Gregoire's CleanTech Blog

La Corse à la pointe des énergies renouvelables

Le pôle de compétitivité PACA-Corse, dédié aux énergies non génératrices de gaz à effet de serre, a lancé à Ajaccio un projet de plate-forme technologique destinée à devenir une "première mondiale" combinant énergie solaire et pile à hydrogène pour fabriquer de l'électricité à grande échelle.

La plate-forme technologique solaire de Vignola (Corse-du-Sud) doit voir le jour par étapes entre 2007 et 2013, en bordure de mer sur le site magnifique des Sanguinaires, à Ajaccio. L'investissement total devrait dépasser 32 millions d'euros répartis entre partenaires publics et privés, ont annoncé devant la presse le président de la Collectivité territoriale de Corse (CTC) Ange Santini, le préfet de Corse Michel Delpuech et le directeur du pôle Capenergies, Jean-Christophe Delvallet.
A terme, la plate-forme de Vignola prévoit de produire 3,5 MW, selon le groupe corse Raffalli, principal partenaire du projet.
Rappelons que l'île tire près de 25% de sa consommation énergétique des énergies renouvelables (essentiellement l'hydraulique et l'éolien), contre une moyenne nationale de 11%, et la CTC a fixé pour objectif de dépasser les 30% à l'horizon 2013-2015.

Konarka gets White House backing

President George W. Bush's program to help solar energy compete with conventional electricity sources will help fund Konarka Technologies' development of flexible plastic solar cell strips -- material that could be embedded into the casings of laptop computers and even woven into power-producing clothing to energize digital media players or other electronics.

The technology, which received its first Pentagon funding three years ago, offers a lightweight, flexible alternative to conventional rigid photovoltaic cells on glass panels.

Energy Secretary Samuel Bodman is scheduled Thursday afternoon to tour Konarka's headquarters in a former textile mill in Lowell, where he's expected to announce funding from Bush's Solar America Initiative.

The award amount and other details were to be announced in a news conference at Konarka, a six-year-old private company that has attracted nearly $60 million (euro46 million) in venture capital funding.

Konarka's nearly $10 million (euro7.6 million) in grant money to date from U.S. and European governments includes funding from the Pentagon to supply lightweight portable battery chargers and material for tents to draw power from sunlight.

Chief Executive Howard Berke said the new White House support is a milestone for Konarka.

The first commercial product using Konarka's technology is not expected to hit the market until next year, and the company is not saying what that product might be. Konarka expects to provide prototypes in the second half of this year to commercial partners that would bring the technology to market.

Konarka's approach ''is potentially a great breakthrough technology, but like all breakthroughs, they don't happen instantaneously,'' Berke said in a phone interview.

Observers say Konarka has a good chance of becoming a leader in solar power, an industry enjoying a recent surge in initial public stock offerings by startup companies as well as growing investments from traditional energy companies -- for example, one of Konarka's financial backers is Chevron Corp.

Konarka's development of plastic solar cell strips that can be manufactured like rolls of photographic film ''has the promise of becoming a low-cost manufacturing technique,'' said Jeffrey Bencik, a Jefferies & Co. analyst who follows the solar industry. ''Some of their laboratory production has worked as advertised. But can they mass-produce it and get the same result? That's the biggest question.''

Among developers of solar technology for small-scale uses, Konarka is ''definitely doing the best job at developing what ultimately will have to be a mass-manufactured material,'' said Dan Nocera, a Massachusetts Institute of Technology chemistry professor.

However, Nocera said it remains to be seen whether Konarka's so-called ''Power Plastic'' is sufficiently chemically stable to convert energy efficiently both when light is dim and when it's bright.

Konarka, which takes its name from an ancient temple in India dedicated to the sun god Surya, was founded by Berke and Alan Heeger, who shared the 2000 Nobel Chemistry prize for showing that certain plastics can be made to conduct electricity.

The discovery about polymers -- long considered to be useful only as electrical insulators -- led to the development of new types of plastics to create flexible and lightweight alternatives to traditional solar cells on heavy glass panels.

Konarka developed low-cost plastics that could be used as the top and bottom surfaces of the photovoltaic cell. The 50-employee company says it has more than 280 patents and patent applications for materials, manufacturing and other processes and devices.

