A Piezoelectric Energy Harvester for Mechanical Keyboards to Enable Self-Powered Computers

Abstract

A 2015 NRDC research study revealed that electronic devices consume alarming amounts of energy. To reduce the
energy consumption of these devices, this project proposes a novel energy-harvesting keyboard design that allows a
computer to charge as the user types on it. The keyboard generates electricity via piezoelectric materials. A novel
key structure and transducer circuit were proposed to integrate the piezo materials in the keyboard and transform the
electricity generated through keystrokes into a usable form. A keyboard prototype with 9 keys was used for testing.
Data was collected in two rounds; the first round tested the power generated per keystroke. It was determined that
the average power generated from a single key press was 0.342 μW. The second round of testing involved
determining the power generated after typing at a constant rate for 5-25 seconds. The peak electrical output occurred
at 25 seconds of typing, during which the total power generated was 2.38 mW. Thus, after 25 seconds of typing,
62% of a 22μF capacitor can be charged. This power output of the prototype is nearly 9 times higher than the
expected power output. Given that the expected value was calculated using a higher-quality piezo than the one used
in the prototype, it can be concluded that the keyboard design significantly increased the power generated. Although
the needs of a computer are not fully met, this research may be applied to a hybrid charging system utilizing both
the plug-in charger and the keyboard.