Preface

On behalf of the organizing committee, it is our great pleasure to present the proceedings of the 11th International Conference on Sustainable and Renewable Energy Engineering (ICSREE 2026), held in the vibrant city of San Sebastián, Spain, from May 20 to 23, 2026.Building on the success of previous editions, this year's conference once again served as a vital platform for researchers, engineers, and policymakers to share latest advancements and practical solutions in the pursuit of a sustainable energy future.ICSREE 2026 attracted participants from 19 countries across four continents, representing a broad range of geographic and institutional backgrounds.This diversity enriched the dialogue on both global energy transitions and locally relevant strategies.