The company invested an undisclosed amount in Gazelle Wind Power, a Dublin-based startup that develops floating platforms for offshore wind turbines. The deal, previously unreported, was made in the summer last year.

It is the first such investment made by Wah Kwong in the renewable energy sector, chairman Hing Chao, whose grandfather founded the shipping company in 1952, revealed in an interview on the sidelines of the Forbes Global CEO Conference last month in Singapore.

"Whether it's ammonia or methanol, if it's green, it will derive from hydrogen, and hydrogen will be produced most effectively by the sea," said Mr Chao, who is also chairman of Italian certification group RINA's Asia decarbonization committee.

"We strongly believe that having a good, sustainable offshore wind system will become the key to unlocking future marine fuel," said Mr Chao. That's important because ocean shipping is responsible for about 3 per cent of global greenhouse-gas emissions annually, according to the International Maritime Organization. which has set a target for the industry to achieve net-zero greenhouse gas emissions by around 2050.

Ammonia and methanol, as well as liquefied natural gas, are among several being floated as possible cleaner alternatives to bunker fuel, making it difficult to find consensus.

"If you look at how complex shipping is - the different types of cargo, different types of trade routes, different types of infrastructure and the different stages of economic development in different ports - there is no single solution," said Mr Chao. "A lot of propositions and ideas have been put forward, but not enough action."

Wah Kwong currently manages a fleet of 79 vessels, which includes oil tankers and dry-bulk and liquefied petroleum gas (LPG) carriers. The majority of its clients are said to be Chinese ship leasing companies, but Mr Chao is aiming to diversify Wah Kwong's client base and the class of ships it manages. The company itself owns and charters a modern fleet of thirty-seven vessels.

More recently, Wah Kwong is looking to use artificial intelligence technology to increase its ships' efficiency and thus lower carbon emissions. In August, the shipping company formed a strategic partnership with a Shenzhen-based AI startup, ZhenDui Industry Artificial Intelligence, that's backed by China's dominant shipbuilder China State Shipbuilding Corp.