences in the composition between biodiesel and conventional marine fuels that result in differences in their physical and chemical properties, with long-term continuous use potentially impacting vessel operations. In recent years, engine and equipment OEMs, classification societies and research centres have published service letters and technical guidance when using biodiesel to provide general caution and raise awareness of potential issues such as corrosion, clogging and material incompatibility and highlight mitigation measures. These include prompt consumption of fuel to prevent biofuel degradation and the formation of by-products, regular water drainage from fuel tanks and the use of additives to mitigate microbial growth.
To fully understand the opportunity biodiesel presents to the shipping sector, there is a need to evaluate the total cost of its adoption and comprehensively understand the impact of its long-term use. It is with this objective that the Global Centre for Maritime Decarbonisation (GCMD) launched Project LOTUS to address this knowledge gap by establishing industry guidelines for monitoring engine and equipment performance when using biodiesel. This pilot will also evaluate the total cost of ownership of using biodiesel, covering the cost of fuel and additional maintenance costs associated with its use.
This article outlines GCMD’s approach and its operationalisation within commercial operations to capture real-world challenges and ensure that the learnings are applicable to industry. Partnering with NYK Line, GCMD is trialling the continuous use of a biodiesel blend consisting of 24% Fatty Acid Methyl Esters and very low sulphur fuel oil (VLSFO) aboard a short-sea vehicle carrier that will call at multiple ports. Given frequent loading and offloading cargo operations, short-sea carriers often spend longer time in ports, which can negatively impact their Carbon Intensity Indicator (CII) rating. The use of biodiesel as a drop-in fuel can help this vessel class maintain compliance today. Specific to Project LOTUS, the use of a short-sea vessel allows regular access to onboard fuel storage tanks for sampling and testing during the frequent port calls.
The following questions must be addressed with the systematic collation and analysis of in-service usage data obtained from ships that are continuously running on biodiesel blends.
- Which protocol in the current onboard handling procedures for biodiesel needs to be updated?
- What is the impact on biodiesel quality from its extended storage onboard the vessel?
- What properties of biodiesel will impact the reliability of engines, fuel delivery and auxiliary systems?
- Where along the fuel delivery system will anticipated concerns manifest themselves?
- Will the performance efficiency of the fuel centrifugal system be affected?
- What characteristics should be monitored to track the quality of in-service biodiesel for performance assurance of the propulsion train?
- What additives or mitigating actions should be adopted to improve the quality assurance of in-service biodiesel?
- Are there characteristics from lube oil analysis that should be monitored to pin-point problems in the fuel delivery system or serve as early alarm performance indicators?
- What testing frequency should be adopted to optimise quality monitoring regimes and from which sampling point along the fuel delivery system?
- Which aspects of the fuel system maintenance regime needs to be modified or updated?
To develop a better understanding of the impact from the long-term use of biodiesel on-board vessels, Project LOTUS will undertake three major tasks. The first will be a shipboard trial using biodiesel blended with VLSFO (see Figure 1)
The project will systematically collect all required data according to the following plan:
- Pre-trial preparation: Conduct a pre-trial inspection, replace parts where necessary, and install measurement instruments and sensors.
- Pre-bunkering fuel quality analysis: Before bunkering, analyse neat biodiesel, VLSFO and their blends for quality in accordance with EN 14214, ISO 8217 and other relevant standards.
- Bunkering observation: Identify any potential impact on fuel quality.
- Duration of biodiesel blend use: Replenish the selected vessel with biodiesel-blended VLSFO and should continue using this blend for minimally 6 months (i.e., 4,000 hours).
- Lubricant oil analysis: Monitor both main propulsion and auxiliary engine lubricant oil analyses.
- Baseline data collection: Gather baseline data ideally from the past one to two years when the vessel was operating on VLSFO. This data should include lubricant oil analyses, engine maintenance reports, centrifuge performance, fuel tank inspections and other relevant information.
The second major task will be to conduct interviews with end users on their experience with using biodiesel on-board.
This will involve undertaking a structured interview with the chief engineer using a set of questionnaires covering these three aspects:
- Fuels used: Specify the types of biodiesel and marine fuels used, the blend ratios, the fuel quality at the bunkering port, in the storage tanks, and other relevant details.
Bunkering operations: Understand the recommended best practices for bunkering operations from relevant stakeholders (such as marine fuel suppliers, fuel test laboratory providers, etc.) - Biodiesel blend usage: Gather information on the fuel switching process, the duration of continuous use, data/observations from the operations, data on maintenance (if any), and other relevant information.
The third major task will be to investigate the quality of biodiesel-blended VLSFO at bunkering ports and onboard vessels.
This will entail:
- Analysis: Conduct quality and compatibility analyses of biodiesel, VLSFO and their blends from different bunkering ports.
Monitoring: Track and monitor the biodiesel blend quality throughout their storage in fuel tanks, under real-world operating conditions of the vessel.
The project has made two preliminary findings and observations. The first concerns the impact on the fuel-delivery system. Since the vessel changed over its fuel use from VLSFO to B24 on 9 July 2024, preliminary observations as of 25 August 2024 indicate no significant adverse effects on the fuel delivery system. The project team conducted a comparative analysis against baseline observations before the fuel switch across the three stages of fuel delivery: storage tank to settling tank, settling tank to service tank, and service tank to engine inlet. To date, there have been no significant changes in pump pressure, filter changeover frequency, or residue accumulation levels within the filters.
The second concerns the impact on the fuel consumption. Likewise, since the vessel changed over its fuel use from VLSFO to B24, preliminary observations indicate no significant changes in the fuel consumption pattern for the main engine as well as the generator engine during sea voyages for both conventional and biodiesel B24 blends.
The project team analysed the collected data focusing on those for main engine running hours exceeding 20 per day. Additionally, the net calorific value (NCV) of both VLSFO and the B24 blend were found to be comparable at 41.1 MJ/kg and 40.2 MJ/kg, respectively, per ASTM D240 test method.
These initial findings are encouraging. Future steps will include continued monitoring of the aforementioned parameters, as well as in-depth analyses of fuel quality at various sampling points throughout the fuel delivery system and assessing fuel quality during their long-term storage in tanks.
When completed, the quantitative findings from Project LOTUS will offer crucial learnings for shipowners and operators who are considering biodiesel blends to meet vessel compliance with regulations, like the Carbon Intensity Indicator (CII) and the FuelEU Maritime Standards.
