Whales And Dolphins Influence New Wind Turbine Design

ScienceDaily (July 8, 2008) — Sea creatures have evolved over millions of years to maximise efficiency of movement through water; humans have been trying to perfect streamlined designs for barely a century. So shouldn't we be taking more notice of the experts?

Biologists and engineers from across the US have been doing just that. By studying the flippers, fins and tails of whales and dolphins, these scientists have discovered some features of their structure that contradict long-held engineering theories. Dr Frank Fish (West Chester University) will talk about the exciting impact that these discoveries may have on traditional industrial designs on July 8th at the Society for Experimental Biology's Annual Meeting in Marseille.

Some of his observations are already being applied to real life engineering problems, a concept known as biomimetics. The shape of whale flippers with one bumpy edge has inspired the creation of a completely novel design for wind turbine blades. This design has been shown to be more efficient and also quieter, but defies traditional engineering theories.

"Engineers have previously tried to ensure steady flow patterns on rigid and simple lifting surfaces, such as wings. The lesson from biomimicry is that unsteady flow and complex shapes can increase lift, reduce drag and delay 'stall', a dramatic and abrupt loss of lift, beyond what existing engineered systems can accomplish," Dr Fish advises. "There are even possibilities that this technology could be applied to aeronautical designs such as helicopter blades in the future."

The work centres on studies of vortices, tornado-shaped water formations that develop in the wake of the animals. "In the case of the humpback whale, vortices formed from tubercles (bumps) on the front edge of flippers help to generate more lift without the occurrence of stall, as well as enhancing manoeuvrability and agility," explains Dr Fish. "In the case of the tails of dolphins, vortices are formed at the end of the up and down strokes. These vortices are involved in the production of a jet in the wake of the dolphin that produces high thrust. By regulating the production of the vortices, the dolphin can maximize its efficiency while swimming."

This work was funded by the US National Science Foundation and the US Office of Naval Research.

Journal reference:

1. Fish et al. Hydrodynamic flow control in marine mammals. Integrative and Comparative Biology, 2008; DOI: 10.1093/icb/icn029

Adapted from materials provided by Society for Experimental Biology, via EurekAlert!, a service of AAAS.

New 'Window' Opens On Solar Energy: Cost Effective Devices Available Soon

ScienceDaily (July 11, 2008) — Imagine windows that not only provide a clear view and illuminate rooms, but also use sunlight to efficiently help power the building they are part of. MIT engineers report a new approach to harnessing the sun's energy that could allow just that.

The work, reported in the July 11 issue of Science, involves the creation of a novel "solar concentrator." "Light is collected over a large area [like a window] and gathered, or concentrated, at the edges," explains Marc A. Baldo, leader of the work and the Esther and Harold E. Edgerton Career Development Associate Professor of Electrical Engineering.

As a result, rather than covering a roof with expensive solar cells (the semiconductor devices that transform sunlight into electricity), the cells only need to be around the edges of a flat glass panel. In addition, the focused light increases the electrical power obtained from each solar cell "by a factor of over 40," Baldo says.

Because the system is simple to manufacture, the team believes that it could be implemented within three years--even added onto existing solar-panel systems to increase their efficiency by 50 percent for minimal additional cost. That, in turn, would substantially reduce the cost of solar electricity.

In addition to Baldo, the researchers involved are Michael Currie, Jon Mapel, and Timothy Heidel, all graduate students in the Department of Electrical Engineering and Computer Science, and Shalom Goffri, a postdoctoral associate in MIT's Research Laboratory of Electronics.

"Professor Baldo's project utilizes innovative design to achieve superior solar conversion without optical tracking," says Dr. Aravinda Kini, program manager in the Office of Basic Energy Sciences in the U.S. Department of Energy's Office of Science, a sponsor of the work. "This accomplishment demonstrates the critical importance of innovative basic research in bringing about revolutionary advances in solar energy utilization in a cost-effective manner."

Solar concentrators in use today "track the sun to generate high optical intensities, often by using large mobile mirrors that are expensive to deploy and maintain," Baldo and colleagues write in Science. Further, "solar cells at the focal point of the mirrors must be cooled, and the entire assembly wastes space around the perimeter to avoid shadowing neighboring concentrators."

The MIT solar concentrator involves a mixture of two or more dyes that is essentially painted onto a pane of glass or plastic. The dyes work together to absorb light across a range of wavelengths, which is then re-emitted at a different wavelength and transported across the pane to waiting solar cells at the edges.

In the 1970s, similar solar concentrators were developed by impregnating dyes in plastic. But the idea was abandoned because, among other things, not enough of the collected light could reach the edges of the concentrator. Much of it was lost en route.

