Scottish operator CalMac admits newest ferry emits more CO2 compared to predecessor

Scottish government-owned transport company Caledonian Macbrayne (CalMac) has released an analysis showing that its newest dual-fuel Ro-Pax ferry generates more carbon dioxide (CO2) emissions compared to the vessel it is intended to replace.

Glen Sannox belongs to a series of two dual-fuel ferries built by Ferguson Marine for CalMac for operation on the Clyde and Hebrides Ferry Services on the west coast of Scotland. The vessels' twin 3,000kW engines are configured to be capable of running on either low-sulphur MGO or LNG to deliver a service speed of 16.5 knots.

CalMac officials had earlier promised that Glen Sannox and sister ship Glen Rosa would each emit up to 25 per cent fewer CO2 emissions compared to the 31-year-old, similar-sized vessel Caledonian Isles, which runs on diesel.

However, the BBC reported that an emissions analysis recently conducted by CalMac revealed Glen Sannox will in fact emit nearly 10,400 tonnes of CO2 each year whereas Caledonian Isles will have just over 7,700 tonnes during the same period. The analysis took a number of factors into account, such as anticipated methane leaks and the overland transport of the vessel's LNG fuel via truck following importation from Qatar.

Tristan Smith, Professor at University College London's Energy Institute, explained that having Glen Sannox run on MGO appears the more viable approach when considering the overall environmental impact of importing LNG fuel from Qatar.

"In a best-case scenario, there’s a negligible benefit to using LNG, and at worst, there would be a deterioration," Professor Smith said.

Glen Sannox's procurement and construction have been marred by issues such as cost overruns and the vessel's failure to satisfy design requirements, thus resulting in delays.

The ferry was originally scheduled to enter service with CalMac in 2018 but was only delivered in late 2024.