14 Jan 2016
|Perovskites, substances that perfectly absorb light, are the future of solar energy. The opportunity for their rapid dissemination has just increased thanks to a cheap and environmentally safe method of production of these materials, developed by chemists from Warsaw, Poland. Rather than in solutions at a high temperature, perovskites can now be synthesized by solid-state mechanochemical processes: by grinding powders.|
|We associate the milling of chemicals less often with progress than with old-fashioned pharmacies and their inherent attributes: the pestle and mortar. It’s time to change this! Recent research findings show that by the use of mechanical force, effective chemical transformations take place in solid state. Mechanochemical reactions have been under investigation for many years by the teams of Prof. Janusz Lewinski from the Institute of Physical Chemistry of the Polish Academy of Sciences (IPC PAS) and the Faculty of Chemistry of Warsaw University of Technology.|
|In their latest publication (“Mechanosynthesis of the hybrid perovskite CH3NH3PbI3: characterization and the corresponding solar cell efficiency”), the Warsaw researchers describe a surprisingly simple and effective method of obtaining perovskites – futuristic photovoltaic materials with a spatially complex crystal structure.|
|A simple, fast and safe method of obtaining perovskites has been discovered by scientists from IPC PAS in Warsaw, Poland. The perovskite (a black powder) is milled from two powders: a white one, methylammonium iodide, and a yellow one, lead iodide.|
|“With the aid of mechanochemistry we are able to synthesize a variety of hybrid inorganic-organic functional materials with a potentially great significance for the energy sector. Our youngest ‘offspring’ are high quality perovskites. These compounds can be used to produce thin light-sensitive layers for high efficiency solar cells,” says Prof. Lewinski.|
|Perovskites are a large group of materials, characterized by a defined spatial crystalline structure. In nature, the perovskite naturally occurring as a mineral is calcium titanium(IV) oxide CaTiO3. Here the calcium atoms are arranged in the corners of the cube, in the middle of each wall there is an oxygen atom and at the centre of the cube lies a titanium atom. In other types of perovskite the same crystalline structure can be constructed of various organic and inorganic compounds, which means titanium can be replaced by, for example, lead, tin or germanium. As a result, the properties of the perovskite can be adjusted so as to best fit the specific application, for example, in photovoltaics or catalysis, but also in the construction of superconducting electromagnets, high voltage transformers, magnetic refrigerators, magnetic field sensors, or RAM memories.|
|At first glance, the method of production of perovskites using mechanical force, developed at the IPC PAS, looks a little like magic.|
|“Two powders are poured into the ball mill: a white one, methylammonium iodide CH3NH3I, and a yellow one, lead iodide PbI2. After several minutes of milling no trace is left of the substrates. Inside the mill there is only a homogeneous black powder: the perovskite CH3NH3PbI3,” explains doctoral student Anna Maria Cieslak (IPC PAS).|
|“Hour after hour of waiting for the reaction product? Solvents? High temperatures? In our method, all this turns out to be unnecessary! We produce chemical compounds by reactions occurring only in solids at room temperature,” stresses Dr. Daniel Prochowicz (IPC PAS).|
|The mechanochemically manufactured perovskites were sent to the team of Prof. Michael Graetzel from the Ecole Polytechnique de Lausanne in Switzerland, where they were used to build a new laboratory solar cell. The performance of the cell containing the perovskite with a mechanochemical pedigree proved to be more than 10% greater than a cell’s performance with the same construction, but containing an analogous perovskite obtained by the traditional method, involving solvents.|
|“The mechanochemical method of synthesis of perovskites is the most environmentally friendly method of producing this class of materials. Simple, efficient and fast, it is ideal for industrial applications. With full responsibility we can state: perovskites are the materials of the future, and mechanochemistry is the future of perovskites,” concludes Prof. Lewinski.|
|The described research will be developed within GOTSolar collaborative project funded by the European Commission under the Horizon 2020 Future and Emerging Technologies action.|
|Perovskites are not the only group of three-dimensional materials that has been produced mechanochemically by Prof. Lewinski’s team. In a recent publication the Warsaw researchers showed that by using the milling technique they can also synthesize inorganic-organic microporous MOF (Metal-Organic Framework) materials. The free space inside these materials is the perfect place to store different chemicals, including hydrogen.|
|Source: Institute of Physical Chemistry of the Polish Academy of Sciences|
Australian solar power experts making up the Victorian Organic Solar Cell Consortium have developed and begun to market solar cells that are created with a 3D printer.
The group, consisting of scientists from the CSIRO, the University of Melbourne and Monash University have been working on the technology for over seven years and have figured out a way to cheaply print the panels onto plastic, including smart-phones and laptops, enabling self charging electronics. They are also able to print directly on to walls and windows using an opaque solar film and claim that they can line a skyscraper with panels, making it totally electrically self sufficient.
“We print them onto plastic in more or less the same way we print our plastic banknotes,” said Fiona Scholes, senior research scientist at CSIRO. “Connecting our solar panels is as simple as connecting a battery. It’s very cheap. The way in which it looks and works is quite different to conventional silicon rooftop solar.”
