Will the spending review affect feed-in tariffs?

Homeowners will be eagerly awaiting news of whether or not the government's comprehensive spending review will bring with it cuts to the feed-in tariff.

Chancellor George Osborne will announce details of any spending cuts to government departments tomorrow (October 20th).

Among the cuts could be reduced funds for the scheme, which was introduced in April this year.
Consumers who buy solar panels can sell their excess energy back to the grid in return for payment from the government.

Farmers in particular have found this to be a lucrative prospect, using their lands for large-scale solar operations, the BBC reported.

Michael Eavis, owner of Worthy Farm and host of music festival Glastonbury, has created the UK's largest agricultural solar array, which will too benefit from the tariff.

He told the news source that he will make his return after about ten years.
However, if the tariff is cut, there could be less of a demand for the technology.
Ray Noble from the Renewable Energy Association told the BBC: "If they touch the feed-in tariff, you can forget about private sector funding for renewables."

View the original article here

New equation could advance research in solar cell materials

ScienceDaily (Oct. 21, 2010) — A groundbreaking new equation developed in part by researchers at the University of Michigan could do for organic semiconductors what the Shockley ideal diode equation did for inorganic semiconductors: help to enable their wider adoption.

Without the Shockley equation, the computers of today would not be possible.

Developed in 1949 by William Shockley, the inventor of the transistor, the Shockley equation describes the relationship between electric current and voltage in inorganic semiconductors such as silicon.
The new equation describes the relationship of current to voltage at the junctions of organic semiconductors -- carbon-rich compounds that don't necessarily come from a biological source, but resemble them. Organic semiconductors present special challenges for researchers because they are more disordered than their inorganic counterparts. But they could enable advanced solar cells, thin and intense OLED (organic light-emitting diode) displays, and high-efficiency lighting.
"The field of organic semiconductor research is still in its infancy. We're not making complicated circuits with them yet, but in order to do that someday, we need to know the precise relationship of current and voltage. Our new equation gives us fundamental insights into how charge moves in this class of materials. From my perspective, it's a very significant advance," said Steve Forrest, the William Gould Dow Collegiate Professor of Electrical Engineering and U-M vice president for research.
Forrest and his doctoral students, Noel Giebink (now at Argonne National Laboratories) and Brian Lassiter, in the U-M Department of Electrical Engineering and Computer Science, contributed to this research. Two papers on the work are published in the current edition of Physical Review B.
About six years ago, researchers in Forrest's lab realized that they could use Shockley's equation to describe the current/voltage relationship in their organic solar cells to a degree.
"It fit nicely if you didn't look too hard," Forrest said.
Their findings were published, and from that time on, many physicists and engineers used the Shockley equation for organic semiconductors even though it didn't describe the physics perfectly. The new equation does.
Forrest says it will allow researchers to better describe and predict the properties of the different organic semiconductors they're working with. And in that way, they'll be able to more efficiently choose which material best suits the needs of the device they're working on.
"People have been investigating organic semiconductors for 70 or 80 years, but we're just entering the world of applications," Forrest said. "This work will help advance the field forward."
The papers are titled, "The Ideal Diode Equation for Organic Heterojunctions. I. Derivation and Application," and "The Ideal Diode Equation for Organic Heterojunctions. II. The Role of Polaron Pair Recombination."
Forrest is also a professor in the departments of Physics, and Materials Science and Engineering. Others contributing to this work are affiliated with Argonne National Laboratory's Center for Nanoscale Materials and Northwestern University.
This research is funded in party by the Department of Energy's Office of Basic Energy Sciences through the U-M Center for Solar and Thermal Energy Conversion, and the Argonne-Northwestern Solar Energy Research Center.
Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by University of Michigan.

Journal References:
N. Giebink, G. Wiederrecht, M. Wasielewski, S. Forrest. Ideal diode equation for organic heterojunctions. I. Derivation and application. Physical Review B, 2010; 82 (15) DOI: 10.1103/PhysRevB.82.155305N. Giebink, B. Lassiter, G. Wiederrecht, M. Wasielewski, S. Forrest. Ideal diode equation for organic heterojunctions. II. The role of polaron pair recombination. Physical Review B, 2010; 82 (15) DOI: 10.1103/PhysRevB.82.155306
Note: If no author is given, the source is cited instead.
View the original article here

Photovoltaic medicine: Miniature solar cells might make chemotherapy less toxic

Micro-scaled photovoltaic devices may one day be used to deliver chemotherapeutic drugs directly to tumors, rendering chemotherapy less toxic to surrounding tissue.

