Techno-economic analysis of the transition towards the large-scale hybrid wind-tidal supported coastal zero-energy communities

In the current academic fields of zero-energy community, there is still limited knowledge on the integration of a coastal community with hybrid ocean-related energy systems. This study investigates the feasibility of a coastal community to reach zero-energy with the support of a hybrid offshore wind and tidal stream energy generation system, as well as an ocean and solar thermal energy supported district cooling and heating system. TRNSYS simulation was performed to demonstrate a proposed community that comprises 8 high-rise residential buildings and 2 mid-rise office buildings with a 9.86 MW community peak power demand. This study considered 21 hybrid renewable energy cases and investigated their performance in 2 scenarios - scenario 1 without battery and scenario 2 with battery. The system performance is assessed from the technical, economic, and emission perspectives by analysing the system load matching, net present value, discounted payback period, and equivalent CO2 emission. In scenario 1, the hybrid renewable energy case 5 with 6 offshore wind turbines (12 MW) and 117 tidal stream converters (29.25 MW) has the best annual load matching (56.68% "onsite energy matching " and 57.84% "onsite energy fraction ") mainly due to their complementary generation pattern during specific periods. In scenario 2, the community-scale electricity storage significantly increases the system technical performance by raising the "onsite energy matching " and "onsite energy fraction " of case 5 to 75.25% and 74.75%, respectively. In addition, the techno-economic analysis reveals the market competitiveness of the 21 RE cases and demonstrates the significant economic impact of the FiT policy. The comparison between scenario 1 and scenario 2 indicates that the community-scale battery diminishes the operation-cycle profits but reduces the equivalent CO2 emission. Furthermore, with the current price settings, tidal stream energy generation is considered less profitable than offshore wind energy generation. This study could provide important insights into the development of coastal zero-energy communities with hybrid offshore wind and tidal stream energy generation at other locations worldwide, especially densely populated coastal cities.