21-07-2022 | By Robin Mitchell
Recently, Dryad Networks announced that their smart sensors designed to fight forest fires are being installed in Italy. What challenges do forest fires present, what does the Dryad solution do, and how will LoRAWAN help with remote applications?
Forest fires are likely as old as the first plants that sprung from the primordial soup responsible for all life on earth. During times of intense heat and drought, smaller plants such as grasses can die and turn into a form of hay that is highly combustible. If this combustible material is not removed either by nature or by authorities, then the material builds up over time to form tinder.
At this point, it only takes a small smoulder to start a wildfire that is virtually impossible to stop. Such ignition sources can include lightning strikes, glass waste acting as a magnifying glass, or human activities such as campfires and fireworks. While trees themselves are combustible, it is rare for a tree to be the source of a forest fire as fires typically start from tinder and build up to larger fuel sources (exceptions to this include dead trees and those with high oil content such as eucalyptus trees).
Once a wildfire moves from tinder to trees, it can be incredibly difficult to put out as the intense heat from larger fuels can reignite itself after being extinguished, the extent of the area currently being burned, and the drying effect of such fires whereby the heat from the border of the fire dries material in front of it. Furthermore, environmental factors such as hills and wind can rapidly accelerate fires in size and intensity.
As such, it goes without saying that the best solution to fighting forest fires is to prevent the fire in the first place. In the past, people would often intentionally burn large areas of land to ensure that unexpected wildfires could not spread, but some governments have either restricted or banned this activity (some would argue that this is a major cause of wild and forest fires). Other solutions include the formation of firebreaks between large portions of land whereby a vast stretch of land is decimated of all trees and vegetation. That way, if a fire does spread into one area, it cannot cross into a second area.
Failing these options, detecting a smoulder before it turns into a fire can be the difference between dropping a bucket of water over the smoulder or evacuating thousands of people as thousands of acres of forest are destroyed. But trying to detect a smoulder is virtually impossible; only a small amount of smoke is released, there are no large flames, and even if a sensor was positioned close enough, the large size of the forests makes it difficult to get a signal out.
Recognising the challenges faced by forest fires, Dryad Networks has recently announced that it will be deploying its smart sensor solution in Montiferru, Italy. Last year, Italy was struck by devastating forest fires that destroyed over 150,000 hectares of forest and have seen, on average, 40,000 hectares of forest lost yearly since 2008. The loss of forests is not only damaging to the local wildlife in Italy but also contributes to global CO2 emissions while reducing the environment’s ability to reabsorb carbon from the atmosphere.
The solution developed by Dryad Networks combines the use of energy harvesting technologies and LoRAWAN to create a smart forest able to monitor its environment and report back data in real-time to remote operators. Each sensor has a solar panel for charging and operating during the day and has an array of onboard sensors, including smoke, temperature, humidity, and air pressure detectors. LoRAWAN gateways installed at the edge of the forest allow for sensors inside the forest to report back readings, and mesh networking technologies allow for devices extremely far away to have their data piggybacked on other sensors until the data reaches the gateway.
To prevent forest fires, the sensors have been designed to identify signs of smouldering tinder before it becomes an uncontrollable flame. Once identified, firefights are called to the area where a smoulder is suspected and, if discovered, put out. For small smoulders, a fire crew don’t even need to carry water as a small fire can be fought by allowing itself to burn out in a controlled manner (i.e., clear a path around the fire).
When it comes to integrating sensors in remote locations, one of the biggest challenges faced is connectivity. Even though power sources are non-existent, the use of energy harvesters such as solar panels, wind turbines, thermal gradients, and mechanical vibration can often be sufficient to power a microcontroller with sensors, but trying to communicate with a device 100km inside a forest is one hell of a challenge.
Solutions for remote devices do exist but will often come with a multitude of issues. For example, satellite internet is one option for remote devices, but the large amount of power and the high cost make it impractical for large-scale sensor deployments. Cellular is another option for large-scale deployments, but the need for cell towers makes this impossible for remote locations.
As such, one of the best options currently available to engineers is the combination of mesh networks and LoRAWAN. Mesh networks allow for devices to work with each other in getting a message from one remote location to another, while the use of long-range, low-power radio gateways can detect messages well over 15km from the source. If powered with the use of solar panels, wind turbines, and a small energy storage device, a LoRAWAN gateway can even mesh itself to another gateway to allow for connectivity over hundreds of kilometres, where it can eventually bridge to a cellular tower.
Overall, Dryas Networks have clearly demonstrated the power of LoRAWAN when used with remote IoT devices and how such networks can help combat environmental challenges that would benefit from technology.