Hybrid power ship

 

We spotted this in Aberdeen harbour. It turns out that a hybrid power ship is one that runs on diesel but also has a large storage battery system. Despite having looked it up, I don't fully understand the charging of the batteries. It seems that battery power is used in low power situations (this might well mean low speed) such as going in and out of port. Perhaps the diesel is run at a flat rate and any surplus goes to the batteries. They are claiming various advantages.