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Recycling WEEE: Extraction and concentration of silver from waste crystalline silicon photovoltaic modules
Abstract
Photovoltaic modules (or panels) are important power generators with limited lifespans. The modules contain known pollutants and valuable materials such as silicon, silver, copper, aluminum and glass. Thus, recycling such waste is of great importance. To date, there have been few published studies on recycling silver from silicon photovoltaic panels, even though silicon technology represents the majority of the photovoltaic market. In this study, the extraction of silver from waste modules is justified and evaluated. It is shown that the silver content in crystalline silicon photovoltaic modules reaches 600g/t. Moreover, two methods to concentrate silver from waste modules were studied, and the use of pyrolysis was evaluated. In the first method, the modules were milled, sieved and leached in 64% nitric acid solution with 99% sodium chloride; the silver concentration yield was 94%. In the second method, photovoltaic modules were milled, sieved, subjected to pyrolysis at 500°C and leached in 64% nitric acid solution with 99% sodium chloride; the silver concentration yield was 92%. The first method is preferred as it consumes less energy and presents a higher yield of silver. This study shows that the use of pyrolysis does not assist in the extraction of silver, as the yield was similar for both methods with and without pyrolysis.
... Table 1 Thus, there will invariably be increased waste generation with increased PV demand. Dias et al. (2016), state that the amount of WEEE generated worldwide has been underestimated since there are no accurate methods for determining the total amount of WEEE discarded worldwide. However, PVSW waste can be determined more efficiently based on how these systems are implemented, e.g., in Brazil, where all systems legally connected to the grid are registered with ANEEL, similar to what is done worldwide. ...
... However, PVSW waste can be determined more efficiently based on how these systems are implemented, e.g., in Brazil, where all systems legally connected to the grid are registered with ANEEL, similar to what is done worldwide. Komoto and Lee (2018) emphasise that development strategies for managing system life cycles will establish more reliable future projections on the actual amounts of generated PVSW which will serve as a basis for dealing with problems posed by Dias et al. (2016), relative to PVSW applications. However, if actions are not taken to develop strategies, as per Komoto and Lee (2018), future PVSW waste scenarios could be quite harmful to the environment, constituting a serious threat to human health (Li et al., 2022). ...
... Chemical processes use dissolution via acids or solvents (Kim & Lee, 2012). Physical processes use pyrolysis decomposition (Dias et al., 2016). It is believed that this method is not still feasible on an industrial scale (Sica, 2018;Kim & Lee, 2012), given the difficulties of eliminating chemical products, the need for treating toxic gases, and the high levels of required energy. ...
Photovoltaic (PV) energy production is a promising and mature technology for producing renewable energy. By contrast, solar panel disposals can generate problems for waste management, given that the amount of PV solar energy e-waste is more significant than other types of e-waste, given that this waste contains abundant metals and toxic materials, and given that this energy is being increasingly used. Local solutions need to be discussed and evaluated so that the PV industry can provide sustainable renewable energy. This paper discusses the environmental impacts of PV solar energy and PV panel recycling in Brazil. More efficient technological solutions and process developments will be needed to adequately treat problems arising at the end of the useful life cycle of PV systems. However, more than these technological solutions and process developments are required. Political mechanisms and regulatory structures will also need to be developed and implemented at the end of the life cycle stage to prepare, encourage, and develop appropriate industrial waste treatment applications. The advent of sector agreements for electrical and electronic equipment in Brazil has partially dealt with these waste problems. Sector agreements list equipment and devices that must have defined reverse logistics systems.
... The significant amounts of EoL panels foreseen in the coming years, the potential environmental impact, mainly related to the leaching of heavy metals (e.g. Pb) at landfills and the potential benefit from the recovery of precious (Ag), rare (In, Ge, Ga, Te) and energy-intensive elements (Si), are the main reasons for the development of sustainable and environmentally friendly management practices and technologies [1,3]. ...
... Recycling of silicon PV modules essentially involves three main stages [4]: (i) manual/mechanical disassembly of decommissioned PV panels which yields the aluminum frame, junction boxes and copper cables; (ii) delamination via mechanical, chemical [12] or thermal [3,13] treatment for glass recovery and (iii) leaching/etching for metal extraction. Upon dismantling, thermal treatment has proven, from an economic and ecological point of view, the more favorable alternative when compared to chemical treatment, which requires the use of expensive and toxic organic solvents [14]. ...
... Silver recovery from leaching solutions was experimentally tested by: (i) precipitation of soluble Ag as AgCl [3]; pure metallic Ag can be subsequently recovered from solid AgCl [1,21] and (ii) electrowinning of metallic Ag. ...
This work proposes an integrated process flowsheet for the recovery of pure crystalline Si and Ag from end of life (EoL) Si photovoltaic (PV) panels consisting of a primary thermal treatment, followed by downstream hydrometallurgical processes. The proposed flowsheet resulted from extensive experimental work and comprises the following unit operations: Shredding the PV modules to − 4 mm, after the removal and recovery of aluminum frames, junction boxes and copper cables. Delamination of the Si cells from the front soda-lime protective glass, through a thermal treatment at 550 °C for 15 min, in excess of air, in order to disintegrate the encapsulating organic material (ethylene vinyl acetate (EVA)) and the polyvinyl fluoride (PVF) polymer backsheet (Tedlar®). Separation of the detached Si flakes from the front glass and the “ash residue” and classification via mechanical screening by a perforated trommel rotary screen equipped with square wire mesh sieves. Further grinding of the recovered Si flakes by ball milling to − 90 μm, in order to increase the specific surface area, prior to the downstream hydrometallurgical process. Quantitative leaching of Ag and Al from the Si flakes in one stage by HNO3 at ambient temperature. Alternatively, acid leaching in two stages can be applied: initially by H2SO4 for Al quantitative extraction and subsequently by HNO3 for Ag quantitative extraction at ambient temperature. In order to remove the anti-reflection coating, etching of the leached Si flakes by 2.5 M NaOH has been proven efficient and crystalline silicon of high purity was recovered. Separation and precipitation of Ag as AgCl or alternatively, Ag electrowinning from nitrate solutions and Al precipitation via solution neutralization.
Graphical Abstract
... The recycling, upcycling, refurbishment and reuse of PV modules, their constituent parts and materials are consequently areas of increasing concern and interest both within the academic community and more widely. PV modules usually come under Waste Electrical and Electronic Equipment (WEEE) legislation, and many locations are producing more stringent guidelines and legislation to cover these types of waste [8][9][10]. The EU in particular has introduced more detailed regulations It is important to note that this paper does not claim to present an exhaustive examination of all published methods for the recycling of crystalline silicon, CIGS and CdTe photovoltaic modules. ...
... Whilst this approach enables the use of existing facilities, it fails to allow for effective separation and reuse of materials, and in particular the silicon. In a standard silicon module the silicon cells themselves are considered to be the highest value component, and typically constitute approximately half the total value of the module [4,10,20,22,27]. In addition the silicon constitutes a significant fraction of the embodied energy of the module [4]. ...
... The silicon and glass fractions can then be sorted manually, by machine, or by a process such as density separation [43,45]. The wafers typically undergo further chemical treatments to remove the metal contacts, in particular the silver busbars, which whilst being a relatively minor fraction of the total module, are economically important [4,10,27,45]. Silver can be removed using a nitric acid or sulphuric acid etch followed either by electrolysis of the solution, or precipitation, which can be achieved through the addition of hydrochloric acid to the mixture [10,27,45,[49][50][51][52]. ...
The market for photovoltaic modules is expanding rapidly, with more than 500 GW installed capacity. Consequently, there is an urgent need to prepare for the comprehensive recycling of end-of-life solar modules. Crystalline silicon remains the primary photovoltaic technology, with CdTe and CIGS taking up much of the remaining market. Modules can be separated by crushing or cutting, or by thermal or solvent-based delamination. Separation and extraction of semiconductor materials can be achieved through manual, mechanical, wet or dry chemical means, or a combination. Crystalline silicon modules are currently recycled through crushing and mechanical separation, but procedures do exist for extraction and processing of intact wafers or wafer pieces. Use of these processes
could lead to the recovery of higher grades of silicon. CdTe panels are mostly recycled using a chemical leaching process, with the metals recovered from the leachate. CIGS can be recycled through oxidative removal of selenium and thermochemical recovery of the metals, or by electrochemical or hydrometallurgical means. A remaining area of concern is recycling of the polymeric encapsulant and backsheet materials. There is a move away from the use of fluorinated backsheet polymers which may allow for improved recycling, but further research is required to identify materials which can be recycled readily whilst also being able to withstand outdoor environments for multi-decadal timespans.
... These tiny fragments cause the embedded EVA film to lose its adhesiveness. It also negates EVA's influence on metal leaching [52], thus paving the way for the fragments to be directly soaked in an acid leaching reagent consisting of nitric acid, sulfuric acid, and hydrogen peroxide at 60 • C. Glass will not be dissolved during this process and can be recovered directly [53]. In contrast, valuable metals are recovered with hydrometallurgical techniques [54]. ...
... It needs to be crushed into recyclates of less than 0.5 mm. The fragments are then etched with nitric acid, allowing the silver particles to be precipitated and form silver chloride in the subsequent stages [52]. Other studies also demonstrated the possibility of attaining a 100% leaching recovery of silver by utilizing the nitric acid leaching reagents under optimal leaching conditions [62]. ...
More than 78 million tons of photovoltaic modules (PVMs) will reach their end of life (EOL) by 2050. If they are not responsibly managed, they can (a) pollute our terrestrial ecosystem, (b) indirectly encourage continuous mining and extraction of Earth’s finite resources, and (c) diminish the net environmental benefit of harvesting solar energy. Conversely, successfully recovering them could reduce resource extraction and waste and generate sufficient economic return and value to finance the production of another 2 billion PVMs by 2050. Therefore, EOL PVMs must participate in the circular economy, and business and political leaders are actively devising strategies to enable their participation. This article aims to facilitate and expedite their efforts by comprehensively reviewing and presenting the latest progress and developments in EOL PVM recovery methods and processes. It also identifies and thoroughly discusses several interrelated observations that impede or accelerate their efforts. Overall, our approach to this article differs but synergistically complements and builds upon existing life cycle assessment-based (LCA-based) contributions.
