Evaluation of a floating wave energy converter for Sipora Island, Mentawai, Indonesia: wave resource, annual energy production and levelized cost of energy

Abstract

The Mentawai Islands in Indonesia face the Indian Ocean and get most of their electricity from diesel generators. This study evaluates a floating wave power plant at a point 16.5 km west of Sipora Island, in 120 m of water, using hourly modelled wave data (ERA5) for 2022 from the European Centre for Medium-Range Weather Forecasts. Waves came mainly from 191.25° to 213.75°, and significant wave height ranged from 0.61 m to 2.33 m over the year. Mean wave power was 9.7 to 10.2 kW/m, depending on which hours were counted and how water depth was treated. That is below the 15 kW/m that a published criterion sets for a good site. The annual energy production of three devices was estimated with the power matrix and scatter table method, using only the hours from the dominant direction. The overtopping device Wave Dragon produced 3,382,126 kWh in the year, more than the attenuator or the floating oscillating water column, and seven units would cover the projected 2025 consumption of 23,395 MWh. Costs were taken from floating offshore wind references and discounted over a 25-year life. On that basis one Wave Dragon unit has a levelized cost of energy of 12,425 rupiah per kWh, against a regional supply cost of 2,319 rupiah per kWh and a cost of 4,677 to 7,795 rupiah per kWh for diesel generators. At the regional supply cost the plant is not feasible, and it would cost more than diesel generation. The wave data still need checking against measurements. The device power matrices are indexed by peak period but were read against energy period, and the borrowed cost basis is uncertain.