"In the first step, we were able to prove the concept," says Tao Xu, Ph.D., an assistant professor at the University of Texas in El Paso. Xu and his colleagues presented their findings at the AVS 57th International Symposium & Exhibition, which took place recently at the Albuquerque Convention Center in New Mexico.

Currently, chemotherapeutic drugs are piped through an IV drip into the bloodstream, where they travel and come in contact with many organs on the way to their target. Patients are affected systemically, with toxic side effects that are well known. Ideally, clinicians would like to have a way to deliver these powerful drugs only where needed -- to target them specifically to tumor tissue. Xu's device is designed to do just that -- release drug only when stimulated by light, focusing it directly on a tumor during treatment. Near infrared or laser light is believed to penetrate tissues over 10 cm deep.

The novel device converts light into electric current. In an in vitro model system, positively or negatively charged "model" drugs were used to coated opposite sides of the miniature solar cell. Upon introduction of a light beam, one side of the device became positively charged, repelling the positive charged molecules the investigators had placed there, releasing them; the same thing happened with the negatively charged side and negative model molecules.

It appears that "our hypothesis will work," says Xu, adding that the amount of drug released can also be controlled by varying the intensity of light. The first phase employed an in vitro model; according to Xu, the next step for the work would be its application in small animal models.

Editor's Note: This article is not intended to provide medical advice, diagnosis or treatment.
Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by American Institute of Physics, via EurekAlert!, a service of AAAS.

Note: If no author is given, the source is cited instead.
View the original article here

Knight Frank: Solar PV offers unrivalled investment opportunity

Solar photovoltaic (PV) technology offers consumers an unrivalled investment opportunity, Knight Frank has said.


The estate agent predicts - so long as the government's spending review does not reduce the feed-in tariff – that there will be a major uptake of the renewable energy technology.

Under the scheme, landowners can generate up to £260,000 a year on a six-acre PV plot.

Oliver Routledge from Knight Franks' Renewable Energy Team commented: "We are seeing a huge amount of interest in all types of renewable energy at the moment, but PV is proving especially popular with landowners and investors."

Consumers in the UK can earn 41.3p/kWh of the energy generated that is sold back to the grid over the next 25 years.

Mr Routledge added: "Renewable energy projects and their associated support at the national, European and international level, represent an unrivalled investment opportunity for landowners, both rural and commercial, to diversify income streams from their property."

He noted that the UK generates six per cent of electricity from renewables, but the government aims to achieve 15.4 per cent by 2016, highlighting the potential investment.

For more information please see: Knight Frank press release

View the original article here

Efficient, inexpensive plastic solar cells coming soon

Physicists at Rutgers University have discovered new properties in a material that could result in efficient and inexpensive plastic solar cells for pollution-free electricity production.

The discovery, posted online and slated for publication in an upcoming issue of the journal Nature Materials, reveals that energy-carrying particles generated by packets of light can travel on the order of a thousand times farther in organic (carbon-based) semiconductors than scientists previously observed. This boosts scientists' hopes that solar cells based on this budding technology may one day overtake silicon solar cells in cost and performance, thereby increasing the practicality of solar-generated electricity as an alternate energy source to fossil fuels.

"Organic semiconductors are promising for solar cells and other uses, such as video displays, because they can be fabricated in large plastic sheets," said Vitaly Podzorov, assistant professor of Physics at Rutgers. "But their limited photo-voltaic conversion efficiency has held them back. We expect our discovery to stimulate further development and progress."

Podzorov and his colleagues observed that excitons -- particles that form when semiconducting materials absorb photons, or light particles -- can travel a thousand times farther in an extremely pure crystal organic semiconductor called rubrene. Until now, excitons were typically observed to travel less than 20 nanometers -- billionths of a meter -- in organic semiconductors.

"This is the first time we observed excitons migrating a few microns," said Podzorov, noting that they measured diffusion lengths from two to eight microns, or millionths of a meter. This is similar to exciton diffusion in inorganic solar cell materials such as silicon and gallium arsenide.

"Once the exciton diffusion distance becomes comparable to the light absorption length, you can collect most of the sunlight for energy conversion," he said.

Excitons are particle-like entities consisting of an electron and an electron hole (a positive charge attributed to the absence of an electron). They can generate a photo-voltage when they hit a semiconductor boundary or junction, and the electrons move to one side and the holes move to the other side of the junction. If excitons diffuse only tens of nanometers, only those closest to the junctions or boundaries generate photo-voltage. This accounts for the low electrical conversion efficiencies in today's organic solar cells.
"Now we lose 99 percent of the sunlight," Podzorov noted.

