Long-term climate impact can’t be ignored hence aiming for energy-efficiency measures to reduce fuel usage and emissions is observed.
At the moment, all public ferries operating run on fossil fuels. Smaller boats use diesel that's akin to what's sold at petrol stations. However, larger boats such as the Cook Strait ferries, burn a fuel made of leftovers from the refining process. These leftovers used are thicker, blacker and more polluting. Moreover, they contain a lot of toxic heavy metals which increases air pollution. They contain around 2% sulphur by volume, which is two thousand times more than normal diesel. Particulates from shipping, mostly carbon, contribute to glacial melting as they darken the surface of the ice and also influence the formation of thunderclouds along shipping routes
Awaiting for the change, local ferry companies in Wellington and Auckland are expecting deliveries of fully electric ferries. These ferries will operate on grid electricity. KiwiRail, which runs the Interislander service, is also buying two new two ships. Under the Official Information Act, the replacement vessels could cut Interislander’s carbon footprint by 27,500 tons of carbon dioxide a year – about 10% of our total domestic shipping emissions based on design details.
Upcoming Interislander ferries which will replace Aratere, Kaiarahi and Kaitaki will have diesel generators to produce the electricity to power them, plus batteries to store electricity. This type of ferry is often called a hybrid. Like hybrid cars, its power can be provided either by fossil fuels or battery-stored electricity. Near about eighty per cent of the electricity in the grid comes from renewable sources, including hydro dams and wind farms. In comparison with running the ships on diesel, the actual cost of recharging the batteries in port is economical.
The new Interislander’s’ batteries will be used for short journeys that will reduce air pollution and noise in the harbors – providing relief for coastal communities and marine life. Hence investing in biofuels – fuels produced from organic material, which don’t increase carbon dioxide in the atmosphere – to replace diesel is the aim of future ferries for a green future.