... Few research groups have been studying more efficient ways to recycle PV panels since 2000, in particular, to recover metals contained therein (Dias et al., 2016;Tao and Yu, 2015). Life cycle assessment of recycling was also investigated, demonstrating that such a process generates 370 kgCO 2 eq and requires 2780 MJ for recycling 1000 kg of PV waste. ...
... Silver is the most precious metal contained in Si-based PV modules. After milling, sieving, pyrolysis at 500°C was applied and the resulting material leached in HNO3/NaCl: the silver extraction yield was 92% (Dias et al., 2016). ...
Photovoltaic (PV) panels have a crucial role in coping with the global warming mitigation and the energetic crisis currently affecting the European Community. However, from the circular perspective of end-of-life (EoL) management, there are still big issues to be solved in order to recover materials from this kind of e-wastes. Because of several reasons (e.g. type of embedded materials, illegal shipments, location of manufacturers) EoL businesses do not have the interest in approaching them. This poses a significant environmental concern in terms of their management. This work wants to assess the profitability of a specific PV module recycling plant, by evaluating several market contexts in which multiple scenarios of material price, investment and process costs will be considered. The results for a 3000 tonnes plant show that profitability is not verified in the absence of an avoided landfill cost. Instead, when a value of 200 €/tonnes is applied, the net present value is positive in 35.2% of the scenarios and at 87.6% when a value of 350 €/tonnes is considered. The policy choice of this value requires linking the PV module disposal fee to the circular benefits associated with its recovery.
... The methods used here allow for the recovery of silicon. The implementation method affects the purity of the recovered material [45,46]. In the case of complex methods, it is possible to recover high-purity silicon, which can be reused in photovoltaic products. ...
... Based on the results of upcycling research available in the literature, the currently achievable recovery rates of individual materials contained in the EoL of photovoltaic panels were determined. Data are presented in Table 1 [41][42][43][44][45][46][47][48][49][50][51][52]. Assessment of the environmental impact of recycling waste PV panels carried out by [53][54][55][56] indicates a significant advantage over other management methods. ...
A significant development of the photovoltaic market in the European Union has been observed recently. This is mainly due to the adopted climate policy and the development of photovoltaic technology, resulting in increased availability for consumers at lower prices. In the long run, increased installed PV capacity is associated with an increased amount of photovoltaic waste generated at the end of life. Since this waste belongs to the group of WEEE (waste electrical and electronic equipment) waste, it is subjected to high recovery levels. Existing installations for the highly efficient recycling of PV panels are just proofs of concept. However, the situation will change in the near future, and it will be necessary to implement a full-scale waste management system dedicated to PV waste. The paper estimates mass streams of photovoltaic waste generated by 2050 in individual EU countries. Consequently, the characteristics of the European market of waste PV panels are considered together with the demand of individual Member States for installations. The estimation enables the fulfillment of the Directive on WEEE recovery rates.
... While this has led to a reduction of the silver content in solar PVs, silver is essential due to its excellent conductivity properties. Current hydrometallurgical technologies for the processing of waste solar PVs generally include the use of strong mineral acids to solubilise silver and/or aluminium (Dias et al., 2016;Jung et al., 2016;Klugmann-Radziemska and Ostrowski, 2010;Luo et al., 2021), or concentrated sodium hydroxide for the hydrolysis and solubilisation of aluminium and silicon (Rahman et al., 2021;Zhang et al., 2021). Once the target metals have been dissolved, solvent extraction, flotation, cementation, and selective AgCl precipitation are among the techniques available to recover metals from leach liquor (Dias et al., 2016;Jung et al., 2016;Luo et al., 2021;Xanthopoulos et al., 2022). ...
... Current hydrometallurgical technologies for the processing of waste solar PVs generally include the use of strong mineral acids to solubilise silver and/or aluminium (Dias et al., 2016;Jung et al., 2016;Klugmann-Radziemska and Ostrowski, 2010;Luo et al., 2021), or concentrated sodium hydroxide for the hydrolysis and solubilisation of aluminium and silicon (Rahman et al., 2021;Zhang et al., 2021). Once the target metals have been dissolved, solvent extraction, flotation, cementation, and selective AgCl precipitation are among the techniques available to recover metals from leach liquor (Dias et al., 2016;Jung et al., 2016;Luo et al., 2021;Xanthopoulos et al., 2022). However, hydrometallurgical methods require large amounts of noxious mineral acids or caustic solutions, and hence generate large amounts of wastes that will require further treatment before disposal. ...
Due to the recent trend towards increasing renewable energy production, a large proportion of this demand will be addressed by solar energy. This greater consumption of solar cells will inevitably result in an equally large amount of end-of-life material that should be recycled to recover the valuable metal components. In the present work, the dissolution of silver and aluminium from silicon solar cells was investigated using copper(II) chloride and iron(III) chloride as redox catalysts, dissolving up to 95% of the target metals within 10 minutes. A mixed hydro- and ionometallurgical approach was taken, with a 2-step selective leaching process. Initially, aluminium and other lower value metals are removed using iron(III) or aluminium(III) chloride in water, with the help of ultrasound to delaminate the aluminium layer. Silver is then leached using iron(III) chloride in a choline chloride: water brine. A high recovery of silver (95%) with high purity (98 wt.%) is possible just by adding water to the leach liquor to precipitate silver chloride. Use of brines for the processing of metals is a new and interesting approach to replace mineral acids by cheaper and environmentally friendlier solvents.
... In 2020, China's newly PV installations was 48.2GW, ranking first in the world for 8 consecutive years; The cumulative PV installations in China reached 252.5 GW by the end of 2020, ranking first in the world for 6 consecutive years ( Zhao et al., 2013 ;Zhao et al., 2015 ;Sun et al., 2017 ;NEA, 2021 ). In compliance with the accepted technical standards, the service life of PV modules is 20 ∼30 years ( Kang et al., 2012 ;Dias, 2016aDias, , 2016b. But due to factors such as the modules themselves, PV plant engineering, acceptance, operation and maintenance, and natural and man-made factors, some completed PV plants and their PV modules have premature quality problems ( Cao, 2015 ;, making some PV modules scrapped or abandoned earlier than their normal lifespan ( Wang et al., 2014 ). ...
... Furthermore, the economic feasibility of waste PV modules recycling is an important factor in limiting the sustainable development of the recycling industry ( Hosenuzzaman et al., 2015 ;Guo and Kluse, 2020 ). Some studies have demonstrated that the recycling technologies for integral waste PV modules ( Marwede et al., 2013 ;Palitzsch and Loser, 2015 ;Dias et al., 2016b ) and for specific types of materials in modules ( Kang et al., 2012 ;2016a ;Lee et al., 2017 ) have already had certain recycling efficiency and economic feasibility ( Tammaro et al., 2015 ;Liu et al., 2016 ;Ashfaq et al., 2014 ;Fiandra et al., 2019 ;ECOPV, 2020 ). The recycling feasibility will be increasingly enhanced with technological breakthroughs and innovations. ...
The growing photovoltaic (PV) generation installation accelerates the increase of waste PV modules in China, and the recycling of used modules is inevitable and urgent. However, the economic feasibility of recycling is uncertain due to factors like policy, technology, and market. In this regard, the aim of this paper is to investigate the impact of a subsidy policy on the comprehensive economic feasibility of waste module recycling, and to identify a reasonable subsidy scheme. In particular, we developed the system dynamics model for PV waste modules recycling that can simulate the evolution of the recycling ROI (return on investment), the recovery rate and the subsidy cost for a baseline and reasonable scenarios with different subsidies. We also considered cost factors, for example, learning rates for recycling technology, buyback prices and recovery transportation distances, etc. The results show that, in the early stages of recycling (before 2026), the comprehensive cost-economic feasibility of recycling is low without subsidies, and therefore subsidy policies are needed to support and guide recycling. However, we also need to set reasonable subsidy standards and exit mechanisms for different recycling stages considering the changes of recycling technology costs, recovery rates and subsidy costs, etc.
... Therefore, the first large-scale waste PV modules will be generated shortly due to their limited lifespan and the replacement of some outdated modules (IRENA and Dhabi 2019; Kahoul et al. 2017). PV modules contain valuable resources like silicon, copper, aluminum, and silver, with the silver content of PV modules reaching 600 g/t, comparable to the silver content of ore (Deng et al. 2019;Dias et al. 2016). At the same time, organic packaging materials and heavy metal lead in PV modules has potential threats to the environment (Fu 2019). ...
As a large number of photovoltaic (PV) modules are approaching the end of their lifespan, the management of end-of-life crystalline silicon PV modules, especially the recycling of solar cells, is imminent. The premise of sufficiently recycling solar cells containing valuable resources from PV modules is to eliminate EVA for bonding glass, solar cells, and backsheet. Compared with physical methods and pyrolysis, the chemical swelling method for separating different layers to recover solar cells has the advantages of low energy consumption and high separation efficiency. However, the toxicity of swelling reagents and the uncontrollable swelling process are major problems. In this context, a novel green reagent dibasic ester (DBE, C21H36O12) was used to separate the glass-EVA layer. In order to expose the solar cells for subsequent resource recovery, the effect of various parameters on the separation of different layers was studied. The mechanism of glass-EVA separation with DBE was examined by FTIR, SEM, and GC–MS. Compared with traditional chemical reagents, the swelling of EVA by DBE is controllable, which can prevent excessive cracking of solar cells and facilitate the recycling of solar cells. This research has crucial implications for the green and sufficient recycling of solar cells from PV modules.
Graphical abstract
... These devices contain cadmium and lead, which can infiltrate the soil and, consequently, pollute the environment. Photovoltaic modules and other waste electrical and electronic equipment are composed of glass, aluminum, rare earth, brominated flame retardants (BFRs) and other hazardous substances (WIDMER et al., 2005;DIAS et al. 2016). ...
... Various projects [6,10] have been implemented on the recovery of the EoL-PVs and up to now solutions are given for recycling of the glass [11][12][13], recovery of the silver [14][15][16][17][18][19][20][21], but still there is no scalable method for the recovery of Si from PVs and rebuilding the solar cells. Various techniques and technologies have been applied for the recovery of the materials from c-Si cells and about 178 patents were filed in between 1976 and 2016 [3]. ...
