## 4 Cost of Energy Results and Discussion
### LCoE and SLCoE Comparison with Other Studies  
Studying \"100% renewable energy systems\" is relatively new [130], and no integrated transportation and energy systems are the same. Comparing the SLCOE\({}_{\text{e}}\) with other 100% renewable energy systems should be taken as a general indication since there are many differences; for example, differences in geographical locations, renewable energy sources, energy carriers, storage technologies, and simulation criteria, such as energy self-sufficiency ratios or cost input parameters. Despite such differences, we can, to a certain extent, compare some subsystem costs, onshore wind and solar electricity, stored and dispensed hydrogen, and all-time available system electricity costs, including daily and seasonal storage. * _Onshor wind electricity costs (LCoE\({}_{e,W}\)) are relatively low in comparison with other studies._ Near Future scenario 24-27 \(\upxi\)/MWh compared to 30-50 \(\upxi\)/MWh for 2025 [131], and Mid Century scenario 16-18 \(\upxi\)/MWh with 20-35 \(\upxi\)/MWh for 2050 [131]. There are three reasons for this. First, the exclusion of grid connection costs of 11.5% [132, 133] in this study, because of the direct coupling between the wind turbine and the electrolyzer. Second, the use of a lower WACC (3%) compared to other studies (3.5-10%) [131]. Third, the placement of wind turbines on sites with good wind conditions, resulting in good onshore wind capacity factors (33-38%). * _Rooftop solar electricity costs (LCoE\({}_{e,S}\)) are comparable to the average small rooftop and utility-scale solar electricity costs_, also known as community-scale or large rooftop. Near Future scenario costs of 38-68 \(\upxi\)/MWh are similar to 20-90 \(\upxi\)/MWh [134, 135] in 2025, and Mid Century scenario costs of 18-32 \(\upxi\)/MWh to 15-44 \(\upxi\)/MWh [134] in 2050. The aforementioned values from the literature have similar global horizontal irradiation, although higher WACC (4-5%) [134, 135]. * _Stored and dispensed hydrogen costs (SLCoE\({}_{H}\)) are similar or lower compared to other studies._ Near Future scenario costs of 4.9-5.2 \(\upxi\)/kg H\({}_{2}\) are similar to the 4-7 \(\upxi\)/kg H\({}_{2}\) according to studies by the Fuel Cell Hydrogen Joint Undertaking (FCH JU) and United States Department of Energy (US DoE) [136, 137, 138, 139]. The SLCoE\({}_{\text{H}}\) in the Mid Century scenario of 2.6-3.0 \(\upxi\)/kg H\({}_{2}\) is slightly lower than the US DoE targets of dispensed hydrogen (3.3-3.9 \(\upxi\)/kg H\({}_{2}\)) [140]. The major reasons for this are the higher electricity and expensive electrolyzer costs assumed by the US DoE. * _System electricity costs (SCLoE\({}_{e}\)) are similar to or lower than those in other studies_ on 100% renewable energy systems, including energy and transportation. The Near Future scenario SCLoE\({}_{\text{e}}\) of 179-239 \(\upxi\)/MWh is lower compared to the transportation and energy system of the United States National Renewable Energy Laboratory (NREL) [3]. The difference can be explained by the system's smaller scale, higher, and older component cost figures, and the use of stationary fuel cells instead of FCEV2G technology. The Mid Century scenario SLCoE\({}_{\text{e}}\) of 71-104 \(\upxi\)/MWh is close to the SLCoE\({}_{\text{e}}\) of 88 \(\upxi\)/MWh for an average European smart city area, excluding seasonal hydrogen storage [36]. Several hydrogen electricity reconversion pathways in the north of Germany have been designed and evaluated for the year 2050, including underground seasonal hydrogen storage [141]. The study reports higher values of 176-247 \(\upxi\)/MWh, although it confirms that the costs are dominated in all pathways by the costs of purchasing electricity [141]. The authors of [102] and [142] report similar values of 75-85 \(\upxi\)/MWh and 100 \(\upxi\)/MWh for 100% renewable and self-sufficient energy systems in 2050.