Final Report Summary - SIKELOR (Silicon kerf loss recycling)
Executive Summary:
The objective of the SIKELOR project was to develop an innovative electromagnetic technology for recycling silicon kerf loss which arises from slicing of silicon ingots into thin wafers. The technology proposed for reclaiming silicon from kerf loss combines methods for densification, purification, and casting of ingots. Such a process is not available in the current production pattern of the feedstock. The technology for silicon recycling is composed of the following three steps:
1. Improved technology for densification of the dry silicon powder without introducing cross-contamination.
2. Melting of the compacted material and purification by electromagnetic processing.
3. Casting of poly-crystalline silicon blocks by directional solidification.
Compaction of silicon powders is mandatory as the first step for recycling because of the extremely small size of the particles in the kerf loss. GARBO has developed a binder assisted densification method to produce porous bodies of relatively high density and mechanical stiffness from silicon powders. Optimization of the process steps was accomplished in terms of good product quality, low process costs and possibility of scale-up at industrial level with high throughputs. A pilot plant is available at GARBO with a capacity of approx. 7 kg of recycled silicon per day.
Electromagnetic processing of materials is the means to achieve three necessary tasks: AC magnetic fields melt the silicon compacts, stir the melt, and separate impurity particles. Advanced numerical codes have been implemented by University of Greenwich (UNIG) for calculating complex flows under the impact of variable electromagnetic fields. A specific particle tracking model was developed taking into account the time-dependent evolution of the crystallization front. Validation of the numerical predictions was provided by model experiments at Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The investigations revealed that the flow pattern at high shielding parameters differ significantly from well-known time-averaged flow structure referred in the literature. Complicated vortex structures appear showing a distinct transient behaviour and inducing a significant mixing effect by the AMF. The knowledge gained from the modeling was used for designing the magnetic system for the Demonstrator in the i-DSS crystallization furnace at the University of Padova (UNIPD). Two variants of experimental configurations have been realized: In addition to the G2.5 experiment a G1 setup was built to demonstrate the separation of SiC particles. New designs were developed for both the hot zone and the inductor. In this way serious problems had to be solved. In particular, the formerly used graphite parts in the hot zone had to be substituted by a material which does not shield the high-frequency magnetic field as needed for efficient separation and can be accepted by the industry. Crystallization experiments were performed using a 50:50 mixture composed of recycled silicon and new polycrystalline material. A new type of electric power supply was developed by EAAT for the Demonstrator. The innovative concept allows for the allocation of two super-imposed frequencies using only one resonant circuit.
In summary, the project achieved (i) the development of a technology for cleaning and densification of the Si kerf loss, (ii) numerical and experimental modelling for identifying optimal process parameters for electromagnetic processing, and (iii) the implementation of the Demonstrator on laboratory scale. However, not all objectives were achieved as planned at the beginning of the project, (a) the crystallization experiments in Demonstrator II have not been completed, and (b) the Demonstrator I was substituted by sintering experiments for reducing the oxygen content in the kerf loss.
Project Context and Objectives:
Achieving the European goals on climate stability requires an almost carbon free power system to be installed until 2050 [1]. Besides the development of innovative technologies to improve the efficiency of processes in energy-intensive economic branches such as chemical industry, metallurgy, cement or paper industry, the expansion of renewable energy production as a carbon free power sector plays an important role for achieving these ambitious goals. However, the global demand on energy will further increase in the near future while at the same time meeting the target of limiting global temperature increase to 2 degrees Celsius must be satisfied. Therefore, further exploitation of remaining fossil fuel reserves is not an option, and both renewable energy and energy efficiency will have to be scaled up dramatically. While the short-term target to increase the fraction of renewable power generation up to 20% of the total energy production by 2020 can be considered as challenge, decarbonizing the whole energy sector by 2050 demands an industrial revolution. On the other hand, it is widely expected that the transformation towards the new energy technologies during the coming years will bring substantial benefit for the society in terms of green jobs and sustainable growth.
The upsurge in renewable energy technologies has led to a rapidly increasing demand for photovoltaic (PV) solar cells. The challenge today is to create efficient and productive technologies needed to establish solar energy as a practical and economical alternative to energy produced by fuels - and to use that solar-produced energy in a wide variety of applications. Concerning PV module production in 2015, China and Taiwan hold the lead with a share of 67 %, followed by rest of Asia-Pacific & Central Asia (ROAP/CA) with 14%. Europe contributed with a share of only 5 % (was 6% in 2014); USA/CAN contributed 3 % [2]. Bringing to mind Europe’s leading position with respect to the total cumulative PV installations one has to note a remarkable discrepancy between installation and production of solar panels in Europe. Europe’s percentage of solar silicon wafers produced on the global market has been decreasing drastically for several years. This situation is explained by the fact that other countries, in particular China, have gained on technological advance and offer the silicon wafers at considerably reduced prices. New innovative technologies are necessary to strengthen Europe’s position in the worldwide competition.
Si-wafer based PV technology accounted for about 93 % of the total production in 2015. The share of multi-crystalline technology is now about 68 % of total production [3]. Over 90% of current dominant materials used in PV cells is silicon. Solar Grade silicon feedstock can be obtained using either a chemical approach or a pyro-metallurgical approach. In both cases, the starting point is metallurgical grade silicon and the target is to produce a high purity silicon feedstock for production of high performance devices [4]. The semiconductor industry uses the chemical approach to achieve purities in the ppba range. MG silicon has to be converted into a gaseous or liquid chemical (e.g. trichlorosilane, silane, etc.), which is then put through multiple distillations for purification and finally reduced via gaseous phase reactions. The resultant product is high purity polysilicon, which is left with B and P, the most difficult elements to remove from silicon [5], at levels less than 1 ppba and all other impurities even lower. Moreover, the silicon feedstock is produced with an enormous consumption of energy (~ 100 kWh/kg). A major amount of this energy is spent for the production of the silicon feedstock. Usually, the silicon is cast in form of large ingots. Still to date, the majority of the thin wafers are sliced by wire sawing. After the sawing step, only 45%-50% of the silicon feedstock finally ends up in a wafer. The remaining 50%-55% is lost in the block cutting process (tops, tails and slabs) and the biggest portion (up to 40%) is lost as sawing slurry in the wafer saw process and is currently not recoverable [3].