The company says its solar cells are efficient across a much broader spectrum of light than traditional cells, allowing them to draw energy from both the sun and indoor lighting.

Konarka says its material is lightweight and flexible so that it can be colored, patterned and cut to fit almost any device. The firm envisions embedding its material in cell phones, laptops and toys to provide power on the go. Clothing could be woven with the material to supply power for handheld electronics, and signboards, traffic lights and rooftops could be fitted with solar strips.

Berke foresees wide use of such technology in the developing world and areas off the electrical grid.

To that end, Berke said Konarka has held confidential discussions with the manufacturer of an inexpensive portable computer developed for the nonprofit One Laptop Per Child project, which seeks to provide computers to young students in the developing world. The project's current design features a hand crank for charging batteries.

''In the developing world, great demand exists for off-the-grid support of electronic devices,'' Berke said.

First Solar to Supply Modules for 40 MW Solar Plant

First Solar to Supply Modules for 40 MW Solar Plant: "First Solar, Inc. announced that it will supply solar modules for a 40-megawatt solar power plant that will be constructed in the Saxon region of Germany in the municipality of Brandis by juwi solar GmbH. Upon completion, the project will be one of the largest photovoltaic projects ever constructed. Project construction is scheduled to begin in the second quarter of 2007 and is expected to be completed within 30 months.

(Via Clean Edge - The Clean-Tech Market Authority.)

Quantum-dot solar power could boost output in cheap photovoltaics

No renewable power source has as much theoretical potential as solar energy. But the promise of cheap and abundant solar power remains unmet, largely because today's solar cells are so costly to make.

Photovoltaic cells use semiconductors to convert light energy into electrical current. The workhorse photo­voltaic material, silicon, performs this conversion fairly efficiently, but silicon cells are relatively expensive to manufacture. Some other semiconductors, which can be deposited as thin films, have reached market, but although they're cheaper, their efficiency doesn't compare to that of silicon. A new solution may be in the offing: some chemists think that quantum dots--tiny crystals of semi­conductors just a few nanometers wide--could at last make solar power cost-competitive with electricity from fossil fuels.

By dint of their size, quantum dots have unique abilities to interact with light. In silicon, one photon of light frees one electron from its atomic orbit. In the late 1990s, Arthur Nozik, a senior research fellow at the National Renewable Energy Laboratory in Golden, CO, postulated that quantum dots of certain semiconductor materials­ could release two or more electrons when struck by high-energy photons, such as those found toward the blue and ultraviolet end of the spectrum.

In 2004, Victor Klimov of Los Alamos­ National Laboratory in New Mexico provided the first experimental proof that Nozik was right; last year he showed that quantum dots of lead selenide could produce up to seven electrons per photon when exposed to high-energy ultraviolet light. Nozik's team soon demonstrated the effect in dots made of other semiconductors, such as lead sulfide and lead telluride.

These experiments have not yet produced a material suitable for commercialization, but they do suggest that quantum dots could someday increase the efficiency of converting sunlight into electricity. And since quantum dots can be made using simple chemical reactions, they could also make solar cells far less expensive. Researchers in Nozik's lab, whose results have not been published, recently demonstrated the extra-electron effect in quantum dots made of silicon; these dots would be far less costly to incorporate into solar cells than the large crystalline sheets of silicon used today.

To date, the extra-electron effect has been seen only in isolated quantum dots; it was not evident in the first proto­type photovoltaic devices to use the dots. The trouble is that in a working solar cell, electrons must travel out of the semiconductor and into an external electrical circuit. Some of the electrons freed in any photovoltaic cell are inevitably "lost," recaptured by positive "holes" in the semiconductor. In quantum dots, this recapture happens far faster than it does in larger pieces of a semiconductor; many of the freed electrons are immediately swallowed up.

The Nozik team's best quantum­-dot solar cells have managed only about 2 percent efficiency, far less than is needed for a practical device. However, the group hopes to boost the efficiency by modifying the surfaces of the quantum dots or improving electron transport between dots.

