Optimal planning of renewable energy infrastructure for ports under multiple design scenarios considering system constraints and growing transport demand

Planning, designing and building renewable energy systems at ports is a crucial strategy for achieving their green development goals. Previous studies have focused on the current electricity load demand (ELD) of Port Renewable Energy Systems (PRESs) without considering the impact of the growing transportation demand on such load. They also overlooked the electricity supply condition of the national grid (e.g., strong, weak or no presence) at ports and whether a PRES operates under an on-grid (ONG, connected with the national grid) or off-grid (OFFG) mode. This study proposes a Mixed Integer Programming (MIP) method for planning PRESs that considers growing transportation demand and system constraints, including budget, carbon reduction targets, safety margins with other port equipment, and system reliability under multiple design scenarios. The first step within the proposed method is to forecast hourly ELD based on the estimated transportation demand of the specified planning period and historical hourly ELD data. The second step is to determine the “lowest” self-sufficiency rate (SSR) of the port electricity system, which is determined by the carbon reduction target of the port under study and set by its administration. The above two numbers are then used to estimate the “minimum” capacity of the PRES based on the total ELD of the port and the SSR. Then, the proposed MIP method is applied for planning PRESs under various design scenarios, including the presence of a strong or weak national grid (SNG or WNG) conditions, under ONG or OFFG modes, and with/without storage devices. Finally, the impact of different design schemes of PRESs and related choices of devices on its Rate of Investment (ROI), SSR, and system reliability are also analyzed. A case study of a container port on the eastern coast of China shows that, under the ONG scenario without any storage device, excessive renewable energy can be sold to the national grid, making its economic benefits superior to the OFFG scenario. The ROI for the ONG operation is 38.73% and 35.91% higher than the OFFG operation with the storage equipment in the case of SNG and WNG, respectively. Under the OFFG scenario, installing energy storage equipment reduces power abandonment costs and increases the consumption of renewable energy, making its environmental benefits superior to its counterpart under the ONG operation. Under the OFFG operation with the SNG and WNG scenarios, the PRES is configured with 3.6MW and 80