A technology which converts more than half of the energy invested into waste can hardly be considered to be efficient. In total, ~70% of the silicon feedstock that enters the PV production chain is lost as silicon-containing wastes. This quantity corresponds to almost 10 ton of lost silicon per MWp (MegaWatt peak) obtained module power, based on an assumed quantity of 15 ton silicon per produced MWp module power [5]. The trend to produce thinner wafers provides a larger total surface area and increases this kerf loss. As the wafer thickness approaches the wire diameter, the fraction of loss may reach 50%. According to the current production processes, this equals to about 140,000 tons of discarded silicon per year. Alternative techniques avoiding the kerf loss such as implanting/cleaving, the ribbon growth on substrate or the string ribbon technology have up to now not led to commercially sustainable routes.
A technology allowing for the recycling of the silicon kerf loss at reasonable effort and price would considerably improve the energy balance of the PV electricity production. The recipe for reclaiming silicon from kerf loss has to combine different methods for densification, purification, and casting of ingots. Such a process is not available in the current production pattern of the feedstock, but it is the only economical and the most-green solution to recover the valuable raw material. During the course of the SIKELOR project, thinner diamond wires have been introduced to the production, with core wire diameters shrinking from initial 120 micron to the present 80 micron, and 60 micron diamond wires are presently under testing. This has the consequence that the sawdust becomes distinctly finer and the oxygen content of the kerf due to the high surface-to-volume ratio becomes much higher. Silicon carbide pollution is finally the major problems with the recycling of kerf loss. Recycling of kerf loss demands a costly mechanical separation, an energy intensive high-temperature process, and zone melting. A large fraction of the valuable raw material silicon finally ends in waste or it is converted to much lower valued ceramics. Recycling of that silicon is thus in compliance with the European Union Raw Materials Initiative. Waste reduction is a valuable contribution to improving the environment in view of the fact that production of virgin solar grade silicon involves energy and consumable intensive processes.
SIKELOR aims at technologies that permit reuse of the majority of the silicon raw material from kerf loss. The technological goal of the project is developing an innovative process for silicon recycling, which is composed of:
1. An improved technology for densification of the dry silicon powder without introducing cross-contamination.
2. Melting of the compacted material and purification of the liquid silicon by electromagnetic processing.
3. Casting of poly-crystalline silicon blocks by directional solidification.
This process chain has been further developed up to a pilot plant production of the reclaimed silicon. The key issue is the removal of SiC particles from the Si melt. An innovative method has been developed to separate the impurities by tailored electromagnetic forces. Moreover, electromagnetically induced flow and solidification phenomena are far from being completely understood. It is thus an important and indispensable scientific goal to gain more insight into these phenomena.
The project comprises a combination of numerical simulation, physical modelling, and demonstration experiments. All process steps, which are compaction, melting, purification, and casting, have been considered by research activities in four strategic tasks:
1. Controlling the fluid flow: The contaminant particles suspended in the silicon melt are affected by the electromagnetically driven flow, transient drag, buoyancy, surface tension, turbulent fluctuations, evaporation, and the local electromagnetic pressure. The combination of physical and numerical modeling provides insights into the underlying mechanisms. Optimized magnetic fields parameters have been identified.
2. Electromagnetic design and implementation: The achievement of optimized combinations of induction heating, electromagnetic stirring and electromagnetic separation is a challenging engineering task. Two different magnetic field types are required for heating and separation (alternating magnetic field, AMF) and electromagnetic stirring (traveling magnetic field, TMF). Creating these by separate coil systems seems impossible due to the space limitations and the mutual electro-magnetic interference (crosstalk). A sophisticated solution for an inverter delivering a current comprising the superposition of two harmonics of different frequencies was realized in the project. The necessity of matching the respective impedances of the loads required an intensive collaboration between the partners developing the power supply and the partners concerned with the overall design and the implementation of the coil system for the melt treatment.
3. Reclaiming silicon product: The existing proprietary compaction process had to be improved. The focus was on decreasing the surface-to-volume ratio and the treatment of the very small size silicon particles. Upon completion of the pilot plant, compacted feedstock needed for crystallization experiments was produced in the first test production cycle using an advanced treatment developed within this project. The new production line demonstrated the feasibility and the reliability of the process, thus opening the path for exploitation and commercialization.
4. Crystallization of silicon into ingot casts: An experimental demonstrator was built for casting of the silicon ingots ready to be sliced into wafers. This unique facility is equipped with tailored magnetic systems for controlling the fluid flow and the separation of impurities during crystallization under the influence of external fields. Both heating and melting are achieved using the electromagnetic induction heating. The AMF also generates the Leenov-Kolin force for separating the SiC inclusions. Particle capturing is supported by TMF-driven electromagnetic stirring for transporting the particles into regions where separation is highly efficient.
In summary, the SIKELOR project is aimed to demonstrate the feasibility of the approach to recycle the silicon kerf loss and to purify silicon melts by electromagnetic processing on laboratory scale. The project establish the scientific basis which allows a detailed understanding of the underlying processes and enable an optimal design and choice of the relevant process parameter. At the end of the project the feasibility and the reliability of the process has been shown by a demonstrator, which could become the model for a prototypic facility, thus paving the way for exploitation and commercialization.
References:
[1] IPCC (2007): Intergovernmental Panel on Climate Change, Fourth Assessment Report, Synthesis report, 52p, http://www.ipcc.ch
[2] Fraunhofer ISE (2016): Photovoltaics Report, updated: 17 November 2016, https://www.ise.fraunhofer.de/de/downloads/pdf-files/aktuelles/photovoltaics-report-in-englischer-sprache.pdf
[3] D. Singh and P. Jennings (2007): The Outlook for Crystalline Solar Photovoltaic Technology over the Next Decade, AIP Conference Proceedings 941, 98-110.
[4] C.P. Khattak, D.B. Joyce and F. Schmid (1998-1999): Production of Solar Grade (SoG) Silicon by Refining Liquid Metallurgical Grade (MG) Silicon, National Renewable Energy Laboratory, Report.
[5] D. Sarti and R. Einhaus (2002): Silicon feedstock for the multi-crystalline photovoltaic industry, Solar Energy Materials & Solar Cells 72, 27-40.
Project Results:
see attachment
Potential Impact:
I Dissemination of results
The European project SIKELOR is concerned with innovative technologies for silicon kerf loss recycling. The project consortium developed a dissemination strategy to achieve a maximum impact of the SIKELOR results in Europe. Especially in the fields of sustainable energy, waste reduction, and saving both valuable materials and energy, dissemination is of elevated interest; the efficient methods to be developed in the project have the potential to increase the competitiveness of Europe’s solar silicon industry against Asian players.
At the end of the project the following main outcomes have been achieved:
• The understanding of fluid flow, transport processes and particle behavior inside a metallic melt agitated by an alternating magnetic field was significantly improved.
