Anti-soiling coating performance assessment on the reduction of soiling effect in second-surface solar mirror

Soiling represents a major problem for CSP plants, since the accumulation of particles onto the reflective surface cause absorption and scattering of solar irradiance, leading to a significant decrease in the mirrors’ reflectance. Such problem can be amplified, particularly in CSP plants that are installed in semi-arid or arid regions which possess a high direct normal irradiance availability, prone to higher particle deposition due to sand storms, red rain events and, in general, higher atmospheric particle concentration. As means to reduce the amount of dust adhering to the mirrors, anti-soiling coatings are being developed to reduce particle deposition, minimizing maintenance costs due to cleaning processes, leading to an enhancement of energy production. In this paper, a Tracking Cleanliness Sensor was used to compare the Soiling Index between a set of coated and uncoated mirrors, which were left outdoors to naturally accumulate soiling in two different positions, horizontal and tilted 45°. The anti-soiling coating was developed by a partnership between RIOGLASS and IK4-TEKNIKER. Moreover, a simple economical model is proposed here for different possible scenarios regarding the coating used

Durability testing of a newly developed hydrophilic anti-soiling coating for solar reflectors

Anti-soiling coatings for solar reflectors are one of the most useful technical tools to reduce the amount of soiling accumulated on the reflector surfaces, contributing to reduce the water consumption and to increase efficiency in concentrating solar fields. A new anti-soiling coating formulation based on the hydrophilic effect has been recently developed by Tekniker and Rioglass. Reflector samples with this innovative coating were assessed through an accelerated aging test campaign as well as an outdoor exposition at the PSA by CIEMAT and DLR. According to the results obtained, the coating exhibited an appropriate behavior, which implies that the new product represents a promising solution to reduce water consumption

Ultrasound and Eco-Detergents for Sustainable Cleaning

Green chemistry faces a major challenge imposed by the Sustainable Development Goals (6, 14 and 15) defined in the 2030 Agenda. In the case of cleaning products (detergents), the challenges often become a paradox: even if it is biodegradable, no surfactant is harmless to aquatic life. Compared to other studies in the field, this paper covers ultrasound–detergent interactions beyond the cavitation removal process. It also considers synergistic effects with regard to the initial wetting phase and final rinsing. It concludes that the best detergent–ultrasound combination is that which minimises receding and critical sliding angles. At the same time, detergent concentration should be reduced so as to just to capture grease in micelles and avoid reattachment during rinsing. In combination with ultrasound, the concentration of eco-detergents can thus be reduced by up to 10% of their nominal value while attaining the same results.The projects leading to this research have received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreements No. 654479 WASCOP and No. 792103 SOLWARIS

Electrochemical Evaluation of Different Graphite Felt Electrode Treatments in Full Vanadium Redox Flow Batteries

The use of flow batteries for energy storage has attracted considerable attention with the increased use of renewable resources. It is well known that the performance of a flow battery depends, among other factors, on the properties of the electrodes, which are generally composed of graphite felt (GF). In this work, thermal, chemical and plasma treatments have been employed to modify the surface of the graphite felt to improve the electrochemical activity of the redox flow cell. The influence of the variables of each of these processes on the generation of surface functional groups and on changes in the obtained surface area have been examined. In this work, the kinetics of redox reactions relevant to the VO2+/VO2+ reaction have been studied with these treated electrodes and the relationship between the nature of the surface and electrochemical activity of the GF is discussed. As a result, an enhanced electrochemical performance (reduction over 200 mV of the separation between anodic and cathodic peaks and 110 mV of the onset potential) in comparison to the untreated GF is obtained for those GF treatments with low oxygenated groups concentration

Development of a Kinetic Model for the Redox Reactions of Co_2.4Ni_0.6O₄ and SiO₂/Co_2.4Ni_0.6O₄ Oxides for Thermochemical Energy Storage

One of the possible solutions for the transition of the actual energetic model is the use of thermal energy storage technologies. Among them, thermochemical energy storage based on redox reactions involving metal oxides is very promising due to its high energy density. This paper deals with the development of the kinetic study based on data extracted from the thermogravimetric analysis of a cobalt-nickel mixed oxide (Co2.4Ni0.6O4) without and with the addition of SiO2 particles to improve the cyclability. The results show that in the reduction reaction the activation energy is not affected by the addition of SiO2 particles while in the oxidation reaction an increase in the activation energy is observed. The theoretical models fitting with the experimental data are different for each material in the reduction reaction. The mixed oxide is controlled by a nucleation and growth mechanism for conversion ratios higher than 0.5, while the added material is controlled by diffusion mechanisms. In the oxidation reaction, the two materials are controlled by a nucleation and growth mechanism for conversion ratios higher than 0.5

Redox flow batteries : Status and perspective towards sustainable stationary energy storage

| openaire: EC/H2020/875605/EU//CUBERRedox-flow batteries, based on their particular ability to decouple power and energy, stand as prime candidates for cost-effective stationary storage, particularly in the case of long discharges and long storage times. Integration of renewables and subsequent need for energy storage is promoting effort on the development of mature and emerging redox-flow technologies. This review aims at providing a critical analysis of redox-flow technologies that can potentially fulfill cost requirements and enable large scale storage, mainly aqueous based systems. A comprehensive overview of the status of those technologies, including advantages and weaknesses, is presented. Compiled data on the market permeability, performance and cost should serve, together with the perspective included, to understand the different strategies to reach the successful implementation, from component development to innovative designs.Peer reviewe