The MIT engineers, experts in optical techniques developed for lasers and organic light-emitting diodes, realized that perhaps those same advances could be applied to solar concentrators. The result? A mixture of dyes in specific ratios, applied only to the surface of the glass, that allows some level of control over light absorption and emission. "We made it so the light can travel a much longer distance," Mapel says. "We were able to substantially reduce light transport losses, resulting in a tenfold increase in the amount of power converted by the solar cells."

This work was also supported by the National Science Foundation. Baldo is also affiliated with MIT's Research Laboratory of Electronics, Microsystems Technology Laboratories, and Institute for Soldier Nanotechnologies.

Mapel, Currie and Goffri are starting a company, Covalent Solar, to develop and commercialize the new technology. Earlier this year Covalent Solar won two prizes in the MIT $100K Entrepreneurship Competition. The company placed first in the Energy category ($20,000) and won the Audience Judging Award ($10,000), voted on by all who attended the awards.
Adapted from materials provided by Massachusetts Institute of Technology.

Solar Cooling Becomes A New Air-conditioning System

ScienceDaily (July 20, 2008) — Scientists from the Universidad Carlos III of Madrid (UC3M) and the Consejo Superior de Investigaciones Científicas (CSIC) have developed an environmentally friendly cooling technology that does not harm the ozone layer. This is achieved by using solar energy and therefore reducing the use of greenhouse gases.

A research team has designed and built an absorption chiller capable of using solar and residual heat as an energy source to drive the cooling system. The technology used in this machine, which looks like an ordinary air-conditioning system, minimises its environmental impact by combining the use of a lithium bromide solution, which does not damage the ozone layer or increase the greenhouse effect, with a reduction in the use of water by the machine.

The team, managed by Professor Marcelo Izquierdo from the Department of Thermal Engineering and Fluid Mechanics of the UC3M, who is also a researcher at the Instituto de Ciencias de la Construcción Eduardo Torroja (IETCC) of the CSIC, is building a solar cooling system that unlike the existing machines on the market, uses an improved absorption mechanism capable of producing cold water at a range of temperatures from 7º C to 18º C when the exterior temperature ranges from 33º C to 43º C.

Residential use

Professor Marcelo Izquierdo states that the conclusions reached by a study with a commercial air condensed absorption machine prove that given an outside temperature ranging from 28ºC and 34ºC, the machine can produce cold water at a range of 12 to 16ºC, with a source temperature at the generator between 80ºC to 95ºC. Under these conditions, the cold water produced can be used for climate control applications in houses by combining it with a water-to-air heat exchanger (fan coil).

Quoting Raquel Lizarte, a researcher at the Department of Thermal Engineering and Fluid Mechanics of the UC3M, “There are few absorption machines at a commercial level that are adapted for residential use”, and since it is very hard to go without climate control, it is important to find a cooling technology that has minimal environmental impact. “The machine that we're studying produces enough cold water to cool down a room of 40 m2 of floor area and with a volume of 120 m3”, she states.

In 2007, 191 countries were involved in the Montreal protocol; a signed agreement to avoid the use of ozone depleting substances such as the HCFC refrigerants used in the air-conditioning industry as well as to set a limit such that by the year 2010 the energy consumption should be just 25% of the level that was allowed in 1996. Also, by the year 2020 all the HCFC refrigerants used in developed countries will have to be replaced with substitutes. This protocol makes research into this kind of technology extremely important for the near future.

The study has been published in the current edition of the magazine Applied Thermal Engineering under the title: ‘Air conditioning using an air-cooled single effect lithium bromide absorption chiller: Results of a trial conducted in Madrid in August 2005’. In this investigation scientists from the Universidad Carlos III of Madrid and Universidad Nacional de Educación a Distancia have collaborated under the coordination of the Instituto de Ciencias de la Construcción Eduardo Torroja-CSIC.
Adapted from materials provided by Universidad Carlos III de Madrid, via AlphaGalileo.

A Healthier July Fourth: Eco-friendly Fireworks And Flares Poised To Light Up The Sky

ScienceDaily (July 3, 2008) — From the rockets' red glare to bombs bursting in air, researchers are developing more environmentally friendly fireworks and flares to light up the night sky while minimizing potential health risks, according to an article scheduled for the June 30 issue of Chemical & Engineering News. Some eco-friendly fireworks may soon appear at a Fourth of July display or rock concert near you.

In the C&EN cover story, Associate Editor Bethany Halford points out that fireworks, flares and other so-called pyrotechnics commonly include potassium perchlorate to speed up the fuel-burning process. But some studies have linked perchlorate, which can accumulate in the soil, air and water, to thyroid damage. Pyrotechnics also contain color-producing heavy metals, such as barium and copper, which have also been linked to toxic effects.