The next step is to create a solar spray coating to enhance the power of the panel. “We would like to improve the efficiency of solar panels – we need to develop solar inks to generate more energy from sunlight,” said Scholes. “We are confident we can push the technology further in the years to come.”
22 Oct 2015
Posted: Oct 21, 2015
Sun and wind are important sources of renewable energy, but they suffer from natural fluctuations: In stormy weather or bright sunshine electricity produced exceeds demand, whereas clouds or a lull in the wind inevitably cause a power shortage.
For continuity in electricity supply and stable power grids, energy storage devices will become essential.
So-called redox-flow batteries are the most promising technology to solve this problem. However, they still have one crucial disadvantage: They require expensive materials and aggressive acids.
A team of researchers at the Friedrich Schiller University Jena (FSU Jena), in the Center for Energy and Environmental Chemistry (CEEC Jena) and the JenaBatteries GmbH (a spin-off of the University Jena), made a decisive step towards a redox-flow battery which is simple to handle, safe and economical at the same time: They developed a system on the basis of organic polymers and a harmless saline solution.
“What’s new and innovative about our battery is that it can be produced at much less cost, while nearly reaching the capacity of traditional metal and acid containing systems,” Dr. Martin Hager says.
CAPTION Jena research team and its innovative battery (from left to right) are: Prof. Dr. Ulrich S. Schubert, Tobias Janoschka und Dr. Martin Hager.
The scientists present their battery technology in the current edition of the renowned scientific journal Nature (“An aqueous, polymer-based redox-flow battery using non-corrosive, safe, and low-cost materials”).
In contrast to conventional batteries, the electrodes of a redox-flow battery are not made of solid materials (e.g., metals or metal salts) but they come in a dissolved form: The electrolyte solutions are stored in two tanks, which form the positive and negative terminal of the battery.
With the help of pumps the polymer solutions are transferred to an electrochemical cell, in which the polymers are electrochemically reduced or oxidized, thereby charging or discharging the battery. To prevent the electrolytes from intermixing, the cell is divided into two compartments by a membrane.
“In these systems the amount of energy stored as well as the power rating can be individually adjusted. Moreover, hardly any self-discharge occurs,” Martin Hager explains.
Traditional redox-flow systems mostly use the heavy metal vanadium, dissolved in sulphuric acid as electrolyte.
“This is not only extremely expensive, but the solution is highly corrosive, so that a specific membrane has to be used and the life-span of the battery is limited,” Hager points out.
In the redox-flow battery of the Jena scientists, on the other hand, novel synthetic materials are used: In their core structure they resemble Plexiglas and Styrofoam (polystyrene), but functional groups have been added enabling the material to accept or donate electrons. No aggressive acids are necessary anymore; the polymers rather ‘swim’ in an aqueous solution.
“Thus we are able to use a simple and low-cost cellulose membrane and avoid poisonous and expensive materials”, Tobias Janoschka, first author of the new study, explains. “This polymer-based redox-flow battery is ideally suited as energy storage for large wind farms and photovoltaic power stations,” Prof. Dr. Ulrich S. Schubert says. He is chair for Organic and Macromolecular Chemistry at the FSU Jena and director of the CEEC Jena, a unique energy research center run in collaboration with the Fraunhofer Institute for Ceramic Technologies and Systems Hermsdorf/Dresden (IKTS).
In first tests the redox-flow battery from Jena could withstand up to 10.000 charging cycles without losing a crucial amount of capacity. The energy density of the system presented in the study is ten watt-hours per liter. Yet, the scientists are already working on larger, more efficient systems. In addition to the fundamental research at the University, the chemists develop their system, within the framework of the start-up company JenaBatteries GmbH, towards marketable products.
Source: Friedrich-Schiller-Universitaet Jena
21 Oct 2015
The opportunity is electricity storage, which until now has been limited by technology to a relatively modest scale. That’s about to change. And it means that Canada – and specifically Ontario – can become an ideal seedbed for storage technology, because there are ready markets for both large- and small-scale storage systems.
First, the large scale. Ontario has a fleet of nuclear generators that operate around the clock, and come close to filling the demand for power at off-peak hours. In addition, Ontario has developed a large renewable energy sector of wind and solar generation (in addition to its traditional hydro stations.) Problems sometimes arise when the natural weather cycles that drive wind and solar production are out of synch with the market cycle. On a sunny, breezy Saturday afternoon in May, with the nuclear plants running flat out, the hydro stations churning out power with the spring runoff and solar and wind systems near peak production, Ontario may have more electricity than it needs.
Our electricity system operators have a solution, of course: Sell the excess electricity to our neighbours. But since our neighbours are often in the same boat, Ontario must cut the price close to zero – or in extreme situations, even pay neighbouring states or provinces to absorb our overproduction.
Wouldn’t it make far more sense to store that excess energy, knowing that it will be needed in a matter of days, or even hours? What’s been lacking is the technology to do the job.
That’s changing however, as Ontario’s current program to procure 50 megawatts of storage capacity demonstrates. Companies with a variety of approaches are working hard to bring their solutions to market – many of them clustered at the MaRS centre in Toronto. Some, such as Hydrogenics Corp., convert electricity into hydrogen, which can be used to supplement natural gas.
