The shipping industry transports about 90% of world trade, and accounts for nearly 3% of the world's carbon dioxide emissions; and installing ship engines that burn cleaner fuels could help slow global warming trends.

The International Maritime Organization (IMO) has set a target of net-zero greenhouse gas emissions by around 2050, for which cleaner fuels such as ammonia are key.

The two companies have signed a memorandum of understanding to explore options for ammonia-fuelled ship ownership and operation and would also study usage of methanol and energy-saving devices in the maritime industry, Itochu said.

Across the Asia-Pacific region, countries from Malaysia and Indonesia to India and South Korea are conducting ammonia co-firing trials at power stations which use fossil fuels, with many projects involving Japanese investors.

Last year, Itochu agreed to study development of an ammonia bunkering hub in Algeciras on the Gibraltar Strait in Spain, part of its efforts to establish a global ammonia supply chain.

In the power sector, Japan's top power generator, JERA, plans to co-fire 20% of ammonia with coal at its Hekinan thermal power station, in what it said will be the world's first trial using a large amount of the gas at a major commercial plant.

(Reporting by Katya Golubkova. Editing by Gerry Doyle)