• A pilot-plant production for cleaning and compaction of silicon kerf loss was successfully installed at GARBO.
• A demonstrator for purification and crystallization of liquid silicon molten from a recycled feedstock was installed and put into commission on laboratory scale at the University of Padova.
• A prototype of a new type of power supply was designed and built by EAAT for the demonstrator.
Potential commercialization by integration of the devices into respective product lines, in particular the integration of tailored magnetic fields into the furnace equipment, has to be examined by means of a market analysis. Both the pilot-plant for cleaning and densification of silicon kerf loss and the demonstrator for purification and crystallization of silicon will serve to support the prospect of success for market launch.
At the beginning of the project we identified the following main target groups for dissemination:
1) Scientific community
2) Industry
3) Policy groups
4) The interested public
Dissemination material has been created specifically for the above groups and communicated to them via appropriate ways.
The SIKELOR website (www.sikelor.eu) was installed as a basic and main tool for distributing information and presenting the outcome of the project. Moreover, the website was also used for exchange of confidential information among the partners. The webpage has been activated since January 31th, 2014. According to the progress in the project the content of the website has been continuously extended and updated.
The SIKELOR workshop organized in the framework of the Seventh Triennial Conference on Heating by Electromagnetic Sources (HES-16) in Padova (May 2016) was the key issue for dissemination of the results arising from the project. HES-16 comprised an international conference, an industrial exhibition and a summer school for young scientists. The conference had more than 150 participants (18 countries) from universities, research centres and industry. For many years HES is a well-known and well-established international forum for making new contacts and for exchanging information and ideas. The SIKELOR workshop was organized in form of a special session which was attended by more than 100 participants. Each partner presented the research activities and the corresponding results. Many problems and details were put forward for discussion. The scientific results achieved in SIKELOR will find its way directly into the education of the students.
Another important forum for SIKELOR is the initiative “MagnetSep” (www.magnetsep.de) an innovation cluster funded by the German Federal Ministry of Education and Research. This innovation clusters forms a wide network of research institutes and industrial partners mainly on the national level inside Germany. However, the future perspective of “MagnetSep” also considers an expansion to European level. The focus of “MagnetSep” is on the development of new, innovative electromagnetic techniques for separation of impurities and particles from metallic and other high-temperature melts. Future applications are expected for many fields like mining, metallurgy, casting, silicon production and various technologies for recycling. The technology for recycling of silicon kerf loss by applying electromagnetic stirring and separation is a prominent example which fits very well into this initiative. Within the framework of “MagnetSep” a workshop with more than hundred participants from universities, research institutes and industry was organized in Dresden in April 2016. The SIKELOR project was presented to this wide audience as invited lecture at this workshop.
During the duration of the SIKELOR project the partners produced 28 publications in diverse scientific journals, magazines, conferences and exhibitions. Publications in peer-reviewed scientific journals and contributions to international scientific conferences are the appropriate means to bring the projects results to the attention of the scientific community. Fundamental aspects of the project findings have been submitted to the international journals in the respective research field. The academic partners had the leadership of preparation and submission of journal articles and conference contributions.
During the reporting period the SIKELOR consortium established contacts to other activities and research groups working in the fields of Si production, liquid metal handling or magnetohydrodynamics. All partners are closely cross-linked with the scientific community in the fields of electromagnetic processing of materials, electrical engineering, crystal growth and numerical computations. For instance, the Computational Science and Engineering Group at the University of Greenwich is involved in other large scale projects, e.g. in FP7 EXOMET and IMPRESS. Likewise, HZDR contributes to many other projects funded on European or national level. For instance, a bilateral French-German research project was started recently in 2016 considering the removal of impurities from liquid metals by gas injection. A very close cooperation and exchange was established with the Helmholtz Alliance LIMTECH (http://www.hzdr.de/db/Cms?pNid=2920) which is funded by the German Helmholtz Association and bundles the R&D activities on Liquid Metal Technologies in Germany. The basic concept of LIMTECH consists in a joint research program among Helmholtz institutes and universities. Most of the projects are related to research topics in the fields Renewable Energies and Efficient Energy Conversion, for instance, the increase of energy and resource efficiency in metal casting and photovoltaic silicon production is addressed by several activities. Contacts were also made to the SolarPure project which is a French-German initiative of research institutes and industrial partners for developing technologies of silicon purification. SolarPure focuses especially on metallurgical methods for boron and phosphorous removal. A close cooperation also exists with the Helmholtz Institute Freiberg for Resource Technology (HIF). The HIF pursues the objective of developing innovative technologies for the economy so that mineral and metalliferous raw materials can be made available and used more efficiently and recycled in an environmentally friendly manner. Innovative separation techniques are very important for that purpose too. The HIF was founded in 2011, belongs to Helmholtz-Zentrum Dresden-Rossendorf and is cooperating closely with TU Bergakademie Freiberg.
In general, the methodologies and fundamental results to be achieved in SIKELOR are closely related to those in the other projects.
The attention of the target audience from the industry as particular users, vendors of equipment and industrial associations was primarily attracted by the presence of SIKELOR representatives at relevant conferences and exhibitions. This measure was shown to be very efficient with respect to identifying potential users, partners, and sources of finance for commercialization, thus stimulating the market uptake of project results. For instance, the new power supply developed by EAAT was presented at the Hannover Fair in April 2016. GARBO has attended many exhibitions connected to the international high-impact photovoltaic conferences. Here, the project outcomes were demonstrated by specific exhibits, posters, brochures and handouts. The presence of the SME partners at exhibitions was an important tool for advertising the technical project achievements towards the innovation community. Furthermore, the industrial partners distributed the information about the progressing activities within SIKELOR using their own network. In particular, GARBO has a variety of projects with and bilateral connections to other industrial partners or application-oriented research institutes. Common activities are casting and analysis of solar silicon ingots from GARBO’s recycled silicon kerf to test the feasibility of re-use. Information about the SIKELOR project was distributed among the European solar industry. First discussions concerning the perspectives of putting the potential outcome of SIKELOR into industrial practice were initiated with the following contacts:
- Total New Energies
- REC GROUP
- Silicon Products GmbH
- Meyer Burger AG
- Norsun AS
- SolarWorld Innovation
- Brembo/BremboSGL
- Petroceramics
Specific conclusions for policy groups have been included into the summary report of the project achievements and the policy brief at the end of SIKELOR. This document focuses on relevant information for politicians and decision makers for facilitating the European photovoltaic branch and for supporting the implementation of EC environmental policies (Renewable Energy Directive, Europe 2020 Strategy for sustainable growth, etc.) Furthermore, this document concludes the potential impact of SIKELOR with respect to future organization of research and development activities in the field of material recycling in the photovoltaic industry.
