The application of the fractional calculus for modeling electrochemical double layer capacitors is a novel way to get simpler and precise models. This paper provides a summarized report of several models of Electrochemical Double Layer Capacitors (EDLC). From classical models based on simple structures composed by networks of passive elements (RLC), to models which involve the fractional behavior of EDLC. The fractional models are based on one hand by a function with fractional poles and zeros and for other one by electrochemical elements (Warburg, Bounded Warburg, Havriliak-Negami). On using the impedance spectroscopy method, experimental results for different EDLCs have been obtained. Coming to the conclusion that the fractional models are fitted better than the classical models.

The application of the fractional calculus for modeling electrochemical double layer capacitors is a novel way to get simpler and precise models. On using the impedance spectroscopy method, experimental results for different values have been obtained. In this paper, several classical mathematical models are studied and a different method is introduced in order to get a model from electrochemical double layer capacitors. This method is based on distinct models with fractional elements, and some parameters of the models are fitted to the experimental data, with minimal error. Finally, a Havriliak–Negami function based model is proposed. It achieves excellent fitting to the whole frequency interval analyzed.

This article shows the optimization of the reverse osmosis process in seawater desalination plants, taking the example of the Canary Islands, where there are more than 320 units of different sizes, both private and public. The objective is to improve the energy efficiency of the system in order to save on operation costs as well as reduce the carbon and ecological footprints. Reverse osmosis membranes with higher surface area have lower energy consumption, as well as energy recovery systems to recover the brine pressure and introduce it in the system. Accounting for the operation, maintenance and handling of the membranes is also important in energy savings, in order to improve the energy efficiency. The energy consumption depends on the permeate water quality required and the model of the reverse osmosis membrane installed in the seawater desalination plant, as it is shown in this study.

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.

The classification, assessment, and estimation of the atmospheric corrosivity are fixed by the ISO 9223 standard. Its recent second edition introduced a new corrosivity category for extreme environments CX, and defined mathematical models that contain dose–response functions for normative corrosivity estimations. It is shown here that application of the ISO 9223 standard to archipelagic subtropical areas exhibits major shortcomings. Firstly, the corrosion rates of zinc and copper exceed the range employed to define the CX category. Secondly, normative corrosivity estimation would require the mathematical models to be redefined introducing the time of wetness and a new set of operation constants.