ANN ARBOR, Mich.—The latest bright idea in energy-efficient lighting for homes and offices uses big science in nano-small packages to dim the future Edison's light bulb.
In the August issue of Nature Photonics, available online, scientists at the University of Michigan and Princeton University announce a discovery that pushes more appealing white light from organic light-emitting devices.
More white light is the holy grail of the next generation of lighting. The innovation in the paper "Enhanced Light Out-Coupling of Organic Light-Emitting Devices Using Embedded Low-Index Grids" describes a way to deliver significantly more bright light from a watt than incandescent bulbs.
"Our demonstration here shows that OLEDs are a very exciting technology for use in interior illumination," said Stephen Forrest, U-M professor of electrical engineering and physics and vice president for research. "We hope that white emitting OLEDs will play a major role in the world of energy conservation."
Forrest and co-author Yuri Sun, visiting U-M from Princeton University, have wrestled with a classic problem in the new generation of lighting called white organic light-emitting devices, or WOLED: Freeing the light generated, but mostly trapped, inside the device.
A lighting primer: Incandescent light bulbs give off light as a by-product of heat, The light is appealing, but inefficient, putting out 15 lumens of light for every watt or electricity.
The best fluorescent tube lights put out some 90 lumens of light per watt, but the light can be harsh, the fixtures are expensive, and the tubes lose their efficiency with age. And they rely on many environmentally unfriendly substances such as mercury.
WOLEDs show promise of providing a light that's much easier to manipulate, while being long lasting and able to provide in different shapes, from panels to bulbs and more. WOLEDs generate white light by using electricity to send an electron into nanometer thick layers of organic materials that serve as semiconductors. These carbon-based materials are dyes, the ones used in photographic prints and car paint, so they are very inexpensive, and can be put on plastic sheets or metal foils, further reducing costs.
The excited electron in these layers casts bright white light. The bad news, Forrest said, has been that some 60 percent of it is trapped inside the layers, much the way light under water reflects back into the pool, making the water surface seem like a mirror when viewed from underneath.
The Nature Photonics paper describes a tandem system of organic grids and micro lenses that guide the light out of the thin layers and into the air. The grids refract the trapped light, bouncing it into a layer of dome-shaped lenses that then pull the light out.
This process—all of which is packed into a lighting sandwich roughly the thickness of a sheet of paper—was shown to emit approximately 70 lumens from a single watt of power.
More light out means getting more bang for the electricity buck, a crucial question since 22 percent of the U.S. electricity consumption is lighting.
"If you can change the light efficiency by just a few percentage points, there's a few less coal plants you'll need," Forrest said.
Reducing the amount of coal-generated electricity and finding more efficient ways to power appliances and lighting is one of the focuses of U-M's Michigan Memorial Phoenix Energy Institute, and the WOLED work is one example of how science can open new doors in conservation, said Gary Was, institute director.
"That energy efficient lighting can be made from the same materials as car paint and that they can be made in such thin, formable sheets boggles the mind," Was said. "This is one of many exciting creations that research is giving us in the pursuit of energy efficiency. This is also the kind of innovation that is required in the drive for energy sustainability.
Forrest said WOLED work isn't done yet. The fun part, he said, is that WOLEDs can be framed in different forms.
"Plugging into a wall at low voltage, putting it on a flexible metal foil, or on plastic that won't break when you drop it," Forrest said. "This is what makes it so fun because it's such a unique lighting source."
The research was funded by the U.S. Department of Energy through a subcontract from the University of Southern California and by Universal Display Corp.
Forrest is part of the Michigan Memorial Phoenix Energy Institute, which develops, coordinates and promotes multidisciplinary energy research and education at U-M. He also is on the scientific advisory board of Universal Display Corp.
The next challenge, he said, is to reduce the cost, which currently is too high to be commercially competitive.
"You have to be able to do this dirt cheap, Forrest said. "People don't spend much for their light bulbs."
Original here
Wednesday, July 16, 2008
First U.S. Town Powered Completely By Wind
By Andrea Thompson, Senior Writer
Rock Port, Mo., has an unusual crop: wind turbines.
The four turbines that supply electricity to the small town of 1,300 residents make it the first community in the United States to operate solely on wind power.
"That's something to be very proud of, especially in a rural area like this — that we're doing our part for the environment," said Jim Crawford, a natural resource engineer at the University of Missouri Extension in Columbia.
A map published by the U.S. Department of Energy indicates that northwest Missouri has the state's highest concentrations of wind resources and contains a number of locations that are potentially suitable for utility-scale wind development. The four turbines that power Rock Port are part of a larger set of 75 turbines across three counties that are used to harvest the power of wind.
"We're farming the wind, which is something that we have up here," Crawford said. "The payback on a per-acre basis is generally quite good when compared to a lot of other crops, and it's as simple as getting a cup of coffee and watching the blades spin."
And the turbines have another benefit besides produces clean energy: MU Extension specialists said that the Missouri wind farms will bring in more than $1.1 million annually in county real estate taxes, to be paid by Wind Capital Group, a wind energy developer based in St. Louis.
