From fermentation emissions to renewable energy: demonstration of on-site CO₂-to-CH₄ methanation in wineries

Abstract

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

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

This demonstration introduces three major industrial innovations to the sector:

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

During the 2025 vintage (9^th–26th of September), the system successfully recovered 17 tons of CO₂. A portion of this captured CO₂ was used to feed the methanation demonstrator. The tests, utilizing this real fermentation CO₂, produced outlet gas containing approximately 80 % CH₄ (dry basis) and achieved a 90 % CO₂ conversion. These operational values are consistent with literature [2]. The reactor operated continuously for over 300 hours with no observed catalyst deactivation, proving high operational stability.

Ongoing work is focused on improving thermal control to push the overall CO₂ conversion closer to thermodynamic equilibrium, as well as validating numerical models and composition profiles to support future optimization and scale-up.

Initial results demonstrate a viable and highly replicable technological pathway for wineries to valorize fermentation CO₂ into renewable CH₄. This innovation not only reduces direct emissions but also produces a locally usable fuel for heating, process energy or mobility, driving true circularity within this 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

3. Sanz-Martínez, A. From Fermentation Emissions to Renewable Energy: Demonstration of On-Site CO2-to-CH4 Methanation in Wineries. Recording of the presentation delivered at Enoforum Spain 2026, Zaragoza, 20–21 May 2026. Available at: https://www.youtube.com/watch?v=sJc1N2kzIi0 ; https://www.youtube.com/watch?v=Q4f0HIWb2e8