An overview of hydrogen valleys: Current status, challenges and their role in increased renewable energy penetration

Renewable hydrogen is a flexible and versatile energy vector that can facilitate the decarbonization of several sectors and simultaneously ease the stress on the electricity grids that are currently being saturated with intermittent renewable power. But hydrogen technologies, are currently facing limitations related to existing infrastructure limitations, available markets as well as production, storage and distribution costs. These challenges will be gradually addressed through the establishment, operation and scaling-up of hydrogen valleys. Hydrogen valleys are an important stepping stone towards the full-scale implementation of the hydrogen economy with the target to foster sustainability, lower carbon emissions, and derisk the associated hydrogen technologies. These hydrogen ecosystems integrate renewable energy sources, efficient hydrogen production, storage, transportation technologies as well as diverse end-users within a defined geographical region. This study offers an overview of the hydrogen valleys concept analyzing the critical aspects of their design and the key segments that constitute the framework of a hydrogen valley. Α holistic overview of the key characteristics of a hydrogen valley is provided whereas an overview of key, on-going hydrogen valley projects is presented. This work underscores the importance of addressing challenges related to the integration of renewable energy sources into electricity grids as well as scale-up challenges associated with economic and market conditions, society awareness and political decision-making.