Ironically, the accident happened only one day before a ship carrying nuclear fuel made up of mixed uranium and plutonium docked in Japan, surrounded by coast guard vessels and greeted by demonstrators.

CNN: 'We're Scared for Our Baby'

On Tuesday, the U.S. Coast Guard said the fire started with a leak in a fuel-oil return line running from one of the ship's engines.

CNN: STORY HIGHLIGHTS

"The bigger the ship the lower the fuel consumption, that's one thing, " said Thomas Riber Knudsen, Asia Pacific CEO of shipping line Maersk.

CNN: Shipping looks to clean up its act

Ship operators who lease most of their ships only have one easy option to save fuel: slow steaming.

FORBES: A Leader in Efficient Shipping