While the extremely pure rubrene crystals fabricated by the Rutgers physicists are suitable only for laboratory research at this time, the research shows that the exciton diffusion bottleneck is not an intrinsic limitation of organic semiconductors. Continuing development could result in more efficient and manufacturable materials.
The scientists discovered that excitons in their rubrene crystals behaved more like the excitons observed in inorganic crystals -- a delocalized form known as Wannier-Mott, or WM, excitons. Scientists previously believed that only the more localized form of excitons, called Frenkel excitons, were present in organic semiconductors. WM excitons move more rapidly through crystal lattices, resulting in better opto-electronic properties.

Podzorov noted that the research also produced a new methodology of measuring excitons based on optical spectroscopy. Since excitons are not charged, they are hard to measure using conventional methods. The researchers developed a technique called polarization resolved photocurrent spectroscopy, which dissociates excitons at the crystal's surface and reveals a large photocurrent. The technique should be applicable to other materials, Podzorov claims.
Collaborating with Podzorov on the research were postdoctoral researcher Hikmat Najafov, graduate students Bumsu Lee and Qibin Zhou, and Leonard Feldman, director of the Rutgers Institute for Advanced Materials, Devices and Nanotechnology (IAMDN). Najafov and Podzorov are also affiliated with IAMDN.
Funding was provided by the National Science Foundation's Division of Materials Research and Japan's New Energy and Industrial Technology Development Organization (NEDO).
Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Rutgers University, via EurekAlert!, a service of AAAS.

Note: If no author is given, the source is cited instead.
View the original article here

Committee calls for DECC spending to be saved

One committee chairman has called for the budget of the Department for Energy and Climate Change (DECC) to be saved.

Speaking to the Guardian, Tim Yeo, chairman of the Energy and Climate Change Committee, highlighted the problems that the UK will face if spending is cut to the DECC in nine days time.

Concerns were also raised about funding for new wind farms in the UK and the protection of energy quangos.
Mr Yeo told the news source that cutting spending on low carbon technologies would be like reducing funds for Spitfires in 1939, claiming that the "destabilisation of the global climate also poses a grave threat to our long term national security".

He added: "In future, climate change could jeopardise our food security, cause unprecedented mass migration and conceivably even spark wars. It would be folly, and something of a false economy, to cut investment on green infrastructure now."

View the original article here

Solar glazing firm enjoys moment in the sun

A British start-up working on "solar glazing" technology has walked away with a £100,000 grant from the Technology Strategy Board (TSB) after winning a Dragons’ Den style audition yesterday.

Kevin Arthur, founder and chief executive of Oxford Photovoltaics, convinced a four-man panel of experts that his company's technology, organic compound-imprinted glass capable of generating solar energy, was the most commercially viable proposition among the start-ups on display.

Oxford PV was one of four winning companies out of the 12 finalists in the TSB’s Competition for Disruptive Solutions. The 12 companies were chosen from 548 video entries in four areas – energy, sustainability, digital and healthcare. Each was awarded £25,000 and given the chance to pitch for the full £100,000 prize.
Arthur said that the money would be used to take on another technical expert to further develop the product, which he predicted could become "a dominant solution in the Building Integrated Photovoltaic (BIPV) market".
He admitted that the company's first challenge is to improve the efficiency at which the glazing converts light into energy, pushing it up from the current five per cent conversion rate into double digits.

However, he insisted that while it currently required one square metre of solar glazing to produce 100W, the technology was available at a significantly lower cost than traditional solar PV panels. He predicted that the technology could be rolled out at a cost of around $8 per square metre, making it a renewable energy option for new build and retrofit projects.

"Once we can get these generation three technologies going we can dominate the market," he said of the higher efficiency technology the company is working on.

Two other clean tech firms made the energy final: RE Hydrogen unveiled an alkaline electrolyser stack producing 2.3kg of hydrogen for synthetic diesel and fuel cells, while Arcola Energy demonstrated LED lighting powered by a range of inputs, from solar PV to hydrogen fuel cells.

View the original article here

Structure of plastic solar cells impedes their efficiency

A team of researchers from North Carolina State University and the U.K. has found that the low rate of energy conversion in all-polymer solar-cell technology is caused by the structure of the solar cells themselves. They hope that their findings will lead to the creation of more efficient solar cells.

Polymeric solar cells are made of thin layers of interpenetrating structures from two different conducting plastics and are increasingly popular because they are both potentially cheaper to make than those currently in use and can be "painted" or printed onto a variety of surfaces, including flexible films made from the same material as most soda bottles. However, these solar cells aren't yet cost-effective to make because they only have a power conversion rate of about three percent, as opposed to the 15 to 20 percent rate in existing solar technology.

