We are accustomed to transpiration, an evaporation process through which plants constantly lose water extracted right down from the roots. Based on the phenomenon, Michel Maharbiz from the University of California together with scientists from MIT and Michigan, is developing synthetic leaves which also lose water through evaporation, creating a similar suction effect like the plants – using the same to generate power.
The leaves are made in glass wafers with tiny water-filled networks inside. The channeled water (like in a real plant) gushes up water from the main stem at 1.5cm per second, while water moves toward the edges of the leaves, from where it evaporates through the created pores. The main stem has metal plates connected to circuits attached with its walls, the charged plates and water within the stem form two conducting layers separated by an insulating layer - the capacitor in this case. Thus, when bubbles of air pass through the capacitor, because of different electrical properties of air and water, the device charges and a small electric current is generated, thus making the leaf a power source.
By this evaporation-driven flow, the device is good to produce an output voltage of some 2 to 5 microvolts with power density of about 2 microwatts per cubic centimeter. Though that may not be anywhere in level with the other alternative sources of power that we have already tapped, the process does have potential, and we needn’t forget, we haven’t actually flirted enough with artificial photosynthesis yet, so there is still time.
Via: NewScientist