Considering the boom of Si solar cell installation, it is necessary to establish a process for recycling of Si from End-of-life photovoltaics (PVs). Silicon in the PVs is synthetically doped and coated by various elements and hence dedicated methods will be required for recycling of Si, back to the SoG-Si. In this research, recycling of Si from the shredded solar cells is studied by means of vacuum refining process. In this research the rejected solar cells after the firing step are treated by acid etching techniques to remove the Al back layer and the Ag finger on the front side of the cells, providing a product called de-metallized Si fragments. The vacuum refining experiments were carried out on demetallized Si fragments. Results showed the demetallized Si contained presence of P (11.67 ppmw), B (1 ppmw), Ca with up to 0.28 wt%, Ag (96 ppmw) and Sn (136 ppmw), while other metallic impurities were lower. We have shown that Sn, Ag, O, N, and Mg can be removed from the Si melt via short vacuum refining, while a complete removal of Ca and P required longer times compared to the mentioned impurities. Because vacuum refining process is not limited by thermodynamic equilibrium, a full removal of all the volatile impurities at extended times is expected and then this process has a high chance for returning the recovered Si to the solar grade requirements.
... Followed by either thermal treatment of the panel (at 450 • C-600 • C) [4] or chemical treatment (using different organic solvents like toluene, cyclohexane etc.) [15,25,26] to remove polymeric layers from the panel and recover glass, connecting wires and solar cells. In majority of the studies, glass and connecting wires are separated, and solar cells are further processed to get silicon wafer, silver, and aluminium from the metallic contacts [27][28][29][30][31][32]. Only a very few studies [13,33,34] have been made on lead, tin, and copper recovery. ...
Photovoltaic (PV) technology has seen exponential growth in the last few decades with the total global installation
reaching 849 GW by year 2021. With the estimated solar waste of nearly 78 million tonnes by year 2050,
its high time to emphasise on the development of the recycling processes for valuable materials contained in endof-
life (EoL) solar panels. Crystalline silicon (c-Si) technology, owing to the largest market share, is forecasted to
generate the majority of solar waste flux. A c-Si panel contains metals like Ag, Cu, Al, Pb and Sn. Most of the
metallic fraction (Cu, Pb and Sn) by weight is contained in the connecting wires of the panel. In the present study,
a process is developed for recovery of metallic Cu along with Pb and Sn without their exposure to the environment.
Initially, connecting wires were separate out from panel using toluene solution. These wires were then
thermally treated at 800 ◦C for 7 h in a sealed quartz tube to get impure Cu strips and Pb-Sn powder. A set of
chemical reactions was carried out next to first recover CuO powder followed by subsequent treatment with
H2SO4 and Zn dust to recover 97.27% pure reddish brown Cu powder. As high purity copper powder with a good
recovery rate of around 90% is obtained as the end product, the present study demonstrates a very simple process
to recycle connecting wires in an ecological way with trapping toxic Pb and Sn.
... In [54], the extraction of Ag from waste PV modules was evaluated. The average Ag content in c-Si PV modules was 630 g/t. ...
As human activities are increasingly exploiting our planet’s scarce resources, managing them has become of primary importance. Specifically, this study examines the management of photovoltaic (PV) waste that is produced when PV modules reach end-of-life (EoL). PV modules contain precious and valuable materials, as well as toxic materials that may be harmful to human health and the environment if not disposed of properly. First, this study aims to review and analyze the current literature in order to gain a deeper understanding of the recycling of PV modules, particularly c-Si modules, which represent the largest market share. In the second part, an analysis is conducted of the energy consumption of these recycling processes using a proposed model based on the full recovery end-of-life photovoltaic (FRELP) process. PV modules manufactured from raw materials and PV modules manufactured from recycled materials are also compared in this section. In addition, improvements are suggested with respect to the design of PV modules (eco-design). According to this study, c-Si PV modules can be recycled with an energy consumption as low as 130 ÷ 300 kWh/ton of treated PV waste, estimating an overall recycling yield of about 84%.
... The aluminum frames and the j-boxes were manually removed from all modules. The remaining PV sandwich structure (referred to as laminate hereafter) were then shredded with a SM300 knives shredder (Retsch, Haan, Germany) with the experimental parameters based on previous work [33,36]. The module was fed through the shredder until the output material went through a screen with 2 mm opening. ...
The recycling of silicon photovoltaic modules is technically viable, but often not feasible economically due to reasons that vary from high processing cost to low waste volumes that do not justify investment cost. In this study, a novel, simple, cost-effective and environmentally friendly processing method is proposed. The process consists of module deframing, laminate shredding and material concentration using electrostatic separation. The latter outputs two fractions: a valuable mixture of silver, copper, aluminum and silicon, and a mixture of mostly glass, silicon and polymers. The valuable mixture accounts for only 2-3 wt% of the total module, which can be forwarded to the downstream industry for further refinement. This paper evaluates the technical aspects of the process (quantifies material separation, energy and time) while using life cycle assessment and life cycle costing to evaluate the environmental impacts and economic prospects, respectively. The results are compared to a full recovery alternative (FRELP) and to landfilling. Environmentally, a full recovery is preferred, followed by the proposed process, both of which have a net positive impact and are better than landfilling the whole module. Economic assessment shows the process has potential to be more profitable than FRELP i) at lower waste volumes (smaller than 4 kt/y), because of the smaller equipment capital cost, ii) if there is no market for the recovered glass, which is currently the case in many locations or iii) when the end-processing industry is located afar, since only the valuable mixture would require shipping.
... Following the removal of polymeric layers, the next step is to recover silicon from the solar cells by removing contact layers and anti-reflective coating (ARC). For which several chemical combinations have been investigated so far by various groups across the world [22][23][24][25][26][27]. Strong oxidising agents like HNO 3 and alkali like KOH, and NaOH are the preferred etching reagents for the removal of silver and aluminium contact, respectively, from the solar cells, and a few of them have even employed hazardous chemicals like HF for the removal of different layers [22,23,25,26]. ...
Mechanical, thermal, and chemical treatments were employed on a discarded small-sized silicon solar module to recover valuable materials from it. Materials like glass, junction box, polymer back sheet, and aluminium frame were recovered without damage. Ethylene-vinyl acetate layer (EVA) was obtained through the treatment of the panel with toluene solution. Optimised solution of 2 M HCl was used for Pb and Sn stripping from connecting wires to recover Cu Strips. Pb was extracted as PbCl 2 from the solution through precipitation in an ice bath. Sn was recovered as SnO 2 and SnCl 2 through electrolysis of the residual solution. Al from the back contact was recovered as Al(OH) 3 through sequential treatment with KOH and H 2 SO 4. The effect of the molar concentration of KOH solution on Al etching was also investigated, and it was found that the 2 M solution was optimal. An innovative and cost-effective approach was adopted for the recovery of silver. Ag extraction involved, the treatment of solar cell pieces with HNO 3 acid followed by reduction of AgNO 3 with the copper strips. As recovered Cu strips were reused for Ag recovery, it can be considered a cost-reducing step for the reported recycling process. At last, ARC coating was removed by employing an H 3 PO 4 solution to get silicon wafer pieces. X-Ray Diffraction and Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) were used for phase identification and purity of the recovered materials. An overall recovery rate of 92.4% is achieved. Environmental impact and revenue generation through the process is also discussed.
... Later, the resulting ash undergoes the following chemical treatment: sieving, acid leaching, filtration, electrolysis, neutralization, and filtering press. 35 These initial steps in the FRELP demand the most significant amount of electricity and material inputs from the recycling process. ...
The circular economy concept resonates as a new approach to optimize limited resource usage and reduce waste generation. However, most solar PV power plant analyses do not consider the sustainable disposal of used systems at the End of Life (EoL) or at the time for potential refurbishment. The 50 MWp Burnoye‐1 solar power plant in the Jambyl region in Kazakhstan was modeled using the RETScreen Expert platform to determine how the circular economy concept may increase its environmental benefits and impact the levelized cost of produced electricity. Results proved that recycling Burnoye‐1's photovoltaic panels at EoL would increase the project's Net Present profit by almost 0.373 million USD, marginally raising its Benefit‐Cost and Internal Rate of Return (IRR) on equity by much less than 1% each, with respect to the non‐recycling baseline. However, a significant impact on the 25‐year lifetime GHG emissions is achieved when PV recycling is considered. Recycling the PV panels in Burnoye‐1 at the EoL would add an extra 76.5 ktCO2e emissions reduction, representing an increase of 8.7% in its avoided lifetime GHG emissions. Furthermore, PV recycling may generate local jobs benefitting the neighboring communities. Thus, this study demonstrates that the circular economy approach is viable in Kazakhstan and will help the country meet its goal of becoming carbon neutral by 2060. This article is protected by copyright. All rights reserved.
... In a separate study, while Chung et al. (2021) utilized an environmentally friendly iodine-iodide system to extract Ag and Al, both Ag and AI are inherently difficult to separate as both components are coexisting, thus requiring special treatment for separation. Furthermore, while some studies present a simple process for Ag recycling, the leaching rates was low and the reaction time taken was rather long, i.e. 24 h (Dias et al., 2016;Wongnaree et al., 2020). This study presents an adequate leaching rate with a fast reaction time with the use of common chemicals. ...
The utilization of solar technology for clean energy generation has seen a dramatic increase over the past decade. Eyeing the ever-growing solar capacity and the subsequent inevitable deluge of solar panel wastes, the ideal approach to handle End-of-Life (EoL) solar photovoltaic (PV) panels is to recycle their materials for reuse. This present study explores an optimal recycling process with a high resource recovery efficiency on a laboratory pilot scale, which comprise of three main steps: module delamination, acid etching and sequential electrodeposition. A high recovery of 86, 95 and 97% were achieved for silver, lead and aluminum, respectively. The acquired results are further applied in a life cycle assessment. The process was scaled up to simulate an industrial process and its human and environmental impacts were compared to those of the landfilling disposal method, with six main impact categories analyzed and described: global warming potential, human toxicity potential, freshwater ecotoxicity potential, acidification potential, eutrophication potential and ozone depletion potential. Mitigation strategies are also proposed. Lastly, economic analysis demonstrated that at a treatment capacity of 892.5 kg/h, the process is feasible with an internal revenue rate of 28.2% and a payback time of less than a year, provided the waste collection is subsidized.
