Tree power could help run electronic devices

Could the future see a new generation of forest-based environmental monitors powered entirely by the energy from trees? US researchers say it’s possible, having found a way to run an electronic circuit by essentially “plugging into” living trees.

The findings by engineers at the University of Washington (UW) are set to be published in the journal, Institute of Electrical and Electronics Engineers’ Transactions on Nanotechnology.

“As far as we know this is the first peer-reviewed paper of someone powering something entirely by sticking electrodes into a tree,” said Babak Parviz, co-author of the study and a UW associate professor of electrical engineering.

The new research builds on a study last year from the Massachusetts Institute of Technology (MIT), where researchers found that plants could generate a voltage of up to 200 millivolts when one electrode was placed in the plant and another was placed in the surrounding soil. The MIT team has since started a company to develop forest sensors that tap into that energy source.

The UW researchers took those findings a step further by successfully building — for the first time — a circuit that can solely off tree power. Built from parts measuring just 130 nanometers, the circuit consumes an average of 10 nanowatts (one nanowatt is a billionth of a watt) of power during operation.

“Normal electronics are not going to run on the types of voltages and currents that we get out of a tree,” Parviz said. “But the nanoscale is not just in size, but also in the energy and power consumption.”

He added, “As new generations of technology come online, I think it’s warranted to look back at what’s doable or what’s not doable in terms of a power source.”

Tree power is different from the energy many budding chemists have generated using potatoes or lemons, which requires two different metals to react with the food to create an electric potential difference that causes a current to flow. In the UW research, both electrodes were made of the same type of metal.

“It’s not exactly established where these voltages come from,” Parviz said. “But there seems to be some signalling in trees, similar to what happens in the human body but with slower speed. I’m interested in applying our results as a way of investigating what the tree is doing. When you go to the doctor, the first thing that they measure is your pulse. We don’t really have something similar for trees.”