Nanotechnology leading innovation in power generation.
Nanotechnology is seen as having a significant influence on the role of solar power in future energy mixes, and there is increasing interest in emulating the nanoscale structures of light-harvesting systems in plants. Scientists at Tel Aviv University (TAU), in Israel, for instance, have found a novel way to control the atoms and molecules of peptides so that they grow to resemble nano-sized forests of grass. Operating in the range of 100 nanometres (roughly one-billionth of a metre) and even smaller, a team working under Prof. Ehud Gazit in TAU's department of molecular microbiology and biotechnology have found that these 'peptide forests' repel dust and water, making them a self-cleaning coating for windows or solar panels which, when dirty, become far less efficient. This would means saving money on maintenance and cleaning, which is especially a problem in dusty, arid regions, where most solar farms are installed today.
The same researchers have also established that "self-assembled nano-tubules", created in a vacuum under high temperatures, can withstand extreme heat and are resistant to water. The thinking is that this technology may lead to storage material with a high density. As a capacitor with unusually high energy density, such nano-tech material could give existing electric batteries a boost, overcoming the problem of thrust in electric cars and helping to start an electric car, go uphill, or overtake other vehicles.
One hurdle that has slowed the commercial development of nanotech-based fuel cells and fuel-cell vehicles is the carbon monoxide contamination of active platinum catalyst sites, which renders them ineffective and prevents fuel oxidation. However scientists at the University of Ulster's Nanotechnology Institute--with colleagues from Peking University and the University of Oxford--have discovered a new catalyst-support combination that could make fuel cells more efficient and more resistant to CO contamination. To create a catalyst system that can tolerate more carbon monoxide, they deposited platinum nanocrystals on a support material of graphene oxide and reduced it slightly with radiation to increase its electrical conductivity. They used a simple scalable, fast and eco-friendly microwave approach that has the advantage of reducing graphene oxide (RGO) and forming platinum nanoparticles simultaneously. Their research shows that the new material displays an unprecedented CO poisoning tolerance, a longer-term stability and a higher electrocatalytic activity.
Another nano-based fuel cell technology of the future may also be inspired by an unlikely source--a virus that devastates tomatoes, tobacco and peppers. Engineers have discovered that they can harness the characteristics of the rigid, rod-shaped tobacco mosaic virus (TMV) to build tiny components for lithium ion batteries. The scientists at the University of Maryland established that TMV's nanostructure is the ideal size and shape to use as a template for building battery electrodes.
The rods are coated with a conductive thin film that acts as a current collector, and then another layer of material that participates in the battery's electrochemical reactions. The conductive metal is mainly nickel. The tiny, dense forest of coated rods creates an 80-fold increase in the electrode's surface area and up to a 10-fold increase in its energy storage capacity over standard lithium ion batteries, enabling fast charge and discharge times, plus a longer life. "The resulting batteries are a leap forward and will be ideal for use not only in consumer electronic devices, but also in other technologies that have been limited so far by the size of their power source," said project leader Reza Ghodssi. "We can produce millimetreor sub-millimetre-sized energy storage devices for use in large networks of tiny, wireless sensors that can be deployed to monitor security, agriculture, or the environment in remote locations."
Meanwhile, in Norway, Statkraft, a renewable energy company is operating the world's first prototype osmotic power plant. Working with the Norwegian Institute of Technology, Statkraft is operating the prototype plant at Tofte on a fjord 40 miles south of Oslo.
Osmotic energy is based on the natural phenomenon of osmosis, which allows trees to drink through their leaves and plays on the different concentration levels of liquids. When freshwater and seawater meet on either side of a membrane of polyethylene plastic--a thin layer that retains salt but lets water pass--freshwater is drawn towards the seawater side. The flow puts pressure on the seawater side, and that pressure can be used to drive a turbine, producing electricity. Contrary to other renewable energy sources such as wind and solar power, osmotic power produces a stable electricity flow regardless of weather conditions. According to Statkraft, if the technology can be proven to scale up it could account for 50% of energy demand within the European Union. That possibility lies in the future though: Statkraft is looking to address issues raised by the plant--the cost of the membranes, their relatively low efficiency, and the embryonic state of the manufacturing market for the membranes, as very companies make them. "We are in the process of preparing new components for testing in early 2011 and we have made significant improvements in energy efficiency of the prototype," said spokesman Torbjorn Steen.
