## 1 Introduction
Research has demonstrated that effective energy management through digitalized systems can reduce costs by approximately 21.7%, while optimized payback periods make renewable energy investments more financially viable. These findings underscore the importance of integrating digitalization and hybrid technologies to drive sustainability and efficiency in port operations [20; 21]. Ports have made significant efforts to enhance energy efficiency through operational strategies and the adoption of low- and zero-carbon fuels [22]. Many also participate in environmental management protocols, including Port Environmental Review System (PERS), ISO 50001, and EN 16001 [23]. As an alternative to conventional energy sources, marine renewable energy (MRE)--such as tidal energy, marine currents, and wave energy--offers a sustainable solution for electricity generation [24]. The adoption of hydrogen is considered a crucial strategy for decarbonizing port areas and the shipping sector [25], positioning ports as key players in the transition to a renewable energy-based economy [26]. While this strategy has been implemented in various ports, challenges remain in optimizing its operation [27] and ensuring a reliable and clean power supply for its effective deployment. A new methodology is proposed [28] to transform urban waterfronts (UWFs) into positive energy districts (PEDs), highlighting coastal cities, ports, and urban waterfronts as ideal locations for such developments through community collaboration. Similarly, [29] advocates for the establishment of HESs in ports, recognizing their potential as central hubs for clean energy. Their analysis of Italian ports demonstrated that they can enhance renewable energy adoption, positioning them as a key strategy for port sector decarbonization. As part of the ongoing HY4 RES project, advanced energy management models are being developed and implemented across various regions, including Spain, Portugal, France, and Ireland. This paper presents one of the key pilot case studies conducted at the Port of Aviles, Asturias, Spain. The study applied a range of modeling approaches and integrated various energy management components to assess their performance. In this context, newly developed tools such as the Energy Management Tool (EMTv1) [30], an interactive model created using MS 365 Excel(r) Solver, as well as the Hybrid for Renewable Energy Solutions (HY4 RES) model [31; 32], also implemented in Python, were explored. These models were specifically tested for their performance, flexibility, adaptability, and reliability and benchmarked against the widely recognized commercial software, Hybrid Optimization of Multiple Energy Resources (HOMER(r) 3.16.2 Pro) [32; 33]. Both were designed to assist in the planning and optimization of microgrids and distributed energy systems in different energy sectors, namely for a port. Widely used in the energy sector, HOMER(r) 3.16.2 Pro aids in planning, designing, and analyzing microgrid projects, especially those incorporating renewable energy sources. HY4 RES and EMT are tailored developed models, where the combination of elements and the flexibility of operation are added values, requiring knowledge of mathematical languages and optimization algorithms [34].