The collaboration between CEA-Leti and SOLEM began in 2019. The latter, a specialist in connected irrigation solutions for residential sprinklers, municipalities or connected agriculture, was looking to boost its technological distinctiveness.
SOLEM has positioned itself as a high-end player, placing innovation at the heart of its strategy,” explains Swan Gerome, head of industrial partnerships at CEA-Leti. “At the time, they already had a connected irrigation module and they wanted to add a system that would extend its autonomy.”
The solution was obvious: Why not harness the energy generated by the flow of water used for irrigation in order to power sensors? A simple enough solution to imagine, but obviously more difficult to implement.The analysis of the Earth's magnetic field is therefore of prime importance in many sectors.
Electromagnetism and fluid mechanics
SOLEM approached CEA-Leti as the organization already had expertise in the field thanks to previous R&D to develop a prototype hydrogenator capable of recovering energy from water pipelines. “It's an electromagnetic energy harvesting device, which is almost neutral in terms of pressure losses and can be easily integrated into a water pipeline,” comments Elise Saoutieff, research engineer and project leader at CEA-Leti.
The project conducted with SOLEM first led the researchers to improve on this hydrogenator system before tackling a number of scientific challenges. “We needed to gain a detailed understanding of the fluid's behavior in different configurations,” says Elise Saoutieff. “We therefore carried out numerous multi-physics simulations in order to find the most appropriate parameters for the fluid's behavior.” To facilitate testing, the research team also developed an in-lab characterization benchmark to carry out closed-circuit tests.
In addition, the researchers adapted this technology to suit SOLEM's connected irrigation solutions. For instance, this involved developing specific electronic components to meet low-power requirements. Likewise, the materials used were the subject of particular scrutiny, both in terms of their watertightness and their robustness when in contact with high pressure water and other industrial constraints.
Harvesting energy with minimal loss of pressure
Several research projects were carried out in collaboration with CEA Tech's regional technology transfer platform (PRTT) in Occitanie. As a result, three prototypes of different sizes were created with promising results. The smallest of them - SOLEM's priority - can recover an average power of 20 mW. “This is more than enough to power a sensor,” adds Elise Saoutieff. What's more, the hydrogenator can provide flow rate measurements, which is essential data for optimal irrigation management.
The device also boasts excellent performance in terms of pressure loss, i.e. the pressure drop induced by harvesting energy is negligible: “Our system has been optimized to achieve a pressure drop of less than 0.1 bar, which is a real improvement on the state-of-the-art,” concludes Elise Saoutieff.
As a result, the hydrogenerator has been integrated into SOLEM's LR-IP-ECO irrigation programmer, which has been on the market since the end of 2023. “Our collaboration with the company is not yet over,” reveals Swan Gerome. “We're continuing to work together, on various subjects that we expect to see the light of day in the near future...”