Recently, the National Development and Reform Commission and the State owned Assets Supervision and Administration Commission entrusted relevant industry associations and research institutes to carry out research on the development path of key industries such as power, building materials and nonferrous metals under the constraints of carbon peaking and carbon neutrality. Aluminum industry is the basic industry for developing national economy and improving people's living standards, and it is also the largest carbon dioxide emission source of nonferrous industry. CO2 will be emitted in all links of its life cycle, including bauxite mining, alumina smelting, primary aluminum electrolysis, aluminum materials, final product production and recycling of recycled aluminum, as well as the production process of upstream energy. Therefore, exploring the path of carbon emission reduction in aluminum industry is crucial to achieving China's carbon peak and carbon neutrality goals.
Emission status of aluminum industry
In 2018, the global aluminum output was 95 million tons, including 64 million tons of primary aluminum and 31 million tons of recycled aluminum. The global aluminum industry's CO2 emissions are 1.13 billion t equivalent. In the same period, China's aluminum output was 42.75 million tons, including 35.8 million tons of raw aluminum, 6.95 million tons of recycled aluminum, and 520 million tons of CO2 equivalent emissions from China's aluminum industry.
Figure 1 CO2 emissions of global and Chinese aluminum industry in 2018
The aluminum industry includes the primary aluminum production (aluminum mining and mining, aluminum oxide production, anode production, electrolytic aluminum production), recycled aluminum, aluminum processing and product manufacturing and other industrial chains. The CO2 emissions from the primary aluminum production account for 94.85% of the CO2 emissions of the aluminum industry, as shown in Figure 2.
Figure 2 Proportion of carbon dioxide emissions of various industries in the aluminum industry
In the production of primary aluminum, energy consumption and emission of CO2 account for a large proportion, up to 77.5% (of which, electricity consumption and emission of CO2 account for about 64.3% and thermal energy consumption and emission of CO2 account for 13.1%).
Figure 3 Proportion of Emission Sources in Raw Aluminum Production
Carbon emission characteristics of China's aluminum industry
Coal power accounts for a large proportion in electrolytic aluminum production in China
Compared with European and American electrolytic aluminum enterprises, China's electrolytic aluminum industry has a higher carbon emission in the electrolytic link, which is mainly due to the heavy dependence of domestic raw aluminum power on thermal power. According to statistics, by the end of 2020, China's electrolytic aluminum operating capacity will consume 65.2% of its own power and 34.8% of its grid power. Among them, all the self provided power is thermal power, and the grid power is divided according to the power generation structure of the regional grid. It is estimated that in the energy structure of electrolytic aluminum, thermal power accounts for 88.1% and non fossil energy accounts for 11.9%.
Table 1 Comparison of energy structure of foreign mainstream aluminum enterprises in 2020
There is limited space for the energy consumption index of electrolytic aluminum and aluminum oxide to decrease significantly
At present, the most typical production process of primary aluminum production is still cryolite alumina molten salt electrolysis (Hall Elut molten salt electrolysis). After more than 100 years of continuous process optimization, the potential of alumina and electrolytic aluminum production process indicators has reached the limit. Without disruptive production process changes, there is limited room for aluminum smelting indicators to decline.
Key carbon reduction technologies still have bottlenecks
In aluminum smelting production, the reserves of zero carbon and negative carbon core technologies such as low temperature waste heat recovery, waste free metallurgy, inert anode, high-efficiency ultra low energy consumption aluminum electrolysis, carbon dioxide capture and utilization are insufficient.
Low proportion of recycled aluminum
The calculation shows that the carbon dioxide emission of recycled aluminum is only about 4% of that of the original aluminum. In 2020, the global aluminum output will be 99.1 million tons, including 33.8 million tons of recycled aluminum, accounting for 34.1% of the global aluminum output. In the same year, China's aluminum output was 44.48 million tons, including 7.4 million tons of recycled aluminum, accounting for 16.6% of the domestic aluminum output. There is a big gap between the output of recycled aluminum in China and the international average level.
The aluminum industry achieves carbon peak and carbon neutral path
In combination with the carbon emission characteristics of China's aluminum industry, the path to achieve carbon peak and carbon neutrality mainly includes improving energy utilization efficiency, industrial structure adjustment, energy structure adjustment, zero carbon (negative carbon) technology development, etc.
Energy saving and efficiency improvement, reducing carbon emission intensity
In 2005, the Proposal of the CPC Central Committee on Formulating the Eleventh Five Year Plan for National Economic and Social Development for the first time raised resource conservation to China's“ Basic National Policy”. Three“ s since 2006; Five Year Plan” In, the energy saving indicator for reducing energy consumption per unit GDP is always listed as“ Five Year Plan” One of the important restrictive indicators of. 2006— In 2019, China's energy consumption per unit of GDP decreased by 42.5%, carbon dioxide emissions per unit of GDP decreased by 47.9%, and the AC power consumption of electrolytic aluminum decreased from 14575 kWh/t to 13555 kWh/t, down by about 7.0%.
