Archive for the ‘Electricity’ Category
2009
“Artificial photosynthesis has yet to be cracked, but electrical engineers in the US think that synthetic leaves could be used to generate electricity in a different way – by sweating. Natural leaves constantly lose water through evaporation in a process called transpiration, which draws water from the roots to the very top of even the tallest trees. The new synthetic leaves also lose water through evaporation to create that mechanical water pump effect, and use it to generate power…
Michel Maharbiz at the University of California, Berkeley, working with colleagues at the University of Michigan and MIT, built their leaves from glass wafers shot through with a branching network of tiny water-filled channels arranged like the veins of a leaf. The smaller channels extend to the edge of the plate and have open ends that allow water to evaporate, drawing fluid along the leaf’s central stem at a rate of 1.5 centimetres per second.The researchers added metal plates to the walls of the central stem and connected them to a circuit. The charged plates and the water within the stem create a sandwich of two conducting layers separated by an insulating layer – in effect, a capacitor.The leaf is transformed into a source of power by periodically interrupting the water flowing into the leaf with air bubbles. Thanks to the different electrical properties of air and water, every time a bubble passes between the plates the capacitance of the device changes and a small electric current is generated, which passes to an external circuit where it’s used to pump up the voltage on a storage capacitor. ‘We use the mechanical energy in the liquid flow to change the capacitance and add energy to the capacitor,’ says Maharbiz…”
source: newscienties.com