"Solar cells have to be simultaneously thick enough to absorb photons from the sun, but have structures small enough for that captured energy -- known as an exciton -- to be able to travel to the site of charge separation and conversion into the electricity that we use," says Dr. Harald Ade, professor of physics and one of the authors of a paper describing the research. "The solar cells capture the photons, but the exciton has too far to travel, the interface between the two different plastics used is too rough for efficient charge separation, and its energy gets lost."

The researchers' results appear online in Advanced Functional Materials and Nano Letters.
In order for the solar cell to be most efficient, Ade says, the layer that absorbs the photons should be around 150-200 nanometers thick (a nanometer is thousands of times smaller than the width of a human hair). The resulting exciton, however, should only have to travel a distance of 10 nanometers before charge separation. The way that polymeric solar cells are currently structured impedes this process.

Ade continues, "In the all-polymer system investigated, the minimum distance that the exciton must travel is 80 nanometers, the size of the structures formed inside the thin film. Additionally, the way devices are currently manufactured, the interface between the structures isn't sharply defined, which means that the excitons, or charges, get trapped. New fabrication methods that provide smaller structures and sharper interfaces need to be found."

Ade and his team plan to look at different types of polymer-based solar cells to see if their low efficiencies are due to this same structural problem. They hope that their data will lead chemists and manufacturers to explore different ways of putting these cells together to increase efficiency.

"Now that we know why the existing technology doesn't work as well as it could, our next steps will be in looking at physical and chemical processes that will correct for those problems. Once we get a baseline of efficiency, we can redirect research and manufacturing efforts."

The research was funded by a grant by the U.S. Department of Energy and the Engineering and Physical Sciences Research Council, U.K. The Department of Physics is part of NC State's College of Physical and Mathematical Sciences.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by North Carolina State University.

Journal References:
Sufal Swaraj, Cheng Wang, Hongping Yan, Benjamin Watts, Jan Lu¨ning, Christopher R. McNeill, Harald Ade. Nanomorphology of Bulk Heterojunction Photovoltaic Thin Films Probed with Resonant Soft X-ray Scattering. Nano Letters, 2010; 10 (8): 2863 DOI: 10.1021/nl1009266Hongping Yan, Sufal Swaraj, Cheng Wang, Inchan Hwang, Neil C. Greenham, Chris Groves, Harald Ade, Christopher R. McNeill. Influence of Annealing and Interfacial Roughness on the Performance of Bilayer Donor/Acceptor Polymer Photovoltaic Devices. Advanced Functional Materials, 2010; DOI: 10.1002/adfm.201001292
Note: If no author is given, the source is cited instead.
View the original article here

White House to install solar panels

President Obama has agreed to install solar panels on the roof of the White House.

It is hoped that the move will encourage more homeowners in the US to follow his lead and install the renewable energy as well.

In 1979 Jimmy Carter installed a solar water heater, but Ronald Regan had taken the technology down.
Now, President Obama will use a water heating system as well as have between 20 and 50 panels installed to generate electricity.

US energy secretary Steven Chu commented: "This project reflects President Obama's strong commitment to US leadership in solar energy and the jobs it will create here at home.

"Deploying solar energy technologies across the country will help America lead the global economy for years to come."

It comes after Prince Charles was in August granted planning permission to install solar panels on the roof of Clarence House, his main residence.

The panels are expected to produce 4,000 kw hours of electricity a year.
For more information please see: White House press release


View the original article here

Chris Huhne speech to the Carbon Show

It is a great pleasure to be here today for the opening of the Carbon Show, and to see such energy and enthusiasm on display.

Emissions trading is an economic curiosity. It is a negative market. For the first time in human history, we are trading in consequences.

That the carbon market exists – and is successful - is testament to just how far we’ve come.
The US National Air Pollution Control Administration first modelled cap-and-trade forty years ago. Ironically, we adopted the ETS to make it easier to sell it back to the US. You can’t win them all.
Over the next forty years, we must hasten our emissions reductions and build a new kind of economy.
Because the next global growth sector is green. Countries – and companies – who do not see the opportunities before them will be left behind.

At this point of the business cycle, people are asking where the jobs will come from.
The answer is here. In this room, today.

The promise of the low-carbon economy is breathtaking. In jobs, in goods and services, and in finance, green opportunities are not just emerging. They are blossoming.

From wind turbines to eco-kettles, low carbon products form a multi-trillion pound market, with growth that outstrips world GDP.

With a vibrant technology and research sector, the UK is well placed to take advantage of the new clean tech markets.

From offshore wind to carbon capture and storage, we are already leading the way.

If we can convert our scientific advantages into hard commercial successes, we can cut carbon and lock-in profits. Making us more secure at home, and more competitive abroad.

