Lifecycle Emissions, Regulatory Compliance, and Cost Competitiveness of Ethanol as a Marine Fuel Retrofit Candidate

Yuksel, O; Bayraktar, M; Der, O; Blanco-Davis, E; Díaz-Secades, LA; Ringsberg, JW; Guedes-Soares, C

Lifecycle Emissions, Regulatory Compliance, and Cost Competitiveness of Ethanol as a Marine Fuel Retrofit Candidate

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Yuksel, O, Bayraktar, M, Der, O, Blanco-Davis, E ORCID: 0000-0001-8080-4997, Díaz-Secades, LA, Ringsberg, JW and Guedes-Soares, C (2026) Lifecycle Emissions, Regulatory Compliance, and Cost Competitiveness of Ethanol as a Marine Fuel Retrofit Candidate. Journal of Marine Science and Engineering, 14 (20). ISSN 2077-1312

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Publisher URL: https://doi.org/10.3390/jmse14201971

Abstract

Bioethanol is evaluated as a retrofit marine fuel candidate through a comparative assessment against liquefied natural gas (LNG) and methanol (MeOH) under the Energy Efficiency Existing Ship Index (EEXI), Carbon Intensity Indicator (CII), and Greenhouse Gas Fuel Intensity (GFI) frameworks. Fuel consumption profiles are derived from a multi-year empirical dataset using a dual-fuel (DF) engine retrofit, and lifecycle emissions are quantified across corn, sugarcane, and green algae feedstocks under IMO lifecycle guidelines. All DF configurations achieve EEXI compliance, whereas very-low-sulphur fuel oil (VLSFO) fails. A structural divergence emerges between regulatory metrics: under the tank-to-wake CII framework, MeOH and ethanol degrade to a marginal ‘D’ rating by 2027, while under the well-to-wake GFI framework the same configurations generate compliance surpluses from 2028 onward. Feedstock selection proves as consequential as fuel type, with bioethanol GFI ranging from 7.5 gCO<inf>2</inf>eq/MJ for green algae to 56.4 gCO<inf>2</inf>eq/MJ for corn. Cumulative surpluses reach 70,556 t CO<inf>2</inf>eq for electro-fuels and 30,952 t CO<inf>2</inf>eq for green algae bioethanol, whereas grey MeOH and VLSFO incur remedial costs of USD 3.91 million and USD 2.61 million, respectively. Despite a favourable price ceiling of 557.06 to 615.03 USD/t, the most favourable bioethanol pathway remains above this threshold. Ethanol therefore emerges as significant but not yet commercially viable.

Item Type:	Article
Uncontrolled Keywords:	maritime decarbonization; Greenhouse Gas Fuel Intensity (GFI); well-to-wake lifecycle assessment; FuelEU Maritime; ethanol; 4015 Maritime Engineering; 40 Engineering; 7 Affordable and Clean Energy; 13 Climate Action; 0405 Oceanography; 0704 Fisheries Sciences; 0911 Maritime Engineering; 3005 Fisheries sciences; 3709 Physical geography and environmental geoscience; 4015 Maritime engineering
Subjects:	T Technology > TA Engineering (General). Civil engineering (General) T Technology > TC Hydraulic engineering. Ocean engineering
Divisions:	Engineering and Built Environment
Publisher:	MDPI
Date of acceptance:	17 October 2026
Date of first compliant Open Access:	9 November 2026
Date Deposited:	09 Nov 2026 14:13
Last Modified:	09 Nov 2026 14:13
DOI or ID number:	10.3390/jmse14201971
URI:	https://researchonline.ljmu.ac.uk/id/eprint/29850

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