Co-ordinations of ocean energy supported energy sharing between zero-emission cross-harbour buildings in the Greater Bay Area

Energy sharing between multiple zero-emission buildings is an important energy management strategy that can reduce the negative effects of energy mismatch. This study proposed a cross-harbour nearshore and offshore ocean renewable energy system connected by submarine cables to support two large-scale zero-emission harbour-to-harbour buildings in the Greater Bay Area. Two scenarios named were proposed based on the absence or presence of intermediate submarine cables and the energy sharing between the two regions. Eight representative renewable energy combinations consisting of wind turbines, tidal stream generators, and floating photovoltaic systems were designed to demonstrate the impact of different renewable energy systems on the overall performance. Two integration policies were designed based on the different renewable energy policies of the two regions, and their characteristics were tested. The impact of the submarine cable capacity on the system performance, the possible installation of batteries at offshore sites to replace some of the submarine cable capacity, and the impact of realistic land prices in Hong Kong and Macau on different renewable energy combinations were also investigated. The results showed that the combination with only the nearshore wind turbine system achieved the best economic performance, with relative net present values of 25.63 × 108 and 30.78 × 108 HKD in the two scenarios when the nearshore and offshore sites had equally cheap land prices. When the true land price was introduced, only the combinations with the all-offshore system had positive relative net present values, while the combinations with nearshore systems all had negative relative net present values. Meanwhile, batteries could not replace the role of submarine cables in this system. Installing intermediate submarine cables and sharing energy between the two regions could significantly improve the energy matching by 8 to 21% and economic performance by 4.44 × 108 to 5.30 × 108 HKD of the system. When all submarine cables were maintained at 40% of their maximum capacity, the energy usage ratio could be guaranteed to be 100% without dumped energy.