The Terragr’eau methaniser on the Evian water impluvium plateau

Chaire Paysage et énergie (ENSP), 2022

To download : terragreauplaquette.pdf (3.6 MiB), ledauphine.com-eau_devian.pdf (200 KiB)

The Evian water impluvium, an agricultural plateau in the heart of a mountainous setting

1 - A humid agricultural plateau in the heart of the mountains, a viewpoint over Lake Geneva

The Gavot high plateau offers very wide views of Lake Geneva, which it dominates on its northern side. It is surrounded by a mountainous barrier to the east and south-east. It has a mainly agrarian and forestry character. The main activity is livestock farming. Numerous protected wetlands dot the area. The climate is humid, and the plateau is often bathed in mist, partially obstructing views of the lake and the mountains. The habitat is rather scattered, consisting of isolated farms or hamlets.

2 - The landscapes of « douce France » and their sustainability

This pastoral landscape seems to correspond to the archetypal representation of the countryside, still made up of many familiar elements such as the bell tower, the path, the river, the hedge, the isolated tree, the meadow, the herd… It is a place of tourism linked to desires for « nature » and landscapes: hiking and cycling circuits, etc. The economy is essentially based on rural activities. They are mainly linked to dairy and cheese production. These local agricultural products are identified as remarkable, and have been classified since the 1990s in various PDO and PGI: Abondance, Emmental, Reblochon, Beaufort, Chevrotin, Tome des Bauges, Tomme de Savoie, Raclette. Farmers must comply with strict specifications. Local products contribute to the appeal of the region for tourists and to the overall mountain economy, which helps to preserve agricultural landscapes and resist the industrialisation of agriculture. The landscapes of the Gavot region are becoming urbanised relatively quickly in the vicinity of Evian-les-Bains. There is a risk of agricultural abandonment, linked to a certain amount of land pressure. The existing hamlets are also gradually expanding.

3 - The humid mountainous plateau, impluvium of the waters of Evian

The biological diversity of the Pays de Gavot is classified as a Ramsar site, designating a wetland of international importance. The Gavot plateau has also been awarded the « Chablais Geopark » label, due to its remarkable geological base. This bedrock forms an impluvium and is the source of Evian© natural mineral water. The impluvium is the part located on the Gavot plateau where the rain and snow fall and are stored. This rain and snow is then slowly filtered and purified through the multiple geological strata at a rate of about 300 m/year, before emerging in Evian-les-Bains as natural mineral water. The minimum filtration time is 15 years.

Since the end of the 18th century, the waters of Evian have been recognised as beneficial. The spa towns of Evian-les-Bains and Thonon-les-Bains bear witness to this reputation. The water resource was first used by the Société Anonyme des Eaux d’Evian, and then the company Danone bought the group in 1970. For more than thirty years, an original model has been put in place in the area, in order to protect the impluvium and the perpetuity of the purity of Evian water, while encouraging the development of the area, and in particular agriculture on the Gavot plateau.

An energy project as a link in an assembly: agricultural practices and protection of water resources

1 - Water on the Gavot plateau, a resource under pressure

At the end of the 20th century, the various AOC and IGP labels were awarded to the agricultural practices of the plateau, living witnesses of a local culture. They establish a set of specifications that farmers must respect and allow for the perpetuation of an agropastoral agriculture that offers a strong identity to the local landscape. The creation of the association for the protection of the Evian© mineral water impluvium (APIEME) in 1992 stems from the need felt by the local elected representatives to take their responsibilities upstream. Indeed, if the water protection parameters are not respected, it can no longer be qualified as mineral water, it loses quality and therefore economic value, and this for a long time because of the long storage time of the water in the impluvium. Measurements of the water in Lake Geneva indicate that the salinity level is very high, which is worrying for Evian’s water resources. The elected representatives then decided to join forces.

2 - Associations between different actors for agriculture and water

The APIEME association brings together 13 communes: 4 communes where Evian© water emerges, including Evian-les-Bains, and 9 communes on the Gavot plateau where the impluvium zone is located. This association was born from the desire of the communities to share the fiscal advantages linked to the exploitation of the mineral water resource. Until now, only the emerging communes benefited from this, whereas it was the responsibility of the plateau communes to protect the resource. Through the legal means of the association, they joined forces with the private company Danone, which owns the Evian© brand of mineral water. The first actions implemented by the APIEME are linked to the AOC and IGP standards in the area, with a marked interest in agricultural practices. Awareness campaigns for farmers are carried out, with various public meetings informing them about current knowledge in terms of sustainable agriculture. APIEME also carries out financial campaigns for wastewater treatment with connections to the sewage system, as well as the reduction of fuel tanks. The wetlands of the plateau are also the object of vigilance, with annual mowing campaigns. APIEME spends 600,000 euros per year to finance these various actions.

3 - The Terragr’eau methaniser project, for the control of livestock effluents

At present, 70 farms are present within the perimeter of the impluvium. One of the main issues for the preservation of water resources is the spreading of manure on crops. Livestock effluents must be of exemplary quality, in particular by meeting the AOC and IGP specifications. Farmers tend to concentrate their spreading on certain areas of the impluvium, which puts pressure on the water resource.

The idea of pooling the management of these effluents allows for quality control and spreading principles, while generating a renewable energy source, biogas. For the Terrag’reau methanizer-composting project initiated in 2006, APIEME has an initiating role, by persuading the Pays d’Evian Vallée d’Abondance Community of Municipalities to participate, and by going to meet with the farmers.

