As projects have become more and more complex, there has been an increasing concern about the concept of project complexity. An understanding of project complexity and how it might be managed is of significant importance for project managers because of the differences associated with decision‐making and goal attainment that are related to complexity. Complexity influences project planning and control; it can hinder the clear identification of goals and objectives, it can affect the selection of an appropriate project organization form, or it can even affect project outcomes. Identifying the different concepts associated to project complexity, its main factors and characteristics, the different types of project complexity, and the main project complexity models, can be of great support in assisting the global project management community. In this paper, we give a general overview of how complexity has been investigated by the project management community and propose several ideas to address this topic in the future.

Society and its leaders are increasingly aware of the need to fight climate change and CO₂ emissions in the search for sustainability. Maritime transport and ports are important sources of pollution and, while industry and the rest of the large-scale emitters have achieved considerable reductions in this area, “shipping” is still not advancing at the same rate, falling behind in this race. The aim of this article is to underline the importance of an early implementation of On-Shore Power Supply (OPS), Cold Ironing (CI) or Alternative Marine Power (AMP) by making a study of potentially avoidable CO₂ emissions from vessels docked (on the basis of the EPA [Environmental Protection Agency] and ENTEC [Environmental Engineering Consultancy, an environmental and engineering consultancy in UK] methods) close to urban areas in the Port of Santander (Spain). It is the first time potential reductions have been calculated for the last 11 years (2011–2021), distinguishing yearly emissions per type of vessel and providing real information to port authorities to prioritize the installation of this technological basis for the operation of piers/terminals to optimize investments and outcomes. In this case study, results demonstrate the outcomes of ROROs, ferries, and cruises being the first target of OPS implementation (reaching total of 37.95% of total emitted tons of CO₂ during the period of study). As a clear conclusion to this paper, the reader can understand the enormous and growing potential of this technology multiplied by the continuous development, increase and implementation of green energies.