http://www.sciencemag.org/news/2020/08/self-powered-wildfire-detector-could-help-prevent-deadly-blazes

Firefighters in Lake county battle one of the numerous wildfires presently raging across California.

As wildfires once again rage across California, scientists say they have hit on a cheaper, easier way to detect and warn of such deadly blazes: a new type of forest fire sensor powered by nothing more than the swaying of trees. The device—the size of a soup can and costing just $20 to produce—would theoretically be much cheaper than satellite monitoring or manned patrols.