Through HACDOS, new ways of producing renewable hydrogen from wastewater using solar energy have been explored.
The HACDOS project has been completed, a research initiative that has studied new ways of producing renewable hydrogen from wastewater using solar panels specifically designed for this purpose. The technology analysed aims to transform used water into a clean energy source, while simultaneously reducing its pollutant load.
The project has been developed by a consortium formed by Facsa –leading entity–, Enagás (with the collaboration of Enagás Emprende), Universitat Rovira i Virgili and the technology centre Eurecat, with the collaboration of Consorci Besòs Tordera, which provided the facilities of the Granollers WWTP for pilot testing.
HACDOS was carried out between October 2022 and November 2025 and was conceived with a dual objective: to explore more sustainable alternatives for wastewater treatment while, at the same time, generating hydrogen in a more accessible and environmentally friendly way. Unlike conventional technologies, which often rely on fossil fuels or high electricity consumption, this research has focused on solar photocatalysis, a process that uses sunlight to activate materials capable of generating hydrogen.
The first phase of the project consisted of studying different types of wastewater in the laboratory to assess how much hydrogen they could produce. Following these tests, the team built two photocatalytic solar panel prototypes, of 1 m² and 10 m², which were installed at the Granollers WWTP to be tested under real conditions, using wastewater and natural sunlight.
The results show that, although the technology is still at an early stage and the amount of hydrogen produced is low, the project confirms its potential and opens up new lines of development for further progress. The knowledge generated will enable the optimisation of future photocatalytic system designs and reinforces the commitment to new solutions that integrate water management and renewable energy. With HACDOS, the consortium lays a solid foundation for future developments and explores innovations that contribute to a more sustainable energy transition.
This project has a total budget of €555,116.72. Project CPP2021-008619, funded by MCIN/AEI /10.13039/501100011033 and by the European Union NextGenerationEU/ PRTR.
