There is at least one "large" partly commercial, partly experimental ship -
http://vikinglady.no/ and several small ones, some experimental, some operational (such as a passenger excursion vessel on the lake Alster in Hamburg)...
...but GL was a bit lagging behind some other class societies (especially DNV) in "producing" marketing gimmicks in shape of "concept ships", so they must have done something to show (or show off)
Everething "green" and "environmentally friendly" is so much trendy today... (and as every fashion - often "empty")...