MIT adding to solar cell efficiency
By MB-BigB | November 25, 2008
A team of researchers at MIT have come up with a way to increase the efficiency of thin-film crystalline silicon solar cells by as much as 50%. What they done is to combine an antireflection coating on the front of the cell along with a multi-layered reflective coating and a tightly spaced diffraction grating to the back of the cell. The net effect is to trap light in the cell longer - this gives the cell a better chance to take that light and convert it into electricity. Lab tests have shown that cells built this way could take the 10% efficiency seen by most thin film silicon cells and increase that up to 15.6%. Unfortunately at this time the process used to make these cells is “not production ready.” The process used to create the diffraction grating is called holographic lithography, and is only performed at a few specialized locations, and the reflective coatings used wouldn’t be economical in mass production. However, as the technology improves, the cost could come down.
via: Greentech Media
Popularity: 15% [?]
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New York Times review of the Green Car of the Year - the 2009 Volkswagen Jetta TDI
By MB-BigB | November 22, 2008
It’s not a plug-in, nor is it a regular hybrid, its a clean diesel. But the 2009 Volkswagen Jetta TDI was just named the Green Car of the Year at the Los Angeles Auto Show, and its rated at 30 mpg in city driving and 41 mpg on the highway. Plus you can get a $1,300 alternative fuel tax credit. The New York Times took one for a spin and got even better mileage than advertised - they averaged 48 mpg on the highway.
Hit the link above for the NY Times Review.
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2008 Los Angeles Auto Show opens
By MB-BigB | November 20, 2008
Lots of news from Day 1 of the Los Angeles Auto Show. There’s not going to be any new model introductions from GM or Chrysler, but there’s some action from Ford - they introduced their new Hybrid Fusion. BMW Mini subsidiary introduced an all electric version of the Mini Cooper, and even Porsche is coming out with a hybrid versio of the Cayenne. Renault-Nissan CEO Carlos Ghosn says that Nissan will have an electric car in the US by 2010 with a pilot program in Oregon. And the 2009 Volkswagen Jetta TDI was named the Green Car of the year - the first time a diesel has won this award.
Here’s some links to sites that have more details and pictures - FoxNews, Wired News, UK Telegraph
The Los Angeles Times has some news on the Nissan electric program in a exclusive interview with Renault-Nissan CEO Carlos Ghosn.
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Greenfield Solar’s new concentrator solar generator could revolutionize industry
By MB-BigB | November 16, 2008
Greenfield Solar’s new concentrating solar generator tracks the sun, concentrates sunlight 900 times, and produces 1.5 kilowatts, plus they hope to sell it for about $6,000 installed. What makes the Greenfield Solar set up different than other panels is the computerized electro-mechanical sun tracking system and its unique 40 layer edge mounted solar cells.The solar concentrator is designed to track the sun from sunup to sundown, thereby generating power much longer during the day than fixed solar panels.
The PhotoVolt designed ‘edge illuminated’ 40 layer solar cells are actually chips, much smaller than a penny - the cell structure looks like a stack of pancake, cut in half and then turned on edge. The edge mounting allows light to penetrate the silicon wafer edge and for electricity to be efficiently routed through the low resistance junctions at the cells’ other end. Each solar concentrator contains 200 chips laid out in two strips measuring 10 inches by 1 3/4 inches - the cells are about 20 percent efficient in generating electricity.
Two Ohio based utilities - Duke Energy and American Electric Power have ordered concentrators for testing purposes. Depending on how the testing goes, Duke Energy will explore various options for deployment, because in addition to generating electricity, the concentrators produce waste heat that could be used for heating buildings. In addition the US Government has bought two for testing purposes. Roshanak Hakimzadeh, chief of the PV and Power Technologies Branch at NASA Lewis, says that, “We are going to tie them to the building’s grid and have them generate some electricity. And we’d like to use the waste heat, hook it up to a radiator, and actually heat the conference room.”
For more information on Greenfield Solar, go here.
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T. Boone Pickens wind plan being delayed
By MB-BigB | November 12, 2008
The Pickens Plan is being delayed. Due to falling natural gas prices and the tight credit market, T. Boone Pickens is being forced to temporarily delay his huge Texas wind project, known as the Pickens Plan, which he’s promoting to wean the US off of foreign oil by switching over to wind and natural gas.
The proposed wind farm, at 4,000 megawatts, was going to be the largest wind farm in the world when completed. The shaky credit markets are causing lots of alternative power projects to dial back, but Jay Rosser, a spokesman for Mesa Power, Pickens’ company, says that “…we are still going forward with our wind business.” Pickens says that they are still buying the turbines for the first phase of the project, which will produce 1,000 megawatts of power. Pickens has also said that natural gas prices need to be around $9/Btu for wind power to be competitive - right now natural gas is priced at about $6/Btu. It was over $12/Btu last summer.