We can do our bit to help. The Government is committed to an ambitious programme to reduce emissions – and close the gap between energy supply and energy demand.

Our approach is based on three simple principles.


Firstly, we need to save energy.
Every day, the UK’s housing stock leaks heat – and carbon. Later this year we will launch the Green Deal, a radical scheme to bring our outdated homes up to scratch.

26 million households will qualify for energy efficiency improvements under the Green Deal. And the cost will be offset against future energy bills.

Thousands of jobs insulating homes and businesses will be created across the country, with ripple effects across supply chains and local economies.

A whole new industry will emerge, one that can claw back the ground lost during the recession. This multi-billion pound nationwide retrofit will save money – and energy.

Homes and businesses will make huge efficiency savings. But there is room for improvement in power-hungry industries, too. The CRC Energy Efficiency Scheme is already causing ripples in the sectors which use the most energy.

No-one, least of all this government, wants to burden businesses with extra responsibilities without clear benefit.

We will keep a close eye on the CRC. Making sure it is effective, simple and streamlined; encouraging those industries that need it most. If it can be improved, we will make changes before the next stage in 2013.
Secondly, we need to clean our supply of power.

The replacement of our outdated energy infrastructure, and the creation of new low-carbon power plants, will present real opportunities for British business.

With £200bn of capital needed over the next ten years, investors and manufacturers alike can benefit from the shift to low-carbon power generation.

Again, we will do our bit to help.
The Green Investment Bank will help us catalyse private sector finance, bringing forward a new generation of low-carbon energy production.

By leveraging private finance on behalf of public policy aims, we can spend a little to secure a lot.
The next generation of wind, wave, and waste energy help us get off the oil hook – and onto clean, green growth. So that by the end of this Parliament, we will be the fastest improving European nation when it comes to renewable energy.

Two weeks ago I launched the world’s largest offshore windfarm, at Thanet in Kent. It is a spectacular creation; 300 megawatts of capacity, bringing our offshore total to 5 gigawatts. Each of the 100 turbines is higher than Nelson’s column, and to my mind just as majestic. Within the next decade, industry is aiming for a tenfold increase in capacity.

Few sectors are comfortable making claims like that in the current climate. Even fewer would expect to honour them. But I expect they will.

The growth in renewable power generation and the replacement of our ageing energy infrastructure make a compelling case. Green growth is the best bet for our future prosperity.

It’s also best for the future of our planet. A third of UK emissions come from electricity generation. Conversion losses compound the problem. Burning fossil fuels isn’t just bad for the atmosphere, it’s also an inefficient way of transforming energy.

We need to get the right mix of technologies and energy sources, so that we play to our strengths.
That includes cleaning our existing fossil fuel plants. With strong emissions performance standards, and a commitment to carbon capture and storage pilots.

Some dismiss CCS as a sticking plaster solution to a critical situation. But until we can produce our electricity cleanly, we must minimise the damage done by dirty fuels.

With a new coal powered power plant switching on every week in China, our ability to develop and export CCS on a commercial scale makes environmental and business sense.

Finally, it’s vital that we set out a credible path towards a global emissions deal. That means working with our European partners in support of an ambitious international climate change agenda.
And that is why, together with my French and German colleagues, I have called for a more challenging EU emissions target: a 30% reduction by 2020.

A higher target will strengthen Europe’s intent. Aspiration is important; it tells investors that Europe’s future prosperity is tied to the low-carbon economy.

At the moment, the EU ETS carbon price is not high enough.
It does not provide the long-term certainty investors need to commit to low-carbon generation.
As we announced in the Budget, we will publish proposals this autumn to reform the climate change levy to secure a more effective, more representative carbon price.

That will consolidate our first mover advantage, and open up opportunities for British businesses.
The Coalition agreement is clear: we will seek an ambitious, legally binding global deal on emissions reductions.

Such a deal is unlikely this year. Instead, we will focus our energies on rebuilding political consensus; and getting the right structures in place before the next round of negotiations.
The first step will be to bring emissions offers made since Copenhagen into the UNFCCC process.
Then we can strengthen the measurement, reporting and verification system. So that developing and developed countries have faith that progress is measured fairly and firmly.
And finally, we can clarify the structure and governance of long-term climate finance.

These are practical, achievable steps we can take to firm up the international climate change negotiations, and prepare the ground for a global deal.

• Action on energy efficiency, to manage our demand.
• Action on energy generation, to clean our supply.
• And action on the international stage, to secure a binding legal deal to cut emissions.
• These are the three principles that underpin our approach.
• They will drive us toward a new, low-carbon economy.
• One that is more competitive, more secure, and more sustainable.

