The water-energy nexus, together with the need for sustainable management of these interconnected resources, has attracted growing attention from the scientific community. This paper focuses on this nexus from the point of view of the energy that is required by wastewater treatment plants, which are intensive energy consumers and major emitters of greenhouse gases. The main objective of the study is to investigate the possible use of a wastewater plant’s internal chemical, potential, and kinetic energy, and the addition of external renewable technologies with a view to achieving clean energy consumption and reducing greenhouse gas emissions. For this purpose, an analysis is made of the feasibility of introducing alternative technologies—anaerobic digestion, hydraulic turbines, wind turbines, and photovoltaic modules— to meet the plant’s energy needs. The plant chosen as case study (Jinamar plant, Canary Islands, Spain) has an energy consumption of 2956 MWh/year, but the employed methodological framework is suitable for other plants in locations where the renewable energy potential has previously been analyzed. The results show that a renewable energy production of 3396 MWh/year can be obtained, more than enough to meet plant consumption, but also confirm the need for an energy storage system, due to seasonal variability in energy resource availability. In terms of climate change mitigation, the emission of 2754 tons/year of greenhouse gases is avoided. In addition, the economic viability of the proposed system is also confirmed.

This article analyzes whether the use of videos in flipped classrooms applied to lab practices in higher-education degrees improves the students’ performance. For this purpose, the flipped classroom methodology was used in the Sustainability and Environment Technologies subject, which is included in the curriculum of different engineering degrees. The results were evaluated by considering three different aspects: student satisfaction, student performance during the lab practice, and academic marks. The methodology of the study combines qualitative and quantitative approaches. The results show an improvement in student satisfaction, as well as in student performance during the lab practice. The academic marks of the test students in comparison to the control students also show some improvement. Overall, those who undertook the flipped classroom lab practice noted many benefits, including increased student engagement and satisfaction, as well as improvements in student skills and academic results. Novel aspects such as the qualitative and quantitative evaluations of the performance of the lab practice have been introduced in this research.

In places where water and land are scarce it is vital to look for innovative solutions that can ensure water production for agricultural purposes. This study considers the treatment of water using desalination processes to meet the quality requirements needed for irrigation purposes in agriculture. As the water is stored in a pond, an inland floating photovoltaic (FPV) system is proposed to meet the desalination energy demand. This system would enable energy production without using additional land that could otherwise be used for agricultural purposes. The use of FPV technology also reduces water evaporation, thus avoiding unnecessary energy consumption. To generate enough electricity to treat 12,000 m³/day of water, using an electrodialysis reversal desalination plant, a 1.85 MWp FPV farm is proposed. The results indicate that this FPV farm would generate 3,005,828 kWh per year while avoiding the emission of 58,300 tons of CO₂ and the evaporation of 159,950 m³ of water during its 25-year lifetime. Such systems allow higher renewable penetration in the energy mix and preserve the original use of the land.