My own company, NRStor, has partnered with Temporal Power and is operating a flywheel storage system in Minto, Ont., that helps the market operator to maintain consistent voltage on the grid.
Of course, businesses around the globe are looking at the same opportunities as we are, and here lies the opportunity for Canada to rebrand its energy economy.
A recent report by Deutsche Bank calls battery storage the “holy grail of solar penetration,” and believes that with the current rate of progress in improving efficiency, mass adoption of lithium ion batteries at a commercial/utility scale could occur before 2020.
Analysis by Prof. Andrew Ford of Washington State University calculates that a 1,000-megawatt air storage system from U.S.-based General Compression Inc. could deliver $6- to $8-billion of value to Ontario – in the form of lower energy costs to local utilities – over a 20-year period. All this is of interest to large-scale electricity system operators, big utilities and their customers.
But there is another reason for us to pay attention to energy storage – a reason grounded on a much more human scale. There are still large rural areas around the globe where there is no reliable electrical grid – including Northern Canada.
There is great potential for these communities, including remote First Nations communities, to improve their standard of living by installing microscale renewable generation in combination with storage, and relying less on carbon-spewing diesel generators, powered by fuel that must be transported long distances at great expense.
Storage is the key to making renewable energy a fully competitive component of any electrical grid. It can make our grid cleaner and more efficient, for the benefit of all consumers – large and small, urban and rural. We have the chance, in Canada, to become world leaders in developing this technology. Let’s seize it.
Annette Verschuren is the chairwoman and CEO of NRStor and on the board of MaRS Discovery District.
Annette Verschuren is speaking at the Cleantech Canadian Innovation Exchange (CIX Cleantech) conference in Toronto on Oct. 15.
A discovery made in Leiden helps not only to make natural gas from CO2 but also to store renewable energy. Research by Professor Marc Koper and PhD student Jing Shen shows how this process can be implemented in a cost-effective and controllable way.
The conversion of the greenhouse gas CO2 into natural gas is achieved using a chemical process in which CO2 is bubbled through an acid solution. The solution contains a graphite electrode — to which a small negative voltage is applied — with a cobalt-porphyrin catalyst attached to it. It was already known that this catalyst can convert CO2 into carbon monoxide and methane, but the reaction always released unwanted hydrogen. In their investigation, Koper and Shen show for the first time how the process works. They therefore know exactly what the best acidity degree is in order to minimise the amount of hydrogen and to convert as much CO2 as possible into natural gas.
An added benefit is that the catalyst is entirely made up of common materials. Cobalt porphyrin is a part of vitamin B12, while the graphite for the electrode is similar to a pencil lead. Therefore the catalyst only costs a few euros. Comparable methods of converting CO2 into methane often use rare and expensive metals, such as platinum.
Realising a dream
Koper hopes that this discovery will bring his dream a little closer to realisation: to convert CO2 and water, the by-products of fuels, into new energy or building blocks for the chemical industry. If this can be achieved using solar energy, this process will also offer a method of storing renewable energy.
Using renewable energy efficiently
‘We’re generating more and more electricity using solar panels and windmills, but that energy is by no means always used straight away,’ Koper explains. ‘In Germany, for example, too much renewable electricity is generated sometimes, so you want to store it. That is the most important potential application of our research: to use renewable energy efficiently by converting water and CO2 into valuable products.’
A fundamentally different way
Still, Koper thinks that it will take a while to get to that point. ‘This is something for the long term and it could be another fifty years before we have a method that makes valuable products and is also robust, scalable and cost-effective. But I’m nevertheless convinced that this is the way to go. It will not be easy, but this discovery is helpful. We have to find a fundamentally different way to manage energy, and our discovery can contribute to that.’
- Jing Shen, Ruud Kortlever, Recep Kas, Yuvraj Y. Birdja, Oscar Diaz-Morales, Youngkook Kwon, Isis Ledezma-Yanez, Klaas Jan P. Schouten, Guido Mul, Marc T. M. Koper. Electrocatalytic reduction of carbon dioxide to carbon monoxide and methane at an immobilized cobalt protoporphyrin. Nature Communications, 2015; 6: 8177 DOI: 10.1038/ncomms9177
13 Aug 2015
Environmental sustainability remains a big trend; topics such as climate change and global warming are generating a lot of discussion. Growing world energy demand from fossil fuels plays a key role in the upward trend in CO2 emissions and is the main source of human-induced climate changes. While energy systems around the world remain at vastly different stages of development, all countries share a common problem: they are far away from achieving sustainable energy systems. As levels of CO2 and other greenhouse gases continue to rise in the atmosphere, with historical maximums reached lately, sustainability in energy generation and energy efficiency principles is becoming ever more important.
For the first time in recorded history, more people worldwide are living in urban areas than in rural. The urbanization trend picked up pace in the 20th century and has accelerated since. Urbanization manifests itself in two ways: expansion of existing cities and creation of new ones.1 Cities are already the source of close to 80% of global CO2 (carbon-dioxide) emissions and will account for an ever-higher percentage in the coming years.
