USA — MIT researchers have discovered that trees carry a (small) charge. Now, green energy takes on new meaning with wildfire sensors powered by the woody plants themselves. Here’s how it works.
Voltree Powers big idea started as a rumor on theInternet: If you drive a nail into a tree trunk and another piece of metal into the ground nearby, the claim goes, you can measure a voltage difference between the two. It turned out to be true. Now the startup company is racing to complete prototypes of miniature treepowered forestfire sensors in time for this spring, when it will fieldtest its detection gear during a controlled burn set by the U.S. Forest Service.
Its been quite a journey for a project that started in 2006 when a small Massachusetts engineering firm called MagCap (whose officers now helm Voltree) put up $10,000 to hire a Massachusetts Institute of Technology chemistry freshman to figure out whether trees really produce electricity. It turned out that a slight difference of acidity between tree and soil creates an imbalance of hydrogen ions, generating voltage. The next question was: What could be done with such limited power?
The MIT researchers devised a sensor that could measure temperature and humidity and store enough energy to broadcast data four times a day. Since the power source is limited, the range of the signals is low. But a meshnetwork of sensors could bounce a signal from tree to wired tree until it reaches one of the 2200 automated weather stations scattered through the country. These, in turn, would beam the data via satellite back to the National Interagency Fire Center in Idaho.