The credibility of the mass media was employed to inform the interested public about the SIKELOR project. Contributions were also sent to newspaper and magazines. For instance, articles about the SIKELOR project have been published in magazines like the German journals “VDI Nachrichten” or “Silicon Saxony” or “Il Sole 24 Ore” from Italy. In this respect the project was supported by the department of public relation activities at HZDR which periodically publishes press releases. All public information is available on the SIKELOR website. In particular, this offer comprises information leaflets, fact sheets and links to related information sources. The respective texts were prepared in a popular scientific way.
II Exploitation
The evaluation of possibilities for exploitation of project results is a main issue especially for the SME partners. The installation of the pilot plant for cleaning and densification of silicon kerf loss is an important milestone for GARBO which provides a substantial basis for intensifying the cooperation with European-based silicon wafer producers using a glycol-based coolant. Furthermore, GARBO can establish oneself as vendor of recycled silicon feedstock.
The cooperative work within SIKELOR resulted in a significant extension of capabilities for the SME partner EAAT. EAAT accumulated new substantial knowledge about the design and appropriate control of resonant circuits. This allows for designing of efficient power supplies for the range of higher frequencies offering new features and capabilities. Thus, electric currents in the range of several kA can be achieved using parallel resonant circuits. The new type of power supply offers two superimposed output frequencies which differ significantly from those were used so far for other applications like annealing treatments. The availability of such new capabilities opens the doors for new applications such as metal refinement, equipment for metallurgical smelters, inspection of capacitors or diverse recycling technologies. With this new power supply EAAT could break into new markets. A corresponding market analysis will be conducted. Advertising campaigns are envisaged in the case of a positive outcome of the analysis.
The University of Padova developed the iDSS furnace in the framework of the common spin-off inovaLAB with SAET group, Leinì, TO, Italy. SAET, a large-scale enterprise with overseas branches in the US, India, and China, is one of Europe’s centers of competence for heat treat machines and power supplies. SAET certainly will show interest in the project results. If they will confirm their intentions as expected, a market analysis on implementing the SIKELOR technologies in iDSS furnaces will be conducted. In the case of a positive outcome, this may provide the means to sell European technologies even on the dominating Asian market.
III Potential impact
A technology allowing for the recycling of the silicon kerf loss at reasonable effort and price would considerably improve the energy balance of the PV electricity production. Silicon wafers are produced with an enormous consumption of energy (~ 100 kWh/kg). A major amount of this energy is spent for the production of the silicon feedstock. Still to date, the majority of the thin wafers are sliced by wire sawing. After the sawing step, only 45%-50% of the silicon feedstock finally ends up in a wafer. The remaining 50%-55% is lost in the block cutting process (tops, tails and slabs) and the biggest portion (up to 40%) is lost as sawing slurry in the wafer saw process and is currently not recoverable. The continuing trend to produce more and thinner wafers providing a larger total surface area, increases this kerf loss. In total, ~70% of the silicon feedstock that enters the PV production chain is lost as silicon-containing wastes. A technology which converts more than half of the energy invested into waste can hardly be considered to be efficient.
The recipe for reclaiming silicon from kerf loss has to combine different methods for densification, purification, and casting of ingots. Such a process is not available in the current production pattern of the feedstock, but it is the only economical and the most-green solution to recover the valuable raw material. A large fraction of the valuable raw material silicon finally ends in waste or it is converted to much lower valued ceramics. Recycling of that silicon is thus in compliance with the European Union Raw Materials Initiative. Waste reduction is a valuable contribution to improving the environment in view of the fact that production of virgin solar grade silicon involves energy and consumable intensive processes.
In summary, as the efficiency of a solar cell depends strongly on the quality of the ingots, exploiting the results of the project could distinctly increase the competitiveness of the European photovoltaic industry and the furnace equipment producers against Asian players. However, further research activities, for instance with respect to the development of a suitable refractory material for the hot zone, will be necessary before transferring the technology into industrial practice.
At present it is rather difficult to estimate the impact of SIKELOR on the photovoltaic industry. Any further consideration to what extent electromagnetic technologies can be applied for purification of silicon melts requires the demonstration of the capability of the LKF to achieve an efficient separation of SiC particles in larger scale devices. Only on the basis of such experiments serious predictions can be made for the separation efficiency, achievable purities or the competitiveness of the new technology for kerf loss recycling in comparison to the processing of virgin feedstock. The application of high-frequency magnetic fields to generate a sufficient LKF unfortunately was not possible in the crystallization experiments done in Demonstrator II using the G2.5 setup. The infrared analysis of the solidified ingots performed by CSP Halle demonstrated a high amount of SiC found in both tests, but, surprisingly, the ingot cast with the recycled material supplied by GARBO does not show an increase but a decrease of the SiC content as compared to the silicon ingot cast from virgin silicon. This finding appears to be rather promising. The issue of finding a new material for the substitution of graphite components in the hot zone by another suitable material remains an unresolved problem.
Finally, the new technology to be developed by the SIKELOR project can also be extended and adapted for recycling of silicon material accruing from spent solar modules. The resulting powders from grounding worn out solar panels have to be processed for partitioning the non-silicon material for retrieving the silicon. Obviously, with growing utilization of solar power world-wide the relevance of this problem will take on greater significance during the next decades. The recycling of solar panels will become a non-negligible issue in future what the society should start thinking about now. As of mid 2014 there were already around 8 million tons of solar panels installed that will one day need to be recycled. These kinds of quantities won’t be recyclable without developing corresponding strategies, technologies and standards for the industry. The approach followed by the SIKELOR project points out a possibility to adapt inductive techniques of electromagnetic processing for that purpose. The new technology developed here can also be extended and adapted for recycling of silicon material accruing from spent solar modules. The resulting powders from grounding worn out solar panels have to be processed for partitioning the non-silicon material for retrieving the silicon. Obviously, with growing utilization of solar power world-wide the relevance of this problem will take on greater significance during the next decades.