4 - Shared governance for a common energy and agricultural project

A double governance system has been established for the management of the methaniser, including the stakeholders concerned. SAS Terrag’reau brings together the community of communes, which owns the site, and the SERFIM group, which specialises in the environmental sector, to manage the site. The Community of Municipalities had launched a call for tenders to choose this company. The SAS collects agricultural effluents from farmers and provides them with standardised compost and quality digestate, produces the gas and sells it to GRDF. The SICA Terrag’reau groups together farmers in a cooperative associated with APIEME and the company Danone through the Evian water company. It supervises the return of the effluents to the soil, with an employee who establishes a global planning of spreading for the year. The investments made for the methaniser are made up to 5% of the mineral water tax for the municipalities involved. The Danone company invests twice as much as the municipalities. The project also benefits from subsidies from the Region, the Water Agency and Europe. The cost of treatment of the manure by the methaniser remains low for the farmers. One tonne treated costs 9 euros, the APIEME finances 7 and the farmer 2.

The terrag’reau methaniser project, sustainable energy and agricultural cycles

1 - Integration of the methaniser project into existing agricultural practices

The biogas plant/composting project is part of a territory where the traditions of livestock farming, perpetuated by PDO and PGI standards, manage the landscape. The agricultural plots are grazed extensively, to allow crop rotation and food autonomy. The cows produce milk and effluents, and these products are part of a virtuous circle. The average size of a farm on the Gavot plateau is 40 ha. The recovery of livestock effluents was already part of the crop rotation system before the methaniser project. The project has not led to any fundamental changes in farming practices or landscapes. However, it does bring benefits to the farmers involved in the pooling of resource management:

• An increase in effluent storage capacity

• A significant reduction in odours: 98% deodorised

• High-performance equipment used collectively: a skid ramp deposits the product on the ground. This agricultural machine replaces the old nozzle, used by farmers before the collective system was set up. With the skid ramp, the nitrogen product is not dispersed in the air, and it is not lost to the plant

• Cost sharing and price division

The participating farms of the SICA Terragr’eau have no direct link with gas production. However, the farmers note the importance and personal satisfaction of being part of a larger collective project. The PDO and PGI charters instil real territorial policies, linked in particular to the protection of the impluvium. They are a fundamental point of local dynamism. They bring with them a mountain, economic, tourist and landscape ecosystem. The Terragr’eau methaniser project is part of this circular economy as an additional asset. Today, out of 70 farms in the impluvium, 40 have signed up to the methaniser project.

2 - The methaniser, an installation on the move

An important part of the call for tenders for the design of the methaniser was focused on the project’s integration into the landscape. The ANTEA group, the project delegator chosen by the Communauté de communes, is carrying out the impact studies for the building permit. Various graphic landscape documents (landscape sections, 3D views, view cones on photographs, etc.) were produced. The opinions of the State’s landscape consultant at the DDT Haute-Savoie are sought.

38,000 tonnes of organic matter per year are processed by the methaniser. These are agricultural effluents, as well as a small amount of green waste from municipalities, craftsmen, local landscape companies and bio-waste from school canteens. Every day, material enters and leaves the tanks to produce liquid digestate (land application) or solid digestate (compost). The average residence time of digestate in the tanks is 60 days. The organic product is then transformed into a fertiliser product. In terms of landscape, the plots of land allocated to the methaniser project are located :

• In a clearing, with a surrounding wooded area making the site hardly perceptible from the outside

• At a distance from the main road

• At a distance from houses, to limit the impact of odours from the methanisation process

• On former private agricultural land, bought by the community of communes

• Right next to the existing waste disposal centre, for a coherent continuity of a space already used for storage and having the same type of olfactory and visual constraints.

The natural gas produced is injected directly into the GRDF network. An electrical substation is present on the site. The boiler of the methanizer, with a power of 400 Kw, is fed by the biogas produced on site. The distribution network is made up of a network of pipes under the ground. GRDF’s customers buy this « green gas », which is more expensive to purchase but is partially tax deductible. The Terragr’eau methaniser is part of two territorial networks: the first extends from Thonon-les-Bains to the Swiss border, and the second is around Annemasse. Another biogas plant is present in the region. The two methanisers share the two gas networks according to demand. The Terragr’eau biogas plant’s role as an exemplary pilot site has priority over resale to GRDF, so there are never any losses. It produces 61 m3 of biogas per hour. Production could reach 110 m3, but the effluent products (liquid manure and dung) are not very methanogenic. To achieve a higher output, more bio-waste would have to be collected. As the effluents are redistributed on the Gavot plateau, the PDO and PGI specifications prohibit the presence of meat and fish in the spreading materials.

Multiple actors, sources of future development on a local and global scale

1 - From Evian water to Volvic water

Following the Terragr’eau methaniser project, the company Danone is trying to reproduce this model for Volvic© mineral water, in a relatively similar territory where the problems between agricultural production and protection of water resources are similar. The methaniser has made it possible to federate actors and to bring added value to the farmers involved in the project, enabling them to continue to engage in sustainable agricultural practices for the water resource, the territorial economy and the associated landscapes.

2 - Agricultural and energy production, transport, storage and regeneration

In the future, the biogas plant project could be developed locally, in particular with an extension of the storage capacities, and therefore the possibility of enlarging the territory of influence of the biogas plant. Storage could be done in pockets in remote areas, thus allowing savings on transport. The Danone company is currently carrying out a regenerative agriculture project, which it wishes to disseminate in the region. It aims to accelerate the development of sustainable agriculture on the impluviums. The means proposed are the commitment of farmers to the specifications of regenerative agriculture and/or organic agriculture with financial support for the transition to regenerative agriculture for 7 years. This project seems interesting, with attention to its implementation, which currently seems disconnected from the other actors in the territory. Its governance would benefit from not being carried solely by a private actor.

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