Thank you very much.

View the original article here

Rain or shine, researchers find new ways to forecast large photovoltaic power plant output

Sandia National Laboratories researchers have developed a new system to monitor how clouds affect large-scale solar photovoltaic (PV) power plants. By observing cloud shape, size and movement, the system provides a way for utility companies to predict and prepare for fluctuations in power output due to changes in weather. The resulting models will provide utility companies with valuable data to assess potential power plant locations, ramp rates and power output.

Sandia researchers' work is currently focused at the 1.2-megawatt La Ola Solar Farm on the Hawaiian island of Lana'i. La Ola is the state's largest solar power system, and can produce enough power to supply up to 30 percent of the island's peak electric demand, which is one of the highest rates of solar PV power penetration in the world. Understanding variability of such a large plant is critical to ensuring that power output is reliable and that output ramp rates remain manageable.

"As solar power continues to develop and take up a larger percentage of grids nationwide, being able to forecast power production is going to become more and more critical," said Chris Lovvorn, director of alternative energy of Castle & Cooke Resorts, LLC, which owns 98 percent of the island. "Sandia's involvement and insight has been invaluable in our efforts to meet 100 percent of the island's energy needs with renewable resources."

The effects of clouds on small PV arrays are well-documented, but there is little research on how large-scale arrays interact and function under cloud cover. A small system can be completely covered by a cloud, which drastically reduces its power output, but what's less well understood is what happens when only part of a large system is covered by a moving cloud shadow, while the rest stays in sunlight.

"Our goal is to get to the point where we can predict what's going to happen at larger scale plants as they go toward hundreds of megawatts. To do that, you need the data, and the opportunity was available at La Ola," said Sandia researcher Scott Kuszmaul.

The high penetration of PV power on Lana'i, combined with the sun and cloud mix at the 10-acre La Ola plant, provides an optimal environment for prediction and modeling research. Research could not interfere with the ongoing operations of the plant, which currently sells power to Maui Electric Company (MECO), so Sandia engineers connected 24 small, nonintrusive sensors to the plant's PV panels and used a radio frequency network to transmit data. The sensors took readings at one-second intervals to provide researchers with unprecedented detail about cloud direction and coverage activity.

A radio frequency transmission system has the added benefit of being portable. "Currently, a utility company that wants to build a large solar PV power plant might have a lot of questions about the plant's output and variability at a proposed site. Work being done at the La Ola plant is leading to new methods that eventually can be used to answer these questions," said Sandia researcher Josh Stein. "These techniques will allow a developer to place a sensor network at a proposed site, make measurements for a period of time and use that to predict plant output variability."

La Ola was commissioned in December 2008 by Castle & Cooke Resorts, LLC, and SunPower Corp., a manufacturer of high-efficiency solar cells. The project uses SunPower's Tracker technology. Panels rotate on a single axis to follow the sun, which increases energy capture by up to 25 percent. Since February, Sandia Labs has held a cooperative research and development agreement (CRADA) with SunPower to conduct research on integrating large-scale PV systems into the grid. The CRADA is funded with about $1 million of combined U.S. Department of Energy and SunPower funding and is expected to achieve significant results, which will be disseminated through joint publications over the next two years.
For more information about Sandia's photovoltaic work, please visit: www.sandia.gov/pv.
Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by DOE/Sandia National Laboratories.

Note: If no author is given, the source is cited instead.

View the original article here

Environmental impact of organic solar cells assessed

Solar energy could be a central alternative to petroleum-based energy production. However, current solar-cell technology often does not produce the same energy yield and is more expensive to mass-produce. In addition, information on the total effect of solar energy production on the environment is incomplete, experts say.

To better understand the energy and environmental benefits and detriments of solar power, a research team from Rochester Institute of Technology has conducted one of the first life-cycle assessments of organic solar cells. The study found that the embodied energy -- or the total energy required to make a product -- is less for organic solar cells compared with conventional inorganic devices.

"This analysis provides a comprehensive assessment of how much energy it takes to manufacture an organic solar cell, which has a significant impact on both the cost and environmental impact of the technology," says Brian Landi, assistant professor of chemical engineering at RIT and a faculty advisor on the project.
"Organic solar cells are flexible and lightweight, and they have the promise of low-cost solution processing, which can have advantages for manufacturing over previous-generation technologies that primarily use inorganic semiconductor materials," adds Annick Anctil, lead researcher on the study and a fourth-year doctoral candidate in RIT's doctoral program in sustainability. "However, previous assessments of the energy and environmental impact of the technology have been incomplete and a broader analysis is needed to better evaluate the overall effect of production and use."

