# Costs and Benefits of Autonomous Shipping--A Literature Review
## 3 Results
### Costs Induced Due to Various Operation Modes  
One of the analysed operational modes suitable for autonomous ships is called a liner shipping network design (LSND-A) in short sea shipping [23]. The objective of such a mode is to minimize the total cost of operating the fleet of ships, leaving operational decisions out of the scope. The liner shipping network design is aimed at designing a set of weekly services within a specific time constraint based on the demands--time limit, demand, and destination [55].  
Figure 2: Increases and decreases in autonomous shipping [21; 42].  
In this mode, a mother vessel and a set of autonomous daughter vessels are anticipated. In the case study presented by [PERSON] et al. 2020, a mother ship serves the hub ports whereas daughter ships serve small ports along Norway. The mother route starts in the continental hub port, Rotterdam, and serves the Norwegian main ports. The daughter routes are routes between Norwegian transhipment port and serve other Norwegian main and small ports. [PERSON] [23] prepared an analysis on the type and number of autonomous daughter ships necessary to meet the transport demand. The fleet of daughter ships is heterogeneous in terms of capacity, which allows adapting the autonomous ship to transport needs. Introduction of autonomous daughter ships reduce operational cost by 11%. The majority of savings is generated by reduced time charter cost (as a result of the absence of crew).  
Nevertheless, the construction cost of a fully autonomous ship is estimated to increase by approx. 5%. As a result, the reduction in operational costs is between 9 and 13% [40].  
Nevertheless, [PERSON] et al. (2020) considered the case of introducing the autonomous mother vessel into operation in LSND-A. The reduction of cost of operating the fleet is 20% in comparison to fully conventional model. The fuel cost is decreased by 10% [23]. In the scenario with the use of a conventional mother vessel and autonomous daughter vessels calling 22 ports, the authors assume that the introduction of autonomous daughter ships is expected to reduce total operational costs by approximately 11%. The majority of the savings (94%) is a result of reduced time charter costs (the crew cost is removed) and fuel costs (6%). The cost of cargo handling in the port is increased by 22% in case of autonomous ships in comparison to conventional vessels.  
The fleet of autonomous daughter ships is larger, but the ships have a smaller capacity in comparison to the conventional fleet, which reduces overall costs [23].  
Similarly to LSND, the concept of the vessel train denotes a manned master-ship and automatically controlled the following vessels [56; 57]. In a semi-autonomous vessel platooning concept, the main cost saving is reduction in crew cost. The increased number of the autonomous following vessels (FV) influences reduction in the cost associated with individual FV. The economic feasibility is due to the length of the vessel train. The cost savings of operating autonomous FVs should be equal to or larger than vessel train dues. The concept is relevant for routes that have constant cargo flow and high demand for transport services [58].