List of Websites:
www.sikelor.eu
Contact persons:
Helmholtz-Zentrum Dresden-Rossendorf, Sven Eckert (coordinator), s.eckert@hzdr.de Tel.: +49 3512602132
GARBO, Guido Fragiacomo, guido.fragiacomo@garbosrl.net
University of Padova, Michele Forzan, michele.forzan@unipd.it
University of Greenwich, Valdis Bojarevics, V.Bojarevics@greenwich.ac.uk
EAAT Chemnitz GmbH, Martin Kroschk, m.kroschk@eaat.de
The objective of the SIKELOR project was to develop an innovative electromagnetic technology for recycling silicon kerf loss which arises from slicing of silicon ingots into thin wafers. The technology proposed for reclaiming silicon from kerf loss combines methods for densification, purification, and casting of ingots. Such a process is not available in the current production pattern of the feedstock. The technology for silicon recycling is composed of the following three steps:
1. Improved technology for densification of the dry silicon powder without introducing cross-contamination.
2. Melting of the compacted material and purification by electromagnetic processing.
3. Casting of poly-crystalline silicon blocks by directional solidification.
Compaction of silicon powders is mandatory as the first step for recycling because of the extremely small size of the particles in the kerf loss. GARBO has developed a binder assisted densification method to produce porous bodies of relatively high density and mechanical stiffness from silicon powders. Optimization of the process steps was accomplished in terms of good product quality, low process costs and possibility of scale-up at industrial level with high throughputs. A pilot plant is available at GARBO with a capacity of approx. 7 kg of recycled silicon per day.
Electromagnetic processing of materials is the means to achieve three necessary tasks: AC magnetic fields melt the silicon compacts, stir the melt, and separate impurity particles. Advanced numerical codes have been implemented by University of Greenwich (UNIG) for calculating complex flows under the impact of variable electromagnetic fields. A specific particle tracking model was developed taking into account the time-dependent evolution of the crystallization front. Validation of the numerical predictions was provided by model experiments at Helmholtz-Zentrum Dresden-Rossendorf (HZDR). The investigations revealed that the flow pattern at high shielding parameters differ significantly from well-known time-averaged flow structure referred in the literature. Complicated vortex structures appear showing a distinct transient behaviour and inducing a significant mixing effect by the AMF. The knowledge gained from the modeling was used for designing the magnetic system for the Demonstrator in the i-DSS crystallization furnace at the University of Padova (UNIPD). Two variants of experimental configurations have been realized: In addition to the G2.5 experiment a G1 setup was built to demonstrate the separation of SiC particles. New designs were developed for both the hot zone and the inductor. In this way serious problems had to be solved. In particular, the formerly used graphite parts in the hot zone had to be substituted by a material which does not shield the high-frequency magnetic field as needed for efficient separation and can be accepted by the industry. Crystallization experiments were performed using a 50:50 mixture composed of recycled silicon and new polycrystalline material. A new type of electric power supply was developed by EAAT for the Demonstrator. The innovative concept allows for the allocation of two super-imposed frequencies using only one resonant circuit.
In summary, the project achieved (i) the development of a technology for cleaning and densification of the Si kerf loss, (ii) numerical and experimental modelling for identifying optimal process parameters for electromagnetic processing, and (iii) the implementation of the Demonstrator on laboratory scale. However, not all objectives were achieved as planned at the beginning of the project, (a) the crystallization experiments in Demonstrator II have not been completed, and (b) the Demonstrator I was substituted by sintering experiments for reducing the oxygen content in the kerf loss.
Project Context and Objectives:
Achieving the European goals on climate stability requires an almost carbon free power system to be installed until 2050 [1]. Besides the development of innovative technologies to improve the efficiency of processes in energy-intensive economic branches such as chemical industry, metallurgy, cement or paper industry, the expansion of renewable energy production as a carbon free power sector plays an important role for achieving these ambitious goals. However, the global demand on energy will further increase in the near future while at the same time meeting the target of limiting global temperature increase to 2 degrees Celsius must be satisfied. Therefore, further exploitation of remaining fossil fuel reserves is not an option, and both renewable energy and energy efficiency will have to be scaled up dramatically. While the short-term target to increase the fraction of renewable power generation up to 20% of the total energy production by 2020 can be considered as challenge, decarbonizing the whole energy sector by 2050 demands an industrial revolution. On the other hand, it is widely expected that the transformation towards the new energy technologies during the coming years will bring substantial benefit for the society in terms of green jobs and sustainable growth.
The upsurge in renewable energy technologies has led to a rapidly increasing demand for photovoltaic (PV) solar cells. The challenge today is to create efficient and productive technologies needed to establish solar energy as a practical and economical alternative to energy produced by fuels - and to use that solar-produced energy in a wide variety of applications. Concerning PV module production in 2015, China and Taiwan hold the lead with a share of 67 %, followed by rest of Asia-Pacific & Central Asia (ROAP/CA) with 14%. Europe contributed with a share of only 5 % (was 6% in 2014); USA/CAN contributed 3 % [2]. Bringing to mind Europe’s leading position with respect to the total cumulative PV installations one has to note a remarkable discrepancy between installation and production of solar panels in Europe. Europe’s percentage of solar silicon wafers produced on the global market has been decreasing drastically for several years. This situation is explained by the fact that other countries, in particular China, have gained on technological advance and offer the silicon wafers at considerably reduced prices. New innovative technologies are necessary to strengthen Europe’s position in the worldwide competition.
Si-wafer based PV technology accounted for about 93 % of the total production in 2015. The share of multi-crystalline technology is now about 68 % of total production [3]. Over 90% of current dominant materials used in PV cells is silicon. Solar Grade silicon feedstock can be obtained using either a chemical approach or a pyro-metallurgical approach. In both cases, the starting point is metallurgical grade silicon and the target is to produce a high purity silicon feedstock for production of high performance devices [4]. The semiconductor industry uses the chemical approach to achieve purities in the ppba range. MG silicon has to be converted into a gaseous or liquid chemical (e.g. trichlorosilane, silane, etc.), which is then put through multiple distillations for purification and finally reduced via gaseous phase reactions. The resultant product is high purity polysilicon, which is left with B and P, the most difficult elements to remove from silicon [5], at levels less than 1 ppba and all other impurities even lower. Moreover, the silicon feedstock is produced with an enormous consumption of energy (~ 100 kWh/kg). A major amount of this energy is spent for the production of the silicon feedstock. Usually, the silicon is cast in form of large ingots. Still to date, the majority of the thin wafers are sliced by wire sawing. After the sawing step, only 45%-50% of the silicon feedstock finally ends up in a wafer. The remaining 50%-55% is lost in the block cutting process (tops, tails and slabs) and the biggest portion (up to 40%) is lost as sawing slurry in the wafer saw process and is currently not recoverable [3].
