At Massachusetts Institute of Technology, Christopher Love and colleagues are working to find out whether energy from trees can be used to prevent forest fires. A sensor system taps into trees as a self-sustaining power supply. Each sensor is equipped with a battery that can be slowly recharged using electricity generated by the tree. 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. The project is called EWAN; Early Wildfire Alert Network.