Over the years, cars have become less and less polluting due to the manufacturers investing all their knowledge and skills into this field. But what’s the situation regarding their manufacturing? With its factory in Tangiers, Renault seems to have taken on the challenge.

The site is said to be the largest in the region and also the cleanest, a venture led by the international corporation, Veolia. They have been involved since the initial conception of the unit, which is to avoid all pollution and make Renault Melloussa a “zero discharge” factory.

One of the key components of the factory is the biomass boiler. It was presented by Veolia as being an advance in the field of creating thermic energy from natural resources, such as wood or even agricultural refuse. It works in a similar way to a traditional boiler room but in an up-to-date way that enables it to achieve higher levels of efficiency and an optimal output according to the kind of combustible material used, as Veolia explained.

From Ashes to Fertilizer

The bio-combustibles arrive at the factory as if on a ‘conveyor belt’ of dumper trucks and are stored in silos. The mixture is then homogenised and, from there, it is transported to the boiler. What might seem an easy task, in fact entails monitoring a whole series of parameters and fine tuning, so that after combustion, only ashes remain. These are collected up, as are those in the combustion gases, to be put into storage. Research is, at present, being carried out on a project for re-use of these ashes. According to Veolia, it would, in fact, be used as as fertilizer, since they are rich in nutritional elements. The boilers supply water at different temperatures for the hot water system in the factory, in particular for the painting department, which uses a lot of energy. In total, two 6 MW boilers have been installed and a third is planned to meet the growing energy requirements.

The result attained is a high-ranking achievement. Carbon dioxide emissions have been reduced by 98%, the equivalent of 135,000 tonnes of CO2 emissions per year; the car production company states that the few remaining tonnes will be compensated by the purchase of carbon credits or by the production of renewable energy in situ.

Water is another focus of attention. It is used in a closed system. The treatment system is as good as a water purification plant with a number of tanks of sizes appropriate for the unit. This water is then filtered by techniques referred to as osmosis, making it possible to produce, at the end of the process, an “industrial water”, a liquid that is pure in the literal sense of the term. This water supplies various essential processes in the factory, including surface treatment of the cars and painting. At the end of the process, the water is full of pollutants including heavy metals which cannot be discharged into the drains, but need rigorous filtering. This results in a reduction of almost 70% in the resources necessary to supply the factory with water, according to Veolia. The resulting waste, in the form of dried mud, is stored and sent to Europe for treatment.

In this respect, also, it’s good value for money, because no industrial waste water at all is discharged from the factory into the natural environment and the use of water resources for industrial processes is reduced by three quarters. This is the equivalent of saving 437,500 m3 of water a year, or the water consumption of around 700 people a year. All this effort has been recognised: in fact, the project won the prize for “Sustainable Energy” from the European Commission in April 2011 in the production category.

For further information, use the following link:

https://group.renault.com/groupe/implantations/implantations-renault/usine-tanger/

Additional information

Olive and Argan pits

The bio-combustibles are produced in the local area. They consist of wood refuse or recycled industrial wood. Olive and argan pits are also used, to complete the mix. Veolia never uses firewood to avoid contributing to desertification or competing with traditional users of this fuel. As for the agricultural waste material – olive and argan pits – these are an excellent source of energy. They have a higher calorific value than wood, which can vary a great deal in its humidity levels. Moreover, it provides an additional income for families, especially in the south where argan pits are collected.

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