... Considering the urgency of developing PV wastes recycling and the low profitability, mandatory recycling schemes are required to nurture the immature recycling industry. The EU revised the Waste Electrical and Electronic Equipment (WEEE) regulations and added photovoltaic modules to the list of waste electrical and electronic equipment in 2014 (Dias et al., 2016). The third-party funds are introduced to manage the prepaid recycling fee from module manufacturer, and more than 80% of installed PV systems will be properly recycled after they are scrapped. ...
Photovoltaic (PV) power generation systems are expected to play an indispensable role in the future power supply towards the carbon-neutrality target in China. However, without appropriate practices and systems being set up for recycling, recovering, and reusing, tremendous waste materials would occupy land space and pollute environment, posing threats to human health. Effective management of End-of-Life (EoL) PV modules serves a critical part for sustainable development of solar PV power. Here, we developed a complex network model considering incomplete and imperfect information to simulate its scheme and policies for PV module recycling. Three types of recycling modes and three policy scenarios were simulated and analyzed, and sensitivity analyses of risk levels, PV manufacturing and recycling costs are conducted for the robustness test. Based on the current status of recycling technology, the policy of mandatory recycling will impose additional costs and negatively impact the PV system adoption, while the subsidy policies can partially offset such negative impacts. Subsidies targeted at either recycled capacity of PV modules or electricity generated from PV power during its life time show similar effects. In addition, the subsidy policies also bring benefits in enhancing the robustness of the whole PV market. The fluctuation caused by unsystematic risks including project relocation, uncertainties in land contracts, PV module replacement, etc., will also be smoothed.
... However, this integration has not been taking into account the reuse and end-of-life perspective. As for the majority of small WEEE, they have been produced as "disposable" items, not having been (Choi and Fthenakis 2014;Dias et al. 2016;Fthenakis and Wang 2006;Jung et al. 2016;Latunussa et al. 2016;McDonald and Pearce 2010;Pagnanelli et al. 2016;Pagnanelli et al. 2017;Paiano 2015;Savvilotidou et al. 2017). Source: Adapted from Choi and Fthenakis (2014), Fthenakis and Wang (2006), Jung et al. (2016), andPagnanelli et al. (2016). ...
The constant increase in volume of waste electrical and electronic equipment (WEEE), linked to the human health concern and environmental protection, has urged the creation of laws aiming to reuse and recycle this waste stream. The most widely accepted categorization is that of the European Commission, which has divided WEEE into different groups, covering a huge amount of equipment that are formed by a wide variety of materials and produced by the most different techniques. From the purest form of a metal to ceramic composites, from metallic alloys to plastics, a single WEEE can contain more than a thousand compounds. Notably, the most common are copper (Cu), iron (Fe), and aluminum (Al), which are related to electric current and physical structure, and different plastics, which provide a great variety of forms and lightweight. However, this significant heterogeneity of materials in WEEE – even within same category – is the main issue regarding sustainable recycling processes. Rare‐earth elements and precious metals are fundamental for some appliances and, at the same time, aggregate value to WEEE, but their contents per unit in most appliances are negligible. In recent years, due mostly to technological innovations, novel products using new materials are developed faster, originating an unbalanced supply and demand of specific chemical elements. Due to this huge mix of materials, the production of equipment requires different manufacturing techniques and especially new perspectives to make disassembly, reuse, remanufacturing, and recycling processes more technically and economically viable.
... Has a very limited influence on environment; Ag and Al are difficult to separate [19] (1) The cells were treated with 4 mol/L HNO 3 for 24 h (2) NaCl precipitates Ag + ; reduction of Ag chloride by C 2 H 2 Reduction of Ag purity to 99.98%; too long processing time [20] 64 wt% HNO 3 treats untreated cells and pyrolyzed cells separately Simple process; low leaching rate [21] Si recycling Treatment of cells with a mixture of H 3 PO 4 , HNO 3 , and HF ...
With the rapid increase of the installed capacity of crystalline silicon photovoltaic (PV) modules, the number of used modules that reach their End of Life (EoL) is accumulating dramatically and it is expected to pose significant environmental hazards. To solve this upcoming issue, this research investigated a comprehensive hydrometallurgical recycling process for crystalline silicon (C-Si) solar cells with regard to the problems of low element separation efficiency, inadequate component recovery rate, and deficient environmental considerations in the current recycling processes. Appropriate hydrometallurgical recovery processes were designed to recover valuable elements and entrap hazardous material lead (Pb) while properly treating wastewater from the recycling process. Nitric acid (HNO3) is an effective choice for elemental leaching from the waste, with 98.12% and 99.57% simultaneous leaching rates of silver (Ag) and aluminum (Al), respectively. The overall recovery rate of Ag was 96.13% using the hydrochloric acid (HCl) precipitation-ammonia solubilization-hydrazine process route. The purity of Ag after reduction was 99.8%. The silicon nitride (SiNx) and silicon phosphide (Si3P4) layers on the surface of the silicon wafer can be completely etched and removed by low-concentration HCl, and the product obtained is pure silicon. Most importantly, heavy metal elements such as Pb were captured to prevent potential damage to the environment and human health.
... Nevertheless, some hydrometallurgical studies are being conducted for their recycling aimed at metals extraction. Lixiviants, such as HNO3 [65,[78][79][80][81] and organic acid [82], are used for Ag leaching, while NaOH [64,76] and KOH [79] are investigated for Al leaching from solar cells. ...
There is a growing interest in electronic wastes (e-wastes) recycling for metal recovery because the fast depletion of worldwide reserves for primary resources is gradually becoming a matter of concern. E-wastes contain metals with a concentration higher than that present in the primary ores, which renders them as an apt resource for metal recovery. Owing to such aspects, research is progressing well to address several issues related to e-waste recycling for metal recovery through both chemical and biological routes. Base metals, for example, Cu, Ni, Zn, Al, etc., can be easily leached out through the typical chemical (with higher kinetics) and microbial (with eco-friendly benefits) routes under ambient temperature conditions in contrast to other metals. This feature makes them the most suitable candidates to be targeted primarily for metal leaching from these waste streams. Hence, the current piece of review aims at providing updated information pertinent to e-waste recycling through chemical and microbial treatment methods. Individual process routes are compared and reviewed with focus on non-ferrous metal leaching (with particular emphasis on base metals dissolution) from some selected e-waste streams. Future outlooks are discussed on the suitability of these two important extractive metallurgical routes for e-waste recycling at a scale-up level along with concluding remarks.
... The module encapsulation materials, especially degradation of ethylene-vinyl acetate (EVA) influence the module performance and stability. The failure modes such as cell cracks, discoloration, and delamination depend mostly on the EVA degradation (Dias, Javimczik, Benevit, Veit, & Bernardes, 2016). But the solar cells in a PV module are connected in series-parallel topology and several PV modules are connected parallel in an array which are then connected in series for achieving expected system power and voltage. ...
Introduces the basic concepts of different photovoltaic cells to audiences from a wide variety of academic backgrounds
Consists of working principles of a particular category of solar technology followed by dissection of every component within the architecture
Crucial experimental procedures for the fabrication of solar cell devices are introduced, aiding picture practical application of the technology
... PV modules are made up of aluminum and glass, including several harmful trace elements, such as antimony, lead, and cadmium [6][7][8]. Some component materials, such as silicon, silver, and copper, are also present and are currently widely recycled and recovered [9][10][11][12]. Recycling is therefore the preferred and most effective means of processing these waste PV modules and recovering the constituent materials [12]. ...
The paper describes one promising method and approach for the recycling, reuse, and co-resource treatment of waste photovoltaic silicon and lithium battery anode graphite. Specifically, this work considers the preparation of nano/micron silicon carbide (SiC) from waste resources. Using activated carbon as a microwave susceptor over a very short timeframe, this research paper shows that nano/micron β-SiC can be successfully synthesized using microwave sintering technology. The used sintering temperature is significantly faster and more energy-efficient than traditional processes. The research results show that the β-SiC particle growth morphology greatly affected by the microwave sintering time. In a short microwave sintering time, the morphology of the β-SiC product is in the form of nano/micron clusters. The clusters tended to be regenerated into β-SiC nanorods after appropriately extending the microwave sintering time. In the context of heat conversion and resource saving, the comprehensive CO2 emission reduction is significantly higher than that of the traditional SiC production method.
Given the daily increase in the number of spent solar panels scrapped worldwide, these materials can be recycled as value-added heavy-metal products because of their high contents of valuable metals, such as Cu, Ag. Firstly, spent solar panels were soaked in acetone solvent and then split into three parts: glass, silicon and ethyl vinyl acetate. The wafers were dissolved in nitric acid solution to produce a leachate with 16.3, 5.9 and 1.5 g/L Cu, Al and Ag, respectively. With the addition of 35 g/L oxalate, 98.9% Cu was separated from the system in the form of high-purity moolooite, whereas the loss of Al and Ag was less than 1%. In the hydrothermal process, with the addition of 3 g glucose and 30 g/L phosphate and under the reaction condition at 190 °C for 10 h, 98.7% Al can be separated efficiently from the system in the form of AlPO4, and the loss of Ag was less than 0.1%. Finally, almost all of the Ag can be recovered efficiently from the system in the form of chlorargyrite through the introduction of sodium chloride. The results of the study provide a way for the effective recycling of Cu, Al and Ag in spent solar panels.
India’s most extensive renewable energy expansion program targets 280 GW of solar energy by 2030. Due to the massive generation of photovoltaic waste (expected 34,600 T by 2030), stringent recycling effort to recover metal resources from end-of-life PVs is required for resource recovery, circular economy, and subsequent reduction in the environmental impact. The present study investigates the recycling potential of end-of-life silicon solar modules. The feed characterization reveals that most of the values in PV modules are concentrated in the frame (pure Al), Si wafer (72–84% Si, 9–12% Al, and 0.13–0.71% Ag), and electrical connections (Cu wire coated with Sn). The Si and Ag values in the feed were beneficiated using water fluidization, and concentrate with 90% Si and 2% Ag was attained in the underflow concentrate. Ag values were recovered in the form of AgCl by leaching in nitric acid and precipitation. After the purification step, the residue containing 99% Si can be further utilized to fabricate Si wafer and Al-Si alloy. The preliminary cost estimations suggest that the proposed process is economically viable for the recycling of solar panels with the maximum value generated from the AgCl precipitate followed by Al panels and Si wafers.
