Electrofuels only take over after 2040, researchers find, and the IMO framework beats FuelEU for driving the switch. File Image / Pixabay

• Soy-based biodiesel named the better near-term option, e-fuels dominant only after 2040
• Bio-LNG cuts lifecycle GHG 47.4% against HFO, bio-methanol 41.5%, bio-hydrogen 31.1%
• E-fuels today priced at just 11.1-35.6% of HFO competitiveness
• IMO Net-Zero Framework judged a better driver than FuelEU Maritime

Soy-based biodiesel offers shipping a faster, cheaper near-term way to cut emissions than electrofuels, a study of the Asia-Europe corridor published in Nature Sustainability has found, with electrofuels only becoming competitive after 2040.

The researchers, led by Chengjiang Li of Guizhou University, assessed 13 alternative fuels through to 2050 using a lifecycle model coupled with system dynamics, across some 1,300 scenarios.

On a well-to-wake basis, bio-LNG cut greenhouse gas emissions by 47.4% against heavy fuel oil, bio-methanol by 41.5%, and bio-hydrogen by 31.1%, the study found.

Soybean-based biodiesel is singled out as the near-term option, available and deployable now, where electrofuels remain far too expensive.

The study puts e-fuels at just 11.1 to 35.6% of the market competitiveness of HFO on current pricing, closing only after 2040 as renewable electricity costs fall.

The authors also find that regulation itself shapes the outcome, concluding that "policy design and regulatory stringency substantially shape fuel transition trajectories for maritime decarbonization."

They judge the IMO Net-Zero Framework, with its annually tightening carbon-intensity targets and two-tier penalties of $100 and $380 per tonne of CO2 equivalent, a more globally balanced driver of the transition than the EU's FuelEU Maritime, which they say adds a cost premium of up to 7.6%.

The findings come with caveats the authors are clear about, chiefly that the model does not account for operator behaviour or market shifts, and that electrofuels only perform where renewable power is already abundant.

Left unsaid is that soybean is a food crop, and under FuelEU Maritime food- and feed-based biofuels earn no compliance credit, so a ship calling at a European port could not count the study's preferred near-term fuel towards its obligations there.

The study's preference for soybean-based biodiesel also highlights a wider issue around the carbon intensity of crop-based fuels.

Crop-based biofuels and biogases tend to have a higher carbon intensity than those derived from agri-food waste, Bastien Declercq of CSC, said in an article in Ship & Bunker last year. 

This puts greater emphasis on waste-based biofuels and other low-carbon fuels options as the industry moves beyond the near term.

The full study, "Phased fuel transitions for decarbonizing the Asia-Europe Green Shipping Corridor", can be read here.