Electrolytic aluminum will be included in the national carbon market management to control greenhouse gases. What are the two types of perfluorocarbons mentioned in addition to CO2?
On September 9, the official website of the Ministry of Ecology and Environment announced that in order to accelerate the expansion of the coverage of the national carbon emissions trading market, the Ministry of Ecology and Environment released the "Work Plan for the National Carbon Emissions Trading Market to Cover the Cement, Steel, and Electrolytic Aluminum Industries (Solicitation for Opinions Draft)"(hereinafter referred to as the "Draft for Comments ").
The "Draft for Comments" proposes that units with annual direct greenhouse gas emissions reaching 26,000 tons of carbon dioxide equivalent in the cement, steel, and electrolytic aluminum industries should be regarded as key emission units and be included in the management of the national carbon emissions trading market. In addition to carbon dioxide, the types of greenhouse gases controlled in the electrolytic aluminum industry in the Draft for Comments also include carbon tetrafluoride (CF4) and carbon hexafluoride (C2F6).
So, what are carbon tetrafluoride (CF4) and carbon hexafluoride (C2F6)? Why would the electrolytic aluminum industry include these two substances in the scope of greenhouse gas control? What is the amount produced?
According to investigations, in the aluminum electrolysis process, in addition to direct carbon dioxide emissions from anode consumption and indirect carbon dioxide emissions from power consumption in the aluminum electrolysis process, carbon tetrafluoride (CF4) and difluoride (C2F6) greenhouse gas emissions are generated due to anode effect during the electrolysis process.
An expert in the electrolytic aluminum industry told reporters that the reason why carbon tetrafluoride (CF) and carbon hexafluoride (C ˇ F) are listed as greenhouse gases is mainly because they have a strong ability to absorb infrared radiation. As a result, heat cannot be effectively emitted from the earth's atmosphere, further exacerbating the greenhouse effect. Both the Kyoto Protocol and the Paris Agreement impose limits on emissions of these gases.
According to the "Technical Guidelines for Enterprise Greenhouse Gas Emissions Verification, Aluminum Smelting Industry (Draft for Comments)" released on March 15 this year, the key parameter for anode effect emission verification is aluminum liquid output, and other parameters such as anode effect carbon tetrafluoride emission factor, carbon tetrafluoride global warming potential (GWP), anode effect carbon hexafluoride emission factor, and carbon hexafluoride global warming potential (GWP) all adopt default values. The default value of the process emission factor for the CF4 emission factor for the anode effect is 0.02 kg CF4/tAl, and the default value of the process emission factor for the anode effect C2F6 emission factor is 0.0011 kg C2F6/tAl. The global warming potential (GWP) for CF4 is 6630, and the global warming potential (GWP) for C2F6 is 11100.
"The global warming potential (GWP) is a measure of the intensity of the greenhouse effect of gases. Using carbon dioxide as the reference gas, the GWP of CO2 is 1 and the GWP of CH4 (methane) is 25. This means that the greenhouse effect released per unit of CF4 and C2F6 is many times stronger than carbon dioxide." The expert told reporters that in addition to the strong greenhouse gas effect, these two substances are extremely stable in the atmosphere and hardly decompose. Once these gases are released into the atmosphere, they will continue to exert greenhouse effect for a very long time.
At a press conference held by the China Nonferrous Metals Industry Association on January 30 this year, Chen Xuesen, member of the Standing Committee of the Party Committee, Vice President and Spokesperson of the China Nonferrous Metals Industry Association, revealed that according to the carbon emission verification data of electrolytic aluminum enterprises, there are more than 80 electrolytic aluminum companies across the country will be included in the national carbon market.
