AP Moller-Maersk is continuing to pump money into future fuel start-up companies.
The Danish containership giant's latest investment is in new Dutch outfit Vertoro, which is developing liquid lignin technology to produce marine bunkers.
Corporate venture division Maersk Growth has taken an unspecified minority stake.
Maersk's cash will allow Vertoro to build a demonstration plant for operation in 2022.
Lignin is a plant material seen as a waste product. It is usually discarded without being used, but is easily accessible and found in large quantities.
In 2019, Maersk and Wilhelmsen said they were teaming up to study lignin blended with ethanol.
Danish shipowner Norden has also said it is interested in the biomass substance.
Maersk expects several fuel types to exist alongside each other in the future.
It has identified four potential pathways to decarbonisation: biodiesel, alcohols, ammonia and lignin-enhanced alcohols.
"Lignin fuels have a promising potential when it comes to decarbonising shipping," said Maersk Growth partner Peter Votkjaer Jorgensen.
Taking carbon out of the air
"We consider Vertoro to be a leading start-up in the sustainable biomass-to-liquids space and we are excited to invest in the company and become part of the efforts to effectively scale up production of green fuels."
Vertoro was founded in 2017 and produces liquid lignin exclusively from sustainably sourced forestry and agricultural residues by means of a patented thermochemical process.
The deal is Maersk's fourth deal involving alternative fuels since August.
In September, it took a minority holding in California's Prometheus Fuels to help it develop direct air-capture technology to enable shipping of cost-efficient, carbon-neutral "electrofuels".
CO2 will be captured from the atmosphere, but scaling up production will be key to reducing the costs involved.
Before that, Maersk bought a stake in US start-up WasteFuel, to increase sustainable bio-methanol production.
Three weeks earlier, it reached an agreement to source e-methanol in Europe.
Maersk named renewables company European Energy and its subsidiary REintegrate as partners in a Danish facility that will produce about 10,000 tonnes of carbon-neutral e-methanol.