With the widespread photovoltaic deployment to achieve the net-zero energy goal, the resulting photovoltaic waste draws attention. In China, considerable steps have not been taken for photovoltaic waste management. The lack of relevant scientific information on photovoltaic waste brings difficulties to the establishment of photovoltaic waste regulatory systems. In this study, the necessity and feasibility of photovoltaic waste recovery were investigated. In China, the photovoltaic waste stream was quantified as 48.67-60.78 million t in 2050. In photovoltaic waste, indium, selenium, cadmium, and gallium were in high risk, judging by the metal criticality analysis, which meant that their recovery was significant to alleviate the resource shortage. The full recovery method was proved to reduce the environmental burdens most. For cost and benefit analysis, the net present value/size was -1.02 $/kg according to the current industrial status. However, it can be profitable with the recovery of silver. This study provides scientific and comprehensive information for photovoltaic waste management in China and is expected to promote the sustainable development of photovoltaic industry.
With the goal of Net-Zero emissions, photovoltaic (PV) technology is rapidly developing and the global installation is increasing exponentially. Meanwhile, the world is coping with a surge in the number of end-of-life (EOL) solar PV panels, of which crystalline silicon (c-Si) PV panels are the main type. Recycling EOL solar PV panels for reuse is an effective way to improve economic returns and more researchers focus on studies on solar PV panels recycling. Most recent recycling technology studies stay at the experimental stage, and problems of high cost, low recycling value, and secondary pollution are usually ignored. In this review, to establish an efficient, economic, and environmentally friendly recycling technology system, we systematically summarized the EOL c-Si PV panel module recycling technologies and condition parameters in three sections: module disassembly, module delamination, and material recycling and reuse. We discussed current technology strengths and weaknesses and research development directions in each section. This review aimed to provide a technical reference for the upcoming recycling surge of EOL PV modules all over the world.
China is the largest market for shared bicycles, and its “bicycle cemetery” phenomenon has attracted widespread attention. The end treatment of abandoned bicycles has become a key issue in the promotion of green travel and sustainable transportation. This paper introduces extended producer responsibility (EPR) and green tax, two WEEE recycling methods in the recycling system for abandoned bicycles in China, and builds a two-party game model based on local government supervision and corporate recycling strategies. The results show that setting a minimum recycling standard of 0.65 and implementing a strategy of rewards as the primary factor and punishment as a supplement helps enterprises to choose the more environmentally friendly EPR approach. The conversion rate and the level of enterprise effort positively affect the adoption of EPR by enterprises and can speed up the evolution of local governments to equilibrium strategies. What's more interesting is that controlling the government's regulatory investment to prevent enterprises from “free-riding” helps to promote the coordinated recycling of abandoned bicycles. This research is based on the current situation in China and offers a new perspective on recycling abandoned bicycles. The conclusions provide a reference for other countries seeking to formulate effective policies for the management of abandoned bicycles.
The rapid deployment of solar photovoltaic (PV) technology around the world brings the ineluctable problem of disposing of and recycling decommissioned solar photovoltaic modules. Recycling will become an essential sector in the value chain of the PV industry. This paper reviews the progress in silicon photovoltaic module recycling processes, from lab-scale and pilot-scale research in order to compare mechanisms, ascertain feasible approaches, recycling yields, equipment, costs, and improvement areas for different recycling processes. Trends, gaps, and outlooks are drawn to guide future R&D. Recycling processes have evolved from mass recovery to value recovery and now full recovery. Selective delamination and automated material sorting are key enablers of high recycling yield. So far, most recycling research focuses on recovering materials, however, it is equally important to explore secondary markets and end-use applications of recovered materials, especially for glass, and polymers. To implement sustainable end-of-life recycling at a large scale, technological feasibility, economic viability, and social desirability need to be addressed altogether by innovative recycling technologies.
The end-of-life (EoL) c-Si photovoltaic (PV) solar cell contains valuable silver, and chemical leaching can extract silver from the cell. However, limited works have been reported on the leaching kinetics and hydrodynamic behaviour of silver leaching process. In this work, an integrated experiment and numerical study are conducted to understand and optimise the silver leaching process in rotating systems. First, the lab-scale physical experiments are conducted to obtain a reaction kinetics model of silver leaching from PV cells. Then, a CFD-DEM model is developed to describe the reacting flow details related to solar cell particles' leaching process including this kinetic model. The model is validated against the lab measurement in terms of flow pattern and leaching performance. Then the CFD-DEM model is applied to a larger rotating system and studies the effects of rotator speed, rotator length, and rotator shape on leaching efficiency. The simulation results indicate that the particles inside the reactor experience mixing, transition, and suspension states with increased rotator length and rotator speed. In the transition state, the particles accumulate near the wall and form a packed bed, leading to the lowest leaching efficiency. In the suspension state, the particles are well fluidized and form a loose, ring-like particle wall. The leaching efficiency has a positive relationship with the fluidization level of the solid phase. The results also show that the leaching efficiency drops when linearly scaling up the reactor size while fixing other operating conditions. This work lays a foundation for process scale-up and optimization of EoL PV panel recycling.
Traditional acid-base leching technology is the primary technology to recycle silver from crystal silicon solar panels, which is fussy and often employs poisonous/harmful chemicals. In the present study, silver was easily recycled from photovoltaic panels in self-synthesized. Deep-Eutectic Solvents System (DESs) without pretreatments and the reaction system could be cyclically utilized. The leaching and precipitation rate can reach 99% under the optimized conditions. In addition, the kinetic results showed that the leaching of silver followed the classical shrinkage core model, in which chemical reaction was the rate-controlling step and the apparent activation energy for leaching process is 172.36 kJ·mol⁻¹. In the recycling process, Cu²⁺ acted as the oxidant, and the redox potential of Cu²⁺ in the DES system is much higher than that in aqueous system. Besides, the HNMR and FTIR analysis indicate that the intermolecular hydrogen bond formed in the DES mixed system, which would raise the melting and boiling point of the mixed system, and would be conducive to the following silver leaching process. Furthermore, the metal complex generation mechanisms were proposed in the present study, and urea plays not only an aprotic solvent which cannot solvate Cl⁻, but also the ligand which can complex with the metals as well as Cl⁻ which can reduce the redox potentials and shift the equilibrium to the silver leaching side. In summary, this study can provide theoretical foundation and practical experience for recycling precious metals from waste crystal silicon solar panels environmentally efficient and cost-effective.
To describe and predict the leaching of Ag, Cu, and Sn from waste, photovoltaic modules with an electrochemical-assisted process kinetic investigations were performed. In this process, peroxydisulfate is generated from sulfuric acid to oxidize metals. It was found that under the reaction conditions peroxymonosulfate is formed as well and has a major contribution to the leaching process. For Ag, autocatalytic decomposition of the leaching reagents is determined to be a limiting step while for Sn passivation influences the process. The leaching is modeled for three different reaction types, a batch reaction, the reaction in a static H-cell with continuous generation of S₂O₈²⁻, and a fed-batch reaction with an electrochemical flow cell for the production of peroxydisulfate.
Fulfilling the SDGs and reaching the climate neutrality target of the EU Green Deal will require a global effort, for which solar energy is indispensable. From 2030 the global number of decommissioned and thus waste solar panels will increase exponentially. This review article specifies the barriers and solutions to creating a closed loop system (CLS) in the crystalline silicon (c-Si) photovoltaics industry in Germany. The conclusions drawn are however relevant for all countries using solar panels, as they will face similar challenges. Specific recommendations are outlined based on identified challenges that will help ensure a CLS for c-Si solar panels. Regarding regulation it is recommended that recycling targets for solar panels should be adjusted so that they are not linked to weight, as this does not encourage the recovery of all materials. It is also crucial that the design of the solar panels is adjusted to ensure that repair, refurbishment and at a later stage recycling are possible. Since the economic feasibility is not given at a small scale it is suggested for companies to join larger recycling schemes. Collaboration and exchange along the supply and value chain is also identified as essential to ensure the development of solutions that will truly enable the creation of a CLS. Product as a service should also be explored by solar panel companies as this would encourage the production of panels that can be easily repaired and later recycled.
Crystalline silicon photovoltaic (PV) modules have dominated the photovoltaic market for a long time and the recycling of crystalline silicon PV modules has become a critical issue due to their limited service life. The separation of glass and backsheet bonded by EVA film is critical to the separation of PV modules for the separation of different layers in PV modules is the premise of adequately recycling valuable elements such as Ag, Al, and Si. Traditional separation reagents, such as toluene, O-dichlorobenzene, and trichloroethylene, are all highly toxic which may cause harm to human body and pollute the environment. This paper innovatively proposes using green separation reagent DMPU (N,N′-dimethylpropenylurea, C6H12N2O) to separate different layers in PV modules. Constituents of each layer in the whole were analyzed by using SEM/EDS, XRD, XRF, and FTIR. Effects of different pieces, reaction temperatures, solid-liquid ratios, and ultrasonic powers were then investigated on the separation ratio, glass recovery ratio and backsheet peeling time. Meanwhile, separation comparison between DMPU and toluene on the separation ratio and silicon wafer breaking degree was also studied. Compared with toluene, the solar cell separated by DMPU can keep its initial size which is convenient for further resource recovery. Separation mechanism of different layers caused by DMPU was also studied by SEM, FTIR, and GC-MS. This study has significant implications for developing environmentally friendly and efficient separation reagents for recycling PV modules.
