Biofuels Paired with Onboard Carbon Capture Could Slash Shipping Emissions by 121%

MOL's tanker equipped with carbon capture unit. Image Credit: Value Maritime

A study by the Global Centre for Maritime Decarbonisation (GCMD) demonstrates that integrating biofuels with onboard carbon capture and storage (OCCS) could achieve up to 121% well-to-wake (WtW) GHG emission savings.

The findings, part of the COLOSSUS project, highlight biofuel blends from used cooking oil as the top performer when paired with OCCS.

By injecting captured CO2 into concrete production, this approach displaces emissions-intensive cement manufacturing ashore, creating a "negative carbon" loop that amplifies environmental benefits, GCMD said in a report shared on Tuesday.

The study, which analysed five OCCS technologies and six marine fuels, focused on MEA (monoethanolamine)-based systems—the most mature carbon capture method.

MEA, a chemical solvent, absorbs CO2 from ship exhaust, which is then compressed and stored or repurposed.

The research assumed a 40% gross capture rate for MEA-based OCCS, consistent with industry benchmarks.

This technology reduced emissions by 29% for HFO-fuelled ships, but pairing it with bio-LNG or biofuels boosted savings to 69-121%, depending on the biofuel source.

Cost remains a critical factor: MEA-based OCCS ranges between $269 and $405 per tonne of avoided CO2.

The hybrid strategy also eases compliance with the IMO's GHG Fuel Intensity (GFI) targets until 2035, allowing ships to delay transition to costly alternative marine fuels. 

For example, HFO-fuelled vessels using MEA-based OCCS could meet the GFI direct compliance target until 2032 and LNG-fuelled vessels using OCCS until 2035.

Professor Lynn Loo, CEO of GCMD, stressed the need for standardised metrics to evaluate cross-sector solutions, urging regulators to formalise OCCS's role in emissions accounting.

"As we face an increasing array of decarbonisation solutions spanning different industries and value chains, coupled with the challenges of quantifying and elucidating carbon flows from source to sink including its re-use, there is a pressing need for a comparable means to understand their net abatement impact," she said.

The study also explored alternative uses for captured CO2, such as producing e-methanol with renewable energy,. While less impactful than concrete integration, this pathway diversifies decarbonisation options.

With biofuels scalable and MEA-based OCCS maturing, the maritime industry now has a viable bridge to reduce emissions - if policies incentivise carbon utilisation and streamline cross-sector collaboration.