Graphene coating harvests energy from flowing water
By Darren Quick
23:07 July 19, 2011
Hydroelectricity is the most widely used form of renewable energy, supplying around 20 percent of the world's electricity in 2006, which accounted for about 88 percent of electricity from renewable sources. Now researchers at the Rensselaer Polytechnic Institute have developed a new method to harvest energy from flowing water using a nanoengineered graphene coating. The new technology only produces small amounts of electricity so isn't aimed at large scale electricity production, but rather at self-powered microsensors to be used in oil exploration.
For their study, the researchers used graphene that was grown by chemical vapor disposition on a copper substrate and then transferred onto silicon dioxide. Using molecular dynamics simulations they discovered that when water flows over the graphene, chlorine ions present in the water stick to its surface. As the water flows, the friction force between the water flow and the layer of adsorbed chlorine ions causes the ions to drift along the flow direction. The motion of these ions drags the free charges present in graphene along with them, resulting in an internal current.
Using a sheet of graphene measuring 0.03 by 0.05 mm, the team was able to generate 85 nanowatts of power. Although this is only a very small amount, Rensselaer Professor Nikhil Koratkar, who led the research, says it should be enough to power tiny sensors that could be introduced into water or other fluids and pumped down into a potential oil well.
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