Scientists Generate Electricity from Lotus Leaves

Scientists in China say they’ve found a way to use lotus leaves to generate electricity from transpiration—the movement of water evaporating out of a leaf—opening a door to generating clean electricity from nature.

Published in the journal Nature Water, the study “not only uncovers the unprecedented hydrovoltaic effect of leaf transpiration, but also provides a fresh perspective for advancing green energy technologies through the widespread phenomenon,” the researchers write.

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Their results could help supply emissions-free electricity for smart grids and the Internet of Things, among other applications, reports Interesting Engineering.

Unlike traditional hydroelectric power, which relies on harnessing the force of moving water pushing against a turbine, hydrovoltaic systems generate energy from interactions within the water itself. They can capture energy generated by water molecules evaporating, condensing, diffusing—or in the case of plants, from ions moving as water is pulled from roots to leaves.

Previous research indicates that harnessing just 1% of the energy available in hydrovoltaic systems with an efficiency of 1% could meet nearly a third of the world’s energy needs—comparable to crude oil.

Other hydrovoltaic systems have been demonstrated, but this study is one of the first to harvest energy directly from the natural transpiration of plant leaves, despite their widespread abundance, the researchers say.

The study team used a lotus leaf to show that it can be done. They created an electrical system by placing a titanium mesh electrode on the leaf to act as a cathode, and inserting a needle electrode in the stalk as an anode. As water moved upward to transpire through the leaf’s stomata—the microscopic pores in plant leaves that release water and vapour—the ions moving between the electrodes, created an electrical potential difference that generated electricity throughout the day.

Connected to a device, the energy from a single leaf would generate only a tiny electrical current—just 50 nanoamperes. But this could be amplified by adding connections together in a series, say the researchers.

Various factors affected the system’s performance: electrical output increased with higher humidity, but declined with greater stem thickness and higher temperatures. For the technology to be commercially viable, researchers will need to find ways to increase the output of individual leaves and optimize energy collection and storage, Interesting Engineering writes.

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