Energy and Exergy Analyses of Different Aluminum Reduction Technologies

Abstract

This paper examines and compares different aluminum reduction technologies found in the literature as alternatives to the current Hall-Heroult technology. The main inefficiencies in the current Hall-Heroult technology were identified and the advantages of the different proposed technologies over the Hall-Heroult technology were determined. The comparison between the different technologies, namely Hall-Heroult, wetted drained cathode, inert anode, and carbothermic, was based on energy and material requirements, and environmental impact. In order to combine all of the evaluation criteria into one numerical value, the exergy concept was utilized as a decision tool. The results emphasize that in order to analyze any conversion system, the exergy of energy, material, environmental impact, and their associated chain production should be taken into consideration.

Effects on primary energy use, greenhouse gas emissions and related costs from improving energy end-use efficiency in the electrolysis in primary aluminium production

“…The generation 3 control system examined in this study is comparable with the intervals from Kermeli et al (2015) when using coal power in global production through the electrolysis process. Obaidat et al (2018) found that wettable cathodes, inert anodes and direct carbothermic reduction can save around 0.88, 1.4 and 0.62 tonnes CO 2 /tonne aluminium, respectively, compared with the GHG emissions prior to their respective implementation. The results in the "Results and analysis" section show that the wettable cathodes, inert anodes and direct carbothermic reduction can save 0.005-2.35, -0.11-2.05 and -0.37-4.98 tonnes CO 2 eq/tonne aluminium, respectively, which covers the values from Obaidat et al (2018).…”

“…Obaidat et al (2018) found that wettable cathodes, inert anodes and direct carbothermic reduction can save around 0.88, 1.4 and 0.62 tonnes CO 2 /tonne aluminium, respectively, compared with the GHG emissions prior to their respective implementation. The results in the "Results and analysis" section show that the wettable cathodes, inert anodes and direct carbothermic reduction can save 0.005-2.35, -0.11-2.05 and -0.37-4.98 tonnes CO 2 eq/tonne aluminium, respectively, which covers the values from Obaidat et al (2018). Additionally, there is a consensus between our article and the article by Obaidat et al (2018) when examining the results for wind power in our article, which indicate that direct carbothermic reduction should provide the smallest GHG emission saving of the three measures.…”

“…Thus, the climate impact of the electrolysis process can be divided into (1) energyrelated GHG emissions from electricity use and (2) process-related GHG emissions resulting from anode consumption and anode effects. The theoretically lowest energy use of the electrolysis is 6.23 MWh/tonne Al (Obaidat et al 2018), while statistics from the International Aluminium Institute (2019c) show that the global average on the energy intensity of the electrolysis in industrial applications is 14.21 MWh/tonne Al. A pilot test on an industrial scale has shown that aluminium production at 12.3 MWh/tonne Al is possible (Svendsen 2018).…”

“…Myklebust and Runde (2005) estimated the reduction in GHG emissions from implementation of direct carbothermic reduction compared with the electrolysis process. Obaidat et al (2018) studied the impact on exergy and CO 2 and CO emissions from implementing wettable cathodes, inert anodes and direct carbothermic reduction compared with conventional electrolysis.…”

Thermo-Chemo-Poromechanical Modeling of the Anode Mixture During the Baking Process: Constitutive Laws and Governing Equations

“…In aluminum industry, Hall-Héroult electrolysis process is highly energy intensive [1]. For this purpose, considerable efforts are invested to optimize this process [2,3].…”