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Segway inventor turning his sights towards Stirling engine hybrid
By MB-BigB | November 10, 2008
Dean Kamen, inventor of the Segway, has built what he says is the world’s first hybrid electic car using a Stirling engine. He’s built a two seat hatchback prototype , called the 2008 DEKA Revolt, using a recycled version of the Ford Think, which was an electric car that Ford last built in 2000. The plug-in Revolt can go about 60 miles on a single charge of its lithium battery.
The Revolt also carries a Stirling engine in its trunk, which is used to power things like the defroster, the heater, and other features that would nomally drain the battery. This way, the battery is used almost exclusively to move the car. The Stirling engine can also recharge the battery if the battery runs low. A Stirling engine is an extremely efficient engine, also known as a closed-cycle regenerative heat engine. While many companies have tried to develop Stirling engines for propulsion, nobody has really figured out how to make it work. By using it strictly to power the electrical features in the car and to recharge the battery, rather than movement, perhaps Mr. Kamen has come up with a propulsion related use for the Stirling. His Stirling engine can use any type of fuel, from biodiesel to gasoline to natural gas, and its a very clean burning engine.
Mr. Kamen says that right now he does not know how much the Revolt will cost, but his goal is to make it affordable for the average consumer. He hopes to have it in production within two years.
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Prisons go green, using alternative energy and recycling to save energy and money
By MB-BigB | November 9, 2008
The Associated Press has an interesting article describing the ways that prisons are using alternative energy and recycling to save money and energy. For example, at the Cedar Creek Corrections Center in Washington State, convicted murderer Robert Knowles has helped grow 8,000 pounds of organic vegetables this year. In Indiana, water boilers that run on waste wood chips were installed, and a wind turbine was built at one prison that generates about 10 kilowatts an hour and saves $2,280 per year in electricity costs. At Ironwood State Prison in Blythe, California, solar panels were installed at one prison - enough to send electricity back into the grid and power about 4,100 homes per year.
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New coating helps solar panels absorb more sunlight
By MB-BigB | November 8, 2008
Researchers from Rensselaer Polytechnic Institute in Troy, New York have come up with a new coating for solar panels that absorbs almost all available sunlight from nearly every angle. This could greatly increase the efficiency of current solar panels.
Current solar panels even with anti-reflective coatings, can only absorb about two-thirds of the sunlight that hits them, but the new coatings allow the cells to absorb a tremendous 96.2% of the available sunlight. Rensselaer’s Shawn-Yu Lin says that their technology allows the cells to capture more colors in the solar spectrum and also light from any angle. Current solar panels look somewhat blue in color - this shows that blue is one of the colors that isn’t being absorbed. The new coating makes the panels look totally black - hardly any frequencies are being reflected. Also, in order to capture light from any angle, the new coating consists of seven layers of porous material stacked on each other so that each layer enhances the antireflective abilities of each layer below. This way, the seven layers trap light from all angles.
Even more importantly, Lin feels that this material could be applied to all types of solar cells and that it won’t require large changes in production techniques to start using it.
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Blue Square Energy gets more efficient solar cells out of cheaper grade silicon
By MB-BigB | November 5, 2008
Blue Square Energy announced today that they have developed silicon solar cells that hit 14.6 percent efficiency. While this might not sound like a big deal compared to other silicon photovoltaic solar cells, Blue Square Energy’s neat trick is that their cells use a lower grade (and therefore much cheaper) type of silicon. Their cells are made from upgraded metallurgical grade (UMG) silicon - the 14.6 percent efficiency is one of the highest efficiencies shown to date with UMG made cells.
Blue Square Energy calls its patent-pending process Bright Point, and it differs from other companies exploring solar cells made from UMG. The Bright Point cells consist of very thin layer of high grade solar grade silicon on top of the much cheaper 4N UMG silicon. Other companies building UMG cells are blending small amounts of the cheaper UMG silicon with the expensive solar grade stuff, which doesn’t result in that much cost reduction over traditional silicon solar cells.
Click the link for the press release.
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New efficiency record and improved stability for dye-sensitized solar cells
By MB-BigB | November 3, 2008
Ressearchers from China and Switzerland have hit the highest efficiency level ever for dye-sensitized solar cells. The new dye-sensitized cells (also known as Gratzel cells) are made up of titanium dioxide and powerful light harvesting dyes. While cheaper to make than silicon based solar cells, they are not as efficient, and the dye-sensitized cells become even less efficient after a relatively short exposure to sunlight.
The researchers created cells with a new type of ruthenium-based dye. The new dye helped boost the light absorbing ability of the sun, and the cells were able to hit efficiencies as high as 10%, which is a record for this type of cells. Additionally, the cells were much more stable than previous generations of dye-sensitized cells - they were able to keep generating electricity at over 90% of their max output even after 1,000 hours in full sunlight.
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