A technology which converts more than half of the energy invested into waste can hardly be considered to be efficient. In total, ~70% of the silicon feedstock that enters the PV production chain is lost as silicon-containing wastes. This quantity corresponds to almost 10 ton of lost silicon per MWp (MegaWatt peak) obtained module power, based on an assumed quantity of 15 ton silicon per produced MWp module power [5]. The trend to produce thinner wafers provides a larger total surface area and increases this kerf loss. As the wafer thickness approaches the wire diameter, the fraction of loss may reach 50%. According to the current production processes, this equals to about 140,000 tons of discarded silicon per year. Alternative techniques avoiding the kerf loss such as implanting/cleaving, the ribbon growth on substrate or the string ribbon technology have up to now not led to commercially sustainable routes.
A technology allowing for the recycling of the silicon kerf loss at reasonable effort and price would considerably improve the energy balance of the PV electricity production. The recipe for reclaiming silicon from kerf loss has to combine different methods for densification, purification, and casting of ingots. Such a process is not available in the current production pattern of the feedstock, but it is the only economical and the most-green solution to recover the valuable raw material. During the course of the SIKELOR project, thinner diamond wires have been introduced to the production, with core wire diameters shrinking from initial 120 micron to the present 80 micron, and 60 micron diamond wires are presently under testing. This has the consequence that the sawdust becomes distinctly finer and the oxygen content of the kerf due to the high surface-to-volume ratio becomes much higher. Silicon carbide pollution is finally the major problems with the recycling of kerf loss. Recycling of kerf loss demands a costly mechanical separation, an energy intensive high-temperature process, and zone melting. A large fraction of the valuable raw material silicon finally ends in waste or it is converted to much lower valued ceramics. Recycling of that silicon is thus in compliance with the European Union Raw Materials Initiative. Waste reduction is a valuable contribution to improving the environment in view of the fact that production of virgin solar grade silicon involves energy and consumable intensive processes.
SIKELOR aims at technologies that permit reuse of the majority of the silicon raw material from kerf loss. The technological goal of the project is developing an innovative process for silicon recycling, which is composed of:
1. An improved technology for densification of the dry silicon powder without introducing cross-contamination.
2. Melting of the compacted material and purification of the liquid silicon by electromagnetic processing.
3. Casting of poly-crystalline silicon blocks by directional solidification.
This process chain has been further developed up to a pilot plant production of the reclaimed silicon. The key issue is the removal of SiC particles from the Si melt. An innovative method has been developed to separate the impurities by tailored electromagnetic forces. Moreover, electromagnetically induced flow and solidification phenomena are far from being completely understood. It is thus an important and indispensable scientific goal to gain more insight into these phenomena.
The project comprises a combination of numerical simulation, physical modelling, and demonstration experiments. All process steps, which are compaction, melting, purification, and casting, have been considered by research activities in four strategic tasks:
1. Controlling the fluid flow: The contaminant particles suspended in the silicon melt are affected by the electromagnetically driven flow, transient drag, buoyancy, surface tension, turbulent fluctuations, evaporation, and the local electromagnetic pressure. The combination of physical and numerical modeling provides insights into the underlying mechanisms. Optimized magnetic fields parameters have been identified.
2. Electromagnetic design and implementation: The achievement of optimized combinations of induction heating, electromagnetic stirring and electromagnetic separation is a challenging engineering task. Two different magnetic field types are required for heating and separation (alternating magnetic field, AMF) and electromagnetic stirring (traveling magnetic field, TMF). Creating these by separate coil systems seems impossible due to the space limitations and the mutual electro-magnetic interference (crosstalk). A sophisticated solution for an inverter delivering a current comprising the superposition of two harmonics of different frequencies was realized in the project. The necessity of matching the respective impedances of the loads required an intensive collaboration between the partners developing the power supply and the partners concerned with the overall design and the implementation of the coil system for the melt treatment.
3. Reclaiming silicon product: The existing proprietary compaction process had to be improved. The focus was on decreasing the surface-to-volume ratio and the treatment of the very small size silicon particles. Upon completion of the pilot plant, compacted feedstock needed for crystallization experiments was produced in the first test production cycle using an advanced treatment developed within this project. The new production line demonstrated the feasibility and the reliability of the process, thus opening the path for exploitation and commercialization.
4. Crystallization of silicon into ingot casts: An experimental demonstrator was built for casting of the silicon ingots ready to be sliced into wafers. This unique facility is equipped with tailored magnetic systems for controlling the fluid flow and the separation of impurities during crystallization under the influence of external fields. Both heating and melting are achieved using the electromagnetic induction heating. The AMF also generates the Leenov-Kolin force for separating the SiC inclusions. Particle capturing is supported by TMF-driven electromagnetic stirring for transporting the particles into regions where separation is highly efficient.
In summary, the SIKELOR project is aimed to demonstrate the feasibility of the approach to recycle the silicon kerf loss and to purify silicon melts by electromagnetic processing on laboratory scale. The project establish the scientific basis which allows a detailed understanding of the underlying processes and enable an optimal design and choice of the relevant process parameter. At the end of the project the feasibility and the reliability of the process has been shown by a demonstrator, which could become the model for a prototypic facility, thus paving the way for exploitation and commercialization.
References:
[1] IPCC (2007): Intergovernmental Panel on Climate Change, Fourth Assessment Report, Synthesis report, 52p, http://www.ipcc.ch
[2] Fraunhofer ISE (2016): Photovoltaics Report, updated: 17 November 2016, https://www.ise.fraunhofer.de/de/downloads/pdf-files/aktuelles/photovoltaics-report-in-englischer-sprache.pdf
[3] D. Singh and P. Jennings (2007): The Outlook for Crystalline Solar Photovoltaic Technology over the Next Decade, AIP Conference Proceedings 941, 98-110.
[4] C.P. Khattak, D.B. Joyce and F. Schmid (1998-1999): Production of Solar Grade (SoG) Silicon by Refining Liquid Metallurgical Grade (MG) Silicon, National Renewable Energy Laboratory, Report.
[5] D. Sarti and R. Einhaus (2002): Silicon feedstock for the multi-crystalline photovoltaic industry, Solar Energy Materials & Solar Cells 72, 27-40.
Project Results:
see attachment
Potential Impact:
I Dissemination of results
The European project SIKELOR is concerned with innovative technologies for silicon kerf loss recycling. The project consortium developed a dissemination strategy to achieve a maximum impact of the SIKELOR results in Europe. Especially in the fields of sustainable energy, waste reduction, and saving both valuable materials and energy, dissemination is of elevated interest; the efficient methods to be developed in the project have the potential to increase the competitiveness of Europe’s solar silicon industry against Asian players.
At the end of the project the following main outcomes have been achieved:
• The understanding of fluid flow, transport processes and particle behavior inside a metallic melt agitated by an alternating magnetic field was significantly improved.
