In the context of a decarbonised and circular economy, renewable gases are set to play a crucial role as an energy source. In addition, there is an increasing demand for new alternative and neutral fuels, which implies the need to advance in the research and implementation of technologies that demonstrate their technical, economic and environmental viability.

In this context, the Joint Research Unit of Renewable Gas was born, promoted with the support of the Xunta de Galicia through the Galician Innovation Agency. This is a joint project between Naturgy, the EnergyLab Technology Centre and EDAR Bens, a supra-municipal public company that provides wastewater treatment services in the municipalities of A Coruña, Arteixo, Cambre, Culleredo and Oleiros.

The origin of the Joint Unit dates back to 2016. The first phase, which ran until 2019, focused on increasing knowledge in renewable natural gas or biomethane production processes in the wastewater treatment plant (WWTP) sector. Very remarkable results were achieved, such as commissioning a membrane-based purification plant and the first biological methanation plant in Spain at the Bens WWTP. In addition, the biomethane generated in these pilot projects is currently being used as an alternative fuel in the fleet of Bens WWTP vans and in an adapted metropolitan bus.

New lines of research

At present, the Joint Unit is in a second consolidation phase with the aim of continuing to make progress in the work being carried out and in which it is committed to research into other renewable gases, such as green hydrogen, biohydrogen and syngas, which will make it possible to assess their impact on current infrastructures and end consumers.

In the specific case of green hydrogen, activities will be undertaken along the entire value chain, covering production, transport, storage and end use. On the one hand, hydrogen generation is being investigated through a biological process called dark fermentation, in which aerobic sludge from the Bens WWTP is the raw material that is converted into biohydrogen. On the other hand, the use of anaerobic sludge from the WWTP as a solid fuel is being studied in a gasification plant located at the EnergyLab facilities.

In addition, the impact of the use of different renewable gases and their mixtures is being studied. For example, for injection into the gas grid and use in stationary and mobile applications (vehicles). The project has the capacity to cover the annual energy needs of around 2,800 homes and supply a fleet of 3,000 cars or more than 60 city buses.

This Joint Unit not only contributes to energy efficiency and environmental sustainability in the area of wastewater treatment, but its results can also be applied to key sectors of the Galician economy, such as the food industry or the agricultural and livestock sector, helping to position Galicia as a European region of reference in the production and application of renewable gas as a new energy vector.