"This is a unique situation because in rural areas it is quite uncommon to have this increase in taxation revenues," said Jerry Baker, and MU Extension community development specialist.
Landowners can also benefit by leasing part of their property for wind turbines.
The turbines will also provide savings to rural electric companies and will provide electric service for at least 20 years, the anticipated lifetime of the turbines.
"Anybody who is currently using Rock Port utilities can expect no increase in rates for the next 15 to 20 years," Crawford said.
Baker added that the turbines could also attract tourists to the area.
An Air Car You Could See in 2009: ZPM’s 106 MPG Compressed-Air Hybrid
Compressed-Air Powered cars could take you over 800 miles on a single fill-up, at speeds of up to 96 mph. They should refuel in less than 3 minutes, and at speeds over 35 mph emit about half the CO2 of a Toyota Prius. Best part? You could see them in the US at the end of next year.
Car-tech aficionados may already be familiar with Zero Pollution Motor’s (ZPM) compressed-air powered car. For those that haven’t heard of it yet, read on:
“The compressed air vehicle is a new generation of vehicle that finally solves the motorist’s dilemma: how to drive and not pollute at a cost that is affordable!”
What happens when you replace the explosions in your car’s combustion chamber with clean compressed air? Well, as long as you lighten things up by replacing heavier parts with aluminum, you end up with a clean, efficient way to power a vehicle.
The world’s first commercial compressed-air powered vehicle is currently being produced by India’s largest automaker, Tata Motors, who is licensing the technology from European-based company MDI (a company powered by the innovation of ex-Formula One engineer Guy Nègre). They anticipate having about 6000 of these vehicles on city streets in India in 2008.
How does an Air Car Work?
Although potentially revolutionary it really isn’t that complicated. What a compressed-air car does is use the force of super-compressed air to move the engine’s pistons up and down, as opposed to explosions produced from injecting a small amount of fuel.
To get things moving on compressed air, weight reduction is a top priority. MDI’s aluminum-based engine weighs half what a normal engine does, and the frame is also built out of lightweight materials (US version will be aluminum?).
ZPM’s US model will store about 3200 cubic feet of compressed air in carbon fiber tanks at 4500 psi. Carbon fiber tanks are used for safety reasons since they tend to split open (as opposed to explode) when punctured.
Compressed air from the tanks will run directly to the engine under speeds of 35 miles per hour. That means that under 35 mph the car qualifies as a zero emissions vehicle. At higher speeds the engine will burn a small amount of fuel to create more compressed air, sort of like how a plug-in hybrid like the Chevy Volt produces on-the-fly electricity. The hybrid air-car setup should be able use any number of fuels, including gasoline, propane, or ethanol.
1 tank of air + 8 gallons of gas = 848 mile range
The car’s compressed air tank can be refilled in about 3 minutes from a service station. To fill it up at home the car would be plugged in, where an onboard compressor would refill the tank in about 4 hours, at an electrical cost of about $2.
If you aren’t sure whether turning electricity into compressed air is really that clean, here are some numbers: at speeds over 35 mph the air car emits about half the CO2 per mile as a 2007 Toyota Prius (0.141lbs of CO2 per mile, while that the Toyota Prius emits 0.34 lbs of CO2 per mile).
Will we actually see a US-model Air Car in 2009/10?
New York startup ZPM, like Tata motors, has licensed technology from Luxembourg-based MDI. MDI also has plans to release these cars in Europe in 2-, 4-, and 6-cylinder models, starting under $15,000.
Despite lightweight construction that could be of concern for passing US safety tests, it appears that air car technology could be available in the US in late 2009. ZPM told PopularMechanics.com earlier this year that it expects to produce the first US model air car at the end of 2009 or early 2010. (Btw, ZPM’s model is also a candidate for the $10 million Automotive X Prize.)
ZPM wants to produce a 6-seater, 75-hp model with a 1000 mile range at 96 mph, all for just $17,800.
The big question I think we all have is: will this car make it through US safety testing? ZPM’s website says that air car models will meet the same safety specifications of all cars driven in the US. As with most of these new hyper-efficient models we’ve seen (like Aptera’s Typ1 or VW’s 1L Car), ZPM claims the vehicle’s “tubular body provides increased resistance in the event of a crash.” The car will also come with Air Bags and ABS braking.
It’s another case of wait-and see, and we can only hope ZPM follows through.
For more info, check out a great youtube video about air cars (embedded below):
Posts Related to the Air Car and Hybrid Vehicles:
- The World’s Most Fuel Efficient Car: 285 MPG, Not A Hybrid
- Aptera’s $26000 Electric Car and 300 MPG Hybrid Coming Soon
- The Cleanest Cars on Earth?: Honda Civic GX and Other Natural Gas Vehicles
- Affordable Electric Cars Coming to US in 2009
- An Electric Car You Can Buy Today: The $20K TRIAC EV
Photo Credit: Zero Pollution Motors
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