Challenge
The DGAC (French civil aviation authority) operates 80 telecommunications masts at isolated sites to manage air traffic across the country. Diesel generators are currently used to ensure that these masts are powered 24/7. The DGAC would like to replace these generators, which are both polluting and expensive to maintain.
In 2019, the DGAC awarded Bouygues Energies & Services and Powidian an initial pilot contract for the Sarlat site in the Dordogne. This design-build project includes civil engineering, high and low voltage electricity, solar panels, hydrogen equipment, management and interfacing with the DGAC’s active telecommunications equipment. The project was delivered at the end of 2020.

Innovative Solution
SEPHER (Secours Electrique par Pile à Hydrogène et Energies Renouvelables [Electrical backup via Hydrogen Fuel Cell and Renewable Energies]) is a DGAC project aiming to replace its diesel generators with a 100% renewable hydrogen-based solution and including:
- Photovoltaic solar power generation to power the mast and an electrolyser
- An electrolyser to produce green hydrogen
- A hydrogen storage tank
- A fuel cell to generate electricity from hydrogen
- A “master-controller” enabling optimum supervision and control in real time and enhancing the lifespan of each piece of equipment while guaranteeing autonomy.

Client Benefits
The SEPHER solution now makes it possible to guarantee 5 days of autonomy, a considerable advantage on isolated sites where restoring the electrical network may be delayed.
There is no longer a need to deliver fuel for generators, and maintenance frequency is reduced. The SEPHER solution enables operations and performance to be monitored remotely. Some incidents can even be resolved remotely without on-site intervention.
Furthermore, the solution designed by Bouygues Energies & Services and Powidian for the DGAC is compact and fully integrated in a container. Preliminary operational tests and on-site installation are simplified. A further benefit: the sound pollution level is a quarter that of diesel generators.

Key Figures
The technical characteristics of the installation in order to achieve and guarantee 5 days of autonomous power supply to the telecommunication mast with the aircraft in flight, at any time and throughout the year, are as follows:
- 19.8 kWp of photovoltaic solar power
- 5 kW: electrolyser power (1 Nm3/h) for hydrogen production
- 4.4 kW fuel cell to generate electricity from hydrogen
- 20.5 kg of hydrogen stored at 35 bars to guarantee 5 days of autonomy
Maturity Level
Level 1 : Proof of Concept or lab test
Level 2: Tested under real life conditions
Level 3: Commercial solution