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Biozone: a tool for optimising the connection of biomethane units to support the development of the sector

In order to optimise the conditions for injecting biomethane into the networks, RICE has contributed to the development of a technical and economic optimisation tool: Biozone. Find out how the use of this tool contributes to the development of the sector.

Biomethane, a player in the energy transition

GRTgaz’s ambition is to be a leading player in the ecological transition to make a secure, affordable and climate-neutral energy future possible. It is thus participating in the development of the biomethane sector in order to move away from the intensive use of fossil gas as quickly as possible.

The legislator is supporting this approach: the Law on the energy transition for green growth has set the objective of increasing the share of renewable gas to 10% of gas consumption in France in 2030 – compared to 1% currently.

Biomethane is a 100% renewable gas produced locally by a methanization process from organic waste: agricultural, household and industrial waste, but also household waste, from the food industry, from collective catering, or even from sludge from wastewater treatment plants. This will help advance the cause of a new industry serving the “greening” of gas and the circular economy.

The sharp increase in the volumes of biomethane injected into the transmission and distribution networks requires adaptations to these networks, which were historically designed to transport the gas in a unidirectional and centralized manner, from upstream to downstream.

For example, when the volume of biomethane injected into a distribution network is too large to be consumed locally, a backflow facility must be installed to bring the gas up to the transmission network.

In order to prepare for the gradual increase in decentralised biomethane production in the years to come, GRTgaz needs to develop a long-term vision of the necessary investments.

Biozone, a decision-making tool for biomethane

To address this issue, GRTgaz has developed the Biozone tool. It is a decision support tool based on Operational Research techniques such as linear programming. Following the realization in 2019 of a first “prototype” version by GRTgaz’s Gas System Department, with the help of SIA Partners’ EnergyLab, the further development and industrialization of the tool have been taken over by RICE, GRTgaz’s R&D center, with its skills in applied mathematics and tool development.

Biozone’s objective is to determine the best possible connection for each biomethane production unit to the transmission or distribution network. The tool can also choose to install backflaw facility on the distribution network and compressors on the transport network when locally, the volumes of the units connected to it require it.

Results are obtained in minutes to meet the operational requirements of users.

Several major challenges had to be overcome during the development of the tool such as :

  • The implementation of a global optimization on the whole territory covered by GRTgaz. In order to determine a solution that minimizes the overall investment, Biozone does not optimize the connections locally, region by region. It carries out global optimization over the entire territory covered by GRTgaz’s systems, i.e. about three quarters of France.
  • Taking into account the transmission and distribution networks. The transport network, several thousand kilometres long, is taken into account almost exactly. The distribution networks are represented via discretizations that result in the consideration of several thousand possible connection points.


In order to allow a direct exploitation of the optimization results, Biozone generates several types of indicators, and displays them through a geographical representation. This allows you to easily zoom in/out on a part of the territory in order to visualize the connections proposed by the tool.



Future biomethane development scenarios studied with Biozone

In concrete terms, Biozone was first used to provide figures – in particular the number of returns and the associated investments – for the discussions on a medium-term horizon (5 years) concerning the implementation of the right to injection, the regulatory basis for the development of the biomethane sector.

This regulatory base provides limiting technical and economic ratios, including the maximum investment cost per unit of biomethane injected into the networks. These limit ratios condition the progress of the sector: if they are too high (i.e. not very restrictive), they lead to a lot of investment that is not always justified; if they are too low (i.e. very restrictive), they slow down investment and therefore the development of biomethane.

More recently, Biozone has also been used to estimate the trajectory of network investments over longer time horizons (10 to 15 years). The study was able to determine a curve of necessary investments according to the volumes of biomethane produced. This made it possible to initiate the reflections on the evolution of the right to injection for the years to come.

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