[prawn]

The article mentioned carbon dioxide output: "the company overhauled the design to address rising fuel costs and cut carbon dioxide emissions"

Though I imagine the fuel costs are a primary consideration and the environmental aspect is mostly there to push press opportunities.

[cardiffspaceman]

Cutting carbon emissions is a separate goal because the EU seems to have a directive that seeks to reduce carbon emissions among the ships that service the EU market (somehow). I don't seem to be able to search the web effectively to find discussions of this directive. It came to my attention while reading about some other maritime silliness. There seems to be mention of something here: http://ec.europa.eu/clima/policies/transport/shipping/index_...