Indonesia’s decarbonisation strategy hinges on how quickly the power system can absorb new renewable classes beyond wind and solar, yet the role of marine renewables has rarely been tested atsystem scale across the country’s grid, notably due to cost constraints. This thesis extends the energy system optimization framework by Langer et al. (2024) [1], Calliope-Indonesia, to analyze wave point-absorber and tidal stream resources’ optimal contribution to the national energy system by 2050 under two grid configurations: a Supergrid with inter-island transmission versus today’s fragmented provincial networks.

The methodology integrates new technology definitions, provincial-level resource assessments from ERA5 reanalysis and TPXO tidal data, and hourly generation profiles into the established Calliope model structure. Four research questions examine MRE impacts on storage requirements, transmission expansion priorities, cost competitiveness against established renewables, and optimal system configurations for least-cost decarbonisation. Wave energy uses point-absorber performance matrices calibrated to Indonesian coastal conditions, while tidal analysis applies velocity-power curves for horizontal-axis turbines deployed in high-flow straits.

Results show that transmission architecture controls MRE integration value. Under Supergrid operation, total storage capacity decreases from 135.7 to 125.1 GW with reference MRE costs (−7.8%) and to 120.2 GW under optimistic learning trajectories (−11.4%). Fragmented networks show minimal storage reduction (+0.6 GW), indicating that MRE benefits require coordinated inter-island power flows. Tidal energy displaces storage more efficiently than wave (0.94 versus 0.09 GW per GW installed) due to predictable semidiurnal generation patterns. Grid expansion concentrates in specific high-value corridors rather than uniform network reinforcement: HVDC capacity increases from 97.1 to 137.6 GW, with the Lampung–Banten connection handling disproportionate additional flows.

Cost competitiveness emerges when interconnection enables optimistic learning curves. Under the Supergrid configuration with accelerated cost reduction, tidal energy reaches 66.1 US$/MWh and wave energy 69.5 US$/MWh.This positions both technologies within the competitive renewable band alongside small hydro (67.5 US$/MWh) and geothermal (61.7 US$/MWh). Marine generation reaches 261.4 TWh annually (17.3% of total demand), compared to 122.8 TWh under fragmented operation, showcasing transmission’s role as a primary value driver rather than background infrastructure.

The analysis identifies targeted deployment strategies: wave clusters positioned behind reinforced transmission gateways on high-resource coasts, and tidal installations near demand centres where network access maximizes predictability benefits. However, single-year operational modeling, coarse nearshore resource resolution, and incomplete spatial exclusions limit precision in site-specific assessments. Despite these constraints, the evidence indicates that MRE technologies can contribute meaningfully to Indonesia’s 2050 power system under cost-optimistic assumptions (CAPEX: 986,000 US$(2023)/MW, OPEX: 50,000 US$(2023)/MW) and remain viable even under reference cost scenarios (CAPEX: 1.76 million US$(2023)/MW, OPEX: 88,000 US$(2023)/MW) when supported by strategic interconnection investments and disciplined resource targeting.