As an important tool for water transportation, ships can be classified into various types based on different navigation areas, navigation states, propulsion methods, power devices, shipbuilding materials, and uses.
According to the currently available power devices, existing ships can be classified into steam ships, internal combustion engine ships, steam turbine ships, electric ships, and nuclear-powered ships, etc.
Currently, electric ships are mainly used in civil areas, focusing on inland lakes, rivers, and nearshore ports. They can be divided into various types of application ships, such as vehicle passenger ferries, passenger ships, port tugboats, port service ships, and offshore engineering ships, etc. Based on the application tonnage, they can be divided into ships below 500 tons, 500-2000 tons, 2000-5000 tons, and over 5000 tons, etc.
Electric ships have the advantages of being environmentally friendly, pollution-free, safe, and low-cost. The operating cost of electric ships is significantly lower than that of diesel and LNG fuel ships. Additionally, due to the simple structure and fewer moving parts of electric ships, their maintenance cost is extremely low. Electric ships are in line with the current trend of developing green ships.
At present, it is difficult to completely replace large ships over 5000 tons with lithium batteries. Only a small number of ships adopt hybrid power systems, and the proportion of ships using lithium batteries will increase year by year with the annual renewal of old ships and the introduction of new ships.
Currently, lithium batteries used in electric ships are lithium iron phosphate cells and need to be certified by ship classification societies before use. Lithium iron phosphate cells have good safety, long cycle performance, good high-temperature stability, and lower cost.
Electric ships require carrying a large number of batteries and have high requirements for batteries, such as short-term high-discharge rate capability. This to some extent will increase the heat generation of batteries. Thus, high-temperature resistance, cycle performance, and cost of batteries become particularly important. Compared to lead-acid batteries, lithium iron phosphate batteries have advantages in terms of energy density and volume.
Lithium iron phosphate batteries are currently more widely used in new energy passenger vehicles and energy storage fields, with a price range of 0.8-1 yuan/Wh. Currently, lithium iron phosphate batteries used in electric ships will need more technical validation, stricter standards, and higher product prices compared to the new energy vehicle field, with a price range of 1.1-1.3 yuan/Wh. As the proportion of lithium iron phosphate cells used in electric ships increases in the future, the product prices will decrease.
The future trend of ship electrification will mainly focus on the following areas: 1) ferries and sightseeing boats in coastal cities and along rivers; 2) river cargo ships; 3) the port tugboat market; 4) some large and medium-sized ships using lithium batteries to replace lead-acid batteries, thus promoting the accelerated application of lithium batteries in ships.
However, the industry still faces some difficulties and bottlenecks, mainly including: 1) the implementation of the IP67 safety standard and the development of high-rate batteries; 2) the standardization of ship battery manufacturing and testing systems still needs improvement; 3) the lack of standardization and imperfect operation system in the small ship market in inland lakes and rivers.