# Electrification in Maritime Vessels: Reviewing Storage Solutions and Long-Term Energy Management
## 2 Electrification of Marine Vessels
### Charging Infrastructure of Marine Vessels
Figure 2: DC BUS and a hybrid power system connected to an AC shore charging station [20]. Figure 3 illustrates a ship with a DC BUS and a hybrid power system linked to a DC shore charging station. After passing through a transformer, the energy from the grid is converted to DC via a converter and then directly connected to the ship's main DC BUS. Like other charging stations, this battery-supported station matches its voltage to the ship using a DC-DC converter. This charging station design can offer a weight advantage for ships [38; 39]. Figure 4 demonstrates that the ship's bus system is configured to operate with an AC setup. This configuration indicates that the ship is designed to work with an alternating current (AC) bus without requiring any alterations or adjustments to the existing charging station. The charging station remains unchanged, maintaining its original design and functionality. This seamless integration suggests compatibility between the ship's AC bus system and the charging infrastructure, highlighting the convenience and efficiency of the setup [40]. These four solutions can be chosen based on various factors, including the size of the ships, the distances they need to travel, and the associated costs. Each solution offers its own set of advantages and disadvantages that must be carefully considered when planning. For instance, all the charging stations mentioned above connect to the ships via standard sockets. However, using socket-based charging stations in salty water environments introduces specific risks. The corrosive nature of salty water can lead to significant corrosion, which, in turn, can cause safety issues and increase maintenance costs for the charging stations. An alternative approach is to address these challenges using wireless charging stations. Wireless charging eliminates the need for direct contact points, thereby reducing the risk of corrosion and enhancing the overall safety and reliability of the charging process in harsh maritime environments. This approach can provide a more robust and maintenance-friendly solution for charging ships operating in saltwater conditions [41]. Figure 3: A ship equipped with a DC BUS and a hybrid power system linked to a DC shore charging station [38]. To transform this charging station into a wireless charging facility, specific components tailored for wireless charging need to be integrated, all without altering the ship's existing charging equipment or the fundamental structure of the charging station. This approach, while convenient in eliminating the need for physical cables, accentuates the critical importance of the charging station's placement. Accurate calculations become paramount to ensure optimal alignment for seamless docking, thus maximizing charging efficiency. Within this setup, the charging station and the ship are outfitted with transmitter and receiver coils positioned at corresponding heights, respectively. The interaction between these coils, characterized by a high magnetization current, leads to reactive power consumption within the charging station's coil. To address this, capacitive compensation networks are employed on both ends to generate the necessary reactive power (Figure 5) [42]. The energy the charging station supplies to these networks follows a square wave pattern, oscillating at a frequency typically in the kilohertz range. Upon reaching the ship, a converter transforms these waves into direct current (DC). Here, the charging  
Figure 4: The ship’s bus system is configured to operate with an AC setup. Figure 5: Wireless charging of marine vessels. station's converter acts as a power supply converter, while the ship's converter functions akin to a diode-based current rectifier. Notably, unlike conventional AC BUS charging stations, this system employs capacitive compensation networks and coils for the transfer of reactive power to the ship.