Sustainable Urban Metabolism : The innovative case study of La Réunion Island ecocity project

What is the context of the urban metabolism on which you worked?

In a nutshell, the  concept  of  urban  metabolism  entails  the  identification  of  the materials and energies which enter the city, those which transformed within the urban system,  the  ones  that  are  stored  and   finally,  those  which are  emitted.This  specific approach  to  urban  phenomena  enables to get a holistic and thorough understanding of the operation of a city and denotes  the  set  of interactions  which  are  produced  in  order  to  meet  its  needs.
Moreover, such an approach  is  very  interesting  since it  equates the  city  to  a  living organism,  and  thus  emphasises  the  complexity  of  the  urban  environment,  urban phenomena, and their deeply interdisciplinary nature.

What was the innovation in your approach?

In my thesis, I proposed a new methodology to study urban metabolism. The premise was that urban metabolism is extremely complex and, in order to be exhaustive it cannot be studied all at once. Therefore, I suggested to divide it into several sub-systems (housing, food supply, electricity supply, etc). The metabolism of each of these sub-systems, should then be studied as a system on its own. And afterwards, linkages could be determined.
The analysis of each sub-system consists of three major steps:

• The flow diagram: At this stage, all the flows and elements composing the sub-system must be identified, as well as their interrelations and its boundaries should be defined.
• The systemic modelling: Bringing  the  contents  defined  with  the  flow  diagram  into  a computer via specific software, enables  to quantify  flows and offers  the  opportunity  to visualise  how  a  direct  impact on a specific flow or element has consequences on the whole sub-system, in a dynamic way.
• The 3D numeric city model: It delves  deeper into  the  understanding  of  the  process  as   it   includes  the  geographic  and  space dimensions. With such a tool, the understanding of the urban metabolism can be linked to a territory and take into account each of its specificities.

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What was the concrete application of your professional thesis for Artelia?

My professional thesis focused on the flow diagram of one sub-system: the fertile soils of a territorial project led by Artelia: La Reunion Island Ecocity.
The fertile soil supply is a central issue for the Ecocity project. Indeed, the soil is barren on that territory and therefore, in order to develop a “garden city”, fertile soils need to be imported.
Artelia and its partners considered the possibility of producing these fertile soils on site with industrial waste and compost. A pre-feasibility study identified the potential components and their available stock. My thesis enabled to identify all the elements of the system and the stakeholders. Also, I managed to quantify some flows and estimate the others, which confirmed the feasibility of the project on an operational level. Thanks to this study, Artelia identified elements of the system that need to be more precisely determined or optimised (i.e the green surfaces, type of crops, etc). This study represents therefore, a step in the implementation of a fertile soil production platform on the Ecocity territory.

What did the EnvIM program bring you?

I have an environmental background, so I did not follow EnvIM to acquire environmental knowledge. However, I did deepen my knowledge in circular economy, industrial ecology and urban metabolism. But I was actually looking for project management skills adapted to the sphere of environment and sustainable urban development. And EnvIM fully met these expectations. Thanks to this program, I am today an urban project management in a real estate company.