Too much CO2 in the atmosphere has been linked to climate change. If humanity continued with the same solutions that have been used to address urban development needs in the past, the resulting urban ecological footprint will not be sustainable: we would need the equivalent of two planets to maintain our lifestyles by the 2030s. The challenge is to meet the demands of urbanization in an economically viable, socially inclusive, and environmentally sustainable fashion.1,2
According to a World Energy Council study,3 global demand for primary energy is expected to increase by between 27% and 61% by 2050. Climate change is expected to lead to changes in a range of climatic variables, most notably temperature levels. Since electricity demand is closely influenced by temperature, there is likely to be an impact on power demand patterns. The magnitude of the potential impact of future climate changes on electricity demand will depend on patterns in the power use, as well as long-term socio-economic trends.
The latest assessment by Working Group I of the Intergovernmental Panel on Climate Change, released in September 2013, concluded that climate change remains one of the greatest challenges facing society. Warming of the climate system is unequivocal, human-influenced, and many unprecedented changes have been observed throughout the climate system since 1950. Limiting climate change will require substantial and sustained reductions of greenhouse gas emissions.4
Consumption patterns, together with aging and urbanization in some countries seem to have bigger implications for health and the reduction of carbon emissions than the total number of people in the world.5 As developing and newly industrialized countries improve their standards of living, their use of air conditioning and other weather-dependent consumption will likely increase their sensitivity to climate change.6 On the other hand, reducing consumption and achieving more sustainable lifestyles in rich countries will likely represent the most effective way to reduce carbon emissions.
How can nanotechnology reduce CO2 emission?
“The Grid” and Improving Efficiencies
Nanotechnology is a platform whereby matter is manipulated at the atomic level. There are various ways that nanotechnology can be applied along the Smart Grid to help reduce CO2 emissions.
The major impact of nanotechnology on the energy sector is likely to improve the efficiency of current technologies to minimize use of fossil fuels. Any effort to reduce emissions in vehicles by reducing their weight and, in turn, decreasing fuel consumption can have an immediate and significant global impact.
It is estimated that a 10% reduction in weight of the vehicle corresponds to a 10% reduction in fuel consumption, leading to a proportionate fall in emissions. In recognition of the above, there is growing interest worldwide in exploring means of achieving weight reduction in automobiles through use of novel materials. For example, use of lighter, stronger, and stiffer nano-composite materials is considered to have the potential to significantly reduce vehicle weight.9,49
Nanotechnology is applied in aircraft coatings, which protect the materials from the special conditions of the environment where they are used (instead of the conventional bulk metals such as steel). Since the amount of CO2 emitted by an aircraft engine is directly related to the amount of fuel burned, CO2 can be reduced by making the airplane lighter.
Nanocoatings are one of the options for aerospace developers, but also for automotive, defense, marine, and plastics industries.49 Lufthansa Cargo uses the most advanced technologies and innovative processes including efficient jet engines, nanotechnology in aircraft coatings, new composites or regular jet engine cleaning – and of course monitoring overall aircraft weight. It is often a matter of only a few grams. However, given 15,000 to 16,000 flights a year and an average flight time of about 6 hours, the cumulative effect of a number of grams can quickly add up to tons. The removal of a 350 gram phone handset resulted in jet fuel savings of 3.5 tons in a year.50
Nanotechnology is already applied to improve fuel efficiency by incorporation of nanocatalysts. Enercat, a third generation nanocatalyst developed by Energenics, uses the oxygen storing cerium oxide nanoparticles to promote complete fuel combustion, which helps in reducing fuel consumption. Recently, the company has demonstrated fuel savings of 8%–10% on a mixed fleet of diesel vehicles in Italy.51
Reducing friction and improving wear resistance in engine and drive train components is of vital importance in the automotive sector. Based on the estimates made by a Swedish company Applied Nano Surfaces, reducing friction can lower the fuel consumption by about 2% and result in cutting down CO2 emissions by 500 million tons per year from trucks and other heavy vehicles in Sweden alone.9 Thanks to nanomaterials like silica, many tires will in the future be capable of attaining the best rating, the green category A. Cars equipped with category A tires consume approximately 7.5% less fuel than those with tires of the minimum standard (category G).52
Residential and commercial buildings contribute to 11% of total greenhouse gas emissions. Space heating and cooling of residential buildings account for 40% of the total residential energy use. Nanostructured materials, such as aerogels, have the potential to greatly reduce heat transfer through building elements and assist in reducing heating loads placed on air-conditioning/heating systems. Aerogel is a nanoporous super-insulating material with extremely low density; silica aerogel is the lightest solid material known with excellent thermal insulating properties, high temperature stability, very low dielectric constant and high surface area.51
Nanotechnology is positioned to create significant change across several domains, especially in energy where it may bring large and possibly sudden performance gains to renewable sources and Smart Grids. Nanotech enhancements may also increase battery power by orders of magnitude, allowing intermittent sources such as solar and wind to provide a larger share of overall electricity supply without sacrificing stability. Nanotech sensors will also enable Smart Grids and foster more flexible and decentralized electricity management.53
Nanotechnology may accelerate the technology behind renewables in various ways:
- experts are discovering means to apply nanotechnology to photovoltaics, which would produce solar panels with double or triple the output by 2020;
- wind turbines stand to be improved from high-performance nano-materials like graphene, a nano-engineered one-atom thick layer of mineral graphite that is 100 times stronger than steel. Nanotechnology will enable light and stiff wind blades that spin at lower wind speeds than regular blades;
- nanotechnology could play a major role in the next generation of batteries. For example, coating the surface of an electrode with nanoparticles increases the surface area, thereby allowing more current to flow between the electrode and the chemicals inside the battery. Such techniques could increase the efficiency of electric and hybrid vehicles by significantly reducing the weight of the batteries. Moreover, superior batteries would complement renewables by storing energy economically, thus offsetting the whole issue of intermittent generation.
