Abstract
One technology with significant potential is concentrated solar technology. The effectiveness of this technique is influenced by both Direct Normal Irradiance (DNI) and the meteorological conditions at the location. Among the crucial components of the concentrated solar system, the reflector material holds particular importance as it is responsible for redirecting the solar energy to the receiver. The reflectivity level of the reflector directly impacts the system’s efficiency influenced by corrosion and dust on the performance of these reflector materials. Traditionally, silver glass with aluminum, polymer, and stainless steel has been employed in reflector construction. However, this study delves into and discusses the use of novel materials in concentrator solar technology as reflector components. The focus on exploring new reflector materials for concentrator solar technology is a novel aspect of the ongoing work, which will reshape future research endeavors in this field.
Introduction
The energy demand is rapidly accelerating due to the large population. Traditional energy sources, like fossil fuels, are being replaced by alternatives with a less aggressive impact on the environment [1]. Renewable energy technologies are seen as a solution in both developed and developing countries to address current energy security, environmental concerns, and global climate change [2]. Various renewable energy technologies exist, starting with wind power, which captures kinetic energy from the wind using turbines for electricity generation [3]. Hydropower, on the other hand, harnesses the energy of flowing water through dams. Biomass, derived from organic materials, is investigated for its potential in electricity or heat generation [4], [5]. Shifting to solar technologies, have been found most clean and efficient source of energy having various applications and harnessing methods like solar still [6], Evacuated tube solar collector [7], [8], [9], [10], Solar Air Heater [11], [12], solar photovoltaic (PV) technology, where semiconductor materials convert sunlight into electricity [13]. Additionally, Concentrated Solar Power (CSP) takes center stage as a technology that intensifies sunlight to generate high-temperature heat for electricity production [14]. Concentrator solar technology transforms abundant sunlight into energy. It comprises a collector, gathering solar radiation, and a receiver, absorbing the collected energy [15], [16], [17]. The conversation of Solar energy to final useful energy in terms of electricity and heat energy is reduced by upto 90 % due to several losses. Several researchers have applied different techniques whether Active or Passive to reduce these losses by using artificial roughness like Ribs [11], [18], [19], Phase change materials [20], Twisted tapes [21], Jet impingement [22], [12], [23], Nanofluids [24], [25], etc. Design modification are the other methods employed by researchers [26], [27], such as optimizing tilt angles of the solar collectors [28], [29] etc.
Material innovation and engineering advancements are pivotal for technology development. New methods and materials are crucial for improved performance and reduced costs. Reflective materials, a cornerstone of this technology, significantly impact its efficiency. Reflectivity, the ratio of reflected to incident energy, is gauged using instruments like spectrophotometers and reflectometers, such as Abengoa Condor SR-6.1 and D & S 15R-USB [30]. Development focuses on achieving high reflectivity, durability, weather resistance, and cost-effectiveness [31]. Rigorous testing, including Damp Heat, Condensation, UV + Water, and others, assesses reflector material performance [32]. Corrosion and dust obstruct reflectance, reducing power output and efficiency. Corrosion alters the chemical structure, manifesting as spots on the material, while dust particles alter surface roughness, scattering radiation. Traditional reflector materials include silver glass with Aluminum, Polymer, and stainless steel. The quest for new materials involves high reflectivity, low cost, durability, and resilience to corrosion and dust. Research has explored topics such as reflectance measurement methods, material performance, durability, cleaning techniques, and the impact of dust and soil on reflector materials [30], [31], [32], [33], [34]. Fig. 1 delineates the scope of prior research. R. Segura et al. [35] conducted a review on the durability of aluminum, glass-based, and silver polymer reflectors, evaluating their performance through accelerated outdoor exposure tests. The research aims to enhance durability and preserve reflectivity. In another study, Bouaddi et al. [36] discussed cleaning techniques for reflective materials in concentrated solar power systems, highlighting conventional and innovative methods. The choice of cleaning technique depends on weather conditions and geographical locations, with water availability influencing the use of conventional methods. In desert regions, dry methods like ultrasonic waves or vibration are preferred, while coastal areas utilize conventional techniques due to water availability. Costa et al. [37] compiled recent research on soiling in solar-electric devices, focusing on finding solutions to mitigate soiling issues and employing advanced methods to understand the impact of dust on reflector materials. The review also addresses measurement devices, their durability, and techniques to clean reflective materials, enhancing their performance against dust. Garcia et al. [38] reviewed the development of instruments and models for measuring reflectivity. The paper discusses measurement standards and methods for reflectance, emphasizing the need for instruments covering a wavelength range from 280 to 2500 nm, with an incident angle of nearly 70 degrees and an acceptance angle of 20 degrees. Malwad et al. [39] addressed the development and performance of reflective materials, noting aluminum and glass as primary materials for solar reflectors, while polymer and stainless steel are less commonly used.
The main gaps identified in the literature review are outlined below:
- 1.Measurement conditions used for evaluating reflectance are insufficient.
- 2.Coatings applied to the surface require further research concerning system lifetime and cleaning methods.
- 3.There is a need for more studies to select the appropriate technology for cleaning mirrors.
- 4.In the field of concentrated solar power, there is a demand for low-cost and long-lasting solar reflector materials.
This paper provides an updated literature review on the impact of corrosion and soiling on the performance of reflective materials. It also explores new reflector materials used in concentrator solar technology. The novelty of this work lies in reviewing these new materials, offering potential directions for future research by other scholars.
Reflective materials
Concentrated solar technology, utilizing reflector materials to optimize sunlight capture, is categorized into various systems, each associated with distinct reflector types. The primary classifications include the Parabolic Trough System, Solar Power Towers, and Parabolic Dish Systems. The Parabolic Trough System employs curved mirrors known as parabolic troughs to focus sunlight onto a receiver tube positioned along the trough’s focal line. The receiver contains a heat-transfer fluid,
Performance of reflective materials under corrosion and dust
The performance of reflective materials depends on their reflectivity throughout their lifespan. High-quality reflective materials maintain their reflectance during operation. Reflectivity is affected by factors such as delamination, corrosion, dust, wind loading, rain, temperature variation, and UV radiation. A protective reflective layer is applied to safeguard the materials from these influences [52]. Girard et al. [53] assessed the impact of temperature, humidity, rain, and solar
4.Techniques for mitigating dust and corrosion
In addressing the challenges of dust and corrosion in concentrated solar technology, it is imperative to consider various techniques beyond the mere selection of materials. Coatings and surface treatments stand out as effective measures to create protective barriers, preventing the accumulation of contaminants and enhancing resistance to environmental factors. Regular cleaning remains a fundamental practice, and different methods such as dry brushing, water washing, or specialized cleaning
The new reflector materials
Apart from conventional reflector materials, experiments have been carried out in the past few years to search for new reflector materials. Chang et al. [72] estimated Al-Ni-Y-based thin-film metallic glass composites (TFMGCs) as reflector materials. They have observed that in a humid environment, bacteria or fungus causes an impact on the reflectivity of the material. The structural evolution, optical reflectivity, and anti-bacterial and anti-fungus responses are studied. They found that the
Conclusion
Reflector materials are a crucial part of concentrated solar technology. Increased reflectivity in these materials enhances the overall performance of concentrated solar technology. This review paper explores the impact of corrosion and dust on reflector materials, shedding light on new materials utilized in concentrator solar technology. Corrosion is identified as a significant factor influencing the performance of reflective materials, affecting the sustainability of conce
