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Development of the optimum AGRAL cermet manufacturing process for aluminium inert anode application and fuel cell interconnect plates.

Periodic Reporting for period 2 - AGRAL (Development of the optimum AGRAL cermet manufacturing process for aluminium inert anode application and fuel cell interconnect plates.)

Reporting period: 2016-11-01 to 2018-10-31

The aluminum industry currently relies on carbon anodes for the electrolysis process involved in the production of primary aluminum. This dependence leads to air pollution and additional costs. The objective of the project is to replace the current carbon anode by the AGRAL (Advanced Green Aluminum Anodes) inert anode leading to zero direct CO2 emission during the electrolysis process and an increase of life duration of the anodes. In this project, the AGRAL cermet will be developed and tested for two applications: the inert anode for the aluminum electrolysis and hydrogen and fuel cell interconnect protection.
This potential breakthrough technology can be a cornerstone of a low-carbon production of aluminum. Carbon anodes are responsible for 7.04 million of tons of CO2 per year in EU for 4 million of tons of primary Aluminum produced (in 2013). To reduce the global CO2 emission, quotas to industry were assigned; the Aluminum industry included; which is estimated to cost this industry more than 140M€ in 2020.
The AGRAL project aims at developing at the industrial level a multi-material inert anode based on a cermet, mix of oxide and metallic compounds, coated on a metallic substrate. Different ways to produce this cermet were identified (Thermal spray (HVOF, cold spray), powder metallurgy (HIP, natural sintering, dip-coating and co-sintering). The objective is to study these processes in detail thanks to partners mastering them and to develop the best candidate for the industrial level.
In the field of hydrogen and fuel cell application, the AGRAL cermet’s properties are interesting to increase the durability of the solid oxide fuel cells and electrolysis cells. The core of the technology is the stack of the electrolysis cells separated by interconnect plates which should present very high properties against corrosion.
The AGRAL project is a 3.5-years project (kick-off date: 01 May 2015) with a budget of 8,5 M€ gathering 9 partners from 5 European countries; led by RioTinto-Aluminium Pechiney, with the collaboration of CEA (France), ENISE (France), FST (Netherland), Bodycote (Germany), Fraunhofer IFAM (Germany), Aachen University RWTH (Germany), Safe Cronite (Czech Republic) and Ecoinnovazione (Italy).
About inert anode application, powder specifications have been defined for both thermal spray and HIP processes. Safety procedures and measures to deal with the cermet powders were established by all the partners to comply with the regulations. Optimization of coating of 26 lab size anodes were carried out using thermal spray processes or cold spray. 30 lab scales anodes and ten pure cermet samples were made using powder metallurgy technique. Oxidation test carried out before using the anode in the electrolysis cell led to formation of material defects due to C diffusion. Limitation of the C-content to prevent severe porosity formation is estimated to be 40 ppm maximum. Pre-prototype upscale was done using HIP process and Ni alloy substrate cast. An electrolysis bench test referred to “BTX1000 test” was designed by AP and implemented in AP’s workshop for the testing of pre-prototype anodes. The tests demonstrated the ability of the cell to ensure homogeneous bath chemistry during more than 500 hours.
Transferability study to Hydrogen and Fuel cell application: spray techniques were tested and the deposition by CCDS (Computer Controlled Detonation Spraying) process was validated. Electrical tests to measure conductivity and resistance of the different have shown good conductivity with adapted thermal pre-treatment for CCDS and screen printing techniques. Oxidation behaviour at 800°C is modified by the AGRAL material coating. A real H2 production test is still running to obtain a minimum of 1000 h of aging.
Techno-economic studies and environmental impact were carried out: production of 1 ton of primary (liquid) aluminium with the inert anode, based on the HIP technology, has a better environmental performance of 22%-50% (depending on the impact category) than the carbon one. Powder consumption and recovery, HIP coating process, metallic core composition have been identified as the main levers for inert anode cost production optimization. For the SOFC/SOEC application, the cost/benefit ratio was assessed positively (including the environmental impact).
In term of exploitation plan, the achievements of the project allowed to progress in the development of the manufacturing of the anode by both HIP and thermal spray processes but did neither complete the scale up of the manufacturing of large size anodes nor the assessment of the anode in operating conditions. Moreover, Alcoa and Rio Tinto launched a new joint venture, ELYSIS, for larger scale development and commercialization of an inert anode technology. The ELYSIS technology is based on Alcoa development, shape and material of the inert anode are different from the AGRAL solution developed by RTA. Following the foundation of ELYSIS joint venture (JV), both ALCOA and RTA partners of the JV contribute to the development of the ELYSIS technology and do not pursue their internal inert anode project. That means that there is no immediate exploitation of what we learned, but knowledge and know-how developed by the AGRAL partners might be reactivated in the future development of ELYSIS technology.
The AGRAL project will bring economically viable solutions and technologies as regards the anodic material. Such step is requested to develop the inert anode technology allowing an ambitious reduction in specific Greenhous Gas (GHG) emission intensity. The use of the AGRAL cermet instead of the carbon anode in the primary Aluminum production is expected to decrease 35% direct CO2 emissions. About the hydrogen and fuel cell application, hydrogen is currently mainly produced through Steam Methane Reforming which is a high CO2 emission process. The improvement of the durability of the hydrogen and fuel cell will enable to have an economically viable technology to provide a non-fossil energy source that could be used in many applications.
This technology could be a decisive trigger for Europe to meet its commitment in terms of Climate Change, regarding the 2050 Roadmap for moving to a competitive low carbon economy. Indeed, inert anode technology will also remove other hazardous components such as SO2 and PAHs. Besides, AGRAL technologies can be applied steel and aluminum or cermet industries. Reduction of CO2 emission will lead to the reduction of the compliance costs of the EU emissions trading system (ETS). This will allow the European aluminum industry to recover competitively.
AGRAL project will participate in boosting Europe’s industrial leadership, fostering employment and opening new market opportunities. The inert anode breakthrough technology is of critical importance for the whole Aluminum industry, exposed to a global competition and suffering from production decline over the last years. Workers must change every 25 days the consumed carbon anode; this exposes them to hazardous fumes and very high heat. Inert anode with an expected life duration of one year will dramatically increase the quality conditions of work. Increase of competitiveness of European aluminum industry is expected to keep employment in Europe and avoid redundancy plans.
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