| dc.description.abstract | This thesis presents the technical and economic feasibility analysis of the subsea shuttle tanker (SST). The SST is proposed as an alternative to subsea pipelines and surface tankers with the primary purpose of transporting CO2 autonomously underwater from onshore facilities to subsea wells for direct injection at marginal subsea fields. In contrast to highly weather-dependent surface tanker operations, the SST can operate in any condition underwater. Technical- and economic-feasibility analysis of the SST is performed on this thesis. First, the technical feasibility analysis is done to examine the presence of technical limitations when the SST baseline cargo capacity is reduced or increased. The results show that SSTs with cargo capacities of 10 572 m3, 23 732 m3, and 42 670 m3 are technically feasible. Then, the economic feasibility is analyzed and discussed by comparing SST with existing CO2 transportations (offshore pipeline, crewed tanker ship, and autonomous tanker ship). ZEP (ZEP, 2011) and MUNIN D9.3 (MUNIN, 2015) reports are used as the primary reference of the analysis. The scenarios considered are CO2 transport volumes of 1, 2.5, 10, and 20 million tons per annum (mtpa) with transport distances of 180, 500, 750, and 1 500 km. All designs are assumed to have an equal safety factor for transportation. The economic analysis shows the SSTs are competitive for the 1 mtpa and 2.5 mtpa cases on 180 km, 500 km, and 750 km transport distances. SSTs are not competitive on 1 500 km for all transport volumes due to slow traveling speed. In addition, the SST CAPEX is higher than tanker ships for similar size vessels, which emphasizes that SST is not a cost-effective alternative to transport a large volume of CO2. Furthermore, it is noted that the SST was developed utilizing DNVGL-RU-NAVAL-Pt4Ch1, which is considering the design of military submarines. It is expected that a specific structural design code optimized for the SST will reduce the structural weight and CAPEX accordingly.
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