I’ve visited this topic before, but a recent excellent article in IEEE Spectrum induced your author to take another dive into the sustainable ocean.
There is no doubt that the title challenge is the most difficult to address of all of the transportation technologies that currently emit greenhouse gases and hence is a major causes of climate change.
A modern Marine Transportation System is critical to national and economic security. About 99% of U.S. overseas trade, by weight, enters or leaves the U.S. by ship. This waterborne cargo and associated activity contribute more than $500 billion to the U.S. GDP and sustains over 10 million U.S. jobs. Global maritime emissions account for about 3% of total greenhouse gas emissions each year. Decarbonizing the Marine Transportation System is integral to decarbonizing the transportation sector, as well as the broader economy, and will strengthen the competitiveness of the industry through technology innovations, training a new generation of mariners and shipbuilders, and the adoption of new, clean energy sources.