Transforming fermentation CO₂ into renewable methane is now possible at winery scale.

Andrés Sanz Martínez’s presentation at Enoforum 2026 showcases the experience developed at Viñas del Vero, where, during the 2025 harvest, 17 tonnes of CO₂ were recovered and a 90% conversion to CH₄ was achieved through methanation using green H₂. The system operated for more than 300 hours without catalyst deactivation, demonstrating its potential to reduce emissions and valorize the CO₂ generated during fermentation within the framework of the European FUELPHORIA project.

Authors: Andrés Sanz-Martínez1, Sergio Iglesias1, Christian Aragón-Briceño1, Daniel Montané2, Francesc Medina2, Abel Toscano2, Ricardo Fernández3, José María Ayuso3

1 CIRCE – Research Centre for Energy Resources and Consumption, Zaragoza, Spain
2 URV-Departament d′Enginyeria Química, Universitat Rovira i Virgili, Tarragona, Spain
1 Gonzalez Byass, Viñas del Vero, Barbastro, Spain

Corresponding Author: lasanz@fcirce.es

Work presented at Enoforum 2026 (Zaragoza, 20–21 May).

The wine industry releases significant amounts of biogenic CO₂ during alcoholic and malolactic fermentation, a valuable resource that is generally emitted directly into the atmosphere [1]. To address this issue, the EU FUELPHORIA project is testing a pioneering circular-economy solution at the Viñas del Vero winery (Somontano, Aragón, Spain).

From Fermentation CO₂ to Renewable CH₄ in the Winery

The value chain comprises: (i) CO₂ collection from multiple fermentation tanks; (ii) purification to 99.95% and compression for storage; (iii) supply of green H₂ via electrolysis; and (iv) conversion in two-stage methanation reactors. In addition, the captured CO₂ has further uses within the winery, including: (a) gas mixing with the solid–liquid must during red winemaking to improve homogenization while reducing electricity consumption; (b) inerting tanks and presses to displace O₂ and mitigate microbial growth; (c) acidification of wash water to improve cleaning efficiency and reduce water consumption; and (d) recovery of volatile aroma compounds captured in the CO₂ for reintroduction into the wine.

This demonstration presents three major industrial innovations for the sector:

  • It is the first CO₂-to-CH₄ conversion system integrated into a winery in Europe.
  • It uses advanced nickel-based catalysts that provide high activity and stability for CO₂ conversion [2].
  • It features a modular and scalable design, tailored to accommodate the seasonal availability of CO₂ during the harvest period.

Winery Methanation: Results from the 2025 Harvest

During the 2025 harvest (9–26 September), the system successfully recovered 17 tonnes of CO₂. Part of the captured CO₂ was used to feed the methanation demonstrator. Tests using this real fermentation-derived CO₂ produced an outlet gas containing approximately 80% CH₄ on a dry basis and achieved a CO₂ conversion rate of 90%. These operating values are consistent with the literature [2]. The reactor operated continuously for more than 300 hours without any observed catalyst deactivation, demonstrating high operational stability.

Ongoing work focuses on improving thermal control to bring overall CO₂ conversion closer to thermodynamic equilibrium, while also validating numerical models and composition profiles to support future process optimization and scale-up.

The initial results demonstrate a viable and highly replicable technological pathway for wineries to valorize fermentation-derived CO₂ by converting it into renewable CH₄. This innovation not only reduces direct emissions, but also produces a fuel that can be used locally for heating, process energy, or mobility, thereby promoting true circularity within the sector.

References:

1.Gueddari A. et al., J. CO2 Util., 2025, 96, 103094. https://doi.org/10.1016/j.jcou.2025.103094

2.Tommasi M. et al., Chem. Eng. Res. Des., 2024, 201, 457–482. https://doi.org/10.1016/j.cherd.2023.11.060