Fuels used to represent global marine fuel market
80.0%
No transitional Discouraged
70.0%
Assumed GFI (g CO₂e/MJ)
60.0%
Base case
Strongly encouraged Encouraged
Fuel oil
94 80 60 10
50.0%
LNG
40.0%
Other transitional fuels
30.0%
ZNZ fuels
20.0%
Table 1
10.0%
0.0%
in 2016 to about 17 million ton FOE in 2023, representing a compound annual growth rate (CAGR) of 10.4%. Other alternative fuels have tripled between 2021 and 2023, increasing from 0.11% to 0.36% of the total, with biofuels as the largest contributor. Most biofuels are used as blends with fuel oils. B24 and B30 are popular blends and relatively available in various ports around the world. They are essentially a drop-in fuel, provided that the engine, fuel tanks, and fuel injection systems are compatible from a materials perspective. Biofuels are more expensive than conventional fuels, and their use until now has been on a voluntary basis, allowing shipping customers to reduce their Scope 3 emissions. DNV estimated total biofuel use at just 0.7 million tons in 2023. Blended biofuels represent about 0.3% of marine energy use ( Einar, 2025 ). This DNV estimate is almost double the value reported by IMO. However, we should realise that the IMO data covers only the data from ships that reported under the DCS regulation, amounting to 211 million tons of fuel in 2023, which may explain at least part of the discrepancy between these two data sources. Both sources confirm that biofuel use is growing. FuelEU Maritime, which became effective in 2025, and the forthcoming IMO NZF can drive growing demand for biofuels, as both regulatory instruments create incentives to reduce the average GHG footprint of fuels used on board. It should be noted that other sectors are also looking at biofuel options to reduce emissions, while suitable sustainable feedstocks are limited. As a result, supplies may be short, and biofuel prices may increase. Today, there are a little more than 100 ships on the water that can use methanol ( DNV, 2025 ), but the volume of methanol consumed
remains very small, having grown from 0.01% in 2021 to 0.04% of the total in 2023, according to the IMO data. ICCT ( Xiaoli Mao, 2024 ) reports a similar penetration in 2023 at about 0.05% of the market. With methanol, it is important to ensure that only low-carbon methanol (green or blue) reaches the marine fuels market (either directly or through book and claim arrangements), as grey methanol has a higher Well-to-Wake (WtW) GHG footprint than fuel oil. Blends of grey and low-carbon methanol should not be used as a way to reduce shipping GHG emissions. Fuel mix scenarios Starting from today’s fuel mix, a number of simplified fuel scenarios have been developed using just four representative fuels to cover the full marine fuels market: conventional fuel oils, LNG, other transitional fuels, and ZNZ fuels. In reality, we should expect a rather wide variety of low-carbon fuels, based on multiple pathways, each with its own default or demonstrated GHG fuel intensity (GFI). However, there is little point in trying to be precise to explore the role transitional fuels can play in the energy transition. The purpose of the exercise is to compare scenarios with a limited amount of transitional fuels and a fast transition to ZNZs with scenarios that allow a more important role for transitional fuels. For fuel oils, a GHG footprint slightly above the reference value of 93.3g CO 2 e/MJ has been used. This should be representative of a mix of high-sulphur fuel oil (HSFO), very low- Figure 2 ZNZ uptake needed to meet the NZF Base Target for different transitional fuel scenarios
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