Life Methamorphosis

The new biogas biological purification plant, is part of the Mixed Unit of Renewable Gas research second phase, which starts at the end of 2016 as a joint project of Naturgy and EnergyLab Technology Centre. This research unit has the collaboration of Bens S.A. WWTP, the financing of FEDER funds from the European Union and the co-financing of GAIN (Axencia Galega de Innovación).

In this project, part of the biogas generated in the WWTP is purified. It means that the concentration of CO2 is reduced in order to produce biomethane. In practice, different industrial scale purification systems can be found, which are based on processes of chemical absorption, adsorption or other methods such as cryogenic or the use of selective membranes. The main problem of these technologies is the high price, especially on a small scale, so EnergyLab has been specializing in low cost purification technologies since 2014. Among which the accelerated carbonation and biological methanation stand out. In this latest technology, hydrogenotrophic arches use H2 and CO2 to produce CH4, this system is also known as Power2Gas because it allows the use of surplus renewable energy through the generation of H2 and its conversion to biomethane, which can be injected into the gas network or used in mobility. These technologies allow to reach purification ratios above 95% of CH4.

The biological purification plant installed in the WWTP may use both the CO2 present in the biogas, and the existing one from the residual current of the other pilot (membrane plant).

This pioneer upgrading plant is an important achievement that positions Galicia, not only as a benchmark for innovation in the field of bioenergy but also as an example to follow in terms of decarbonisation and circular economy.