Tuesday, July 31, 2007

Solar Cell Efficiency of 42.8% achieved in Lab


Ref: University of Delaware-led team sets solar cell record, joins DuPont on $100 million project. Newark, Delaware [RenewableEnergyAccess.com]

Using a novel technology that adds multiple innovations to a very high-performance crystalline silicon solar cell platform, a consortium led by the University of Delaware (UD) has achieved a record-breaking combined solar cell efficiency of 42.8 percent. The current record of 40.7 percent was attained in December 2006 by Boeing's Spectrolab, Inc.

The research was led by Allen Barnett, principal investigator and UD professor of electrical and computer engineering, and Christiana Honsberg, co-principal investigator and associate professor of electrical and computer engineering. The two direct the University's High Performance Solar Power Program and have been working to achieve the 50 percent efficiency goal set by the Defense Advanced Research Projects Agency (DARPA).

Barnett and Honsberg said that reaching the 42.8 percent mark is a significant advance in solar cell efficiency, particularly given the unique small and portable architecture being used by the consortium and the short time—21 months—in which it was developed.

Honsberg said the previous best of 40.7 percent efficiency was achieved with a high concentration device that requires sophisticated tracking optics and features a concentrating lens the size of a table and more than 30 centimeters, or about 1 foot, thick. The UD consortium's devices are potentially far thinner at less than 1 centimeter.

"This is a major step toward our goal of 50 percent efficiency," Barnett said. "The percentage is a record under any circumstance, but it's particularly noteworthy because it's at low concentration, approximately 20 times magnification. The low profile and lack of moving parts translates into portability, which means these devices easily could go on a laptop computer or a rooftop."

Honsberg said the advance of 2 percentage points is noteworthy in a field where gains of 0.2 percent are the norm and gains of 1 percent are seen as significant breakthroughs.

"This achievement is the direct result of the new architecture we developed under the DARPA program," Barnett and Honsberg said. "By integrating the optical design with the solar cell design, we have entered previously unoccupied design space leading to a new paradigm about how to make solar cells, how to use them, and what they can do."

In November 2005, the UD-led consortium received approximately $13 million in funding for the initial phases of the DARPA Very High Efficiency Solar Cell (VHESC) program to develop affordable portable solar cell battery chargers.

The highly efficient VHESC solar cell uses a novel lateral optical concentrating system that splits solar light into three different energy bins of high, medium and low, and directs them onto cells of various light sensitive materials to cover the solar spectrum. The system delivers variable concentrations to the different solar cell elements. The concentrator is stationary with a wide acceptance angle optical system that captures large amounts of light and eliminates the need for complicated tracking devices.

The VHESC would have immediate application in the high-technology military, which increasingly relies upon a variety of electronics for individual soldiers and the equipment that supports them. As well, it is hoped the solar cells will have a large number of commercial applications.

Today, the American soldier carries a pack that weighs nearly 100 pounds of which about 20 pounds are the three-day supply of batteries needed to power their gear. The DARPA program aims to dramatically reduce the battery logistics pipeline and provide the soldier with more power at reduced weight, thus improving mobility, survivability and the availability of advanced electronic technologies on the battlefield.

As a result of the consortium's technical performance, DARPA is initiating the next phase of the program by funding the newly formed DuPont-University of Delaware VHESC Consortium to transition the lab-scale work to an engineering and manufacturing prototype model. This three-year effort could be worth as much as $100 million, including industry cost-share.
During the first 21 months of the VHESC program, a diverse team of academia, government lab and industrial partners, led by UD, was focused on developing the technology basis for a new extremely high efficiency solar cell. The rapid success of that effort has enabled the present transition to a focus on prototype product development.

Barnett credits the early success of the program to the team approach taken to solving the problem. Partners in the initial phase included BP Solar, Blue Square Energy, Energy Focus, Emcore and SAIC. Key research contributors included the University of Delaware, National Renewable Energy Laboratory, Georgia Institute of Technology, Purdue University, University of Rochester, Massachusetts Institute of Technology, University of California Santa Barbara, Optical Research Associates and the Australian National University.

