by Emil Morhardt
Harvesting energy from atmospheric dew? Why would dew have any energy in it to harvest? Miljkovic et al. at MIT and Bell Labs, in a paper published this week, discovered it by accident while working with nanoengineered superhydrophobic surfaces (surfaces that really don’t like water on them!). When water condenses on them the droplets can merge and spontaneously jump off, and what’s more, they are positively charged when they do. So, it’s just a matter of collecting that charge and putting it in wires to get electric current that can do work. The authors capture the charged droplets on a superhydrophilic (really likes to have water on it) copper surface. The faster the droplets are going when they jump, the more power generation, and this can be achieved by getting them to jump when they are very small. Thus we have a system with no moving parts, passively generating power purely by the condensation of dew. At the moment it’s just a laboratory experiment, but the authors think that it is scalable at low cost and provides another way to get renewable energy from the environment.
Miljkovic, N., Preston, D.J., Enright, R., Wang, E.N., 2014. Jumping-droplet electrostatic energy harvesting. Applied Physics Letters 105, 013111. http://bit.ly/1oNICeR