Researchers recently developed new pyrotechnic formulas that replace perchlorate with nitrogen-rich materials or nitrocellulose that burn cleaner and produce less smoke. At the same time, these nitrogen-rich formulas also use fewer color-producing chemicals, dramatically cutting down on the amount of heavy metals used and lowering their potentially toxic effects. Some of these fireworks are already being used at circuses, rock concerts, and other events.

The big challenge in developing these "eco-friendly" pyrotechnics is making them as cost-effective as conventional fireworks while maintaining their dazzle and glow, the article states.

Journal reference:

1. Bethany Halford. Pyrotechnics For The Planet: Chemists seek environmentally friendlier compounds and formulations for fireworks and flares. Chemical & Engineering News, June 30 2008 [link]

Adapted from materials provided by American Chemical Society, via EurekAlert!, a service of AAAS.

Getting Wrapped Up In Solar Textiles

ScienceDaily (June 21, 2008) — Sheila Kennedy, an expert in the integration of solar cell technology in architecture who is now at MIT, creates designs for flexible photovoltaic materials that may change the way buildings receive and distribute energy.

These new materials, known as solar textiles, work like the now-familiar photovoltaic cells in solar panels. Made of semiconductor materials, they absorb sunlight and convert it into electricity.

Kennedy uses 3-D modeling software to design with solar textiles, generating membrane-like surfaces that can become energy-efficient cladding for roofs or walls. Solar textiles may also be draped like curtains.

"Surfaces that define space can also be producers of energy," says Kennedy, a visiting lecturer in architecture. "The boundaries between traditional walls and utilities are shifting."

Principal architect in the Boston firm, Kennedy & Violich Architecture, Ltd., and design director of its materials research group, KVA Matx, Kennedy came to MIT this year. She was inspired, she says, by President Susan Hockfield's plan to make MIT the "energy university" and by MIT's interdisciplinary energy curriculum that integrates research and practice.

This spring, Kennedy taught a new MIT architecture course, Soft Space: Sustainable Strategies for Textile Construction. She challenged the students to design architectural proposals for a new fast train station and public market in Porto, Portugal.

For Mary Hale, graduate student in architecture, Kennedy's Soft Space course was an inspiration to pursue photovoltaic technology in her master's thesis.

"I have always been interested in photovoltaics, but before this studio, I am not sure that I would have felt empowered to integrate them into a personal, self-propelled, project," she says.

Kennedy, for her part, will pursue her research in pushing the envelope of energy-efficiency and architecture. A recent project, "Soft House," exhibited at the Vitra Design Museum in Essen, Germany, illustrates what Kennedy means when she says the boundaries between walls and utilities are changing.

For Soft House, Kennedy transformed household curtains into mobile, flexible energy-harvesting surfaces with integrated solid-state lighting. Soft House curtains move to follow the sun and can generate up to 16,000 watt-hours of electricity--more than half the daily power needs of an average American household.

Although full-scale Soft House prototypes were successfully developed, the project points to a challenge energy innovators and other inventors face, Kennedy says. "Emerging technologies tend to under-perform compared with dominant mainstream technologies."

For example, organic photovoltaics (OPV), an emergent solar nano-technology used by the Soft House design team, are currently less efficient than glass-based solar technologies, Kennedy says.

But that lower efficiency needn't be an insurmountable roadblock to the marketplace, Kennedy says, because Soft House provides an actual application of the unique material advantages of solar nano-technologies without having to compete with the centralized grid.

Which brings her back to the hands-on, prototype-building approach Kennedy hopes to draw from in her teaching and work at MIT.

"Working prototypes are a very important demonstration tool for showing people that there are whole new ways to think about energy," she says.
Adapted from materials provided by Massachusetts Institute Of Technology. Original article written by Sarah H. Wright.

Goodbye To Batteries And Power Cords In Factories

ScienceDaily (June 11, 2008) — A broken cable or a soiled connector? If a machine in a factory goes on strike, it could be for any of a thousand reasons. Self-sufficient sensors that provide their own power supply will soon make these machines more robust.

When a factory machine breaks down, it’s hard to know what to do. Production often comes to a standstill until the error has finally been pinpointed – and that can take hours. The causes are legion; in many cases it is all due to a single interrupted contact. Consequently, many manufacturers have long been hoping for a technology that will work without vulnerable power and data cables. The idea is basically feasible, using small devices that harvest energy from their surroundings and provide their own power supply rather like a solar calculator.

Experts speak of energy self-sufficient sensor-actuator systems. These high-tech components normally consist of a sensor, a processor and a radio module. They measure position, force or temperature and transmit the data instantaneously by radio. In this way, vital machine data reach the control center without using cables at all. Is the machine overheating? Is the drive shaft wearing out?

