This review paper examines the applicability of biogas and biomethane as potential maritime fuels and examines issues of these fuels from a supply chain perspective (from production to end use). The objectives are to identify: (1) the latest research, development, and innovation activities; (2) issues and key barriers related to the technology readiness to bring biogas/biomethane to market; and (3) commercialisation issues, including cost parity with natural gas (the main competitor). A survey of the literature was carried out based on research articles and grey literature. The PESTEL and SWOT analyses identified opportunities for these fuels due to the relevant regulations (e.g., Fit for 55; the recent inclusion of the Mediterranean Sea as a SECA and PM control area; MPEC 79), market-based measures, and environmental, social, and governance strategies. The potential of biomass feedstock is estimated to have a substantial value that can satisfy the energy needs of the maritime industry. However, production costs of biomethane are high; estimated to be 2–4 times higher compared to natural gas. The market is moving in the direction of alternative drop-in fuels, including liquefied and compressed biomethane (LBM and CBM) and biogas. In terms of potential market penetration, LBM can be used as a marine drop-in fuel for the existing fleet that already combust LNG and LPG due to similar handling. Currently, these vessels are LNG and LPG tankers. However, in newly built vessels, LBM can be also supplied to container ships, vehicle carriers, and bulk carriers (about 20% of newly built vessels). Provided that compressed natural gas infrastructure exists, CBM can be exploited in vessels with low energy needs and low space requirements and shore-side electrification, because investments in retrofits are lower compared to constructing new infrastructure.

The recent inclusion of shipping in the Fit for 55 legislation package will have large knock-on effects on the industry and consequently on end consumers. The present paper presents an innovative top-down methodology, the MSF455 model, which estimates the new vessel Operational Expenditure (OPEX) as per the provisions of the Fit for 55 package and various scenarios based on carbon tax, penalty allowances, maritime fuel tax and effect. The methodology is presented and tested against six scenarios that are based on Det Norske Veritas’s (DNV) fuel maritime projections. The model illustrates that the distinction between intra-EU and extra-EU penalty allowance creates a large disparity and thus reduction in the competitiveness of goods (produced and transported).

The scope of this paper is to examine proposed e-fuels (e-hydrogen, e-ammonia, e-methanol) as alternative maritime fuels. A techno-economic analysis is conducted considering the current energy demand of the shipping sector, the solutions for decarbonisation that are based on e-fuels, and the projections and scenarios regarding the energy mix towards 2050, to meet the IMO targets. According to the current preliminary study, apart from the barriers related to technological maturity levels, applicability and safety, there are barriers related to (a) the Well-to-Wake characteristics of e-H2, e-NH3, and e-CH3OH, (b) the existing infrastructure that utilises Renewable Energy Sources and the current and projected percentage of RES in the global energy mix, and (c) the availability of resources required for the development of the infrastructure to support e-fuels’ utilisation. Estimated fuel prices in 2050 that include production and distribution costs, indicate that alternative fuels are expected to be uncompetitive. Though they become relatively competitive when carbon-price is added to production and distribution costs of fossil fuels, the Well-to-Wake Analysis of biofuels and e-fuels proves that a significant RES rump-up is required, which further requires huge capital investment costs and raw materials. Ultimately, a re-prioritisation is proposed targeting decarbonisation of “easier-to-abate” sectors before decarbonising “hard-to-abate” sectors such as shipping and aviation.

The purpose of this research article is to perform a greenhouse gas (GHG) impact assessment using a lifecycle analysis of a cold-ironing solution for vessels at anchorage in a retrofitted barge and a marine genset combusting biomethane in dual fuel mode. A lifecycle methodology is developed based on the 4th International Maritime Organization (IMO) GHG study. Eleven impact scenarios are evaluated in terms of CO₂ and harmful pollutants (SO_x, CO, PM₁₀, PM_2.5, NMVOC, and NO_x). Vessels operated by Petronav Ship Management Ltd are examined, specifically M/T Alexandria and M/T Astraia. The scenarios reveal CO₂ reductions of up to 21% and CO increases of up to 60% due to the combustion of biomethane in dual fuel mode, alongside SO_x reductions of up to 20% with increasing biomethane energy substitution. Particulates and NO_x decrease due to the utilization of biomethane. This article presents a pragmatic solution for cold ironing for vessels at anchorage with proven lower GHG emissions with the exception of increased CO emissions, therefore the benefits outweigh the drawbacks.

In response to stringent emission reduction targets imposed by the International Maritime Organization (IMO) and the European Green Deal's Fit for 55 legislation package, the maritime industry has shifted its focus towards decarbonization. While significant attention has been placed on vessels exceeding 5,000 gross tons (GT), emissions from coastal and short sea shipping, amounting to approximately 13% of global shipping transportation and 15% within the European Union (EU), have not received adequate consideration. This abstract introduces the Zero Emission Sea Transporter (ZEST) project, designed to address this issue by developing a zero-emissions multi-purpose catamaran for short sea route