Photovoltaics and carbon dioxide reduction reaction (CO2RR) products are both promising renewable energy sources for conserving the environment. However, the re-utilization of accumulated solar module waste and the development of effective catalysts remain challenging in related industries. In this study, nanoporous Cu (NPC) film with an average ligament size of 30 ± 6 nm was used as a substrate for extracting Ag from end-of-life solar module waste to synthesize a bimetallic catalyst for CO2RR. The results showed that the galvanic replacement reaction produced a dendrite-like Ag morphology, whereas pulse electrodeposition produced two-dimensional Ag precipitates with a plate-like shape. The Faraday efficiency (FE) values for CO, HCOOH, and C2H4, which were the conversion products obtained from CO2RR with this catalyst, were 13%, 29%, and 2%, respectively. The FE ratio for CO relative to that for HCOOH could be adjusted from 0.45 to 3.5 by controlling the amount of Ag deposited, or by using either Cu foil or NPC as the substrate. These results may be explained by the high surface area presented by the nanoporous material, which allowed the NPC structure beneath the deposited Ag to retain its catalytic performance.
In the present work, a new process is reported to recover metallic contacts and wafer from the crystalline silicon solar cell through chemical etching. 2 M KOH was used as an etching solution at temperatures 110 ± 1 °C and 85 ± 1 °C. During the process, metallic contacts were extracted, without breaking, in the form of fingers and foils along with the silicon wafer. The contacts and recovered wafer were characterized through Scanning Electron Microscopy, Energy Dispersive Spectroscopy, X-ray fluorescence spectroscopy, X-Ray Diffraction, Electrochemical Capacitance Voltage Analysis, Four Probe Measurement technique, and Ultraviolet absorption spectroscopy. It was found that the recovered wafer is of P-type with 100 orientation and has a bulk resistivity of ~1 Ω cm with a dopant density of 2× 10¹⁶ – 4.5 × 10¹⁶ atoms per cm³. The recovered wafer thickness was found to be etching temperature-dependent. High processing temperature (110 °C) deteriorated the wafer resulting in deep groove formation on the front surface and led to decrement in wafer thickness. No grooves were observed in the sample treated at a lower temperature (85 °C), and the thickness was also not reduced too much. The recovered contacts were mainly composed of silver. Lead present on the back contact was removed during the process resulting in the recovery of silver contacts with a purity of ~99%. UV absorption spectroscopy confirmed the removal of lead in the form of lead(II) complex ion. The etching process also led to the complete removal of the p-n junction from the solar cells.
The increase in photovoltaic panel installations in Europe will generate vast amounts of waste in the near future. Therefore, it is important to develop new technologies that allow the recycling of end-of-life photovoltaic panels. This material can serve as a secondary resource, not only for precious metals (e.g. silver), but also for base metals. In this work, the extraction and recovery of the base metals copper, zinc and lead from a copper-rich photovoltaic panel residue was investigated. The material was first leached at 80 °C under microwave irradiation with a mixture of hydrochloric acid, sodium chloride and hydrogen peroxide solutions. Based on the Box-Behnken factorial design optimization, it was possible to extract 81.2% of Cu, 96.4% of Zn and 77.6% of Pb, under the following leaching conditions: [HCl] = 0.5 mol L-1, [NaCl] = 200 g L-1, [H2O2] = 7.5 wt% and t = 60 min. Cementation with iron powder at a 1.2 iron-to-copper stoichiometric ratio allowed the recovery of copper nearly quantitatively (99.8%) as a copper-iron sediment. The gas-liquid separation technique of ion flotation was employed to separate lead and zinc from the dilute copper-free leachate. Cetyltrimethylammonium bromide (CTAB), a cationic surfactant, selectively recovered lead (99.4%) over zinc as lead(ii) tetrachloro cetyltrimethylammonium colloid, after eight ion flotation stages and [CTAB]total = 7.2 mmol L-1. The zinc that remained in the solution after the ion flotation step was recovered by precipitation and by adding sodium sulfide at 110% of the stoichiometric amount after removing iron as ferric hydroxide by slowly raising the pH to 3.7.
Photovoltaic (PV) output is calculated in efficiency, which quantifies incident solar irradiation transformed into electricity on a PV module surface. Particularly, the performance is influenced by local environment, such as solar irradiance, temperature, light incident angle, soiling, etc., and own factors, such as solar cell types and efficiency and module layout design, configuration and size. However, because of the various types of stress developed during field operation, the performance of a PV module gradually deteriorates. To increase their commercial viability, it is critical to identify the causes of degradation and failure modes, and find appropriate PV technologies for each site. In this chapter, we discuss the reliability and various failure modes that have been recorded for various PV technologies over the last few years through field and laboratory test investigations.
Sintesis nanokomposit Fe3O4/TiO2 sebagai fotokatalis yang dapat diambil kembali dalam fotoreduksi limbah ion Ag(I) telah dilakukan. Sintesis diawali dengan sintesis magnetit (Fe3O4) melalui kopresipitasi dan sonikasi. Pelapisan TiO2 dilakukan dengan proses sol-gel dengan penambahan benih atau seed TiO2 degusa, dan diikuti perlakuan termal pada suhu 500 °C. Hasil sintesis dikarakterisasi dengan fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscope-energy dispersive X-ray (SEM-EDX), vibrating sample magnetometer (VSM) dan diffuse reflectance-UV (DR-UV). Uji aktivitas fotokatalis nanokomposit Fe3O4/TiO2 dilakukan terhadap fotoreduksi ion Ag(I) dengan sistem batch dalam reaktor tertutup yang dilengkapi dengan lampu UV. Hasil penelitian menunjukkan bahwa nanokomposit Fe3O4/TiO2 memiliki kemampuan fotokatalitik yang baik. Nanokomposit Fe3O4/TiO2 memiliki kemampuan fotoreduksi lebih baik dibanding TiO2 tanpa modifikasi. Fotoreduksi ion Ag(I) 12,5 ppm berlangsung optimum pada pH 6 dan waktu reaksi 90 menit dengan hasil sebesar 98,6 %.
The use of renewable energy is essential for the future of the Earth, and solar photons are the ultimate source of energy to satisfy the ever-increasing global energy demands. Photoconversion using dye-sensitized solar cells (DSCs) is becoming an established technology to contribute to the sustainable energy market, and among state-of-the art DSCs are those which rely on ruthenium(ii) sensitizers and the triiodide/iodide (I3 -/I-) redox mediator. Ruthenium is a critical raw material, and in this review, we focus on the use of coordination complexes of the more abundant first row d-block metals, in particular copper, iron and zinc, as dyes in DSCs. A major challenge in these DSCs is an enhancement of their photoconversion efficiencies (PCEs) which currently lag significantly behind those containing ruthenium-based dyes. The redox mediator in a DSC is responsible for regenerating the ground state of the dye. Although the I3 -/I- couple has become an established redox shuttle, it has disadvantages: its redox potential limits the values of the open-circuit voltage (V OC) in the DSC and its use creates a corrosive chemical environment within the DSC which impacts upon the long-term stability of the cells. First row d-block metal coordination compounds, especially those containing cobalt, and copper, have come to the fore in the development of alternative redox mediators and we detail the progress in this field over the last decade, with particular attention to Cu2+/Cu+ redox mediators which, when coupled with appropriate dyes, have achieved V OC values in excess of 1000 mV. We also draw attention to aspects of the recyclability of DSCs.
The proper disposal of photovoltaic modules has become an emerging environmental and social issue as modules installed around the 2000s have started entering their end-of-life stage. The decommissioning volume will keep increasing, reaching the gigawatt scale, or millions of tons, by 2030. End-of-life silicon photovoltaic modules contain various valuable materials, such as high-purity silicon and silver. Recycling silicon and silver from the end-of-life modules can significantly improve the recycling revenue. We developed an environmentally sustainable chemical process for simultaneously recovering high-purity silver and silicon from waste solar cells in a fast, efficient, and environmentally friendly way. Reverse electroplating with a full-area contact can successfully recover 99.9% purity metallic silver with a 95% yield within a few minutes. The electrolyte can be reused. The applied voltage and current densities play an important role in achieving a high recycling yield. Subsequent alkaline etching can recover 4N purity silicon with a 99% yield. The chemical process minimises chemical consumption and waste disposal, resulting in the avoidance of 1.60 kg CO2-eq Climate Change impact per kg cell recycled. Even though further chemical etching can remove impurities from the silicon surface to recover up to 5N silicon, the use of strong acids involves serious environmental disadvantages, the overall impacts of which are much higher than those of recovering 4N silicon using a simplified chemical process. This journal is
This study presents experimental results for the development of a process for the recovery of indium and gallium from EoL CIGS (CuGa1−xInxSe2) panels. The process consists of a thermal treatment of the panels, followed by a hydrometallurgical treatment, where quantitative leaching of In, Ga, Mo, Cu and Zn is achieved. The elements are subsequently separated and recovered from the leachate by solvent extraction. For the development of the process, samples of EoL CIGS PV panels were used, which contained a thin film of Mo (metal base electrode), sputtered on the supporting soda-lime glass and covered by the thin film containing In, Ga, Cu and Se (1 μm). These films were detected by SEM-EDS in polished sections. The thermal treatment at 550 °C for 15 min, in excess of air, led to the successful disintegration of ethyl vinyl acetate (EVA) and delamination of the thin film-coated glass from the front protective glass. The glass fragments coated by the thin film contained the following: Se: 0.03–0.05%; In: 0.02%; Cu: 0.05%; Ga: 0.004–0.006%; and Mo: 0.04%. Following thermal treatment, thin film-coated glass fragments of about 1.5 cm × 1.5 cm were used in acid leaching experiments using HNO3, HCl and H2SO4. Quantitative leaching of Cu, Ga, In, Mo, Zn and Cu was achieved by HNO3 at ambient temperature. The effects of pulp density and acid concentration on the efficiency of metal leaching were investigated. Part of Se volatilized during the thermal treatment, whereas the rest was insoluble and separated from the solution by filtration. Finally, the separation of the elements was achieved via solvent extraction by D2EHPA.