The project is a gamble, and Nozik readily admits that it might not pay off. Still, the enormous potential of the nanocrystals keeps him going. Nozik calculates that a photovoltaic device based on quantum dots could have a maximum efficiency of 42 percent, far better than silicon's maximum efficiency of 31 percent. The quantum dots themselves would be cheap to manufacture, and they could do their work in combination with materials like conducting polymers that could also be produced inexpensively. A working quantum dot-polymer cell could eventually place solar electricity on a nearly even economic footing with electricity from coal. "If you could [do this], you would be in Stockholm--it would be revolutionary," says Nozik.

A commercial quantum-dot solar cell is many years away, assuming it's even possible. But if it is, it could help put our fossil-fuel days behind us.

Cheap Nano Solar Cells

Carbon nanotubes could help make nanoparticle-based solar cells more efficient and practical.

Escape route: Electrons created in a nanoparticle-based solar cell have to follow a circuitous path (red line) to reach an electrode. Many don't make it, lowering the efficiency of these cells. Researchers at Notre Dame have used carbon nanotubes to help the electrons reach the electrode, improving efficiency.

Researchers at University of Notre Dame, in Indiana, have demonstrated a way to significantly improve the efficiency of solar cells made using low-cost, readily available materials, including a chemical commonly used in paints.

The researchers added single-walled carbon nanotubes to a film made of titanium-dioxide nanoparticles, doubling the efficiency of converting ultraviolet light into electrons when compared with the performance of the nanoparticles alone. The solar cells could be used to make hydrogen for fuel cells directly from water or for producing electricity. Titanium oxide is a main ingredient in white paint.

The approach, developed by Notre Dame professor of chemistry and biochemistry Prashant Kamat and his colleagues, addresses one of the most significant limitations of solar cells based on nanoparticles. (See 'Silicon and Sun.') Such cells are appealing because nanoparticles have a great potential for absorbing light and generating electrons. But so far, the efficiency of actual devices made of such nanoparticles has been considerably lower than that of conventional silicon solar cells. That's largely because it has proved difficult to harness the electrons that are generated to create a current.

Indeed, without the carbon nanotubes, electrons generated when light is absorbed by titanium-oxide particles have to jump from particle to particle to reach an electrode. Many never make it out to generate an electrical current. The carbon nanotubes 'collect' the electrons and provide a more direct route to the electrode, improving the efficiency of the solar cells.

As they wrote online in the journal Nano Letters, the Notre Dame researchers form a mat of carbon nanotubes on an electrode. The nanotubes serve as a scaffold on which the titanium-oxide particles are deposited. 'This is a very simple approach for bringing order into a disordered structure,' Kamat says.

The new carbon-nanotube and nanoparticle system is not yet a practical solar cell. That's because titanium oxide only absorbs ultraviolet light; most of the visible spectrum of light is reflected rather than absorbed. But researchers have already demonstrated ways to modify the nanoparticles to absorb the visible spectrum. In one strategy, a one-molecule-thick layer of light-absorbing dye is applied to the titanium-dioxide nanoparticles. Another approach, which has been demonstrated experimentally by Kamat, is to coat the nanoparticles with quantum dots--tiny semiconductor crystals. Unlike conventional materials in which one photon generates just one electron, quantum dots have the potential to convert high-energy photons into multiple electrons.

Several other groups are exploring approaches to improve the collection of electrons within a cell, including forming titanium-oxide nanotubes or complex branching structures made of various semiconductors. But experts say that Kamat's work could be a significant step in creating cheaper, more-efficient solar cells. 'This is very important work,' says Gerald Meyer, professor of chemistry at Johns Hopkins University. 'Using carbon nanotubes as a conduit for electrons from titanium oxide is a novel idea, and this is a beautiful proof-of-principle experiment.'"

Source : Technology Review

Largest Solar Field

Soon, also in France...

Freiburg Solar Village

When Germans understood there was an economic opportunity & serious scientific business...

Photovoltaïque : vers une réduction des coûts

 

Mené dans le cadre de l'Institut de R&D sur l'énergie photovoltaïque, le projet CISEL qui réunit EDF, le CNRS et l'Ecole Nationale Supérieure de Chimie de Paris, vise à développer une technologie de modules photovoltaïques pour un coût / performance à 1 € par Watt crête.
L'innovation du projet consiste à déposer le matériau actif grâce à un procédé électrolytique à pression atmosphérique, bien adapté à la réalisation de capteurs de grandes surfaces et permettant également de hautes capacités de production. La rupture technologique permet cette fois d'envisager de réduire les coûts !

