Washington, September 23 : Researchers at MIT (Massachusetts Institute of Technology) are developing a network of sensors that may be run on electricity generated by trees, which could be used to prevent forest fires.
What they learn also could raise the possibility of using trees as silent sentinels along the nation's borders to detect potential threats such as smuggled radioactive materials.
The U.S. Forest Service currently predicts and tracks fires with a variety of tools, including remote automated weather stations.
But, these stations are expensive and sparsely distributed. Additional sensors could save trees by providing better local climate data to be used in fire prediction models and earlier alerts.
However, manually recharging or replacing batteries at often very hard-to-reach locations makes this impractical and costly.
The new sensor system seeks to avoid this problem by tapping into trees as a self-sustaining power supply.
Each sensor is equipped with an off-the-shelf battery that can be slowly recharged using electricity generated by the tree.
According to Shuguang Zhang, one of the researchers on the project and the associate director of MIT's Center for Biomedical Engineering (CBE), a single tree doesn't generate a lot of power, but over time the "trickle charge" adds up, "just like a dripping faucet can fill a bucket over time."
The system produces enough electricity to allow the temperature and humidity sensors to wirelessly transmit signals four times a day, or immediately if there's a fire.
Each signal hops from one sensor to another, until it reaches an existing weather station that beams the data by satellite to a forestry command center in Boise, Idaho.
Scientists have long known that trees can produce extremely small amounts of electricity. But, no one knew exactly how the energy was produced or how to take advantage of the power.
According to Andreas Mershin, a postdoctoral associate at the CBE, "It's really a fairly simple phenomenon: An imbalance in pH between a tree and the soil it grows in."
Testing of the wireless sensor network, which is being developed by Voltree Power, is slated to begin in the spring on a 10-acre plot of land provided by the Forest Service.
According to Christopher J. Love from MIT, who with Mershin has a financial interest in Voltree, the bioenergy harvester battery charger module and sensors are ready.
"We expect that we'll need to instrument four trees per acre," he said, noting that the system is designed for easy installation by unskilled workers.
"Right now, we're finalizing exactly how the wireless sensor network will be configured to use the minimum amount of power," he concluded.