Multiple calculations show that energy conservation and improving energy utilization efficiency contribute more than 70% to China's goal of reaching the peak of carbon emissions by 2030, and renewable energy and nuclear power contribute nearly 30%. Carbon dioxide capture and storage technology is difficult to make substantial contributions to China's goal of reaching carbon peak by 2030.
Therefore, in order to achieve carbon peaking and carbon neutrality, we should increase the promotion and application of energy-saving technologies and equipment, innovate third-party energy-saving service modes such as energy contract management, promote energy-saving technologies, energy-saving equipment, energy cascade utilization and waste heat utilization, and make projects to improve energy utilization efficiency come into effect; Strengthen the benchmarking management of the whole process, whole chain and all elements, carry out energy-saving diagnosis, find gaps, carry out lean management, take continuous improvement as the carrier, tap the potential of energy conservation and consumption reduction, and optimize technical and economic indicators.
Optimize the aluminum industrial structure and increase the output of recycled aluminum
Consolidate and eliminate the excess capacity of electrolytic aluminum, and strictly control the ceiling capacity of 45 million tons of electrolytic aluminum; Increase“ Urban Mines” Development efforts, vigorously develop the short process smelting process, greatly improve the production capacity of recycled aluminum, and increase the proportion of recycled aluminum; Select coastal and hydropower rich green energy areas for aluminum industry layout, promote industrial cluster development, build aluminum cluster industrial base, and reduce carbon emissions in the process of logistics transportation and metal remelting.
Optimize energy structure and realize green development of aluminum industry
Optimizing the energy structure, shrinking the thermal power capacity of electrolytic aluminum and increasing the proportion of clean energy use are the most direct and effective ways to achieve carbon peak and carbon neutrality in the aluminum industry. Main measures include:
1) Eliminate coal-fired self owned power plants, or replace power generation rights of self owned units with clean energy;
2) Clean transformation of self owned power plants, replacing coal with low-carbon or zero carbon energy;
3) Utilize the factory buildings and surrounding environment of the enterprise to build wind and photovoltaic stations and cooperate with energy storage technology to realize direct supply of clean energy;
4) Rely on hydropower and nuclear power resources to replace electrolytic aluminum production capacity and realize direct utilization of clean energy;
5) Promote low-carbon transport and gradually introduce electric and hydrogen energy transport vehicles.
Promote technological innovation and achieve disruptive breakthroughs in carbon reduction technology
Integrate domestic scientific research institutes, establish a low-carbon green development innovation platform for China's nonferrous metals industry, focus on energy conservation and carbon reduction, clean production, clean energy and other fields to layout forward-looking, strategic and subversive projects, implement green technology tackling actions, and strive to achieve waste free metallurgy, high-efficient ultra low energy consumption aluminum electrolyzer, inert anode and carbon dioxide capture in the aluminum industry Breakthroughs have been made in utilization and storage technologies to provide technical support for green development.
Carbon peak and carbon neutral target in aluminum industry
In October 2019, the 96th meeting of the Council of the International Aluminum Association decided to establish a working group on ways to reduce greenhouse gas emissions, which is responsible for the work on ways to reduce greenhouse gas carbon emissions in the international aluminum industry, and initially formulated the coverage of greenhouse gas emissions in the aluminum industry and the goal and way of zero net greenhouse gas emissions by 2050.
In March 2021, the International Aluminum Association released the 2050 Aluminum Greenhouse Gas Emission Path, proposing the goal of reducing greenhouse gas emissions in the global aluminum industry: by 2050, the global aluminum industry will cover the whole industry chain (bauxite, alumina and electrolytic aluminum production, aluminum processing and manufacturing, as well as waste recycling and regeneration) under the condition of the global aluminum output of 170 million tons (including 90 million tons of raw aluminum output) The total emission of is 250 million t CO2 equivalent; Among them, the emissions generated by power consumption in all processes related to primary aluminum production (especially smelting process) will be close to zero, with direct emissions of 200 million t CO2 equivalent, and the emissions of fuel combustion and power consumption during recovery and manufacturing will be 50 million t CO2 equivalent.
Referring to the greenhouse gas emission reduction target of international aluminum industry, combined with the current CO2 emission status of China's aluminum industry, and the non-ferrous industry proposed by China Nonferrous Metals Industry Association, it is expected that China's aluminum industry is expected to achieve a carbon peak by 2025, with a peak of about 560 million t CO2 equivalent.
