Perpustakaan Digital ITB

Solar and wind generation’s share in the ASEAN region will reach 20% by 2030 (from just over 1% in 2022) in ASEAN and 69% by 2050. Indonesia’s renewable energy potential for power generation from offshore wind is up to 589 GW (IRENA 2022). Wind turbines are moving further to deeper waters and capturing higher wind speeds in harsher environments. This trend creates additional challenges in the design, installation, operation, maintenance, and decommissioning phases of an offshore wind farm (Ramachandran et al, 2021). There is a novel installation procedure by performing mating at calm water and towing complete structure vertically, such as Aasta Hansteen Spar (O&G) (2018), Hywind Scotland Pilot Park (FOWT) (2017), and Hywind Tampen (FOWT) (2022). This installation method (inshore) is considered more cost-effective than an offshore installation (Myhr et al, 2014). In this study, a floating offshore wind turbine (FOWT) is designed to be transported from the fabrication yard. The mating procedure is performed near the fabrication yard. Then vertical full assembly tow out is performed to an in-place location at Jeneponto Regency, South Sulawesi. The relevant standard from DNVGL-STN001. The analysis was performed to obtain towing configuration, specification, and tug bollard pull (BP). The critical condition of holding the tow position in severe weather conditions is considered limiting and hence used for verification of towing static bollard pull, configuration, and stability. The mating point chosen at 100 m, bathymetry data, and environmental conditions are considered in the process. The environmental condition along the route is analyses. Several aspects as bathymetry, under keel clearance, and existing projected platform and subsea assets are considered in the proposed tow route plan. The phase 1 towing of substructure ballast configuration is designed using hydrostatic stability software so that the stability criteria of intact and damaged complies with the standard with a critical margin of 7% area ratio of wind heeling arm. The towing configuration is proposed to maintain a 100-yr sea state ( ???????? = 3.67 ????, ???????? = 10.8 ????, ????10 = 20 ????. ?????1, ???????? = 110 ????????. ?????1) and analyses with radiation diffraction software and hydrodynamic stability software for 3-hour simulation. The result consists of a minimal deployable towline length (DTL) of 500 m using 76 mm wire rope, 60o bridle apex, shackles and delta MBL of 221 tons. The static BP of 57 tons using Chaterine Queen AHTS of 85-ton BP. The phase 2 full assembly towing configuration is proposed to maintain unrestricted operation condition (???????? = 5 ????, ????10 = 20 ????. ?????1, ???????? = 204 ????????. ?????1) and analyses with radiation diffraction software and hydrodynamic stability software for 3-hour simulation. The result consists of a minimal deployable towline length (DTL) of 500 m using 76 mm wire rope, and shackles and a delta MBL of 439 tons. The BP tug required for a single leading tug is 273 tons. This study also covers station-keeping analysis. The relevant standard using DNVGL-ST-0119. The mooring system is analyses with radiation diffraction software and hydrodynamic stability software for a 3-hour simulation. The iteration of mooring line configuration, specification, and anchor radius are performed to obtain the optimal design. The critical condition of ultimate limit state (ULS) at parked with 50-yr environmental condition, ULS at rated speed at the highest thrust coefficient (???????? ) with 50-yr wave and 1-yr current environmental condition, and accidental limit states (ALS) survival condition with 500-yr abnormal environmental condition are analyses. The cases are considered limiting and hence used for verification of mooring effective tension, tower inclination, and floater offset. Mooring system station-keeping analysis for ultimate limit states (ULS) and accidental limit states (ALS) resulting 3 spread lines with bridle line; configuration one of anchor radius of 935 m; combination of 50 m bridle chain line with nominal diameter 54 mm, and 885m chain line with nominal diameter 73 mm, maximum response of 5.6o tilt and 46.7 m floater offset; alternative configuration two of anchor radius of 528 m; combination of 50 m bridle chain line with nominal diameter 54 mm, 38 m chain line with nominal diameter 73 mm, 100 m polyester line with nominal diameter 152 mm, and 340 m heavy chain line with nominal diameter 127 mm; maximum design value of 5.6o rotor tilt and 42.0 m floater offset.