There is a range of other potential nano-based benefits for energy generation, but the key stumbling block is cost, according to Dr Gerd Bachmann, of the Future Technologies Division of Dusseldorf-based research centre VDI Technologiezentrum.
"Nanotechnology could well have a big influence on renewable energy generation, but it's not the case at the moment," he said. "New power systems always have higher costs at their starting point that existing ones. But in some cases nanotechnology will be very important, along with intelligent software and microscopic parts."
Medium-term benefits include nanocrystalline magnetic materials, according to him, which will enable efficient components in current transformation and supply for transformers and electric meters. There is also the likelihood that the extraordinary electric conductivity of nanomaterials such as carbon nanotubes can be utilised in electric cables and power lines. Nanotechnology will also have a role in providing high temperature superconductors for motors and generators in ships, and nano-structured heat protection layers for gas turbines, along with solar panels. "In classical silicon photovoltaics you are limited by the variable light you need at the high-energy part of the solar spectrum," said Dr Bachmann. "If you want to overcome that limit you have to think of more intelligent systems--multi-layered solar cells. These increase efficiency dramatically and that can be done by very thin nano-layers." Carbon nanotubes can also be incorporated in high-tensile construction materials, such as for rotor blades of wind power stations or as material for low-loss cables and power lines, Dr Bachmann suggested. "Wind turbines are limited in the energy they produce by the height of conventional carbon fibre blades," he said. "Reinforced carbon nanotube composites would allow the blades to be built much higher and that would increase the power they can harness." At the moment, the key obstacle is that researchers have yet to design a way to disperse carbon nanotubes in such big values throughout the blades. Dr Bachmann also believes that nanotechnology will have a role in carbon capture and storage by facilitating the separation of carbon dioxide in carbon capture and storage systems associated with power plants.
The European Commission's Joint Research Council is also pursuing several projects along these lines, including the role nanotechnology can play in clean coal and biomass applications. Among these are research on thermo-chemical hydrogen reactions and CO2 compression and purification, where nanotechnology offers unique features for improved performance. In clean-tech applications such as electric car batteries, nanomaterials can optimise chemical reactions to offer more range and energy density. One company that is making headway with nano-batteries is A123 Systems, based in Massachusetts, New England, which is the supplier to California-based hybrid car specialists Fisker Automotive for its high-performance Karma plug-in hybrid, but is also overseeing a switchable battery demonstration for taxis in Tokyo. The nanocomponent in the battery changes the lattice structure of iron phosphate atoms to improve the conductivity of the iron phosphate cathode, enabling more charge cycles.
There are of course caveats with much of this research, not least the issue of safety, certainty and public perception of an industry that was once notoriously described by Prince Charles as likely to turn the planet into "grey goo." Professor Pietro Perlo, a senior director at the Fiat Research Centre, which is investing heavily in nanotechnology to improve engine and energy performance, noted: "If you stop someone in the street and tell them that there is a lot of nanotechnology in their car the reaction you get might well be one of fear." In the long-term, though, Prof Perlo believes nanotechnology may well be a key selling point, simply because he is certain it transform the use of electric batteries in cars. "We have the chance to brutally re-think the way we intend to have mobility," he said. "We have a big chance to present nanotechnology that will allow this revolution, improving efficiency of batteries by orders of magnitude. That can be done with the right projection." Dr Sally Tinkle, senior science advisor to the US National Institute of Environmental Health Sciences (NIEHS), also acknowledges the risks of public perception. "We are trying to be prepared. In so many nanoproducts the material is embedded in the product--at the end of life does it remain in the matrix or will it break down into tiny compounds? We understand the immediacy of these questions and the need to protect public health and the environment. We're moving as quickly as we can, but good science takes time."
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|Publication:||International News Services.com|
|Date:||Dec 1, 2010|
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