# Costs and Benefits of Autonomous Shipping--A Literature Review
## 3 Results
### Sensitivity Analysis of a Life-Time Cost Assessment  
One of the most popular methods to assess the economic performance of the project is net present value. The indicator presents a difference of future cash flows (both inflow and out-flow) with a given discount rate and the initial capital investment [59]. [PERSON] [21] also presents the required freight rate (RFR) as an indicator of economic effectiveness. RFR is the aggregated cost of owning and operating a vessel divided by total cargo tonnage over a specific period of time [60]. RFR is a freight rate, which produces a zero net present value over the assumed life of the ship [61]. The lower the RFR for the autonomous ship is, the more cost-efficient the ship is in comparison to the conventional one. [PERSON], [PERSON], and [PERSON] (2017) analyses three different scenarios and compares the indicators with the conventional vessel over 25 years. The first scenario (Scenario A) concerns the aspect of a reduced crew [39]. The expected present value (EPV) is the total cost of owning and operating the ship. The expected present value of the cost of owning and operating the autonomous bulker is 0.5 mUSD lower in comparison to a conventional reference vessel. The required freight rate for the autonomous bulk carrier is 0.4% lower than the RFR of the conventional bulk, which indicates that the autonomous bulk carrier is favourable in economic terms. The second scenario (Scenario B), also described as the base scenario, takes into account the aspect of reduced fuel consumption and reduced crew. In this scenario, EPV (Expected Net Present Value) for the autonomous bulker is 4.3 mUSD lower in comparison to a conventional one. The RFR of an autonomous ship (producing 0 NPV--Net Present Value) is 3.4% lower than the RFR of a reference ship. The third scenario (Scenario C) is based on three elements: reduced crew, reduced fuel consumption, and the use of high-grade fuel. The EPV for autonomous ship is estimated as 19.2 mUSD higher than the EPV of the reference vessel, mostly as a result of higher fuel consumption costs. Consequently, the RFR of the unmanned vessel is roughly 15% higher than for a conventional vessel [21]. The results of sensitivity analysis carried out for the three analysed scenarios (Table 7) demonstrates that autonomous ships can be expected to become cost-effective, especially when improvements in ship's fuel efficiency can be achieved, in addition to reduction of crew costs, as presented in Scenario 3 above. As depicted in Figure 3, the benefits in such a case are higher for long voyages and in a high fuel price scenario. Scenario B depicted in Figure 3 considers the reduced fuel consumption and the absence of crew during a sea passage. On the other hand, if the use of HFO (Heavy Fuel Oil) as the main fuel for an autonomous ship would not be possible. Then it would be extremely challenging for the vessel to be cost-competitive, unless she would be operated exclusively in SECA zones (Sulphur Emission Control Area). When it comes to various modes of autonomous ship operation, the liner shipping network design concept demonstrated that its introduction is economically favourable, [23; 40]. The authors also presented the sensitivity analysis for the case of a conventional mother vessel and autonomous daughter vessels. As a result, [23] identified that exceeding 119% of the additional construction cost of the autonomous daughter ship makes the operation of the autonomous ship economically infeasible. The sensitivity analysis performed indicates that introducing autonomous daughter vessels is profitable. The authors focused on the construction cost of an autonomous ship in the case of 22 and 42 ports under normal demand. The introduced boundary of 119% is definitely higher than existing cost estimates [23].