The study sought to calculate the total energy use and environmental impact of the material collection, fabrication, mass production and use of organic solar cells through a comprehensive life-cycle assessment of the technology.

According to Anctil, previous life-cycle assessments had not included a component-by-component breakdown of the individual materials present in an organic solar cell or a calculation of the total energy payback of the device, which is defined as the energy produced from its use versus the energy needed to manufacture the cell.

The team found that when compared to inorganic cells, the energy payback time for organic solar cells was lower. Ongoing studies to verify the device stability are still warranted, however.
"The data produced will help designers and potential manufacturers better assess how to use and improve the technology and analyze its feasibility versus other solar and alternative-energy technologies," adds Landi.
The team presented the results at the Institute for Electrical and Electronics Engineers 2010 Photovoltaic Specialists Conference. Anctil, who won a student award at the conference for best research, hopes to further analyze the environmental impacts of solar cell development with additional life-cycle assessments of other types of solar cell technology.

The study was funded through the United States Department of Energy and also included researchers from RIT's Golisano Institute for Sustainability and NanoPower Research Labs.
Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Rochester Institute of Technology.

Note: If no author is given, the source is cited instead.

View the original article here

Business leaders warn Treasury to leave feed-in tariffs alone

The heads of more than 60 renewable energy companies have warned the government that premature cuts to the feed-in tariff scheme would "cause investors to flee" the microgeneration sector.

Former Renewable Energy Association chief Philip Wolfe, Juliet Davenport of Good Energy and Dr Paul Golby, chief executive of E.ON UK, were among the signatories of the open letter addressed to the Treasury and energy and climate change secretary Chris Huhne.

The letter calls on the government to put an end to recent speculation that feed-in tariffs might fall foul of the ongoing Comprehensive Spending Review by confirming that they will continue at their current level.
Chris Huhne came under pressure only last month to stand up to any Treasury cuts to the scheme after a report concluded that scaling back the tariff would destabilize the UK's microgeneration industry by damaging investor confidence.

The letter echoes the report's findings, warning that early changes to the scheme, which is not scheduled to be reviewed until 2013, would represent an " unprecedented and confidence-shattering intervention."
Alterations would "destroy the value of recent investments", put the sector's "ability to attract future investment in mortal peril" and "seriously jeopardize" the UK's prospects of hitting its mandatory 2020 renewable energy and climate change targets.

"Premature adjustments to the tariff would have a profoundly damaging effect on long-term investor confidence in the clean tech and renewable energy sectors, and may cause investors to flee altogether, thereby stifling any future investment," it read.

And it closed by warning: "In short, investors simply would no longer trust government not to make subsequent, unpredictable interventions."

Dave Sowden, chief executive of the Micropower Council, which organised the letter, called on the government to protect jobs by clarifying its stance on the issue now, rather than waiting until the results of the review are published later this month.

"Customers are already responding to this speculation by canceling orders in case the feed-in-tariff gets scrapped. Thousands of jobs and hundreds of millions of pounds of investment are now hanging by a thread," he said. "It is therefore vital that the government squash this speculation without delay by confirming it will honour the current feed-in-tariffs."

His comments were echoed by Paul Foote, director of the Conservative Environment Network, who warned that any move to cut feed-in tariffs would seriously harm the government's credibility.
"Cutting the feed-in tariff poses extreme risks to the government's commitment to carbon targets, to investor confidence, and to David Cameron's reputation on the environment," he said. "If there isn't an ambitious scheme for feed-in tariffs and a renewable heat incentive, it is game over for our domestic and European targets to reduce carbon. We simply will not meet them."

However, government clarification on the future of the scheme is unlikely to come before the review is published later this month. A spokesman for the Treasury told BusinessGreen.com: "We don't comment on speculation and will not be drawn into running analysis on the spending review."

The government is facing growing fears that the spending review will hit environmental policy particularly hard. The latest letter comes just days after businesses and MPs signed a statement demanding that the Green Investment Bank be provided with £4-6bn over the next four years to boost low-carbon investment and jobs.
However, the latest move in the campaign to protect the feed-in tariffs was overshadowed somewhat by reports that Huhne yesterday went into the government's "star chamber" where the programme of departmental cuts is being finalised, suggesting that the all-important decision on the future of the scheme may have already been taken.

View the original article here

Solar cells thinner than wavelengths of light hold huge power potential

 Ultra-thin solar cells can absorb sunlight more efficiently than the thicker, more expensive-to-make silicon cells used today, because light behaves differently at scales around a nanometer (a billionth of a meter), say Stanford engineers. They calculate that by properly configuring the thicknesses of several thin layers of films, an organic polymer thin film could absorb as much as 10 times more energy from sunlight than was thought possible.

