In 1990, the first GIEC report was published, assessing the influence of human activities on the climate change and its harmful consequences for future generations. More than 30 years later, almost half of the global population is considered as highly vulnerable: drought, heatwaves, forest fires, storms, floods, water shortages…natural disasters have been multiplying at an alarming rate and reducing the emissions of greenhouse gases appears as the main today’s stake. Committed to the Paris Agreement, the European energy system increasingly needs to adapt while electricity cost is undergoing a record-breaking surge influenced by the geopolitical situation. In this framework, COMETES, financed by the European Commission (Marie-Sklodowska-Curie-Action postdoctoral fellowship 2023), was designed to meet the REPowerEU plan objectives: produce affordable, secure and sustainable energy for the European Union. Concentrated Solar Power (CSP) technology emerged these years as one of the most promising solutions. It uses an unlimited energy source that can be combined with thermal energy storage (TES) systems to manage the solar energy intermittency. However, this technology remains technically and economically uncompetitive compared to other energies. This is mainly due to a currently low solar-to-electric conversion and the use of expensive materials required to resist the operating conditions. In particular, these materials are in direct contact with high-temperature molten salts used as heat transfer fluid (HTF) which can lead to dramatic corrosion. One increasingly considered solution is to improve the thermodynamic efficiency of the plant using a Brayton cycle operating with supercritical CO2. However, these new systems would require higher operating temperatures (>700 °C) and thus the use of new molten salt systems (among which carbonates) which constitute a corrosive environment for the plant’s structural materials.
COMETES aims at managing this issue by using slurry aluminide coatings applied on low chromium steels. These coatings, especially developed at INTA, have already demonstrated their potential in nitrate and carbonate salts, and they present the advantage to be 25% less expensive than Ni-based alloys currently used as plant constituent materials. However, limitations remained to allow the industrial use of this technology and COMETES focused on overcoming the current barriers through 6 objectives:
- Develop and improve different coating deposition processes to allow large-scale exploitation and on-site O&M.
- Develop low-cost coated material solutions able to operate on CSP in new HTF/TES fluids at 700 °C.
- Investigate the mechanical and the Stress Corrosion Cracking (SCC) resistance of the coated materials developed.
- Investigate the suitability of the developed coatings on industrial-representative components.
- Investigate the repairability of the developed coating.
- Broaden the existing literature through significant dissemination, communication & exploitation productions.
These objectives were expected to allow the achievement, in the long term, of 3 general objectives (GO): 1/ Increase the solar-to-electric conversion of CSP plants by 20% and the storage capacity by >25%, 2/ Decrease the Capital Expenditures (CAPEX) by >2% and 3/ to decrease the Operational expenditures (OPEX) by 25% as well as the O&M. These expected progresses were supposed to reduce shutdowns, mitigate the risk of leaks, and allow more efficient integration of CSP with other renewable energy sources, contributing to Europe’s strategic goals for energy independence and sustainable power generation. In the framework of CoMeTES, the objective is to increase the Technology Readiness Level (TRL) of the coated technology from 3 to 5 in order to progress through a future industrial exploitation.
Beyond technical results and research analysis, CoMeTES was built to actively promote scientific dissemination, communication, and exploitation of knowledge and coating technology. Through publications, conference presentations, and public outreach activities, the project enhances the visibility of CSP-TES research and fosters collaboration across academic and industrial communities. This integrated approach ensures that the results not only advance scientific understanding but also lay the groundwork for future industrial adoption and societal impact, by supporting more sustainable, reliable, and cost-effective renewable energy technologies.
By achieving these objectives and increasing the TRL, COMETES paves the way for pilot-scale deployment at very short-term, industrial adoption, and measurable reductions in costs and emissions at mid-term, thus bridging the gap between lab-scale research and societal impact.
