Understanding

Chagny, an example of circular economy on a territorial scale

Methanisation is fully in line with the dynamics of the energy and ecological transition. The local production of biomethane makes it possible to reduce greenhouse gas emissions, recycle waste, and reduce our natural gas imports. It also diversifies a region's energy mix, provides income and jobs that cannot be relocated and develops synergies between local economic players.

Biomethane creates a virtuous circle by making it possible to treat locally produced waste while producing decarbonised and renewable energy. With the energy transition, its development prospects are significant; the law of 17 August 2015 on the energy transition for green growth sets the objective of increasing the share of renewable energy to 10% of gas consumption in France by 2030. The realisation of projects such as that of Chagny contributes to the achievement of this objective common to the whole territory.

The stages in the biomethane life cycle at the Chagny site

The household waste produced by half of the households in the Saône-et-Loire department, i.e. more than 300,000 inhabitants, is collected by tipper trucks. This represents 73,000 tonnes of waste each year.

Centralised at the ECOCEA plant, this waste is first sorted mechanically and biologically. The organic, i.e. fermentable, part is separated from plastics, metals and other residues.

After this sorting, the organic waste is introduced into a methaniser which, via a digestion process, produces biogas. The solid residual part, called "digestate", is used as compost after mixing with green waste.

Composed of methane, carbon dioxide and hydrogen sulphide, the biogas obtained is first purified using membrane filters. The methane then retained is called biomethane.

The biomethane compressed by the SMET 71 is injected into the GRTgaz gas transmission network via an injection station located near the ECOCEA site. The functions of the GRTgaz station make it possible to count the quantities of biomethane, to control its characteristics and to odorise it in order to mix it with natural gas. Biomethane has the same properties as natural gas.

The TERREAL industrial site is directly connected to the GRTgaz network. Biomethane (in addition to natural gas) is used to run its kilns and produce clay roof tiles.

Key figures

- 8,000 tonnes of green waste processed per year 

- 1/3 of TERREAL's consumption: this is what biomethane consumption represents

- 5,800 tonnes/year of CO2 emissions avoided

Partners SMET 71

Created in 2004, the Syndicat Mixte d'Etude et de Traitement des déchets ménagers et assimilés is responsible for treating the household waste produced by the 315,000 inhabitants of eastern Saône-et-Loire.

The authority operates a storage facility for non-hazardous waste (household and similar waste) in Chagny. This facility receives approximately 73,000 tonnes of waste per year, in compliance with regulations. It has been ISO 14001 certified since 2004.

GRTgaz partners

As a public service company, GRTgaz ensures the smooth operation of the natural gas market in France in the interests of all consumers:

• industrial sites and gas-fired power stations directly connected to the transmission system
• private individuals, local authorities and businesses served by the distribution networks, which are themselves supplied by the transmission system.