In a somewhat more distant future, we may see electricity systems apply nanotechnology in transmission lines. Research indicates that it is possible to develop electrical wires using carbon nanotubes that can carry higher loads and transmit without power losses even over hundreds of kilometers. The implications are significant, as it would increase the efficiency of generating power where the source is easiest to harness.53
Semiconductor devices, transistors, and sensors will benefit from nanotechnology especially in size and speed. Nanotech sensors could be used for the Smart Grid to detect issues ahead of time, ie, to measure degrading of underground cables or to bring down the price of chemical sensors already available for transformers. Nanotechnology will likely become indispensable for the Smart Grid to fully evolve in the near future.54
Energy efficiency is a way of managing and restraining the growth of energy consumption. It is one of the easiest and most cost effective ways to combat climate change, improve the competitiveness of businesses, and reduce energy costs for consumers.7
More on Using Nanotechnology to Reduce Carbon-Based Emissions
Berkley Lab: A Better Way of Scrubbing CO2
Berkeley Lab Researchers Find Way to Improve the Cost-Effectiveness Through the Use of MOFs
A means by which the removal of carbon dioxide (CO2) from coal-fired power plants might one day be done far more efficiently and at far lower costs than today has been discovered by a team of researchers with the U.S. Department of Energy (DOE)’s Lawrence Berkeley National Laboratory (Berkeley Lab). By appending a diamine molecule to the sponge-like solid materials known as metal-organic-frameworks (MOFs), the researchers were able to more than triple the CO2-scrubbing capacity of the MOFs, while significantly reducing parasitic energy.
Read the Full Article Here: https://genesisnanotech.wordpress.com/2015/03/17/berkley-lab-a-better-way-of-scrubbing-co2/
Nanotechnology material could help reduce CO2 emissions from coal-fired power plants
|The new nanomaterial, described in the Journal of the American Chemical Society (“Post-synthetic Structural Processing in a Metal–Organic Framework Material as a Mechanism for Exceptional CO2/N2 Selectivity”), efficiently separates the greenhouse gas carbon dioxide from nitrogen, the other significant component of the waste gas released by coal-fired power stations. This would allow the carbon dioxide to be separated before being stored, rather than released to the atmosphere.|
|“A considerable amount of Australia‘s – and the world’s – carbon dioxide emissions come from coal-fired power stations,” says Associate Professor Christopher Sumby, project leader and ARC Future Fellow in the University’s School of Chemistry and Physics.
Read the Full Article Here: https://genesisnanotech.wordpress.com/2013/07/10/nanotechnology-material-could-help-reduce-co2-emissions-from-coal-fired-power-plants/
One Nano-Crystal – Many Facets – Reducing Fuel Toxins
When it comes to reducing the toxins released by burning gasoline, coal, or other such fuels, the catalyst needs to be reliable. Yet, a promising catalyst, cerium dioxide (CeO2), seemed erratic. The catalyst’s three different surfaces behaved differently. For the first time, researchers got an atomically resolved view of the three structures, including the placement of previously difficult-to-visualize oxygen atoms. This information may provide insights into why the surfaces have distinct catalytic properties (“Probing the Surface Sites of CeO2 Nanocrystals with Well-Defined Surface Planes via Methanol Adsorption and Desorption”).
Read the Full Article Here: https://genesisnanotech.wordpress.com/2015/06/12/one-nano-crystal-many-facets-reducing-fuel-toxins/
This review demonstrates the potential for reduction of CO2 emissions that Smart Grids can potentially achieve. Power grid modernization is an evolution that will continue for years or decades, and providing a robust foundation for new applications and technologies is imperative.
The electric power industry is facing tremendous opportunities and becoming increasingly important in the emerging low-carbon economy. Governments are still dominant players in high-cost smart-grid investments. This suggests the need for a policy framework that attracts private capital investment, especially from renewable project developers, and communication and ICT companies.
The challenge we face is neither a technical nor policy one – it is political: the current pace of action is simply insufficient. The technologies to reduce emission levels to a level consistent with the 2°C target are available and we know which policies we can use to deploy them. However, the political will to do so remains weak. This lack of political will comes with a price: we will have to undertake steeper and more costly actions to potentially bridge the emissions gap by 2020.4 However, technical possibilities aside, the key to reducing emission levels will be the tough but unavoidable decision that reducing carbon pollution must be of the highest priority.
