Julian Bevis of Maersk New Zealand goes to bat for the shipping industry in this article in the Herald:
Since 2007, more than 100 of our vessels have used super slow steaming and, thanks to our collaboration with engine manufacturers, Maersk’s entire fleet is now capable of sailing at half speed, which yields considerable reductions in fuel consumption and CO2 emissions.
Reducing the speed of a ship substantially reduces the power required. Traditional policy set the minimum engine load at between 40 and 60 per cent.
However, a 2007 study initiated by Maersk showed it was safe to go as low as 10 per cent.
For large container ships such as the Emma Maersk, the ability to select any given speed down to 10 per cent load can save 3500 tonnes of fuel and 10,000 tonnes of CO2 emissions a year.