Technology

Tiny nano-particles pay huge energy dividends

 By RP Siegel

Nanotechnology is one of the great new frontiers of science. The recently acquired ability to see, precisely produce and manipulate particles as tiny as one billionth of a meter has given scientists and engineers the capability to develop new materials with properties that could not have been imagined a few short years ago…

Some of these properties include high strength, light weight and a variety of unusually advantageous magnetic, electrical, optical, chemical and thermal characteristics. These characteristics come about due to the quantum rules that govern really, really small things, giving rise to behaviors that would not be expected from ordinary materials.

While the idea of manipulating matter at the atomic scale was first introduced by Richard Feynman in 1959, it wasn’t until the 1980s when the development of the scanning tunneling microscope allowed particles this small to even be seen. How small are we talking about? Consider the fact that 25 million of these laid end-to-end would span just under an inch, or that a sheet of paper is about 100,000 nanometers thick.

Applications are varied and diverse. Nanoparticles are being used in foods, medicines, sensors, and biomedical applications that combine all three in terms of drug delivery devices and ingestible sensors. They are used in sunscreen, in paints, on window coatings, building materials and in all varieties of electronic circuits. The use of nanoparticles in motor oil can reduce wear and improve fuel economy. Unsurprisingly, they are also showing up in all sorts of ways in the world of energy production. Two of the most widely discussed areas have been photovoltaic cells and batteries. Nanotechnology has been shown to control the formation of crystals within semiconductors and on battery electrodes. This has implications for both the efficiency and the service life of these devices. Anti-reflective coatings made from nanoscale filaments help improve solar cell performance by allowing the cells to reflect less light and absorb more.

Copper zinc tin sulfide nanoparticles contained in solar cells (Oregon State University)

Other advances have leveraged the electrical properties of nanostructures to facilitate improved transport of electrons within the solar cells, improving both performance and efficiency. The building up of materials, starting at the molecular level, is in many ways analogous to the way that living structures are produced in nature. That has led to some solar cells modeled after plants in the quest to develop a functional scalable and efficient “artificial leaf“, that can produce fuel directly from sunlight. Plants produce energy directly from the sun and then store it immediately in the form of sugars and other molecules.

The need for storage to go along with solar energy is implicit, considering that no power is produced at night and reduced amounts are produced during cloudy periods. One of these, developed at Vanderbilt University and funded by the US Department of Agriculture, utilizes nanoporous layers of gold so thin, that the light can pass right through them. Yet another team at Georgia Tech uses molecular self-assembly to improve the performance of low-cost amorphous silicon cells. Professor Vladimir Dyakonov at Würzburg University has developed some similar types of cells. Nanotechnology has been used in so many ways to improve solar energy systems, that there was an international congress held last November in Germany called, “Next Generation Solar Energy Meets Nanotechnology“.

UMWELTnanoTECH – Results

This video shows some of the results of the conference, which include not only organic photovoltaics, but also energy storage, and thermoelectric generators, which produce electricity directly from heat (with no moving parts). The use of nanotechnology has led to increases in thermoelectric performance of as much as 40 percent. With this improved level of performance, thermoelectric devices could become more popular, serving applications such as charging hybrid vehicles using heat from their exhaust.

As for energy storage, nanotechnology is being used in batteries. Brian Landi is an associate professor and researcher at the Microsystems Engineering at Rochester Institute of Technology (RIT). He has been using carbon nanotubes to improve performance of lithium ion batteries. Nanotubes are sheets of carbon, one atom thick, also known as graphene, that have been rolled up into a seamless cylinder. They exhibit exceptionally high electrical conductivity, which allows them to be used as nanowires. These are added to the electrodes, which are made of other, less conductive materials that have been selected for their electrochemical properties. The end result is a composite electrode with improved conductivity. Says Landi, “the highly conductive nanotubes form a network that allows the battery to store 10-15 percent more electricity, charge and discharge twice as fast, all while improving thermal stability by 30-40 percent.”

A nanotube (CSIRO)

The supercapacitor is another energy storage device similar to a battery, except that it stores less energy, but can charge and discharge almost instantly. This makes it very useful in dynamic applications like electric cars. Researchers at Fraunhofer Institute for Manufacturing Engineering and Automation IPA in Stuttgart used graphene electrodes that were constructed such that they had significantly more surface area than conventional supercapacitors, allowing them to store 75 percent more energy.

