Integrated tidal power potential in the Seto Inland Sea in Japan with cost–benefit analysis

Tidal power generation (TPG) provides a predictable and stable energy supply, making it a valuable complement to variable renewable sources such as solar and wind. However, its commercial viability remains constrained by high capital costs, complex installation requirements, and limited specialised infrastructure. This study assesses the economic feasibility of TPG in the Seto Inland Sea in Japan using the levelised cost of energy (LCOE) as a benchmark for competitiveness. The findings indicated that with a 10 % discount rate, the LCOE ave is approximately 85,990 ¥/MWh, whereas a 5 % discount rate reduces it to 31,088 ¥/MWh. The estimated annual energy production (AEP) was 374,640 MWh, sufficient to supply 89,735 households, with an equivalent CO₂ reduction of approximately 166,000 tons per year. Achieving cost competitiveness for TPGs requires large-scale deployment and supportive government incentives. Expanding infrastructure and leveraging economies of volume are crucial for reducing costs and enabling broader adoption. Despite existing challenges, TPG holds significant potential for enhancing Japan's energy security and contributing to its decarbonisation goals. This potential depends on effective grid integration, strong policy support, and sustained strategic investment. • The Seto Inland Sea possesses high potential for tidal power in Japan. • Velocity variance among flood and ebb tide at optimal sites produces constant power. • The average LCOE at the optimal sites is approximately (31–90) JPY/kWh. • Annual generation of 374.64 GWh supplies more than 85,000 households. • 166,000 tons per year reduction in CO₂ emission supports sustainable energy plans.