# Electrification in Maritime Vessels: Reviewing Storage Solutions and Long-Term Energy Management
## 1 Introduction
### Rise of Electric Vessels and Their Power
With its quiet operation, zero-emission design, and efficient performance, Ellen not only enhances the quality of life for local communities but also serves as a powerful model for green innovation in the maritime industry. Its success has inspired interest from other regions around the world looking to transition toward cleaner, more sustainable transportation solutions on water [7]. In 2018, Port Liner launched fully electric barges in the Netherlands, revolutionizing inland shipping with a cleaner, more sustainable alternative to diesel-powered vessels. Capable of carrying up to 280 containers, these barges reduce CO2, nitrogen oxide, and particulate emissions, while also minimizing noise pollution [8]. Their introduction supports public health, aligns with climate goals, and positions the Netherlands as a leader in green maritime innovation, inspiring similar efforts across Europe. The Sea Change, launched in 2021, is the first hydrogen-electric passenger ferry in the US, operating in San Francisco Bay. Powered by hydrogen fuel cells, it produces zero emissions and only emits water vapor, reducing air and noise pollution. The project demonstrates the viability of hydrogen as a clean energy source for maritime transport and supports efforts to decarbonize the industry, setting a precedent for future hydrogen-powered vessels [9]. The Yara Birkeland, launched in 2021, is the world's first fully electric and autonomous cargo ship, operating in Norway to transport fertilizer with zero emissions. Powered by a large battery system and advanced AI navigation, it eliminates the need for fossil fuels and crew, reducing road traffic, operational costs, and emissions [10]. The vessel marks a major advancement in sustainable and automated maritime transport, setting the stage for future innovations in the shipping industry. Japan's e5 Project aims to decarbonize the maritime industry by developing electric and hybrid vessels, such as the e5 Tanker launched in 2022. Powered by lithium-ion batteries and diesel generators, the hybrid tanker is designed for coastal shipping, reducing emissions, fuel use, and noise [11]. The project also promotes smart maritime technologies, positioning Japan as a leader in sustainable shipping and offering a model for global adoption. Movitz, an electric ferry operated by Green City Ferries, began service in Stockholm in 2023 to support the city's low-emission public transport goals [12]. Powered by a 1.000 kWh battery, it carries up to 150 passengers and offers a clean, quiet alternative to diesel ferries. Movitz reduces emissions, improves air quality, and serves as a model for sustainable urban transit, inspiring similar initiatives globally. Undoubtedly, the key factor driving the progress of these developments, as well as the size and range of the ships produced, is the advancement of battery technology. Batteries are a fundamental component of electric vessels, serving as the primary energy source that powers both the propulsion system and onboard electrical systems [13]. Their performance, capacity, and efficiency directly influence the vessel's range, speed, and operational reliability. Among the most commonly used battery types are lithium-ion (Li-ion) and lithium-polymer (Li-polymer) batteries, favored for their high energy density, long cycle life, and relatively compact size [14]. These characteristics make them especially suitable for marine applications where space and weight are critical factors. Li-ion batteries are widely adopted due to their proven performance in a variety of electric mobility solutions, offering a balance between energy storage and durability. Li-polymer batteries, while similar in chemistry, are lighter and can be manufactured in flexible shapes, making them ideal for custom or space-constrained vessel designs. Ongoing advancements in battery technology are also leading to the development of next-generation batteries, such as solid-state and lithium-sulfur batteries, which promise even greater energy density and safety [15].