Meet the requirements of “carbon peak and carbon neutrality” new technology for photovoltaic material granular silicon is coming
The purity of polysilicon required by the photovoltaic industry is over 99.9999%. At present, most of the silicon materials produced by manufacturers in the world use the traditional modified Siemens method, which is the most mature and widely used process technology. Compared with the polysilicon produced by the modified Siemens method, the granular silicon produced by the silane fluidized bed method (FBR) has a smaller volume, and the energy consumption and cost are greatly reduced.
◎Reporter Zhang Ye and intern Ji Tianyu
Investment reduced by 30%, production power consumption reduced by 65%, personnel reduced by 30%…
Poly GCL recently issued an announcement stating that after the company’s silane fluidized bed process (FBR) granular silicon 10,000-ton project was put into operation, after production and operation and the use of downstream customers, new breakthroughs have been achieved in various indicators of granular silicon-head and tail life, Tail carbon, crystallization rate, unit yield, and conversion efficiency are all leading the industry.
After the announcement was released, it attracted great attention from the capital market and the photovoltaic industry.
Currently, the upstream raw material for photovoltaic power generation is mainly the modified Siemens method to prepare polysilicon. After the advent of FBR granular silicon, industry experts have judged that granular silicon is expected to trigger a disruptive technological revolution in polysilicon manufacturing. So what kind of process product is FBR granular silicon? How is it different from traditional polysilicon and why can it emerge? A reporter from Science and Technology Daily conducted an exclusive interview with industry experts on these issues on April 2.
The price and quality of silicon Photovoltaic power generation is very important
As we all know, the photovoltaic industry has a clear and clear industrial chain. Silicon materials, silicon wafers, cells, modules, and application systems are the five major links in the industrial chain. Among them, silicon materials and silicon wafers are in the upper reaches of the photovoltaic industry chain.
The silicon material link not only has a high threshold for manufacturing and R&D, but also has a huge capital investment. At the same time, the price and quality of silicon materials also play a vital role in the cost and efficiency of photovoltaic power generation.
In recent years, the development momentum of the photovoltaic industry has become more and more fierce. In 2020, my country’s newly installed photovoltaic capacity will be 48.2GW, a year-on-year increase of 60%. Driven by the end market and forced by national laws and regulations, various raw material companies are developing new silicon material technologies. In this context, granular silicon has gradually come into people’s sight.
Silicon material is polysilicon, and the purity of polysilicon required by the photovoltaic industry is more than 99.9999%. At present, most of the world’s silicon materials produced by manufacturers use the traditional modified Siemens method, which is the most mature and widely used process technology.
“The main principle of the improved Siemens method is that the quartz sand is smelted and reduced in an electric furnace to produce 99% industrial silicon powder, and then reacted with silicon tetrachloride and hydrogen to obtain trichlorosilane. A series of technological processes such as distillation, purification, high-temperature reduction, and tail gas recovery will eventually produce rod-shaped polysilicon.” said Jiang Limin, vice president of the GCL-Poly Research Institute.
FBR granular silicon is also polycrystalline silicon, but compared with modified Siemens polycrystalline silicon, the granular silicon is smaller, only as big as a mung bean. Since 2010, Zhongneng Silicon Industry, a subsidiary of GCL-Poly, has independently researched and developed granular silicon technology, and finally achieved mass production of granular silicon through the acquisition of overseas assets.
“GCL-Poly granular silicon is manufactured by the original silane fluidized bed method. The raw material trichlorosilane is disproportionated to obtain silane. The silane is decomposed in the fluidized bed to obtain granular polycrystalline silicon. The conversion rate can reach 99%, reducing the tail gas recovery and distillation links, and the reaction temperature is only 60% of the modified Siemens method. Continuous production is possible, and energy consumption and costs are greatly reduced.” Jiang Limin told reporters.
According to the introduction, after downstream silicon wafer manufacturers get traditional polysilicon, they need to be crushed, cleaned and then used to pull the single crystal. The granular silicon does not need to be broken and cleaned. It can be directly fed to pull the single crystal, and it flows. It has good performance and is more suitable for a new generation of continuous feeding Czochralski process than traditional polysilicon.
Carbon neutrality is beneficial to the photovoltaic industry chain Put forward higher requirements
As early as many years ago, when the photovoltaic industry chain landed in China, there were voices questioning the high energy consumption of the photovoltaic industry chain, and the pollution and greenhouse gas emissions caused by the photovoltaic industry chain were higher than the income of power generation.
With the advancement of independent technology and practical testing, this questioning voice has gradually disappeared. However, the high energy consumption of silicon material and silicon wafer manufacturing not only restricts the cost reduction of photovoltaic power generation, but also affects the realization of my country’s “carbon peak and carbon neutral” goal.
According to industry insiders, at present, the highest energy consumption in the photovoltaic industry chain is the silicon manufacturing process, which accounts for 45% of the energy consumption. In May 2020, the Ministry of Industry and Information Technology issued the “Specification Conditions for Photovoltaic Manufacturing Industry (2020 Version” (Draft for Comment), which stipulates that the comprehensive power consumption of new/expanded polysilicon should not exceed 70 kWh/kg.
“According to our actual measurement, the comprehensive power consumption of FBR granular silicon is only 18 kWh/kg, which is far lower than the industry standard.” Jiang Limin said.
China has committed to the total installed capacity of wind power and solar power by 2030. The capacity will reach more than 1.2 billion kilowatts, which will drive a large number of photovoltaic power generation projects to be put into operation. According to the requirements of the Ministry of Industry and Information Technology, the reporter followed the production process of FBR granular silicon and improved Siemens method polysilicon. The path of the photovoltaic industry chain is traced to the source of the carbon footprint. It can be seen that the production of 1 GW of granular silicon in the silicon material link can reduce 130,000 tons of carbon dioxide, which is 74% lower than the improved Siemens method. Watt modules can reduce carbon dioxide emissions by at least 47.7%.
With the advantages of production capacity, cost control, and technology, the world’s photovoltaic industry has gradually shifted its focus to China. As of 2019, China’s The production of wafers, cells, and modules have all accounted for more than 60% of the global output, respectively 67%, 97%, 79% and 71%.
According to the domestic silicon material production capacity in 2020, about 430,000 tons It is estimated that replacing the Siemens method by FBR will reduce carbon dioxide emissions by 19.27 million tons per year. According to research inferred by the Swiss Federal Institute of Technology Zurich, one hectare of canopy area can consume 205 tons of carbon dioxide each year, and 19.27 million tons of carbon dioxide requires 94,000 hectares of canopy area, which is equivalent to each year. A variety of about 94 million trees.
In order to eliminate outdated photovoltaic production capacity, the Ministry of Industry and Information Technology has clearly stated that “photovoltaic manufacturing enterprises should adopt advanced technology, energy saving and environmental protection, good product quality, and low production costs. Equipment”.
Jiang Limin introduced to the reporter of Science and Technology Daily that after 10 years of research and improvement, FBR granular silicon has solved the problems of large-scale industrialization such as product quality, long-term continuous operation, and low cost. 2019 In 2009, it realized the localization of key equipment and the substitution of key materials. GCL-Poly also led the editor-in-chief of the national standard for granular silicon. In the future, FBR granular silicon will play a vital role in reducing carbon emissions in China’s photovoltaic industry chain.