This chapter addresses a set of studies of technologies and trends for recycling electronic waste through hydrometallurgical routes. Industrially, the processes employed are considered hybrids in which pyrometallurgical and hydrometallurgical stages are used. However, hydrometallurgy offers possibilities for recovery and selective separation of metals, in addition to reducing gas emissions and lower‐energy consumption. As in the primary metallurgy processes, in the leaching step, the metals are solubilized. The main parameters are the leaching agent, temperature, pH, and time. Due to the complex multielemental composition of electronic waste, further pregnant leaching solution purification and recovery steps are necessary. These steps can be performed using techniques such as chemical precipitation, cementation, solvent extraction, electrodeposition, and ion exchange. Studies of different metals recovery, such as Cu, Ag, Au, Ni, Al, Zn, Co, Li, Ga and rare earths from waste printed circuit boards, photovoltaic modules, batteries, and light‐emitting diodes, are presented. The rapid development of electronic products requires new strategies for their processing and recycling, so, at the end of this chapter, some trends, such as the use of ionic liquids, nanohydrometallurgy, and supercritical fluids, are mentioned.
The electrical and electronic manufacturing industry is one of the fastest‐growing industries. Electronic devices could contain up to sixty (60) different elements that could be valuable or hazardous. The high consumption of electronic devices also creates the issue of end‐of‐life disposal after being discarded. These discarded electronics, also referred to as e‐waste, have been a growing concern around the world. The total e‐waste generated worldwide in 2019 was 53.6 million tonnes and is growing at a rate of 3–4% per year. If dealt with properly, e‐waste recycling could provide economic incentive as the total contained/potential value of selected metal and materials present in e‐waste was US$57 billion in 2019. E‐waste recycling is an inter/multidisciplinary theme where technical, economic, legislative, social, and environmental aspects are involved throughout the life cycle of all‐electric and electronic equipment, including recycling after their disposal. This book seeks to provide an overview of all aspects of a sustainable future.
Since the starting days of solar cell mass production the exposure of process waste such as broken solar cells and damaged PV modules has been an important issue. The possibility to reclaim the module components was demonstrated in many publications. Some companies offer the recycling of PV glass and resell it as broken fragments back to the glass industry. Despite the good quality of the glass fragments (low Fe contents, no hazardous and EVA/PVB contaminations) it is impossible to return the glass parts to a float zone facility, because of reservations of the float glass manufacturers. In this paper different approaches to re-extract the complete front glass of crystalline modules for re-use-applications will be discussed. Requirements on the “second hand” front glass will be given in order to re-use it for module manufacturing. Another, not less important approach is focused on the re-extraction of silver from solar cells. The silver price has increased significantly over the last years proportional to the solar modules installed. Studies on waste quantities document approx. 0,2 % of total PV waste as manufacturing waste as well as 0,5 % of damaged during transport and installation. Different wet-chemical solutions will be introduced in order to digest the solar cell metallization in its pure components for further use.
Photovoltaic technology is used worldwide to provide reliable and cost-effective electricity for industrial, commercial, residential and community applications. The average lifetime of PV modules can be expected to be more than 25 years. The disposal of PV systems will become a problem in view of the continually increasing production of PV modules. These can be recycled for about the same cost as their disposal.Photovoltaic modules in crystalline silicon solar cells are made from the following elements, in order of mass: glass, aluminium frame, EVA copolymer transparent hermetising layer, photovoltaic cells, installation box, Tedlar® protective foil and assembly bolts. From an economic point of view, taking into account the price and supply level, pure silicon, which can be recycled from PV cells, is the most valuable construction material used.Recovering pure silicon from damaged or end-of-life PV modules can lead to economic and environmental benefits. Because of the high quality requirement for the recovered silicon, chemical processing is the most important stage of the recycling process. The chemical treatment conditions need to be precisely adjusted in order to achieve the required purity level of the recovered silicon. For PV systems based on crystalline silicon, a series of etching processes was carried out as follows: etching of electric connectors, anti-reflective coating and n-p junction. The chemistry of etching solutions was individually adjusted for the different silicon cell types. Efforts were made to formulate a universal composition for the etching solution. The principal task at this point was to optimise the etching temperature, time and alkali concentration in such a way that only as much silicon was removed as necessary.
In our R'07 contribution "The challenge of open cycles" we elaborated on the general constraints in achieving a true recycling society using the example of consumer electronics and cars [Hagelüken 2007]. We showed that the lifecycle structure has a major impact. This contribution now focuses on economic and technology challenges to recycle precious and special metals. These "technology metals" are crucial ingredients for many high tech and clean tech products and their use in such applications has increased significantly over the last years. However, their absolute mass in a single product is usually very low and they are mostly embedded in complex assemblies and connections with other elements, which complicates recycling. Two main groups of products need to be distinguished. Firstly, products in which technology metals are combined with precious metals, so often inherent economic recycling incentives exist, which can lead to additional recovery of special metals as by-products if appropriate processes are used (e.g. mobile phones). More challenging are products where such "paying metals" are missing and the special metals content does not offer sufficient economic attraction (e.g. thin film photovoltaics). To address both product groups metallurgical recovery processes need to be further developed while measures need to be taken to ensure that end-of-life products enter the most advanced recycling channels.
BP Solarex 12 Brooklands Close Windmill Road UK -Sunbury on Thames Middlesex TW 16 7 DX ° IMEC Kapeldreef 75 B-3001 Leuven Belgium + ECN Westerduinweg 3 NL -1755 ZG Petten The Netherlands ∇ Seghers Machinery Gentse Steenweg 311 B-9240 Zele Belgium TFM Pol. Ind. Pla d'en Coll Gaià 5 E -08110 Montcada i Reixac ABSTRACT : The considerable growth of the PV market that started 30 years ago, will lead to a fast growing number end of life modules. If good solutions for recycling are developed, a huge accumulation of this end of life and rejected PV modules can be avoided. The aim of this work was to develop and to evaluate different recycling processes. Finally two methods have given acceptable results namely the pyrolysis in a conveyer belt furnace and the pyrolysis in a fluidised bed reactor. Especially for the fluidised bed reactor process, the development has reached an industrial level with the set-up of a big pilot reactor. The cost effectiveness of the process is demonstrated by the high mechanical yield of the process and the high quality of the reclaimed wafers, as proven by a high cell efficiency after reprocessing. The ecological impact of recycling is very high and the energy pay back time decreases drastically due to the avoided high energy consumption of the reclaimed silicon wafer.
Photovoltaic panels have a limited lifespan and estimates show large amounts of solar modules will be discarded as electronic waste in a near future. In order to retrieve important raw materials, reduce production costs and environmental impacts, recycling such devices is important. Initially, this article investigates which silicon photovoltaic module's components are recyclable through their characterization using X-ray fluorescence, X-ray diffraction, energy dispersion spectroscopy and atomic absorption spectroscopy. Next, different separation methods are tested to favour further recycling processes. The glass was identified as soda-lime glass, the metallic filaments were identified as tin-lead coated copper, the panel cells were made of silicon and had silver filaments attached to it and the modules' frames were identified as aluminium, all of which are recyclable. Moreover, three different components segregation methods have been studied. Mechanical milling followed by sieving was able to separate silver from copper while chemical separation using sulphuric acid was able to detach the semiconductor material. A thermo gravimetric analysis was performed to evaluate the use of a pyrolysis step prior to the component's removal. The analysis showed all polymeric fractions present degrade at 500 °C.
The world's waste electrical and electronic equipment (WEEE) consumption has increased incredibly in recent decades, which have drawn much attention from the public. However, the major economic driving force for recycling of WEEE is the value of the metallic fractions (MFs). The non-metallic fractions (NMFs), which take up a large proportion of E-wastes, were treated by incineration or landfill in the past. NMFs from WEEE contain heavy metals, brominated flame retardant (BFRs) and other toxic and hazardous substances. Combustion as well as landfill may cause serious environmental problems. Therefore, research on resource reutilization and safe disposal of the NMFs from WEEE has a great significance from the viewpoint of environmental protection. Among the enormous variety of NMFs from WEEE, some of them are quite easy to recycle while others are difficult, such as plastics, glass and NMFs from waste printed circuit boards (WPCBs). In this paper, we mainly focus on the intractable NMFs from WEEE. Methods and technologies of recycling the two types of NMFs from WEEE, plastics, glass are reviewed in this paper. For WEEE plastics, the pyrolysis technology has the lowest energy consumption and the pyrolysis oil could be obtained, but the containing of BFRs makes the pyrolysis recycling process problematic. Supercritical fluids (SCF) and gasification technology have a potentially smaller environmental impact than pyrolysis process, but the energy consumption is higher. With regard to WEEE glass, lead removing is requisite before the reutilization of the cathode ray tube (CRT) funnel glass, and the recycling of liquid crystal display (LCD) glass is economically viable for the containing of precious metals (indium and tin). However, the environmental assessment of the recycling process is essential and important before the industrialized production stage. For example, noise and dust should be evaluated during the glass cutting process. This study could contribute significantly to understanding the recycling methods of NMFs from WEEE and serve as guidance for the future technology research and development.
As the growing of photovoltaic (PV) industry, the environmental problems become a new consideration. Therefore, we propose a thermal method to recover materials, such as silicon, glass, and metal from conventional crystalline silicon modules. Two steps heating were used in the thermal treatment process in this study. During the thermal process, the EVA could be burned out and the whole glass plate could be obtained without breaking. The recycle glass could be directly used again as the module component when the temperature was well controlled. The recycle yield of silicon was 62% and the purity of obtained silicon material was ~8N after cleaning by chemical solution treatment. The copper could be recovered in further acid treatment. The recycle yield of copper was 85%. The results show that the recycling of materials from silicon based solar module is promising.
The authors have collected data for the silver market, shedding light on market size, stocks in society and silver flows in society. The world supply from mining, depletion of the remaining reserves, reducing ore grades, market price and turnover of silver was simulated using the SILVER model developed for this study. The model combines mining, trade markets, price mechanisms, populations dynamics, use in society and waste and recycling into an integrated system. At the same time the degree of sustainability and resource time horizon was estimated using different methods such as: 1: burn-off rates, 2: peak discovery early warning, 3: Hubbert's production model, and 4: System dynamic modelling. The Hubbert's model was run for the period of 6000 BC–3000 AD, the SILVER system dynamics model was run for the time range 1840–2340. We have estimated that the ultimately recoverable reserves of silver are in the range 2.7–3.1 million tonne silver at present, of which approximately 1.35–1.46 million tonne have already been mined. The timing estimate range for peak silver production is narrow, in the range 2027–2038, with the best estimate in 2034. By 2240, all silver mines will be nearly empty and exhausted. The outputs from all models converge to emphasize the importance of consistent recycling and the avoidance of irreversible losses to make society more sustainable with respect to silver market supply.
