The Graphene coating on the sensor acts as a tiny generator

Researchers at Rensselaer Polytechnic Institute, USA, have developed a new way to harvest energy from flowing water. This finding aims to accelerate the creation of micro-sensors that self-supply more accurate and less costly and more efficient oil exploration.

Under the leadership of Professor Nikhil Koratkar working at the Rensselaer Polytechnic Institute in the United States, researchers investigated how water flows on the surface covered with a layer of nanomaterials graphene that can produce a small amount of electricity. The team succeeded in generating 85 nanowatts of energy from a graphene sheet with a length of 0.03mm, and a width of 0.015mm.

Nanomaterials Graphene coating on sensors,
allowing the movement of water, into electrical energy.

This amount of energy is sufficient to operate a small electric sensor placed in water or other liquids and pumped to potential oil wells, according to Koratkar. As the sensor moves, and water will also be injected through naturally occurring cracks and deep cracks in the ground, the sensors detect the presence of hydrocarbons and help detect hidden pockets ( of oil and natural gas). As the water flows through the graphene-coated sensor, the coating will act as a nanogenerator to provide the power needed to maintain the sensor's operation. This energy source is needed to help the sensors collect data and relay information back to the ground.

"It is not possible to power these micro-sensors with conventional batteries, because the sensor is too small. So, we create a nanomaterial graphene coating on the sensor, allowing transformation. dynamics of water, electrical energy , "according to Koratkar, professor of mechanical engineering, aerospace industry, and nuclear engineering and engineering and materials science, Rensselaer School of Engineering. " While similar effects have been monitored for carbon nanotubes, this is one of the first studies with nanomaterial graphene coatings . Nanomaterial graphene coatings are capable of producing the least amount of energy. It is in the form of exponential 10 more than carbon nanotubes , and the advantage of the nano-graphene coating is its versatility, which can wrap around almost any geometry or shape . "

Details of the study are entitled " Energy harvesting from Graphene-based water streams ", published online last week in the journal Nano Letters .

It was also the first research project to be funded with a US $ 1 million grant to Koratkar's research team in March 2010 by the Applied Energy Association.

Hydrocarbon exploration is an expensive process that involves drilling deep into the ground to detect the presence of oil or natural gas. Koratkar said that oil and gas companies would further enhance the efficiency of the process by sending a large number of nanoscale sensors or sensors into new and existing wells. The sensors will go deep into the ground, they are transported by water pressure pumped into the wells, and into the network of cracks that exist beneath the ground. The oil company will no longer be limited to longitudinal exploration, and data collected from sensors will be a powerful arm for companies, providing more accurate information for decision making. Best place to drill.

The team's findings are a potential solution to an important challenge to implementing self-powered micro-sensors, and self-powered. By covering microscopes with a graphene coating, the sensor can harvest energy thanks to the flow of water through the coating.

" We will wrap graphene coatings around the sensor, and it will act as a smart skin that serves as a tiny generator ," according to Koratkar.

Graphene is a single atom thick plate of carbon atoms, arranged like a chain link fence. In this study, Koratkar's team used graphene that was developed by chemical vapor deposition on a copper substrate and transferred to silicon dioxide. The researchers created a flow system in the experimental tunnel to test the ability to generate electricity when the water flows through the graphene coating at different speeds.

Along with the ability to generate 85 nanowatts of electricity from a small piece of graphene, the researchers used molecular dynamics simulations to better understand the reason for this phenomenon. They discovered chloride ions present in water clinging to graphene's surface. As the water flows through the graphene layer, the friction force between the water flow and the adsorption of absorbing chloride ions causes the ions to drift in the direction of flow. The motion of these ions pulls the losses present in graphene in the direction that the current produces an internal stream.

This means that the graphene coating requires ions to be present in the water to function properly. Therefore, oil exploration companies will need to add chemicals to the water before pumping into the well. Koratkar said this is an easy and inexpensive solution.

Koratkar's team also experimented with harvesting energy by passing water through carbon nanotubes. However, they are not as effective as using graphene coatings, Koratkar said.

With future potential applications of new technology, Koratkar said he could visualize micro-robots or self-powered ultra-small submarines, and the ability to capture energy from a layer of graphene covered at the bottom of a boat.

Along with Koratkar, co-authors of the experiment included: Yunfeng Shi, associate professor at the department of materials and engineering science at Rensselaer technical school, Prashant Dhiman and Fazel Yavari, graduate student in mechanical engineering, Rensselaer technical school; Xi Mi graduate student in Physics, Rensselaer technical school; along with Pulickel Ajayan, M. Benjamin and Mary Greenwood Anderson, Engineering Professor at Rice University and Fellows Hemtej Gullapalli, at Rice University.