The 9th edition of the International Conference on Renewable Energy and Environment Engineering (REEE 2026) brings together leading researchers, international scientific communities, and industry leaders to explore the latest innovations in renewable and environmental engineering, with a strong emphasis on real-world impact and true global collaboration. REEE 2026 will be held in Astana, Kazakhstan from June 12 to June 15, and is organised by L.N. Gumilyov Eurasian National University (Kazakhstan), co-sponsored by the University of Brest (France) including its CNRS laboratory IRDL, and the University of Agder (Norway). The event is also supported by several partner institutions including Germany’s University of Applied Sciences, Portugal’s Polytechnic of Porto, and France’s ISEN Brest, French Naval Academy and ENIB Brest.