Stay hydrated: Keolis Lyon tests out a new eco-friendly air conditioning system

Air conditioning for technical infrastructure: optimizing the carbon footprint of this operational necessity

The considerable environmental impact of traditional air-conditioning systems is a major concern for Keolis, which is committed to reducing its carbon footprint. In Lyon, as elsewhere, the operator of the city's public transport network is not immune to this challenge when it comes to fighting the heat. In fact, its technical buildings, which house sensitive installations such as electrical equipment, require constant air-conditioning to ensure their smooth operation.

Even when perfectly maintained, conventional systems that use refrigerants are subject to micro-leaks, which represent around 1,500 metric tons of CO2 equivalent per year for the Lyon network. This is equivalent to the annual emissions of 150 people in France (on average).

With this in mind, Keolis Lyon and SYTRAL Mobilités initiated a project to equip a tramway substation managed by Keolis with a water-based eco-friendly air conditioning system, a technology developed by French startup Leviathan Dynamics. This young company has earned the “Team for the Planet” label, a guarantee of its reliable and innovative solutions.

Water-based eco-friendly air conditioning: substantial greenhouse gas emission reductions

Water-based air conditioning represents a major step forward in eco-friendly air conditioning. The principle is based on an innovative double-stage compressor technology that operates in the water-cooling cycle. This cooling cycle makes use of the physical properties of water, which flows through specific pressure and temperature levels. At low pressure and room temperature, the water becomes steam. The residual liquid water then becomes cold and enables air conditioning, while the steam returns to the circuit for compression. The system uses no refrigerants other than water. The Leviathan Dynamics solution also requires less energy to operate: equipment installed in French Guiana achieved a 30% reduction in electricity consumption for a similar cold output.

In early 2024, Keolis Lyon and SYTRAL Mobilités chose the “Ilôt MILLON” tramway substation at Part-Dieu Sud to test out Leviathan Dynamics’ technology. For the startup, this project involved a dual challenge: demonstrating the operational performance of the solution in-situ and testing the innovation with a view to future industrialization.

Performance measurements will be carried out to compare the energy consumption and cooling efficiency gains with a reference system installed at the Rue Marcel Sembat substation.

For Keolis, the goal is to take an eco-friendly approach on every level. That's why the construction of the slab housing the water-based air conditioning equipment was entrusted to Purple Alternative Surface: a partner specializing in the installation of permeable surfaces that avoid soil sealing.

Eco-friendly air conditioning: a virtuous model set for widespread use

The adoption of water-based air conditioning by Keolis Lyon marks an important step towards more sustainable, environmentally-friendly infrastructure. The project, which is in the testing phase throughout 2024, aims to become a model not only for Keolis and its subsidiaries, but also for other companies and local authorities seeking to limit their ecological impact.

Keolis plans to expand this technology to other sites and to work closely with Leviathan Dynamics to further refine and optimize these systems.