Les technologies existent depuis plusieurs années, et même si elles sont moins performantes en terme de rendement photovoltaïque, le gain en matière première constitue un atout. Toutefois, elles font appel à des procédés de fabrication des panneaux qui s'avèrent relativement coûteux et qui ne créent pas la rupture économique par rapport aux systèmes à base de silicium, qui représentent 99 % du marché du photovoltaïque.

Le projet CISEL mise quant à lui sur un procédé innovant permettant de déposer le matériau actif à base de cuivre, indium, sélénium - c'est-à-dire l'absorbeur qui convertit la lumière en électricité - directement sur un substrat verrier associant un contact métallique, divers métaux et de l'oxyde de zinc.
Le meilleur panneau à base de silicium atteint un rendement entre 15 et 18 %. Dans ce domaine, il faut considérer le coût du KWh et le prix de revient de l'électron en €/Wc produit par les panneaux photovoltaïques. Pour abaisser ces coûts, il existe deux leviers : augmenter le rendement ou diminuer le coût de fabrication. Cette approche oblige à différencier deux applications : le cas où la surface disponible est réduite ou onéreuse et donc nécessite des capteurs à rendement élevé, et celui où le prix du Watt crête est prépondérant parce que le m2 de surface est bon marché.

La mission confiée à l'IRDEP à fin 2007, consiste à trouver l'équilibre compétitif qui permettra à cette source d'énergie de se développer sans subvention sur le marché. "Nous nous sommes fixés la réalisation d'un capteur entre 8 et 10 % de rendement pour un coût divisé par 2 ou 3 par rapport aux prix actuels situés entre 2,2 et 2,5 €/Wc", indique Olivier Kerrec, responsable du projet.
Les applications envisagées vont des montres et calculettes aux bâtiments du futur avec des toits et des façades recouverts de panneaux photovoltaïques, en passant par l'électrification des sites isolés, voire l'automobile ?

La pénurie de silicium solaire affecte la production de Schott pour le photovoltaïque

Alors qu'il ne semble pas y avoir de problèmes d'approvisionnement en tranches de silicium pour les fabricants de semiconducteurs, le milieu du photovoltaïque continue de se plaindre d'une pénurie de matières premières. A l'occasion de la publication de son résultat 2006, l'Allemand Schott vient ainsi à son tour de signaler que la production de son usine de cellules solaires en Californie serait freinée par manque d'approvisionnements suffisants en silicium de qualité solaire, à un point tel que l'arrêt de la production pourrait même être envisagé. Schott estime toutefois que, au vu des investissements actuellement réalisés par les fournisseurs de silicium, ces problèmes d'approvisionnement devraient être résolus d'ici mi-2007.

Par ailleurs, il semblerait que de nombreux fabricants potentiels de cellules et de modules solaires, aussi bien européens que chinois, ne peuvent démarrer une production industrielle par manque de matière première. Selon des experts, même la capacité de production de silicium des installations qui commencent à être opérationnelles et de celles qui sont encore prévues serait encore très insuffisante si la croissance de l'industrie photovoltaïque se maintient à 40% par an. Des solutions alternatives, qui consistent à mettre en place des sources de matériaux à partir de silicium monocristallin, de silicium multicristallin moins pur ou de silicium métallurgique, sont à l'étude (à l'instar du projet Photosil soutenu par l'Ademe et les collectivités de Rhône-Alpes).

Googleplex carbure à l'énergie solaire

La célèbre firme Google est en train de finaliser son système d'alimentation à énergie solaire pour son siège social situé à Mountain View.

Cette nouvelle installation sera capable de produire 1,6 megawatts d'électricité, grâce à l'installation de plus de 9 200 panneaux solaires.

Dès ce printemps, Googleplex deviendra le plus grand complexe privé alimenté en énergie solaire aux Etats-Unis. Pas pour longtemps ! Selon business-week, Wal-Mart envisagerait d'équiper 300 de ses magasins en panneaux solaires.

(Via http://www.enerzine.com/backend-breves.php.)