One idea is that whales are trying to distinguish their voices from the sounds of ship engines. (student.societyforscience.org)
The IMO has adopted mandatory rules for new vessels to boost fuel efficiency as a means of cutting CO2 from ship engines. (cnbc.com)
The large ship engines operate more efficiently and at less cost than most fuel cells, and hydraulic hybrids use the energy with double efficiency. (greencarcongress.com)