To Read the Full Article Go Here: http://www.dovepress.com/smart-grid-and-nanotechnologies-a-solution-for-clean-and-sustainable-e-peer-reviewed-fulltext-article-EECT
09 Aug 2015
This post is part of a series examining the connections between nanotechnology and the top 10 trends facing the world, as described in the Outlook on the Global Agenda 2015. All authors are members of the Global Agenda Council on Nanotechnology. Special to the World Economic Forum: By Tim Harper
The late Richard Smalley, often considered to be one of the fathers of nanotechnology following his Nobel Prize-winning work on fullerenes, had a keen interest in energy. In many presentations he would ask the audience to call out what they considered to be the most pressing issues facing humanity. The answers were often similar to those identified in the World Economic Forum’s Global Risks Report, including persistent worries such as disease, clean water, poverty, inequality and access to resources. Smalley would then rearrange the list to put energy at the top and proceed to explain how a happy, healthy world of 9 billion could be achieved if we could only fix the problem of providing cheap and abundant clean energy.
Back in the early 2000s, most of the imagined solutions to the energy challenge involved novel materials such as carbon nanotubes for lossless electricity transmission, or hydrogen storage to enable fuel-cell vehicles. While novel materials like nanotubes never quite lived up to their promise, 15 years later many nanotechnologies, including the latest carbon-based material graphene, are now promising to deliver huge leaps in the way that we generate, store and use energy.
But these advances are not enabled by nanotechnologies in isolation. Many of the technologies identified in the Forum’s top 10 emerging technologies list for the past three years, from gene editing to additive manufacturing, also play a role, supporting our ability to understand the nanoscale processes in nature, generating new insights into how to move beyond conventional solar cells and copy some of nature’s tricks, such as photosynthesis.
The problem is that conventional silicon-based solar cells, while effective, have many drawbacks. They are brittle, which means that they need to be fixed to a rigid support, and they only harvest a small amount of the spectrum of light generated by the sun. For instance, silicon is transparent to infrared light, which means a lot of potential energy available is not harvested.
Researchers at the University of California, Riverside, are helping to solve this by working with hybrid material combining inorganic semiconductor nanoparticles with organic compounds. These first capture two infrared photons that would normally pass right through a solar cell without being converted to electricity, then add their energies together to make one higher energy photon.
An alternative approach is the use of quantum dots. These are nanoscale particles where the response to different wavelengths can be tuned by altering their sizes. Because of their unique optical properties, they are finding increasing uses in lighting and televisions, but these properties are also useful in solar cells. While the efficiency of quantum-dot solar cells reported in recent studies is increasing to as high as 9%, the real breakthrough is that the new devices can be produced at room temperature and in an atmosphere, rather than an expensive and hard-to-maintain vacuum. Perhaps the most exciting aspect of quantum-dot solar cells, though, is that the quantum dots can be dispersed in other materials, leading to “spray on” low-cost and large-area solar cells that can be applied to buildings or vehicles.
A leaf out of nature’s book
But the big prize in advanced photovoltaics will come with achieving artificial photosynthesis. The aim is to enable the production of useful chemicals and fuels directly from sunlight and carbon dioxide, just as plants do. By combining nanotechnology and biology, researchers are mimicking the processes that occur in the leaf of a plant to produce fuels such as butanol and biodegradable plastics. Once combined with synthetic biology to precisely engineer the bacteria, the possibilities are endless.
Generating energy is only half the solution, though. It also has to be stored for later use. This is an addressable issue for energy utilities, who balance peaks and troughs in demand by using techniques such as pumping water uphill into hydro-electric dams. But such large-scale engineering solutions are not an option for off-grid communities in much of the developing world. Local energy use requires a cheap and efficient way of storing energy, as do electric vehicles and smartphones.
Nanomaterials, and graphene in particular, have been attracting significant interest as potential game-changers for energy storage. One driver for this is the high surface area of many nanomaterials, which increases the ability to store charge within a given volume. Graphene – which is formed from layers of carbon a single atom thick – has a tremendous surface area for a given amount of material, and has created a lot of excitement about graphene-based supercapacitors and anodes for lithium ion batteries.
One of the biggest problems with the lithium ion batteries is the amount of charge that can be stored in the conventional graphite-based anodes they use. Lithium is added to the graphite when the battery is charging and removed as it discharges, but the low capacity of graphite means that the anode is limited in the amount of energy it can store. Researchers have been looking at silicon anodes that promise 10 times better capacity for the best part of decade, but the constant stresses on the material results in a short lifetime. One way of addressing this issue has been to place the silicon in cage of fullerenes, nanotubes or nanowires. Companies such as XG Sciences and California Lithium Battery are developing graphene-coated silicon, or “silicon-graphene nano-composite anode material”.
Taking a more bio-inspired approach, the Israeli company StoreDot is combining nanotechnology and biology to create nanoscale peptide crystals to produce a battery that will charge in less than a minute, while researchers in Singapore have recently developed a nanotube-based battery that could last more than 10 times as long as normal ion batteries and can also charge in minutes.
