According to your link (and all other articles I found on that vessel), that ferry is capable of operating all-electric, but actually operating as a hybrid.

Although the news at that time was about delivery of a first electric ferry, that was 2021 and things change. The Ferry company's web site says now it has three electric ferries as a result of conversions and indeed they charge at both ends of the route. It's in Norwegian but the translation looks reasonable to me.

The Seattle ferries GP was talking are also retrofitted to be hybrid-electric, so that does seem very comparable