http://hdl.handle.net/10174/5270 Fri, 03 Apr 2026 18:51:33 GMT 2026-04-03T18:51:33Z http://hdl.handle.net/10174/38825 Title: The governance of the water-energy nexus: Co-produced narratives to take stock and address energy dependencies of the urban water cycle in Atlantic Europe Authors: Willaarts, Barbara; Novais, Maria Helena; González Navarro, José Maria; López Lara, Germán; Morais, Manuela; Zilliox, Erik; Peñate Suárez, Baltasar Abstract: Water and energy (WE) are key resources to support human well-being and are highly interconnected. Intensifying demands of both resources and increasing resource scarcity are exacerbating their interconnectedness and calling for the adoption of an integrated approach called “WE nexus”. This paper explores the barriers and opportunities to govern the WE nexus in the Urban Water Cycle (UWC), particularly, the energy dependencies of the water supply and sanitation services in Atlantic Europe, through the assessment of four contrasting and representative regions: Canary Islands (ES), Western Andalusia (ES), Alentejo (PT) and Brittany (FR). We applied a “Quantitative Story Telling (QST)” method to assess the discourses from 49 stakeholders from across the four regions on WE nexus challenges and opportunities in the UWC, and the evidence that exists on them. The result is a pluralistic narrative incorporating the views of different stakeholders on what are the issues at stake and why, what needs to be done and how, and sustained by available data. The resulting narrative explores the formal aspects underpinning WE nexus governance in the UWC, but also informal rules linked to political economy. Our results revealed that WE nexus challenges are context-specific, however, there are important commonalities across regions and phases of the UWC value chain, suggesting that these are relevant at the Atlantic Europe scale. QST is not instrumental in directly inducing policy change or decision-making, but might be a valuable means for knowledge mobilization to question and enrich the quality of dominant discourses, and thus paving the road for action towards sustainability. Mon, 30 Sep 2024 23:00:00 GMT http://hdl.handle.net/10174/38825 2024-09-30T23:00:00Z http://hdl.handle.net/10174/38821 Title: Floating photovoltaic systems: photovoltaic cable submersion testing and potential impacts Authors: Rebelo, Ricardo; Fialho, Luis; Novais, Maria Helena Abstract: Background: Floating photovoltaics (FPV) is an emerging technology that is gaining attention worldwide. However, little information is still available on its possible impacts in the aquatic ecosystems, as well as on the durability of its components. Therefore, this work intends to provide a contribution to this field, analysing possible obstacles that can compromise the performance of this technology, adding to an increase of its reliability and assessing possible impacts. The problem under study is related to the potential submersion of photovoltaic cables, that can lead to a degradation of its electrical insulation capabilities and, consequently, higher energy production losses and water contamination. Methods: In the present study, the submersion of photovoltaic cables (with two different insulation materials) in freshwater and artificial seawater was tested, in order to replicate real life conditions, when FPV systems are located in reservoirs or in the marine environment. Electrical insulation tests were carried out weekly to assess possible cable degradation, the physical-chemical characteristics of the water were also periodically monitored, complemented by analysis to detect traces of copper and microplastics in the water. Results: The results showed that the submersion of photovoltaic cables with rubber sheath in saltwater can lead to a cable accelerated degradation, with reduction of its electrical insulation and, consequently, copper release into the aquatic environment. Conclusions: The test results pointed a probable relationship between submersion of cables with rubber outer shell and water freezing temperatures and the occurrence of accelerated degradation of the cable insulation layer. Reduced insulation resistance values were measured in this cable type after the occurrence of such temperatures, both in salt and freshwater, the cable presented visible exterior degradation signs. For this case copper residues were detected in the water. Mon, 01 Jan 2024 00:00:00 GMT http://hdl.handle.net/10174/38821 2024-01-01T00:00:00Z http://hdl.handle.net/10174/37447 Title: A comparison of secondary optic designs for linear Fresnel collectors with a single tubular absorber Authors: Santos, André; Canavarro, Diogo; Arancibia-Bulnes, Camilo A.; Horta, Pedro; Collares-Pereira, Manuel Abstract: This work presents a comparison of secondary optics for linear Fresnel collectors with a single absorber tube. The Compound Parabolic Concentrator (CPC) is indicated as the better secondary in different studies and under assessments including efficiency and flux uniformity, although it was never compared to the Compound Elliptical Concentrator (CEC) and to a recently proposed aplanatic design. Moreover, CPC geometries resulting from stochastic optimization needs to be confronted with theoretical edge-ray designs to evaluate the necessity of this optimization procedure. The ensuing ray-tracing results indicate that when the efficiency is the sole objective, CPC optimum geometry highly diverge from the edge-ray design, presenting a better efficiency but far lower performance in terms of flux uniformity and acceptance. In a two-objective problem involving efficiency and flux uniformity, optimum geometries for the CPC get closer to the edge-ray designs, particularly if the later considers the same gap size. Indeed, the gap size emerges as an important decision variable to play with the trade-off between the optical efficiency and flux uniformity. Comparison between CPC and CEC edge-ray designs shows that both optics in practice relate to a trade-off between optical efficiency and acceptance – the CPC presents a higher acceptance, the CEC has higher efficiency, whilst results of flux uniformity are practically the same. Regarding the aplanat design, it performs poorly in terms of acceptance angle compared to edge-ray designs, although outperforms them both in flux uniformity, and is outperformed by the CEC in terms of efficiency. Sat, 31 Aug 2024 23:00:00 GMT http://hdl.handle.net/10174/37447 2024-08-31T23:00:00Z http://hdl.handle.net/10174/36955 Title: Delving into the modeling and operation of energy communities as epicenters for systemic transformations Authors: Cristóbal, Ana B.; Sanz-Cuadrado, Cristina; Zhang, Zhe; Victoria, Marta; Fialho, Luis; Cavaco, Afonso; Bokalič, Matevž; Narvarte, Luis Abstract: With the emergence of energy communities, this paper explores their operationalization as a tool with which to create large and stable citizen science and education hubs focused on energy, where citizens can have the chance of exploring a first-hand approach to the energy transition. We present the rationale behind an energy community, whose purpose is to generate systemic and transformative changes in local environments. The concept of an energy community is used to reflect the legally recognized union of citizens, which is much stronger than any associative mechanism yet without such a structure. While the latter’s actions and interests align with those of energy communities, its operation mode differs in terms of the priority assigned to each of them. The developed model has been submitted for feedback to three European university communities. The feedback received has highlighted the acceptability of the model and encouraged us to move forward with its implementation. Approximately 90% of the participants in the study would partake in this type of energy community in very diverse ways, which shows the capacity of the model for inclusiveness and universal access to energy experiences. The barriers and drivers expressed by the participants of the study were analyzed to identify the aspects that foster or prevent citizens’ participation. This approach will allow us to define a more responsible action plan when turning these models into reality. Wed, 01 Nov 2023 00:00:00 GMT http://hdl.handle.net/10174/36955 2023-11-01T00:00:00Z