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Biomass heating system in La Chantrerie, Nantes, France.

Axel Dargein

Edited: Elisa Heinonen

Introduction :

            Non-renewable energies are a huge issue of our century. Indeed our societies are completely dependant to them and because of ecology matters, rarefaction of some fossil fuels and the will to be self-sufficient, some countries are looking for a transition or have already begun it.

            In 2015, in France, according to the Electricity Transport Network (RTE in french), nuclear energy represented 76.3% of the total production of energy [1]. The same year, bioenergies represented only 1.4% of the whole production with 1.1% which were renewable [1]. It shows that France was deeply dependant to nuclear energy (and still nowadays) but also shows that bioenergies are still insufficiently used, like for renewable energies.

            Initiated by the will of L’École des Mines de Nantes (IMT) to reduce its emissions of greenhouse gases, the project of a global heating system for the whole site of La Chantrerie in Nantes was born. Gathering seven public establishment whose are five superior schools, they worked together to make this project a reality. Finally in 2011, and after only 3 years of conception/construction, the biomass heating device was inaugurated [2].

Description of the technology :

            Description of the device [3]

            The wood combustion boiler room is a 2.5MW device, linked with two others natural gases boiler room of 2.5 and 5 MW efficiency. The two last are used at full efficiency in case of a too important demand and help purpose. This setup is big enough to provide heat for the seven establishments that are part of the project. The device is equiped with a filter component which permits a dust reject inferior to 20 mg/Nm^3 of air. The total length of the supply network is 3200 meters with 12 under-stations.

            Combustible supplier

            The annual consumption of the device is around 3400 m^3 of wood. This wood comes exclusively from Nantes’s region with 50% of wood chips from forests and the other 50% from industrial waste [2-3]. A container of 240 m^3 is used to provide an autonomy of 4 days by stocking wood chips in advance [3].

            Economic description

            First of all, one of the most important criteria was that the investment had to provide a reduction of the heating fees for all those who took part in the project. That’s why concerning the price of the energy, it has to be 5% less expensive than the same quantity produced by a reference: natural gases. In exchange of it, the establishments have to use this source of heat for 20 years [5].

            The whole project represents an investment of 3.5 million euros, combining different sources. We will see it in the description of the policies measures [2].

Description of the market :

            Concerning only this project, the market is only open for the seven establishments which have associated themselves to make it a reality. Nobody else will benefit of this source of heat.

                   From a more global point of view, France is the country of the world which uses the most of plants using wood chips [4]. So it is a technology that we master very well. There are two main applications of it : for the public and for the companies. According to the BASIS Project, an European project, there were 600 plants in France in 2014.

                   However, we have to moderate those words. As we can see, bioenergy represents a tiny percentage of the French energy mix [1], thereby the situation is not as beautiful as what we can interpret with the previous numbers. Certainly, France is the biggest user of biomass plants, but compared to the proportion of people who can benefit of it, we are really late. So we can say that the market is present but it is still small comparing the French population demand in energy. That’s why all the policies measures that were proposed to help our project in La Chantrerie were essential.

Description of the policies measures :

A such project is too big to be only financed by such public organisations, as much when this kind of installations are meant to deliver a such big demand, 9500 MWh for the year 2012-2013 [5].

            First of all, in order to make the advances easier, the seven establishments have created an association which could represent their common interest. That’s how the AFUL (« Association Foncière Urbaine Libre » - free urban land association) was created. It will allow them to find a company which would invest in their project in exchange to a 20 year promise of energy purchase.

            In parallel of it, the ADEME, the French Agency of the environment and energy mastery, subsidized them to help to invest in this project. Indeed, when some organisations or public persons want to put in place this kind of projects, the ADEME can help financially to make it more affordable. Here ADEME’s help was totally essential.

            If we watch the financial distribution more closely. The main financial source is the ADEME with a 1.815.00€ help. Then comes the contractor of the project, Cofely GDF Suez (Energy and Environmental Efficiency Services Company), with a 1.700.000€ investment. The city of Nantes also took part to the project with a 20.000€ help. Finally come the schools with a 2.000€ investment for all of them and 5000€ additional by the IMT for the feasabilities studies [5].

            We can’t consider that the investments of the contractor of the project and the establishments are a policy measure because they invested in this project for they own interests. Cofely GDF Suez finally sell the energy to the AFUL. The different establishments which compose the AFUL were asking for the project to be set up. However without the ADEME and the city of Nantes, nothing would have been possible.

            The creation of the AFUL association is not really a policy measure but it was important to highlight the importance of its creation in order to receive help and becoming able to be listened.

Evaluation of the effect of those measures :

            From a close point of view, the set up of the biomass heater, the measures were essential. Thereby, without a such help, from the French government and the city of Nantes, nothing would have been possible. Now there is a biomass heater in the Chantrerie site which avoid the release of 2200 tons of CO2 in the atmosphere per years and the use of 700 tons of oil equivalent (toe) [5]. This is a « highly relevant use of public funds in the fight against energy and environmental issues » [2].

            Concerning a more global point of view, this action is a real benefit for everything: the initiators of the project use an energy which is cheaper, renewable and green, they show that it’s possible for every big organizations or cities to set up this kind of projects and help to promote the bioenergies. The way to leave our non-renewable-fossil fuels dependance in France is still long but with this kind of “little actions” we can reach bigger goals.

References :

[1] French energy production –  Electricity transport network (Réseau de transport d’électricité – RTE part of EDF Group) - (19.01.2019)

[2] Press release, inauguration of the biomass heater. (19.01.2019)


[3] Device presentation, ADEME (French Agency of the environnement and energy mastery) (21.01.2019)


[4] Bioenergie international newspaper-France world leader of biomass heater (>1MW) (23.01.2019)


[5] Experience feedback – CEREMA (23.01.2019)

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