Transforming rainwater into electricity is possible

Generating electricity by moving water sounds simple on paper. But since the invention of the water turbine, which is used worldwide, many other avenues have proven less successful. A team of researchers from the Department of Chemical and Biomolecular Engineering at the National University of Singapore has developed a novel solution, published in the journal ACS Central Science on April 16.

Faced with two extreme solutions, from the hydroelectric power plant, which requires very large volumes of water, to the production of a current by water passing through nanotubes, which requires an electric pump canceling out the energy benefit, they chose tubes 2 millimeters in diameter, in which the water can flow by its own weight. Their discovery is to ensure that it flows in small packets, like raindrops separated by air bubbles.

This intermittent, "piston-like" flow, the researchers write, creates a charge separation through friction with the conductive walls of the tube, with negative ions escaping to leave the water with a positive charge. The polarity differential between the inlet and outlet of such a 32-centimeter-long tube allowed several LEDs to light up continuously. The device converted more than 10% of the energy of the water falling into the tubes into electricity. And the circuit developed here produced five times more electricity for the same quantity of water than a system with continuous flow.

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