George Caraiman
Chef de projet Mobilités
Published on March 31, 2019

Reading time : 3 min

Managing the city through public lighting

Public lighting, whether formed into a grid or refurbished, transports a current which may also be communicating and could therefore centralise data. Whatever their provenance, these data contribute to urban efficiency and are vectors of development of the Smart City and the Smart Grid. The operating savings made can therefore be reinvested. Public lighting is becoming “smart” and can carry new services.

Eclairage public intelligent

- Crédits : © Sinenkiy -iStock

Public lighting represents 18% of energy consumption and 22% of the energy expenditure cost centre for local authorities. With slightly more than 5.3 billion kWh, it is the biggest electricity consumption centre (45%) and electricity expenditure centre (38%) of a municipality, according to the French environment and energy efficiency agency ADEME. To reduce this electricity consumption, one solution could be to implement a consistent methodological approach without jeopardising two fundamental objectives: the comfort and the safety of users. Savings would be achievable by modernising infrastructure and the control logic (PLC or wireless technology).  

Why public lighting?

It is possible to use the public lighting current and grid to transport other information signals, or to provide power to other services with provision at each lighting point. Such a system would enable network management to be coordinated and thereby optimised through an urban “hypervision” to pool all the information collection networks (technical management of administrative buildings, drainage and safety of pedestrian zones, information to inhabitants, pollution sensors, etc.). It would also reduce urban cluttering by combining the different services (lighting, Wi-Fi, video surveillance, bus information, smart phone recharging, public address, weather, pollution and traffic counting sensors) in a new-generation streetlight.

Public lighting, a vector of urban supervition and savings

We believe that the streetlight possesses all the criteria to become the central fixture in the management of the city. The distribution of streetlights is legally regulated, and they are always installed next to nerve centres. Their power supply, which is now constant, can be optimised and adjusted. It can be made scalable towards a single energy grid to power all the associated systems in the city.

This means that urban planning can take on a new dimension. Bus shelters, electronic payment terminals, information screens and retractable bollards can now communicate thanks to a system, via a data network which supplements optic fibres, radio or other operated systems (ADSL, etc.) and simplifies the interfaces of existing systems.

Public lighting: a key component of the Smart Grid?

Beyond optimising electricity consumption, which constitutes the principal raison d’être of the Smart Grid, public lighting can be used as a physical fixture and provide the electric power to charge electric cars. It could also be the electricity transport vector for the generation of renewable energy.

The concept of mutualisation with electric car charging infrastructure is a very interesting subject, as the electricity grid mesh necessary to power lighting can be used for charging electric cars. Access to charging can be managed by a central system pooled with that of lighting management or through a dedicated system.

Assuming that the electricity grid dedicated to public lighting might also be used tomorrow for the management and integration of the generation of renewable energy, this would offer the considerable advantage of reducing civil engineering works costs and streamlining costs relating to upgrading electrical infrastructure. The objective would then be to pool existing infrastructure with new infrastructure dedicated to carrying renewable energy which might come from an external source (solar panels installed on the roof of a building) or from an integral part of the mast (a mast fitted with solar cells).

Public lighting as a component of the Smart Grid is a means of implementing a central management system to bring about better coordination (lighting, electric vehicle charging, renewable energy generation) and generate overall cost reductions (investment, operation, maintenance and better control over electricity bills).

A successful project: the Saint-Nazaire bridge

On the three-lane Saint-Nazaire bridge, Egis has deployed a system which is highly innovative in France, consisting of changing the direction of traffic of the central lane of the bridge according to traffic requirements. In response to road traffic conditions, the system will allocate three lanes in one direction and one lane in the other, using illuminated road studs indicating the new configuration of the road and supporting roadside equipment (counting panels and station). But this innovative project has a hidden concept: all the facilities and studs are managed and powered through the bridge streetlights. To do so, the teams at Egis modified the power supply control and managed these fixtures through systems using powerline communications. Smart!

Sur le pont à 3 voies de Saint-Nazaire, Egis a mis en service un système très innovant en France qui consiste à modifier le sens de circulation de la voie centrale de l’ouvrage selon les besoins du trafic. En fonction de la circulation donc, ce système va attribuer trois voies dans un sens et une voie dans l’autre grâce à des plots lumineux qui matérialisent la nouvelle configuration de la voirie et des équipements routiers en appui (panneaux et station de comptage). Mais ce projet innovant a un concept caché : l’ensemble des équipements et des plots sont pilotables et alimentés via les candélabres du pont. Pour cela, les équipes d’Egis ont modifié la gestion de l’énergie et géré ces équipements via des systèmes utilisant les courants porteurs en ligne. Pratique !

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