A method that harvests energy from moving liquid droplets is reported this week in Nature Communications. This method for the collection and storage of energy may provide a cheap and environmentally friendly alternative to batteries.

The cost and pollution associated with electrical batteries is currently limiting the performance of portable electronic devices such as mobile phones. Although environmentally friendly, portable high-power energy harvesting — by converting mechanical energy into electricity — has so far been hampered by poor conversion rates. Tom Krupenkin and Ashley Taylor overcome this problem by developing a mechanical-to-electrical conversion method based on reverse electrowetting.

The technique is based on moving microscopic liquid droplets within thin dielectric films, and is capable of reaching high power densities that rivals those of conventional batteries.