The Role of Granule Size on the Kinetics of Electrochemical Reduction of SiO 2 Granules in Molten CaCl 2
- PDF / 3,550,654 Bytes
- 10 Pages / 593.972 x 792 pts Page_size
- 93 Downloads / 208 Views
ODUCTION
THE global photovoltaic (PV) market has been growing rapidly in recent years. In 2013, the annual installation of PV systems in the world reached 37 GW,[1] which was a 60-fold increase as compared to 2003. Yet the power globally generated from solar energy was less than 0.5 pct of the total power generation in 2012.[2] According to a study by the German Advisory Council on Global Change (WBGU), solar energy is expected to become a major energy source, reaching 20 pct of the total world energy by 2050 and 70 pct by 2100.[3] Presently, the dominant material for solar cells is silicon, particularly crystalline silicon. Crystalline silicon solar cells represented 90.1 pct of the global production of all types of solar cells in 2013.[4] Because they offers advantages in terms of high conversion efficiency, high durability, non-toxicity, and abundant resources, silicon solar cells are the only candidate to meet the market demand in the future when PV
XIAO YANG, Programme-Specific Assistant Professor, and TOSHIYUKI NOHIRA, Professor, are with the Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan. Contact e-mail: [email protected] KOUJI YASUDA, Assistant Professor, is with the Graduate School of Energy Science, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 6068501, Japan, and also with the Environment, Safety and Health Organization, Kyoto University. RIKA HAGIWARA, Professor, is with the Graduate School of Energy Science, Kyoto University. TAKAYUKI HOMMA, Professor, is with the Faculty of Science and Engineering, Waseda University, 3-4-1 Okubo, Shinjuku-ku, Tokyo 169-8555, Japan. Manuscript submitted April 9, 2015. METALLURGICAL AND MATERIALS TRANSACTIONS B
installation could climb to several hundred GW per year. The increasing demand for PV systems boosts the production of high-purity polycrystalline Si dramatically. The global production of polycrystalline Si in 2013 saw a 10-fold increase since 2003 to 233,800 t,[5] more than 90 pct of which was supplied to the PV industry. Such growth is expected to continue over the long term. For PV applications, the purity of Si must be at least 6 N (99.9999 pct), and this product is called solar-grade Si (SOG-Si). The dominant technology for SOG-Si production is the Siemens process,[6–8] which represents approximately 90 pct of the global production. In spite of the ability to produce Si at purity levels above 9 N, the Siemens process, which utilizes chemical vapor deposition using trichlorosilane (SiHCl3), requires high energy consumption and results in low productivity. Production of SOG-Si based on pyrolysis of monosilane (SiH4) in a fluidized bed reactor (FBR) is the main competitor to the Siemens process and represents about 10 pct of the market.[8–10] FBR consumes less energy and it is more economical than the Siemens process, yet limitations in terms of purity control and productivity inhibit its commercial application. Upgrading metallurgical-grade silicon (UMG) is an emerging process for SOG-Si production. The a
Data Loading...
