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Datavenue Challenge: a self-contained frost and ice sensor based on temperature differences


“The sensor draws its own energy from the thermal gradient, uses optical measurement to detect frost formation, and sends data through the LoRa protocol.”


GreenSysTech aims to make innovative sensor solutions that can exploit ambient energy more accessible. CEO Mohamed Fall tells us about the FrostD frost detector, a break-through innovation for road safety and agriculture, winner of the special jury award at the 2021 Datavenue Challenge.

What is GreenSysTech’s story?

From the outset, I wanted to explore energy issues through the development of innovative sensors, with one idea in mind: to capture ambient energy. GreenSysTech was first set up as a design company, and we filed patents every year between 2010 and 2015. Now there are five of us, mainly with research profiles. Together we have more than 25 years of research and development experience, and our products are deployed in France, Europe and across the globe. These products include our fill level sensor, used for rubbish bins, agricultural silos etc.; or our technology designed to harvest vibration energy, used in refrigerated lorries, for example. For our frost sensor, winner of the 2021 Datavenue Challenge, we relied on our thermoelectricity expertise.

Can you explain to us what thermoelectricity is?

It is the ability to convert temperature differences, called the thermal gradient, into electric power. For example, we can make good use of the temperature difference between an office at 20°C and an outside temperature of 3°C. The greater the temperature difference, the more energy is converted. But this thermal gradient is most naturally observed in the earth. Soil temperature changes all year round at depths of 10 to 30 cm. If we go down to 30 cm, enough energy can be collected to power a sensor.

Is that how your frost detector works?

Yes. We dig a hole, place the sensor in it, and that’s it. It is self-contained. It generates and uses its own energy from the surrounding thermal gradient, measures and analyses the soil temperature and humidity to detect and anticipate the risk of frost, and transmits data to its receivers through the LoRa protocol. It is the only frost detector in the world that is self-powered; other suppliers have to use cables, install a solar panel, and so on. In addition, our sensor measures the temperature at the closest level to the ground, while a traditional station, usually located over 1.5 m off the ground, needs an anemometer to perform additional calculations and often lacks accuracy. The work required to install this equipment makes it expensive to deploy, costing between €5000 and €10,000, which effectively excludes many towns that would need it. The FrostD sensor is four to ten times cheaper, and offers rapid deployment, accurate data and a very low operating cost.

How can this innovation be used?

We initially designed it to detect the risk of ice on roads, and thus reduce the number of accidents in cities. In 2020, 156,000 car accidents were caused by ice. But the same technology can have numerous other applications. Frost is also a real problem in agriculture. A late freeze can destroy entire harvests, as many French wine regions are currently aware. However, currently, we mainly rely on macro-scale weather forecasts, which do not distinguish between areas more or less at risk. A self-contained sensor can send an alert as soon as the temperature begins to fall, allowing enough time for decision-makers to take specific action according to the real needs: salt the roads, protect crops etc.

How did you approach Orange?

Initially, for data communication, we had to work with 2G, which was not at all designed for these types of bandwidth-efficient objects. To design self-contained sensors, complicated systems had to be created. When the LoRa protocol arrived, we were very pleased to finally have a dedicated network. We have worked closely with Orange in its deployment. Our first joint success was a project to install sensors at Gatwick Airport, for which Orange was in charge of the data part. Since then, we have renewed our collaboration. The players we approach are always reassured that they can count on a reliable network to transport their data. Thanks to Datavenue, Orange can also provide servers, a monitoring platform etc. Together, we are able to offer a robust package. We therefore naturally recommend each other to meet the needs of our customers.

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