• A pilot-plant production for cleaning and compaction of silicon kerf loss was successfully installed at GARBO.
• A demonstrator for purification and crystallization of liquid silicon molten from a recycled feedstock was installed and put into commission on laboratory scale at the University of Padova.
• A prototype of a new type of power supply was designed and built by EAAT for the demonstrator.
Potential commercialization by integration of the devices into respective product lines, in particular the integration of tailored magnetic fields into the furnace equipment, has to be examined by means of a market analysis. Both the pilot-plant for cleaning and densification of silicon kerf loss and the demonstrator for purification and crystallization of silicon will serve to support the prospect of success for market launch.
At the beginning of the project we identified the following main target groups for dissemination:
1) Scientific community
2) Industry
3) Policy groups
4) The interested public
Dissemination material has been created specifically for the above groups and communicated to them via appropriate ways.
The SIKELOR website (www.sikelor.eu) was installed as a basic and main tool for distributing information and presenting the outcome of the project. Moreover, the website was also used for exchange of confidential information among the partners. The webpage has been activated since January 31th, 2014. According to the progress in the project the content of the website has been continuously extended and updated.
The SIKELOR workshop organized in the framework of the Seventh Triennial Conference on Heating by Electromagnetic Sources (HES-16) in Padova (May 2016) was the key issue for dissemination of the results arising from the project. HES-16 comprised an international conference, an industrial exhibition and a summer school for young scientists. The conference had more than 150 participants (18 countries) from universities, research centres and industry. For many years HES is a well-known and well-established international forum for making new contacts and for exchanging information and ideas. The SIKELOR workshop was organized in form of a special session which was attended by more than 100 participants. Each partner presented the research activities and the corresponding results. Many problems and details were put forward for discussion. The scientific results achieved in SIKELOR will find its way directly into the education of the students.
Another important forum for SIKELOR is the initiative “MagnetSep” (www.magnetsep.de) an innovation cluster funded by the German Federal Ministry of Education and Research. This innovation clusters forms a wide network of research institutes and industrial partners mainly on the national level inside Germany. However, the future perspective of “MagnetSep” also considers an expansion to European level. The focus of “MagnetSep” is on the development of new, innovative electromagnetic techniques for separation of impurities and particles from metallic and other high-temperature melts. Future applications are expected for many fields like mining, metallurgy, casting, silicon production and various technologies for recycling. The technology for recycling of silicon kerf loss by applying electromagnetic stirring and separation is a prominent example which fits very well into this initiative. Within the framework of “MagnetSep” a workshop with more than hundred participants from universities, research institutes and industry was organized in Dresden in April 2016. The SIKELOR project was presented to this wide audience as invited lecture at this workshop.
During the duration of the SIKELOR project the partners produced 28 publications in diverse scientific journals, magazines, conferences and exhibitions. Publications in peer-reviewed scientific journals and contributions to international scientific conferences are the appropriate means to bring the projects results to the attention of the scientific community. Fundamental aspects of the project findings have been submitted to the international journals in the respective research field. The academic partners had the leadership of preparation and submission of journal articles and conference contributions.
During the reporting period the SIKELOR consortium established contacts to other activities and research groups working in the fields of Si production, liquid metal handling or magnetohydrodynamics. All partners are closely cross-linked with the scientific community in the fields of electromagnetic processing of materials, electrical engineering, crystal growth and numerical computations. For instance, the Computational Science and Engineering Group at the University of Greenwich is involved in other large scale projects, e.g. in FP7 EXOMET and IMPRESS. Likewise, HZDR contributes to many other projects funded on European or national level. For instance, a bilateral French-German research project was started recently in 2016 considering the removal of impurities from liquid metals by gas injection. A very close cooperation and exchange was established with the Helmholtz Alliance LIMTECH (http://www.hzdr.de/db/Cms?pNid=2920) which is funded by the German Helmholtz Association and bundles the R&D activities on Liquid Metal Technologies in Germany. The basic concept of LIMTECH consists in a joint research program among Helmholtz institutes and universities. Most of the projects are related to research topics in the fields Renewable Energies and Efficient Energy Conversion, for instance, the increase of energy and resource efficiency in metal casting and photovoltaic silicon production is addressed by several activities. Contacts were also made to the SolarPure project which is a French-German initiative of research institutes and industrial partners for developing technologies of silicon purification. SolarPure focuses especially on metallurgical methods for boron and phosphorous removal. A close cooperation also exists with the Helmholtz Institute Freiberg for Resource Technology (HIF). The HIF pursues the objective of developing innovative technologies for the economy so that mineral and metalliferous raw materials can be made available and used more efficiently and recycled in an environmentally friendly manner. Innovative separation techniques are very important for that purpose too. The HIF was founded in 2011, belongs to Helmholtz-Zentrum Dresden-Rossendorf and is cooperating closely with TU Bergakademie Freiberg.
In general, the methodologies and fundamental results to be achieved in SIKELOR are closely related to those in the other projects.
The attention of the target audience from the industry as particular users, vendors of equipment and industrial associations was primarily attracted by the presence of SIKELOR representatives at relevant conferences and exhibitions. This measure was shown to be very efficient with respect to identifying potential users, partners, and sources of finance for commercialization, thus stimulating the market uptake of project results. For instance, the new power supply developed by EAAT was presented at the Hannover Fair in April 2016. GARBO has attended many exhibitions connected to the international high-impact photovoltaic conferences. Here, the project outcomes were demonstrated by specific exhibits, posters, brochures and handouts. The presence of the SME partners at exhibitions was an important tool for advertising the technical project achievements towards the innovation community. Furthermore, the industrial partners distributed the information about the progressing activities within SIKELOR using their own network. In particular, GARBO has a variety of projects with and bilateral connections to other industrial partners or application-oriented research institutes. Common activities are casting and analysis of solar silicon ingots from GARBO’s recycled silicon kerf to test the feasibility of re-use. Information about the SIKELOR project was distributed among the European solar industry. First discussions concerning the perspectives of putting the potential outcome of SIKELOR into industrial practice were initiated with the following contacts:
- Total New Energies
- REC GROUP
- Silicon Products GmbH
- Meyer Burger AG
- Norsun AS
- SolarWorld Innovation
- Brembo/BremboSGL
- Petroceramics
Specific conclusions for policy groups have been included into the summary report of the project achievements and the policy brief at the end of SIKELOR. This document focuses on relevant information for politicians and decision makers for facilitating the European photovoltaic branch and for supporting the implementation of EC environmental policies (Renewable Energy Directive, Europe 2020 Strategy for sustainable growth, etc.) Furthermore, this document concludes the potential impact of SIKELOR with respect to future organization of research and development activities in the field of material recycling in the photovoltaic industry.