This paper reports a new procedure for the recovery of resources from waste photovoltaic modules. The tempered glass was recovered using organic solvents. The metal impurities were removed by applying a chemical etching solution on the surface of the PV cell. We offer a much more efficient approach for recycling PV cells than the conventional method. The highest yield of silicon recovered was 86% when the PV cell was placed in the chemical etching solution for 20 min, along with the surfactant, which accounted for 20% of the total solution's weight at room temperature. This investigation showed that a high yield of pure silicon with purity of 99.999% could be obtained. The recovered pure silicon from waste PV modules would be contributed to the solution of several problems such as the supply of silicon, manufacturing costs, and end-of-life management of PV modules.
Recovering pure silicon from damaged or end-of-life PV modules can lead to environmental and economic benefits [1]. The chemical processing is a very important stage of the recycling process in order to achieve these benefits. In this regard, the authors found a new de-metalization step of broken silicon cells and silicon cells production waste, which resulted in a reduction of waste and they receive salable products.
Raw material supply is essential for all industrial activities. The use of secondary raw material gains more importance since ore grade in primary production is decreasing. Meanwhile urban stock contains considerable amounts of various elements. Photovoltaic (PV) generating systems are part of the urban stock and recycling technologies for PV thin film modules with CdTe as semiconductor are needed because cadmium could cause hazardous environmental impact and tellurium is a scarce element where future supply might be constrained. The paper describes a sequence of mechanical processing techniques for end-of-life PV thin film modules consisting of sandblasting and flotation. Separation of the semiconductor material from the glass surface was possible, however, enrichment and yield of valuables in the flotation step were non-satisfying. Nevertheless, recovery of valuable metals from urban stock is a viable method for the extension of the availability of limited natural resources.
Electronic waste (e-waste) is one of the fastest-growing pollution problems worldwide given the presence if a variety of toxic substances which can contaminate the environment and threaten human health, if disposal protocols are not meticulously managed. This paper presents an overview of toxic substances present in e-waste, their potential environmental and human health impacts together with management strategies currently being used in certain countries. Several tools including Life Cycle Assessment (LCA), Material Flow Analysis (MFA), Multi Criteria Analysis (MCA) and Extended Producer Responsibility (EPR) have been developed to manage e-wastes especially in developed countries. The key to success in terms of e-waste management is to develop eco-design devices, properly collect e-waste, recover and recycle material by safe methods, dispose of e-waste by suitable techniques, forbid the transfer of used electronic devices to developing countries, and raise awareness of the impact of e-waste. No single tool is adequate but together they can complement each other to solve this issue. A national scheme such as EPR is a good policy in solving the growing e-waste problems.
The manufacturing of electronic and electrical equipment (EEE) is a major demand sector for precious and special metals with a strong growth potential. Both precious and special metals are contained in complex components with only small concentrations per unit. After the use-phase, waste electronic and electrical equipment (WEEE) is an important source of these “trace elements.” Their recycling requires appropriate processes in order to cope with the hazardous substances contained in WEEE and to recover efficiently the valuable materials. Although state-of-the-art preprocessing facilities are optimized for recovering mass-relevant materials such as iron and copper, trace elements are often lost. The objective of this article is to show how a substance flow analysis (SFA) on a process level can be used for a holistic approach, covering technical improvement at process scale, optimization of product life cycles, and contributing to knowledge on economy-wide material cycles. An SFA in a full-scale preprocessing facility shows that only 11.5 wt.% of the silver and 25.6 wt.% of the gold and of the palladium reach output fractions from which they may potentially be recovered. For copper this percentage is 60. Considering the environmental rucksack of precious metals, an improvement of the recycling chain would significantly contribute to the optimization of the product life cycle impact of EEE and to ensuring the long-term supply of precious metals.
Electronic waste, or e-waste, is an emerging problem as well as a business opportunity of increasing significance, given the volumes of e-waste being generated and the content of both toxic and valuable materials in them. The fraction including iron, copper, aluminium, gold and other metals in e-waste is over 60%, while pollutants comprise 2.70%. Given the high toxicity of these pollutants especially when burned or recycled in uncontrolled environments, the Basel Convention has identified e-waste as hazardous, and developed a framework for controls on transboundary movement of such waste. The Basel Ban, an amendment to the Basel Convention that has not yet come into force, would go one step further by prohibiting the export of e-waste from developed to industrializing countries.
The status of current and coming solar photovoltaic technologies and their future development are presented. The emphasis is on R&D advances and cell and module performances, with indications of the limitations and strengths of crystalline (Si and GaAs) and thin film (a-Si:H, Si, Cu(In,Ga)(Se,S)2, CdTe). The contributions and technological pathways for now and near-term technologies (silicon, III–Vs, and thin films) and status and forecasts for next-next generation photovoltaics (organics, nanotechnologies, multi-multiple junctions) are evaluated. Recent advances in concentrators, new directions for thin films, and materials/device technology issues are discussed in terms of technology evolution and progress. Insights to technical and other investments needed to tip photovoltaics to its next level of contribution as a significant clean-energy partner in the world energy portfolio.
A great challenge in recycling of silicon cutting kerf loss is the complete removal of silicon carbide particles. High-gravity centrifugation using a heavy medium with a specific gravity in between that of silicon carbide and silicon is not effective for the submicron particles. In this paper, a novel recycling process for obtaining silicon from the kerf loss powders is reported. The obtained silicon after directional solidification was found to be of solar grade. The average lifetime and resistivity of grown crystal were measured to be 1.02 μs and 0.7 Ω cm, respectively, which were close to the original sawing silicon and casted pure Si ingots. The energy conversion efficiencies of the solar cells fabricated from the recycled and pure silicon were found comparable.
We are in a period of economic transition. The `cowboy economy' of the past is obsolescent, if not obsolete. Environmental services are no longer free goods, and this fact is driving major changes. Recycling is the wave of the (immediate) future. The potential savings in terms of energy and capital have long been obvious. The savings in terms of reduced environmental impact are less obvious but increasingly important. The obstacle to greater use recycling has been the fact that economies of scale still favor large primary mining and smelting complexes over (necessarily) smaller and less centralized recyclers. But this advantage is declining over time as the inventory of potentially recyclable metals in industrialized society grows to the point that efficient collection and logistic systems, and efficient markets, justify significant investments in recycling. Increasing energy and other resource costs, together with increasing costs of waste treatment and disposal, will favor this shift in any case. But government policies, driven by unemployment and environmental concerns, taken together, may accelerate the shift by gradually reducing taxes on labor and increasing taxes on extractive resource use.
The popularization of mobile phones, combined with a technological evolution, means a large number of scrap and obsolete equipment are discarded every year, thereby causing economic losses and environmental pollution. In the present study, the printed wiring boards scrap of mobile phones were characterized in order to recycle some of the device components, using techniques of mechanical processing, hydrometallurgy and electrometallurgy. The use of the techniques of mechanical processing (milling, particle size classification, magnetic and electrostatic separation) was an efficient alternative to obtain a concentrated fraction (mainly iron in the magnetic fraction and copper in the conductive fraction) and another fraction containing polymers and ceramics. At the end of mechanical processing, a concentrated fraction of metals could be obtained with an average concentration of 60% copper. This concentrated fraction in metals was dissolved in aqua regia and sent to electrowinning to recover 92% of the dissolved copper. The obtained cathodes have a copper content above 95%, which demonstrates the technical feasibility of recovery of copper using the techniques of mechanical processing, hydrometallurgy and electrometallurgy.
This paper presents and critically analyses the current waste electrical and electronic equipment (WEEE) management practices in various countries and regions. Global trends in (i) the quantities and composition of WEEE; and (ii) the various strategies and practices adopted by selected countries to handle, regulate and prevent WEEE are comprehensively examined. The findings indicate that for (i), the quantities of WEEE generated are high and/or on the increase. IT and telecommunications equipment seem to be the dominant WEEE being generated, at least in terms of numbers, in Africa, in the poorer regions of Asia and in Latin/South America. However, the paper contends that the reported figures on quantities of WEEE generated may be grossly underestimated. For (ii), with the notable exception of Europe, many countries seem to be lacking or are slow in initiating, drafting and adopting WEEE regulations. Handling of WEEE in developing countries is typified by high rate of repair and reuse within a largely informal recycling sector. In both developed and developing nations, the landfilling of WEEE is still a concern. It has been established that stockpiling of unwanted electrical and electronic products is common in both the USA and less developed economies. The paper also identifies and discusses four common priority areas for WEEE across the globe, namely: (i) resource depletion; (ii) ethical concerns; (iii) health and environmental issues; and (iv) WEEE takeback strategies. Further, the paper discusses the future perspectives on WEEE generation, treatment, prevention and regulation. Four key conclusions are drawn from this review: global amounts of WEEE will continue unabated for some time due to emergence of new technologies and affordable electronics; informal recycling in developing nations has the potential of making a valuable contribution if their operations can be changed with strict safety standards as a priority; the pace of initiating and enacting WEEE specific legislation is very slow across the globe and in some cases non-existent; and globally, there is need for more accurate and current data on amounts and types of WEEE generated.
The basic pyrolysis behaviour of ethylene vinyl acetate (EVA) copolymer, which is often used as a lamination agent in solar modules, was investigated in thermogravimetry, differential thermal analysis(DTA) and thermovolumetry. The TG analysis showed that the EVA pyrolysis can be accelerated under the partial oxidizing atmosphere but the end pyrolysis temperature must be higher than in nitrogen, to eliminate the coke formed. Meanwhile, a strong exothermal peak occurs at about 450 degrees C under the air condition and gets weaker obviously at the oxygen content lower than 10 vol. %. The mass balance of EVA pyrolysis was given through the thermovolumetry with the output of 10 wt. % permanent gas, 89.9 wt. % condensate and 0.1% residual coke. Besides, the composition of the permanent gas and condensate at different pyrolysis stages were analysed and interpreted on the known pyrolysis mechanism.
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