"What we've done," he said, "is create a virtual lab by having all of these companies, universities and national laboratories in the consortium. This has given us access to a broad range of capabilities in terms of expertise and equipment."

That approach is exemplified by the fact that the record-breaking system features three types of solar cells-one made by industry (Emcore), one by the National Renewable Energy Laboratory and one by UD.

"This is a solar cell that works," Barnett said, adding, "This technology has the potential to change the way electricity is generated throughout the world."

Barnett believes the 50 percent efficiency mark is just the beginning. "Our best inventions are in front of us," he said. "The consortium has been a super team, and has worked to develop new devices and architectures based on a breakthrough design paradigm."

The newly formed DuPont-University of Delaware VHESC consortium will be made up of industrial partners, national laboratories and universities. The consortium's goal is to create solar cells that operate at 50 percent in production, Barnett said. With the fresh funding and cooperative efforts of the DuPont-UD consortium, he said it is expected new high efficiency solar cells could be in production by 2010.

Monday, July 16, 2007

Global Warming is not just a radical issue


Some people believe that global warming is a hoax. Or they think it's just a petty matter for tree-hugging radicals to fret about. Or they think it's a partisan issue, raised only by the extreme left wing.

All of these assumptions are wrong. And, as long as those in power continue to deny the threat posed by global warming, the future will remain frighteningly grim for our planet and for our future generations.

The scientific truth is that if action isn't taken immediately worldwide to reduce carbon emissions, the consequences could be catastrophic. This isn't just about polar bears and glaciers. It's about humanity. It's about the right to protection from the deliberate and careless destruction of people's homelands, property, and livelihoods. It's about the right to observe one's native culture. It's about the basic human right to physical integrity. All of these things are on the line for millions of people if this problem isn't stopped now.

In other words, global warming a human rights issue. Here's how:

  • Global warming is redrawing the world map, in some cases destroying farm lands or even whole islands.

  • Global warming is spreading disease to new populations as insects migrate northward. Some people are dying as a result.

  • Global warming is forcing some island dwellers to migrate to other lands, leaving behind (and leaving drowned) their native lands and native cultures.

  • Global warming has sparked a new refugee crisis.

  • And global warming is a threat to food security for millions of people worldwide.

This is not just about some nameless dark-skinned people in faraway countries, although that shouldn't matter. Closer to home, global warming could significantly reduce production of several key food crops grown in North America, such as corn, wheat, and potatoes. This will not only affect world hunger but the lives of American farmers as well.

Furthermore, melting ice caps could raise the sea level enough to submerge parts of Manhattan and many other major population centers. Note that the world's financial center is in lower Manhattan, which is a likely flood area. Think of the implications of that, and then tell me if you still don't care.

Much of the world is moving forward to address the issue. However, the U.S. -- with about five percent of the world's population -- remains the world's chief polluter, generating 25 percent of all carbon dioxide emissions. And the Bush administration continues to stonewall, lest new emissions regulations should inconvenience his corporate cronies.

And we need to take matters into our own hands. We need to re-examine our priorities. We need to drive less. We need to choose more fuel-efficient vehicles. We need to conserve energy in our homes and in our workplaces. Every little bit helps. But it will take a serious effort by each and every one of us to make a real difference.

And thus we cn help our Mother Earth from disaster.

Thursday, July 12, 2007

Global Warming not caused by Solar Activities


Scientists have delivered the final blow to the theory that recent global warming can be explained by variations in the natural cycles of the Sun - a favourite refuge for climate sceptics who dismiss the influence of greenhouse-gas emissions.

An analysis of the records of all of the Sun's activities over the past few decades - such as sunspot cycles and magnetic fields - shows that since 1985 solar activity has decreased significantly, while global warming has continued to increase.

Mike Lockwood, of the Rutherford Appleton Laboratory in Chilton, Oxfordshire, said: "In 1985, the Sun did a U-turn in every respect. It no longer went in the right direction to contribute to global warming. We think it's almost completely conclusive proof that the Sun does not account for the recent increases in global warming."

