You might be surprised to learn that trees generate small amounts of electricity. Not enough to shock you, but enough to recharge batteries that could power a network to track forest fires in remote areas. As VOA's Rosanne Skirble reports, a team of scientists at Massachusetts Institute of Technology is working on taking that project from the laboratory into the forest.
Andreas Mershin is a postdoctoral associate at MIT's Center for Biomedical Engineering. He was working on generating energy from spinach plants when a group from a small bioengineering company came to show him that they could produce electricity from trees.
That didn't sound so odd. All living organisms have electricity in their cells. Some do more with it than others. The electric eel, for example, is a freshwater predator that can produce a large electric field around its body, strong enough to stun prey and ward off enemies. But the cellular electricity in the rest of us is at much lower levels.
Mershin and his colleagues wanted to understand how a tree could generate enough power to be measured and why it would. In lab experiments, they eliminated possible power sources such as radio or microwaves and underground cables.
"And to our great surprise, we couldn't make the voltage go away," Mershin says.
The scientists finally concluded that the tree generates electricity as a way to regulate its pH level, reacting to the acidity of its environment. The imbalance between the tree and the soil results in an electric charge.
"The only time you could make the voltage go away was when the soil pH matched the tree's pH," Mershin says.
Over time, the so-called 'trickle charge' can add up and produce enough electricity to recharge batteries. Mershin says a start-up company called Voltree Power wants to transfer that technology into a tree-powered remote sensor network that could help manage forest fires.
"Every few trees is equipped with a little circuit that is buried under the ground where nobody can see it," he says and adds, "It's using this power to very slowly, all day and all night, to charge up a battery, and then when needed, the battery can be discharged through a circuit to report on the humidity and the temperature around that tree."
Mershin says that's important data that can help predict where fires might start and once started, how best to respond. "It means that the firefighters and the firefighting resources can be deployed more strategically and choke off the fires at the best points and know up ahead where [the fires] are going to occur and where they are going to go."
Mershin says while the system has preformed well in the laboratory, it is time to see if it can work in the forest. "We have to make these things weatherproof and bear-proof and vandalism-proof and all these other things."
Mershin is an advisor to Voltree and says the company plans to install a sensor network on a 4-hectare tract in a remote forest in Idaho next year. Mershin and his colleagues discuss their research in a recent issue of the open-access journal, Public Library of Science One.