Mª Begoña Peris Martínez – Agricultural Engineer, Polytechnic University of Valencia (Spain); Master in Natural Environment Protection Techniques, Polytechnic University of Madrid (Spain); Master in Agri-Food and Environmental Economics, Polytechnic University of Valencia (Spain)

Abstract: The implementation of large-scale biogas and biomethane plants has intensified in Europe as part of energy transition and circular economy strategies. However, numerous scientific studies and territorial analyses document environmental, social, and landscape impacts when these installations are located in rural areas of high agricultural and touristic value. This paper reviews international literature on odor emissions, air quality, digestate effects on agricultural soils, landscape transformation, and social acceptance, incorporating empirical examples from municipalities and viticultural regions in Europe. Based on this evidence, the territorial suitability of the biomethane plant project in San Antonio de Requena (Valencia, Spain) is critically assessed. The results suggest that, in territories where economic value depends on terroir, environmental quality, and sensory experience, implementing such infrastructures presents structural incompatibilities that are difficult to mitigate.

Keywords: biomethane; biogas; viticulture; wine tourism; spatial planning; social acceptance

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1. Introduction

Biomethane production via anaerobic digestion has become a relevant technology in European energy policies. However, the sustainability of these facilities depends not only on technical efficiency but also on territorial location, scale, and socioeconomic context (Bacenetti et al., 2016; Lupp et al., 2014).

In winegrowing and wine tourism areas, soil, landscape, environmental quality, and sensory perception are essential productive assets. The central question arises: is the implementation of large-scale biomethane plants compatible with territories whose economy relies on the balance of soil, landscape, and the sensory experience associated with wine?

Experiences from various European municipalities indicate that impacts associated with these facilities are not exceptional but recurrent in certain territorial contexts.

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2. Study Area and Project Location

The project is located in the municipality of Requena (Valencia, Spain), specifically in Industrial Zone 12, plots 202 and 298, according to official documentation published in the Diario Oficial de la Generalitat Valenciana (DOGV, 2025).

The proposed plant would be situated approximately 1.5 km from the inhabited nucleus of San Antonio de Requena and 6 km from the urban center of Requena, in an area dominated by viticulture and wine tourism. These distances are relevant for assessing odor, landscape, and social perception impacts.

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3. Odor Emissions and Environmental Quality

Emissions of odorous compounds, mainly hydrogen sulfide (H₂S), are among the most documented impacts of biogas plants. Zhang et al. (2024) identified H₂S as the main cause of nuisance, with peaks during the reception and handling of manure.

Wiśniewska et al. (2020) demonstrated that odor dispersion depends on meteorological factors, limiting the effectiveness of mitigation measures even in modern facilities. This phenomenon explains persistent conflicts in municipalities such as Babilafuente (Salamanca, Spain), where this type of installation is planned, and in Casasbuenas (Toledo), where the plant is operational and complaints about odors have been filed with the Public Prosecutor.

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4. Air Quality and Associated Risks

Compounds such as ammonia, H₂S, and siloxanes can be released during operational phases or technical failures ( Werkneh , 2022). In tourist areas, these episodes affect perceptions of environmental safety and the destination’s image.

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5. Digestate, Agricultural Soils, and Terroir

Insam et al. (2022) concluded that digestate application can alter soil microbiota, depending on its composition, dose, and agronomic management. These alterations include changes in microbial community structure and biogeochemical cycles of nitrogen and carbon.

Although large-scale biomethane plants are not located directly on vineyards, centralized management of large volumes of manure and digestate can induce indirect and cumulative effects at the territorial scale, through agricultural application of digestate, atmospheric deposition of nitrogen compounds, and changes in fertilization practices.

In viticultural regions such as Piedmont (Italy), debates and local resistance to biogas plant expansion have been documented, linked to perceptions of environmental and social impacts (Paolini, 2018). Since soil microbiota is a functional component of viticultural terroir, these alterations are particularly relevant in areas where product quality, soil stability, and environmental perception form part of the economic value of the production system (Zarraonaindia et al., 2015).

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6. Landscape, Tourism, and Social Acceptance

Gaviglio et al. (2017) demonstrated that the implementation of biogas plants significantly reduces social acceptance in rural landscapes with high aesthetic or touristic value. Lupp et al. (2014) observed similar results in Germany, even in regions with a long tradition of biogas use.

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7. Integrated Assessment of the Requena Case

Requena combines established viticulture, wine tourism, and reliance on landscape and soil. The proximity of the proposed plant to San Antonio de Requena (~1.5 km) and nearby productive and residential areas makes its location a relevant risk factor.

