Aguas de Barcelona (AGBAR) operates 137 wastewater treatment plants in Catalonia, 56 of them were included in the Energy Saving and Efficiency Plan.

AESA carried out some audits to evaluate the power generation potential that could be obtained using the biogas produced in sludge anaerobic digestion processes in those 137 plants, distinguishing between the plants that already had digesters (which would only require the installation of a biogas plant) and those that had not (which would require both the installation of digesters and a biogas plant).