A multi-objective optimization model for the installed capacity of a hybrid renewable energy system for seaport operations considering power disruptions

Seaports prove to be one of the most integral parts of global trade and of any nation’s economy, handling 80 to 90% of global trade volume and contributing as much as 1.9% to a nation’s economy. However, it has been found to also be one of the most harmful industries in the world today, contributing up to 15% of global air pollution emissions. To combat this, seaports worldwide have begun their journey towards a more sustainable way of operations through the implementation of environmental initiatives, present in the form of strategic management of high energy consuming seaport activities to further reduce environmental impact. The study utilizes a MINLP multi-objective optimization model paired with a two-stage framework such that the first stage identifies the optimal installation capacities of HRES energy sub-systems, while the second stage focuses on the optimal management of such energy sub-systems in order to cater to day-to-day seaport operations such as berth allocation and container handling activities. The optimal installed capacities obtained from the first stage were then used as input parameters in the second stage to determine which energy sub-systems will be used or stored, depending on the amount of energy needed per time period. Previous related studies have only considered integrating the dual combination of operation strategies such as berth allocation and onshore power supply (OPS) allocation, or berth allocation with energy management. However, there have not been studies that have explored integrating these operation strategies altogether. Furthermore, with the apparent need for environmental strategies in the seaport, previous studies have only either considered the use of renewable energy or the use of onshore power supply, but never both at the same time. With this, the novel contribution of this study stems from the integration of all these seaport operations, together with the environmental initiatives of renewable energy and OPS connection while also considering the possibility of power disruptions as an additional novelty. For the first stage of the model, it was discovered that cost and emissions are reduced when installed capacities of energy sub-systems are adjusted based on port energy demand from port operations, wherein both OPS and RE are integrated. With regard to the second stage of the model, findings show that costs and emissions are reduced when waiting time is minimized and OPS ships are allocated to OPS berths in berth allocation with HRES components present and used, especially during disruptions so that the diesel generator use is minimal. Moreover, system interplays are heavily influenced by OPS related factors given that the allocation of more OPS installations led to a berth allocation behavior that reduced lateness cost and emissions but with higher energy consumption costs due to OPS demand. Given the dependence of irradiance levels on geographical factors, it was also found that areas with lower irradiance have lower recommended RE installation capacities due to high costs and low returns in terms of how much energy can be generated and obtained. Meanwhile, with the presence of power disruptions in the model, it was found that the ESS is used first when the disruptions are short in duration, while the diesel generator is used first in times of longer disruptions. Overall, findings reinforce the importance of the HRES in terms of maximizing the installation of renewable energy and allocating an optimal capacity for the ESS in order to increase resiliency of port operations amidst power disruptions