The electric propulsion system as a green solution for management strategy of CO 2 emission in ocean shipping: A comprehensive review

Selecting and optimizing propulsion architecture is one of the most practical goals and the most difficult decisions in designing modern commercial ships. That process faces several challenges, namely greenhouse gas emissions from the consumption of fossil fuels, International Maritime Organization's (IMOs) strict international legal system on environmental pollution prevention, and new energy efficiency standards for design and management of commercial fleets. With the integration of electrical systems and power supply equipment in maritime transport in the past several decades, the availability of electric propulsion systems have brought several benefits to ship owners, including improved ability to comply with international laws, increased flexibility and reliability, reduced operating costs, and enhanced access to advanced automation capabilities. However, the introduced benefits of electrical and hybrid electric propulsion system architectures in recent years have put considerable pressure on ship owners and designers when optimizing the vessel's propulsion and power system and their control strategies. This paper presents a comprehensive review of conventional and advanced electrical propulsion systems on current commercial vessels and future smart ships. By highlighting the characteristics of the propulsion system configuration, electric power source, and propulsors, the authors present a detailed comparison and analysis in optimizing the choice of electric or hybrid powertrain systems for commercial fleets. Taking into account the increasingly stringent standards related to energy efficiency and emissions regulated by IMO, this paper also addresses strategies for the development of sustainable maritime transport by proposing the efficient use of renewable energy sources and electrical energy storage system.