In the smooth, white, bunny-suited clean-room world of silicon wafers and solar cells, it turns out that a little roughness may go a long way, perhaps all the way to making solar power an affordable energy source, say Stanford engineers.

Their research shows that light ricocheting around inside the polymer film of a solar cell behaves differently when the film is ultra thin. A film that's nanoscale-thin and has been roughed up a bit can absorb more than 10 times the energy predicted by conventional theory.

The key to overcoming the theoretical limit lies in keeping sunlight in the grip of the solar cell long enough to squeeze the maximum amount of energy from it, using a technique called "light trapping." It's the same as if you were using hamsters running on little wheels to generate your electricity -- you'd want each hamster to log as many miles as possible before it jumped off and ran away.

"The longer a photon of light is in the solar cell, the better chance the photon can get absorbed," said Shanhui Fan, associate professor of electrical engineering. The efficiency with which a given material absorbs sunlight is critically important in determining the overall efficiency of solar energy conversion. Fan is senior author of a paper describing the work published online by Proceedings of the National Academy of Sciences.

Light trapping has been used for several decades with silicon solar cells and is done by roughening the surface of the silicon to cause incoming light to bounce around inside the cell for a while after it penetrates, rather than reflecting right back out as it does off a mirror. But over the years, no matter how much researchers tinkered with the technique, they couldn't boost the efficiency of typical "macroscale" silicon cells beyond a certain amount.

Eventually the scientists realized that there was a physical limit related to the speed at which light travels within a given material.

But light has a dual nature, sometimes behaving as a solid particle (a photon) and other times as a wave of energy, and Fan and postdoctoral researcher Zongfu Yu decided to explore whether the conventional limit on light trapping held true in a nanoscale setting. Yu is the lead author of the PNAS paper.

"We all used to think of light as going in a straight line," Fan said. "For example, a ray of light hits a mirror, it bounces and you see another light ray. That is the typical way we think about light in the macroscopic world.
"But if you go down to the nanoscales that we are interested in, hundreds of millionths of a millimeter in scale, it turns out the wave characteristic really becomes important."

Visible light has wavelengths around 400 to 700 nanometers (billionths of a meter), but even at that small scale, Fan said, many of the structures that Yu analyzed had a theoretical limit comparable to the conventional limit proven by experiment.

"One of the surprises with this work was discovering just how robust the conventional limit is," Fan said.
It was only when Yu began investigating the behavior of light inside a material of deep subwavelength-scale -- substantially smaller than the wavelength of the light -- that it became evident to him that light could be confined for a longer time, increasing energy absorption beyond the conventional limit at the macroscale.
"The amount of benefit of nanoscale confinement we have shown here really is surprising," said Yu. "Overcoming the conventional limit opens a new door to designing highly efficient solar cells."
Yu determined through numerical simulations that the most effective structure for capitalizing on the benefits of nanoscale confinement was a combination of several different types of layers around an organic thin film.

He sandwiched the organic thin film between two layers of material -- called "cladding" layers -- that acted as confining layers once the light passed through the upper one into the thin film. Atop the upper cladding layer, he placed a patterned rough-surfaced layer designed to send the incoming light off in different directions as it entered the thin film.

By varying the parameters of the different layers, he was able to achieve a 12-fold increase in the absorption of light within the thin film, compared to the macroscale limit.

Nanoscale solar cells offer savings in material costs, as the organic polymer thin films and other materials used are less expensive than silicon and, being nanoscale, the quantities required for the cells are much smaller.
The organic materials also have the advantage of being manufactured in chemical reactions in solution, rather than needing high-temperature or vacuum processing, as is required for silicon manufacture.
"Most of the research these days is looking into many different kinds of materials for solar cells," Fan said. "Where this will have a larger impact is in some of the emerging technologies; for example, in organic cells."
"If you do it right, there is enormous potential associated with it," Fan said.

Aaswath Raman, a graduate student in applied physics, also worked on the research and is a coauthor of the paper.
The project was supported by funding from the King Abdullah University of Science and Technology, which supports the Center for Advanced Molecular Photovoltaics at Stanford, and by the U.S. Department of Energy.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Stanford University. The original article was written by Louis Bergeron.

Journal Reference:
Zongfu Yu, Aaswath Raman, Shanhui Fan. Fundamental limit of nanophotonic light trapping in solar cells. Proceedings of the National Academy of Sciences, 2010; DOI: 10.1073/pnas.1008296107
Note: If no author is given, the source is cited instead.

View the original article here