Just because solar and wind power are making an incredible progress, it does not mean that the other renewable energy sources should be neglected and researchers should stop looking for alternative means for energy generation. This is why, researchers from MIT took on the task to see exactly how much energy they can produce from condensation.
It is relatively well-known that water droplets can carry electric charge, yet there is still no functional and practical mean to control this energy and capture it. Of course, as it is with any other gap in research, there is a team that jumps on it the second it is identified. This time, it is Nenad Miljkovic and his team at MIT, who decided to push their work to the limits, and find a way to generate electricity out of air, well, humid air.
At the start of their research about a year ago, the team came across was that water droplets jump spontaneously once in a while when put on a superhydrophobic surfaces, and in the process they gain electric charge. Although it was a small amount, the guys decided to explore the process further and see how much electricity they would be able to produce from it.
The next step was to design an experiment, in which they used conductive plates made of water-repelling copper oxide and water-attracting copper. They layered the plates by placing series of them in alternating order on top of each other, and added some water droplets. The team then observed that the droplets separate from one plate and gained enough charge to make a jump onto the next plate. This resulted in creating an electrical current.
In their paper published in the journal Applied Physics Letters, Miljkovic and team reported that per square centimetre of metal plate, the amount of generated electricity was 15 picowatts. These numbers were relatively low, but highly significant for research in this field, as they suggest that the process can be brought up to a much larger scale. The researchers are convinced that if their set up is made at size of a common camping cooler, then it will generate enough electricity to easily charge up a mobile phone for 12 hours.
The secret to a fully functional design would be to find a way to maintain temperature difference between the instrument and the outside air, in order to trigger condensation. The guys are convinced that such system would be cheap and particularly useful in remote areas where there is limited or no access to the grid.
The work was supported by MIT’s Solid-State Solar-Thermal Energy Conversion Center, funded by the U.S. Department of Energy- the Office of Naval Research; and the National Science Foundation.
Image (c) MIT