Compared to European experiences, the associated risks are neither hypothetical nor easily mitigated, particularly in terms of social perception, landscape, and impacts on high-value agricultural soils.

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8. Comparison Between Centralized and Decentralized Plants

Scientific evidence suggests that the location and scale of biomethane plants critically determine their territorial impact, especially in winegrowing and wine tourism areas (Bacenetti et al., 2016; Lupp et al., 2014).

8.1 Scale and Waste Management
A centralized macroplant receives large volumes of manure from multiple farms, concentrating waste management at a single point. This results in:

• Greater risk of odorous emissions and pollutants (H₂S, NH₃, particulates)
• Frequent manure transport, increasing diffuse emissions, traffic, and spill risks (Zhang et al., 2024)

Decentralized plants at individual farms process only local manure, reducing transport, emission concentrations, and accidental risks.

8.2 Landscape and Social Impact
Macroplants require large industrial buildings and digestate storage, visible from a distance, negatively affecting landscape perception and tourism experience (Gaviglio et al., 2017). On-farm plants are smaller, less visible, and more socially accepted.

8.3 Economic and Energy Efficiency
Macroplant: concentrates biomethane production, but energy efficiency is not always achieved due to fuel consumption, CO₂ emissions, and initial investment associated with transporting manure from multiple farms, limiting circular economy benefits.

Micro/decentralized plants: reduce transport emissions, allow farms to manage manure directly, and facilitate self-sufficiency in energy, with reduced risks.

8.4 Section Conclusion
In viticultural contexts like Requena, where landscape, environmental quality, and sensory perception are strategic assets, a centralized macroplant model increases environmental and social impacts that are difficult to mitigate. Decentralized plants would enable energy recovery from manure with significantly lower territorial impact, preserving soil integrity, landscape, and wine tourism.

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9. Conclusions

Scientific and territorial evidence demonstrates that large-scale biomethane plants generate impacts on air, soils, landscape, and social acceptance. In winegrowing and tourist territories, these effects acquire a structural dimension, directly affecting economic competitiveness based on terroir and sensory experience.

The implementation of a macroplant in San Antonio de Requena presents structural incompatibilities with the existing development model, and its location should be reconsidered based on scientific and territorial planning criteria.

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References
Bacenetti, J., et al. (2016). Life cycle assessment of biogas systems. Frontiers in Bioengineering and Biotechnology, 4, 26.
Capelli, L., et al. (2013). Odour impact assessment in industrial plants. Atmospheric Environment, 79, 731–743.
Gaviglio, A., et al. (2017). Biogas plants and rural landscape perception. Land Use Policy, 67, 330–341.
Insam, H., et al. (2022). Digestate effects on soil microbial communities. Environmental Chemistry Letters, 20, 1565–1583.
Lupp, G., et al. (2014). Public acceptance of biogas plants. Energy Policy, 67, 173–182.
Riva, C., et al. (2014). Environmental impacts of biogas plants in agricultural areas. Science of the Total Environment, 497–498, 299–309.
Paolini, V., et al. (2018). Environmental impact of biogas: A short review of current knowledge. Journal of Environmental Science and Health, Part A, 53(10), 899–906.

Werkneh, A. A. (2022). Biogas impurities: environmental and health implications, removal technologies and future perspectives. Heliyon, 8(10), e10929. https://doi.org/10.1016/j.heliyon.2022.e10929
Zarraonaindia, I., et al. (2015). The soil microbiome influences grapevine-associated microbiota. mBio, 6(2), e02527-14.
Wiśniewska, M., et al. (2020). Odour emissions from biogas plants. Applied Sciences, 10(3), 1093.
Zhang, Y., et al. (2024). Odorous gas emissions from anaerobic digestion plants. Journal of Cleaner Production, 432, 139834.

El País. (2025, November 2). La rebelión de los pueblos contra las plantas de biometano: el gas limpio que asusta por el mal olor [The rebellion of towns against biomethane plants: The “clean gas” that frightens because of bad smell]. El País. https://elpais.com/clima-y-medio-ambiente/2025-11-02/la-rebelion-de-los-pueblos-contra-las-plantas-de-biometano-el-gas-limpio-que-asusta-por-el-mal-olor.html?utm_source=chatgpt.com
DOGV (2025). Proyecto de macroplanta de biometano en San Antonio de Requena. Diario Oficial de la Generalitat Valenciana. https://dogv.gva.es/es/resultat-dogv?signatura=2025%2F44721