In the meantime, while we wait for current nanotechnology research to bear fruit, the biggest contribution that nanotechnology can make today is simply to reduce the amount of energy required to perform common tasks, such as heating and cooling.
The UK company Xefro, for instance, is making use of graphene to create a smart home-heating system which promises savings of up to 70%. The heaters make use of the high surface area of what is effectively a two-dimensional material to create an efficient heating material which is then applied as an ink. The ink can be printed on a variety of materials and in just about any shape, including water heaters. In a two-dimensional material, energy isn’t wasted in heating up the heater, so the heat can be turned on and off quickly. This both reduces energy use and makes the system ideal for use with smart thermostats.
Meanwhile, another UK start-up called Inclusive Designs is addressing the problem of keeping things cool by combining nanomaterials and fractals with 3D printing. The company prints 3D fractal structures designed to absorb infrared (heat) and then removes the heat by making use of the high thermal conductivity of graphene, creating a cooling system with no liquids or moving parts.
Since Richard Smalley’s untimely death in 2005, the energy situation has improved, with an increasing number of countries now generating the majority of their power from renewable sources; electric vehicles are now a common sight. But cheap, efficient renewable-energy production – together with its storage and transmission – remains a challenge. The combination of nanotechnology, with a wide range of other emerging and transformative technologies, promises to make Smalley’s dream of a world of abundant, cheap, clean energy a reality over the coming decade.
Also Read: Genesis Nanotech Home Page
“Great Things from Small Things”
Also Read Our Online “Nano-News and Updates” at: GNT OnLine: “Great Things from Small Things”
Author: Tim Harper, CEO G2O Water International and co-founder of Xefro
Image: Solar panels are seen in the Palm Springs area, California April 13, 2015. REUTERS/Lucy Nicholson
28 Jul 2015
Photographs of upconversion in a cuvette containing cadmium selenide/rubrene mixture. The yellow spot is emission from the rubrene originating from (a) an unfocused continuous wave 800 nm laser with an intensity of 300 W/cm2. (b) a focused continuous wave 980 nm laser with an intensity of 2000 W/cm2. The photographs, taken with an iPhone 5, were not modified in any way.
When it comes to installing solar cells, labor cost and the cost of the land to house them constitute the bulk of the expense. The solar cells — made often of silicon or cadmium telluride — rarely cost more than 20 percent of the total cost. Solar energy could be made cheaper if less land had to be purchased to accommodate solar panels, best achieved if each solar cell could be coaxed to generate more power.
A huge gain in this direction has now been made by a team of chemists at the University of California, Riverside that has found an ingenious way to make solar energy conversion more efficient. The researchers report in Nano Letters that by combining inorganic semiconductor nanocrystals with organic molecules, they have succeeded in “upconverting” photons in the visible and near-infrared regions of the solar spectrum.
“The infrared region of the solar spectrum passes right through the photovoltaic materials that make up today’s solar cells,” explained Christopher Bardeen, a professor of chemistry. The research was a collaborative effort between him and Ming Lee Tang, an assistant professor of chemistry. “This is energy lost, no matter how good your solar cell. The hybrid material we have come up with first captures two infrared photons that would normally pass right through a solar cell without being converted to electricity, then adds their energies together to make one higher energy photon. This upconverted photon is readily absorbed by photovoltaic cells, generating electricity from light that normally would be wasted.”
Bardeen added that these materials are essentially “reshaping the solar spectrum” so that it better matches the photovoltaic materials used today in solar cells. The ability to utilize the infrared portion of the solar spectrum could boost solar photovoltaic efficiencies by 30 percent or more.
In their experiments, Bardeen and Tang worked with cadmium selenide and lead selenide semiconductor nanocrystals. The organic compounds they used to prepare the hybrids were diphenylanthracene and rubrene. The cadmium selenide nanocrystals could convert visible wavelengths to ultraviolet photons, while the lead selenide nanocrystals could convert near-infrared photons to visible photons.
In lab experiments, the researchers directed 980-nanometer infrared light at the hybrid material, which then generated upconverted orange/yellow fluorescent 550-nanometer light, almost doubling the energy of the incoming photons. The researchers were able to boost the upconversion process by up to three orders of magnitude by coating the cadmium selenide nanocrystals with organic ligands, providing a route to higher efficiencies.
“This 550 — nanometer light can be absorbed by any solar cell material,” Bardeen said. “The key to this research is the hybrid composite material — combining inorganic semiconductor nanoparticles with organic compounds. Organic compounds cannot absorb in the infrared but are good at combining two lower energy photons to a higher energy photon. By using a hybrid material, the inorganic component absorbs two photons and passes their energy on to the organic component for combination. The organic compounds then produce one high-energy photon. Put simply, the inorganics in the composite material take light in; the organics get light out.”
Besides solar energy, the ability to upconvert two low energy photons into one high energy photon has potential applications in biological imaging, data storage and organic light-emitting diodes. Bardeen emphasized that the research could have wide-ranging implications.