Another example of the impressive innovation being done in this field is the work of Professor Yun Hang Hu at Michigan Technological University. While graphene is a tremendously valuable material due to its combination of very high surface area and high electrical conductivity, Hu took it a step further by embedding sodium metal into the carbon, further increasing its conductivity nearly a hundred-fold. Says Hu, “previous efforts to introduce metals into graphene were only able to attach them to the surface, where they were immediately oxidized by the surrounding air. We developed a new process that successfully embedded sodium into the carbon, where the air cannot affect it.” This new material will be useful for solar cells, supercapacitors, batteries, and fuel cells where they will be used as electrodes. Carbon nanotubes are also being used to make lightweight wind turbine blades. Because of the reduced weight, the blades can be made longer, which enables them to produce more power. The longer blade also allows turbines to begin producing power at lower wind speeds. At present these blades are being used primarily in small turbines.

Other innovations include a hydrogen storage tank made of graphene. Developed by a doctoral student at Rensselaer Polytechnic Institute, the tank exceeds the targets set forth by the US Department of Energy by 55 percent. Other research being done at Sandia National Lab, stores hydrogen using nano-confinement in a material that holds hydrogen like a sponge. You might think that nanotechnology is only being used for renewables because of their mechanical strength and electrical conductivity, but that’s not the case. In fact, there is a great deal of nanotechnology being used in the oil and gas industry.

One thing that’s not commonly known about oil drilling is how much oil is left behind when a well is considered depleted. That’s because a substantial amount of oil either gets stuck in the rock pores or can’t find a pathway to flow through. Nanoparticles can be mixed with base fluids to enhance the flow of oil through the porous rock, thereby increasing the recovery potential of oil and gas reserves. The particles reduce the forces that bind the oil to rock. Metal particles can also be introduced into the flow, to which heat can be directed. The efficient method of heating can reduce the viscosity of the oil, allowing it to flow more easily.

Nanotech coating (Oregon State University)

Nanomaterials can also be used to produce temporary non-stick coatings within the rock. They are based on the same principal as time-release medicines. Over the past 25 years, very sophisticated computer models of oil and reservoir have been developed which have been extremely useful in directing retrieval operations. However, the models are only as good as the data being fed into them. Nanotechnology can be used to significantly improve the resolution of the data on which these models operate.

This is being done today with nano-sensors that can convey information to operators to guide their drilling path. Nano-sized magnetic particles, for example, can be injected along with the drilling fluid and then tracked with the use of sensitive transmitters and receivers that are housed in underground pipes and connected to operators at the surface. These can be used to clearly illustrate the path that the fluids are taking, where the cracks are, as well as clearly mapping the underground reservoir, keeping the operators from simply shooting in the dark, helping to locate bypassed and trapped oil.
On the near horizon, micro-sized electronic sensors, called micro-fabricated sensors, complete with processing, memory, clock and a power supply, in a package no bigger than the tiniest pebble (about 1 cubic mm) can also be injected into the flow and provide even more detailed information.

That’s not the end of the story. Once the oil is out of the ground, nano-coatings being developed by companies like Quantiam, can be used to line the insides of pipes to reduce both friction and wear. These advances can significantly impact the cost of oil and gas operations. Some of these coatings are formulated for high-temperature application could be used in wells. Similar coatings are also being used to reduce the wear of drilling equipment. The nano story continues at the refinery, where nanotechnology is being used to speed up reactions and tailor final formulations. Specifically, zeolites, also known as molecular sieves, are porous ceramic-like solids that are used as catalysts in the refinery process that converts crude oil into gasoline and other products. Placing aluminum ions inside the zeolite’s pores helps to move things along. Nanotechnology can be used to produce zeolite catalysts with specific pore sizes and determination of which crystal faces are exposed in the locations where the reactions are expected to occur.

Finally, there are some innovators who are putting nanotechnology directly into the fuel. Envirox™ is a diesel fuel additive that is being called a fuel-borne catalyst. Based on nanotechnology it is said to save fuel, reduce emissions and clean the engine. When you step back and look at all these amazing applications, it becomes clear that nanotechnology is perhaps the best thing to happen to energy in a long, long time.

SEE MORE: Great things from small things by  By Robin Wylie

about the author
RP Siegel
Skilled writer. Technology, sustainability, engineering, energy, renewables, solar, wind, poverty, water, food. Studied both English Lit.and Engineering at university level. Inventor.