So far, however, there are hardly any off-the-shelf solutions with their own energy supply. Research scientists from the Fraunhofer Technology Development Group TEG in Stuttgart have now joined forces with industrial partners and universities in the EnAS project, sponsored by the Federal Ministry of Economics and Technology, to build a transportable demonstrator. This is a miniature conveyer system driven by compressed air that transports small components in an endless cycle.

The round workpieces are picked up by a vacuum gripper, transported a short way and set down on a small carrier, which conveys the parts back to the starting point. All steps of the process are monitored by sensors as usual. The special feature of the demonstrator is that the sensing elements have no need of an external power supply.

The machine uses photo diodes, for instance, to check whether the carrier has been correctly loaded – if so, the light from the diodes is obscured by the workpieces. Solar cells supply the energy for this workpiece detector. Another example are pressure sensors which monitor the work of the vacuum gripper. In this case, the power is supplied by piezoelectric flexural transducers. The piezoelectric elements contain ceramics that generate electricity on being deformed. This deformation happens when the vacuum pump is switched on and off. The electricity thus generated is sufficient to send an OK signal to the central control unit. The sensor thus draws its power from pressurized air that is present anyway.

Within the next two years, the various system components are expected to make their way into everyday industrial use.
Adapted from materials provided by Fraunhofer-Gesellschaft.

Rubber 'Snake' Could Help Wave Power Get A Bite Of The Energy Market

ScienceDaily (July 3, 2008) — A device consisting of a giant rubber tube may hold the key to producing affordable electricity from the energy in sea waves. Invented in the UK, the 'Anaconda' is a totally innovative wave energy concept. Its ultra-simple design means it would be cheap to manufacture and maintain, enabling it to produce clean electricity at lower cost than other types of wave energy converter. Cost has been a key barrier to deployment of such converters to date.

Named after the snake of the same name because of its long thin shape, the Anaconda is closed at both ends and filled completely with water. It is designed to be anchored just below the sea's surface, with one end facing the oncoming waves.

A wave hitting the end squeezes it and causes a 'bulge wave'* to form inside the tube. As the bulge wave runs through the tube, the initial sea wave that caused it runs along the outside of the tube at the same speed, squeezing the tube more and more and causing the bulge wave to get bigger and bigger. The bulge wave then turns a turbine fitted at the far end of the device and the power produced is fed to shore via a cable.

Because it is made of rubber, the Anaconda is much lighter than other wave energy devices (which are primarily made of metal) and dispenses with the need for hydraulic rams, hinges and articulated joints. This reduces capital and maintenance costs and scope for breakdowns.

The Anaconda is, however, still at an early stage of development. The concept has only been proven at very small laboratory-scale, so important questions about its potential performance still need to be answered. Funded by the Engineering and Physical Sciences Research Council (EPSRC), and in collaboration with the Anaconda's inventors and with its developer (Checkmate SeaEnergy), engineers at the University of Southampton are now embarking on a programme of larger-scale laboratory experiments and novel mathematical studies designed to do just that.

Using tubes with diameters of 0.25 and 0.5 metres, the experiments will assess the Anaconda's behaviour in regular, irregular and extreme waves. Parameters measured will include internal pressures, changes in tube shape and the forces that mooring cables would be subjected to. As well as providing insights into the device's hydrodynamic behaviour, the data will form the basis of a mathematical model that can estimate exactly how much power a full-scale Anaconda would produce.

When built, each full-scale Anaconda device would be 200 metres long and 7 metres in diameter, and deployed in water depths of between 40 and 100 metres. Initial assessments indicate that the Anaconda would be rated at a power output of 1MW (roughly the electricity consumption of 2000 houses) and might be able to generate power at a cost of 6p per kWh or less. Although around twice as much as the cost of electricity generated from traditional coal-fired power stations, this compares very favourably with generation costs for other leading wave energy concepts.

"The Anaconda could make a valuable contribution to environmental protection by encouraging the use of wave power," says Professor John Chaplin, who is leading the EPSRC-funded project. "A one-third scale model of the Anaconda could be built next year for sea testing and we could see the first full-size device deployed off the UK coast in around five years' time."

The Anaconda was invented by Francis Farley (an experimental physicist) and Rod Rainey (of Atkins Oil and Gas). There may be advantages in making part of the tube inelastic, but this is still under assessment.

Wave-generated electricity is carbon-free and so can help the fight against global warming. Together with tidal energy, it is estimated that wave power could supply up to 20% of the UK's current electricity demand.

The two-year project 'The Hydrodynamics of a Distensible Wave Energy Converter' is receiving EPSRC funding of just over £430,000.

*A bulge wave is a wave of pressure produced when a fluid oscillates forwards and backwards inside a tube.
Adapted from materials provided by Engineering and Physical Sciences Research Council, via EurekAlert!, a service of AAAS.