“The ability to move light energy from one wavelength to another, more useful region, for example, from red to blue, can impact any technology that involves photons as inputs or outputs,” he said.
The research was supported by grants from the National Science Foundation and the US Army.
The research was conducted also by the following coauthors on the research paper: Zhiyuan Huang (first author), Xin Li, Melika Mahboub, Kerry M. Hanson, Valerie M. Nichols and Hoang Le.
Tang’s group helped design the experiments and provided the nanocrystals.
Source:National Institute for Materials Science (NIMS)
Perovskite solar cells are promising low-cost and highly-efficient next-generation solar cells. The ad hoc Team on Perovskite PV Cells (Kenjiro Miyano, Team Leader) at the Global Research Center for Environment and Energy based on Nanomaterials Science (GREEN) (Kohei Uosaki, Director-General), NIMS (Sukekatsu Ushioda, President), successfully developed perovskite solar cells with good reproducibility and stability as well as exhibiting ideal semiconducting properties.
Lead-halide-based perovskite (hereinafter simply referred to as perovskite) has been used as a solar cell material since six years ago. Perovskite solar cells are promising low-cost and highly-efficient next-generation solar cells because they can be produced through low-temperature processes such as spin coating, and generate a large amount of electricity due to their high optical absorption together with the high open-circuit voltage. As such, the research on perovskite solar cells is making rapid progress. In order to identify the semiconducting properties of perovskites and formulate guidelines for the development of highly efficient solar cell materials, NIMS launched an ad hoc Team on Perovskite PV Cells last October led by the deputy director-general of GREEN.
While the conventional perovskite solar cells have demonstrated high conversion efficiency, they were not sufficiently stable plagued by their low reproducibility and the hysteresis in the current-voltage curves depending on the direction of the voltage sweeps. For this reason, the semiconducting properties of perovskites had not been identified. Researchers successfully created reproducible and stable perovskite solar cells as follows;
- They created perovskite solar cells with a simplified structure while strictly eliminating moisture and oxygen by employing the fabrication technique they had developed for the organic solar cells in the past.
- They found that the perovskite solar cells are stable and they observed no hysteresis in the current-voltage curve. Furthermore, they found that the perovskite solar cell material serves as an excellent semiconductor with ideal diode properties.
They proposed an equivalent circuit model that explains the semiconducting properties of perovskites based on analysis of the internal resistance of perovskite solar cells. This model indicated the existence of a charge transport process derived from an impurity level between the conduction and valence bands in the perovskite layer. Due to this transport process, the efficiency of perovskite solar cells may be suppressed to some extent.
In future studies, researchers will investigate into the cause of the impurity level and its influence on solar cells. In addition, they intend to remove the impurity level and improve the efficiency of the solar cells, thereby contributing to energy and environmental conservation.
This study was conducted at GREEN as a part of the MEXT-commissioned project titled “Development of environmental technology using nanotechnology.”
This study had been published in March 2015 in Applied Physics Letters, a journal issued by the American Institute of Physics.
- Kenjiro Miyano, Masatoshi Yanagida, Neeti Tripathi, Yasuhiro Shirai. Simple characterization of electronic processes in perovskite photovoltaic cells. Applied Physics Letters, 2015; 106 (9): 093903 DOI: 10.1063/1.4914086
10 Jun 2015
For many, nuclear fusion is the Holy Grail of energy, offering the possibility of limitless clean energy through harnessing the very same chemical reaction that keeps our Sun burning.
While the potential of fusion is huge, it is a process that requires vast resources and effort, with the International Energy Agency stating that, “extreme temperatures and pressure are needed to initiate and sustain the fusion reaction, making it challenging.”
Fusion is different from the fission power that is used in our nuclear power stations in that energy is generated when atoms are brought together rather than blown apart, which causes radiation.
British Columbia-based General Fusion are hoping that the technology and methods they are developing will herald a new era in nuclear fusion. They have developed what they describe as a “Magnetized Target Fusion system.”
According to the company’s website, the system makes use of a sphere which is filled with molten lead-lithium. This is pumped to create a vortex, into which ‘magnetically confined plasma’ — an electrically charged gas — is injected. Pistons surrounding the sphere are used to drive a wave of pressure into its center, “compressing the plasma to fusion conditions.”
“Fusion is done… [in] two ways,” Michel Laberge, founder and chief scientist of General Fusion, told CNBC’s Sustainable Energy. “Usually… you make a magnetic field and that hold[s] the plasma – which is the hot gas – together, or you have no magnetic field and you crush it very fast with lasers.”
“What we want to do is something in between: we want to make a plasma, a hot gas, with the magnetic field, and then crush the thing with the magnetic field, and because [with] the magnetic field the heat will not escape so fast… that will work a lot better,” Laberge added.
Currently, General Fusion is developing what they describe as ‘full scale subsystems’ that will demonstrate that they can meet performance targets. In the future, they are hoping to build a full scale prototype which they say will be, “designed for single pulse testing, demonstrating full net energy gain on each pulse, a world first.”
“Humanity… needs a source of energy for the future, and we cannot keep on burning fossil fuels,” Laberge said. “Fusion will be powering humanity in the future,” he added.