The credibility of the mass media was employed to inform the interested public about the SIKELOR project. Contributions were also sent to newspaper and magazines. For instance, articles about the SIKELOR project have been published in magazines like the German journals “VDI Nachrichten” or “Silicon Saxony” or “Il Sole 24 Ore” from Italy. In this respect the project was supported by the department of public relation activities at HZDR which periodically publishes press releases. All public information is available on the SIKELOR website. In particular, this offer comprises information leaflets, fact sheets and links to related information sources. The respective texts were prepared in a popular scientific way.
II Exploitation
The evaluation of possibilities for exploitation of project results is a main issue especially for the SME partners. The installation of the pilot plant for cleaning and densification of silicon kerf loss is an important milestone for GARBO which provides a substantial basis for intensifying the cooperation with European-based silicon wafer producers using a glycol-based coolant. Furthermore, GARBO can establish oneself as vendor of recycled silicon feedstock.
The cooperative work within SIKELOR resulted in a significant extension of capabilities for the SME partner EAAT. EAAT accumulated new substantial knowledge about the design and appropriate control of resonant circuits. This allows for designing of efficient power supplies for the range of higher frequencies offering new features and capabilities. Thus, electric currents in the range of several kA can be achieved using parallel resonant circuits. The new type of power supply offers two superimposed output frequencies which differ significantly from those were used so far for other applications like annealing treatments. The availability of such new capabilities opens the doors for new applications such as metal refinement, equipment for metallurgical smelters, inspection of capacitors or diverse recycling technologies. With this new power supply EAAT could break into new markets. A corresponding market analysis will be conducted. Advertising campaigns are envisaged in the case of a positive outcome of the analysis.
The University of Padova developed the iDSS furnace in the framework of the common spin-off inovaLAB with SAET group, Leinì, TO, Italy. SAET, a large-scale enterprise with overseas branches in the US, India, and China, is one of Europe’s centers of competence for heat treat machines and power supplies. SAET certainly will show interest in the project results. If they will confirm their intentions as expected, a market analysis on implementing the SIKELOR technologies in iDSS furnaces will be conducted. In the case of a positive outcome, this may provide the means to sell European technologies even on the dominating Asian market.
III Potential impact
A technology allowing for the recycling of the silicon kerf loss at reasonable effort and price would considerably improve the energy balance of the PV electricity production. Silicon wafers are produced with an enormous consumption of energy (~ 100 kWh/kg). A major amount of this energy is spent for the production of the silicon feedstock. Still to date, the majority of the thin wafers are sliced by wire sawing. After the sawing step, only 45%-50% of the silicon feedstock finally ends up in a wafer. The remaining 50%-55% is lost in the block cutting process (tops, tails and slabs) and the biggest portion (up to 40%) is lost as sawing slurry in the wafer saw process and is currently not recoverable. The continuing trend to produce more and thinner wafers providing a larger total surface area, increases this kerf loss. In total, ~70% of the silicon feedstock that enters the PV production chain is lost as silicon-containing wastes. A technology which converts more than half of the energy invested into waste can hardly be considered to be efficient.
The recipe for reclaiming silicon from kerf loss has to combine different methods for densification, purification, and casting of ingots. Such a process is not available in the current production pattern of the feedstock, but it is the only economical and the most-green solution to recover the valuable raw material. A large fraction of the valuable raw material silicon finally ends in waste or it is converted to much lower valued ceramics. Recycling of that silicon is thus in compliance with the European Union Raw Materials Initiative. Waste reduction is a valuable contribution to improving the environment in view of the fact that production of virgin solar grade silicon involves energy and consumable intensive processes.
In summary, as the efficiency of a solar cell depends strongly on the quality of the ingots, exploiting the results of the project could distinctly increase the competitiveness of the European photovoltaic industry and the furnace equipment producers against Asian players. However, further research activities, for instance with respect to the development of a suitable refractory material for the hot zone, will be necessary before transferring the technology into industrial practice.
At present it is rather difficult to estimate the impact of SIKELOR on the photovoltaic industry. Any further consideration to what extent electromagnetic technologies can be applied for purification of silicon melts requires the demonstration of the capability of the LKF to achieve an efficient separation of SiC particles in larger scale devices. Only on the basis of such experiments serious predictions can be made for the separation efficiency, achievable purities or the competitiveness of the new technology for kerf loss recycling in comparison to the processing of virgin feedstock. The application of high-frequency magnetic fields to generate a sufficient LKF unfortunately was not possible in the crystallization experiments done in Demonstrator II using the G2.5 setup. The infrared analysis of the solidified ingots performed by CSP Halle demonstrated a high amount of SiC found in both tests, but, surprisingly, the ingot cast with the recycled material supplied by GARBO does not show an increase but a decrease of the SiC content as compared to the silicon ingot cast from virgin silicon. This finding appears to be rather promising. The issue of finding a new material for the substitution of graphite components in the hot zone by another suitable material remains an unresolved problem.
Finally, the new technology to be developed by the SIKELOR project can also be extended and adapted for recycling of silicon material accruing from spent solar modules. The resulting powders from grounding worn out solar panels have to be processed for partitioning the non-silicon material for retrieving the silicon. Obviously, with growing utilization of solar power world-wide the relevance of this problem will take on greater significance during the next decades. The recycling of solar panels will become a non-negligible issue in future what the society should start thinking about now. As of mid 2014 there were already around 8 million tons of solar panels installed that will one day need to be recycled. These kinds of quantities won’t be recyclable without developing corresponding strategies, technologies and standards for the industry. The approach followed by the SIKELOR project points out a possibility to adapt inductive techniques of electromagnetic processing for that purpose. The new technology developed here can also be extended and adapted for recycling of silicon material accruing from spent solar modules. The resulting powders from grounding worn out solar panels have to be processed for partitioning the non-silicon material for retrieving the silicon. Obviously, with growing utilization of solar power world-wide the relevance of this problem will take on greater significance during the next decades.
List of Websites:
www.sikelor.eu
Contact persons:
Helmholtz-Zentrum Dresden-Rossendorf, Sven Eckert (coordinator), s.eckert@hzdr.de Tel.: +49 3512602132
GARBO, Guido Fragiacomo, guido.fragiacomo@garbosrl.net
University of Padova, Michele Forzan, michele.forzan@unipd.it
University of Greenwich, Valdis Bojarevics, V.Bojarevics@greenwich.ac.uk
EAAT Chemnitz GmbH, Martin Kroschk, m.kroschk@eaat.de