The study, published in the journal Proceedings of the Royal Society A, shows there is no doubt that solar activity over the past 20 years has run in the opposite direction to global warming, and therefore cannot explain rises in average global temperatures.
Dr Lockwood and his colleague Claus Fröhlich, of the World Radiation Centre in Davos Dorf, Switzerland, have produced the most powerful counter argument to suggestions that current warming is part of the natural cycle of solar activities. "There is considerable evidence for solar influence on Earth's pre-industrial climate, and the Sun may well have been a factor in post-industrial change in the first half of the last century," they write.

However, since about 1940 there has been no evidence to suggest that increases in global average temperatures were caused by solar activity. "Our results show that the observed rapid rise in global mean temperatures seen after 1985 cannot be ascribed to solar variability, whichever of the mechanisms is invoked and no matter how much the solar variation is amplified," the two scientists said.

The theory that past changes in solar activity may have explained some changes in the climate before the industrial revolution is not in dispute. In previous centuries, for instance, notably between about 1420 and 1570, when the Vikings had to abandon their Greenland settlements, solar minima corresponded with unusually cool weather, such as the "little ice age" of the 17th century.

But climate sceptics have exploited this to dispute the idea that man-made emissions are responsible for global warming. In the recent Channel 4 programme The Great Global Warming Swindle, the rise in solar activity over the latter half of the 20th century was erroneously presented as perfectly matching the rise in global average temperatures.

Dr Lockwood said he was outraged when he saw the documentary, because of the way the programme-makers used graphs of temperature rises and sunspot cycles that were cut off in the 1980s, when the two trends went in the opposite direction.

"The trouble is that the theory of solar activity and climate was being misappropriated to apply to modern-day warming. The sceptics were taking perfectly good science and bringing it into disrespect," Dr Lockwood said.

The Royal Society said : "There is a small minority which is seeking to confuse the public on the causes of climate change. They are often misrepresenting the science, when the reality is that the evidence is getting stronger every day."

Monday, July 09, 2007

Germany is keen into its Renewable Energy Law


Germany's Ministry for the Environment has issued revised rules for the country's groundbreaking Renewable Energy Sources Act. The new rules significantly increase the tariffs for offshore wind energy, hydroelectricity and geothermal energy beginning in 2009.

Most significantly, Germany, with the most aggressive renewable energy targets in the world, has increased those targets yet again. The Ministry of Environment announced that the targets for 2020 had increased to 27% from the previous 20% and had added a target of 45% by 2030. Previously, Germany had set a renewable target of 50% of total energy consumption by 2050.

The Ministry's report announced that tariffs for hydroelectricity will be raised to € 0.1267/kWh [US$ 0.17/kWh] for <500>500 kW<2,000>2,000 kW<5,000>

For geothermal, the new rules reduce the number of size classes from four to two and increases the tariff from € 0.15/kWh [US$ 0.20/kWh) to € 0.17/kWh [US$ 0.23/kWh]. The new rules also add a bonus of Euro 0.03/kWh [US $ 0.04/kWh] for geothermal used in heating.
For wind on land, which has been hard hit by rising turbine prices, the new rules reduce the annual tariff degression from 2% to 1% per year. Germany will now also pay a bonus of € 0.007/kWh [US$ 0.01/kWh] for wind turbines that are more compatible with the needs of the grid.

For wind off shore, the program raises tariffs from Euro 0.0874/kWh [US$ 0.12/kWh] in 2009 to Euro 0.11-0.14/kWh [US$ 0.15-0.19/kWh].

For rooftop solar PV, the Ministry of Environment said it would raise the annual degression from the current 5% to 7% per year beginning in (2009) and to 8% beginning in 2011. The revised program will add a new tariff class for systems >1,000 kW of € 0.3548/kWh [US$ 0.47/kWh]. The current tariff is € 0.463 [US$ 0.62/kWh] for systems >100 kW.

For ground-mounted solar PV, the annual degression will be raised from 6.5% to 8.5% beginning in 2009 and to 9.5% beginning in 2011.

Germany is governed by a grand coalition of the Christian Democrats and the Social Democrats. Perpetuation of Germany's renewable energy law was an integral part of the coalition contract between the two political parties. Germany's Renewable Energy Sources Act is reviewed every three years.

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