This book summarizes some key results of a research project based on an innovative eco-design methodology while delivering a practical critical review of existing approaches for dealing with both Eco-Design and Hybrid-Electric Propulsion Trains before considering a proper understanding of these elements and how to make a proper and critical choice for designing zero/low emissions ships. The authors also illustrate the various and different attempts to integrate zero/low emissions with Operational Specifications and the likely features of these attempts are considered, and the scope for developing "fresh" approaches is then presented. One case example is used to show how the methodology can offer an effective approach for designing and operating ships that can meet improved zero/low emissions requirements. Furthermore, this book will present guidelines for new low-emissions designs for passenger ferries, where the scenarios' challenging issue is to achieve both and simultaneously: -"ZERO/LOW EMISSIONS" passenger vessels (limiting the negative environmental impact due to gas emissions and fuel consumption) -Operational capability to reach and maintain an acceptable speed to ensure a daily service, competitive with the other modes of transport.