Majority of the maritime trade happens by sea. These ships transport millions of tons of material across thousands of miles to every corner of the globe. This requires that these ships use a means of propulsion that is safe, widely available, cheap and does not occupy huge amount of space. As of date, the only such fuel is diesel and furnace oil. Though land based transport systems and energy generation systems are moving towards carbon free fuels for energy and renewable sources, the same is not happening in the shipping industry. Some effort has been made to change over to pure electric or hydrogen fuel cell based systems but it is limited to short range and ferry services where the voyage does not last for more than a few hours.
For long distance shipping options like bio-diesel and hydrogen fuel cell have been tried, but hydrogen fuel cell is expensive as of now while bio-fuels are not available widely. As of now, as per DNV-GL only 0.3% of the global fleet uses alternate fuels. In case of new construction, only 6.1% of the ships on order would use alternate fuels. Alarmed by these facts, the International Maritime Organisation aims to introduce a strategy seeking to halve the sector’s emissions by 2050 from 2008 levels and make the industry carbon-neutral by 2100. However, by 2050, excluding trade in oil, maritime trade is expected to grow by 39% which will offset the efforts to reduce carbon emission by the maritime industry and the emissions are actually expected to reduce only by 27%.
One viable option that has emerged till now is using ammonia as fuel. Ammonia is the most promising carbon-neutral option for new ships, thanks to the lower cost of the converter, storage and the fuel compared with hydrogen and liquefied bio gas. However as of now, now engines are available which can burn ammonia. They are expected to be developed over the next few years.