The maritime industry faces a critical challenge: conversion of the fleet to alternative fuel propulsion is not progressing fast enough to meet upcoming decarbonization targets. Over 93.5% of the 35,000 ships under the IMO Net-Zero Framework still operate on conventional fossil fuels. Most of the remainder are LNG-propelled vessels and less than 1% relies on alternatives such as methanol. Fleet turnover is slow, with just 300 new vessels delivered annually, and retrofitting older ships is limited by cost and shipyard capacity. 

No single alternative fuel currently meets all industry requirements—sustainability, emissions intensity, technical readiness, safety, energy density, availability, and cost, and even alternative fuel propulsion still relies on 5–10% pilot fuels with diesel-like combustion properties. 

Drop-in fuels, which can be blended with conventional fuels for use in regular engines, provide a practical option. They reduce emissions without requiring major infrastructure changes or early ship retirement, avoiding additional scope 3 emissions from decommissioning and new construction. 

Established drop-in biofuels like fatty acid methyl esters (FAME) and hydrotreated vegetable oils (HVO) are produced from vegetable oils or waste fats, oils, and greases (FOGs), and are well known in the transport industry. According to the International Energy Agency (IEA), global production in 2024 reached nearly 45 million metric tons for FAME and 15.5 million for HVO, mostly serving road transport. These fuels are already established also for marine use: pure FAME and HVO or blends of these with conventional fuels are covered under ISO 8217:2024, the marine fuel specification standard. However, the availability of sustainably sourced FAME and HVO is limited, and drop-in alternatives are needed to meet growing demand. 

To address this, we are exploring options to increase the availability of sustainable and suitable drop-in fuels for shipping.  

The project is developed around three main areas of research:  

1. Investigating the potential of alternative feedstocks, with an enhanced sustainability profile, to scale supply;  

2. Mapping and facilitating the process of adopting new fuels; 

3. Assessing the sustainability, usability and affordability of ethanol and ethanol derivatives, produced from sustainable feedstocks, as marine fuels.

Biofuels are currently the most accessible and cost-effective alternative to fossil fuels for shipping companies seeking to reduce emissions. However, their production raises sustainability concerns, including impacts on land use, deforestation, biodiversity, and food security. 

Demand for biofuels is expected to rise sharply across shipping, road transport, and aviation, consuming a combined ~120 EJ today. Biofuels are anticipated to deliver the backbone of transport decarbonization until ~ 20351 when alternatives may become cost effective2. However, between 2030-2035, the combined demand for biofuels for transport may be up to 12-13 EJ1.  

By 2035, compliance with the IMO’s emissions reduction schedule3 may generate a demand for drop-in biofuels of 4-5 EJ in shipping only. The IEA projects4 that combined production of FAME and HVO, the only drop-in biofuels established for marine engines, could reach 74-95 million metric tons by 2030 (2.7-3.5 EJ), with two-thirds derived from edible oils like palm and soybean. This is insufficient to cover the anticipated demand by 2035 and increasing biofuel supply by expanding production of conventional feedstocks conflicts with nature conservation and food security goals. 

Given the projected demand for biofuels, it is essential to ensure that biofuels are produced from sustainable feedstocks. Promising pathways to deliver feedstocks with an enhanced sustainability profile include cultivating energy crops on land with limited agricultural potential such as unused, degraded, or marginal lands as well as increasing productivity on existing farmland using cover crops. In this project, we explore sustainability trade-offs and synergies and the potential availability of alternative feedstocks such as Carinata, a drought tolerant winter crop, which may complement summer crops such as cotton or corn in the United States South East5, or be grown in marginal semi-arid areas like the Southern Mediterranean area6 and yield oil for FAME and HVO, or Agave and Opuntia that may be grown in semi-arid areas, such as the Brazilian Sertaõ7, Mexico and United State’s South West, Southern Mediterranean, Southern Africa and others, and are studied as feedstocks for ethanol 8 9 and biomethane 10.

For most stakeholders along the supply chain, the process of adopting new drop-in fuels is unclear, fragmented, and slow. It involves many actors, yet roles and responsibilities are not clearly defined. It is further complicated by overlapping or conflicting national and international regulations, and a lack of incentives to streamline the process. 

As decarbonization efforts face fuel availability and sustainability challenges, the need to adopt new drop-in alternatives becomes more urgent. Without improvements, current bottlenecks could become a major barrier to meeting emissions targets. 

We have mapped the stakeholder landscape and adoption steps, based on feedback from organizations with direct experience. The goal is to accelerate the adoption of new drop-in fuels by promoting knowledge sharing, and encouraging collaboration.

We are evaluating ethanol’s potential as a marine fuel, focusing on sustainability, usability, and affordability.

This initiative is conducted under competition law compliant protocols: neutral facilitation, public or anonymized/aggregated inputs only, and no coordination on commercial conduct. Outputs, where produced, are open and non-discriminatory.