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Archive for the ‘Alt Energy’ Category

New material holds big energy hope

Posted by Anonymous on July 1, 2013

20130701-124142.jpgA new material that can store large amounts of energy with very little energy loss has been developed by researchers at the Australian National University.

The material has practical applications in renewable energy storage, electric cars and defence and space technologies.

“Dielectric materials are used to make fundamental electrical components called capacitors, which store energy,” said Associate Professor Yun Liu of the ANU Research School of Chemistry, co-author of the paper detailing the new material.

The new metal oxide dielectric material outperforms current capacitors in many aspects, storing large amounts of energy and working reliably from -190°C to 180°C, and is cheaper to manufacture than current components.

“Our material performs significantly better than existing high dielectric constant materials so it has huge potential. With further development, the material could be used in “supercapacitors” which store enormous amounts of energy, removing current energy storage limitations and throwing the door wide open for innovation in the areas of renewable energy, electric cars, even space and defence technologies,” said Associate Professor Liu.

The material could be particularly transformative for wind and solar power, which can cause problems when fed into the power grid at low demand times.

“Power going into the grid has to balance with the demand for power at any given time,” said co-author Professor Ray Withers. “This means that it is very important to be able to store energy until such time as it is really needed.”

Researchers have been trying to design new dielectric materials to make more efficient energy storage devices for years.

The design process has proven difficult because the materials need to meet three requirements: a very high dielectric constant, meaning they can store a lot of energy; a very low dielectric loss, meaning energy doesn’t leak out and get wasted; and the capacity to work across a broad range of temperatures. …
http://phys.org/news/2013-07-material-big-energy.html

Posted in Alt Energy, Technology | Leave a Comment »

Is Anything Stopping a Truly Massive Build-Out of Desert Solar Power?

Posted by Anonymous on July 1, 2013

20130701-083604.jpg… The vast and glittering Ivanpah solar facility in California will soon start sending electrons to the grid, likely by the end of the summer. When all three of its units are operating by the end of the year, its 392-megawatt output will make it the largest concentrating solar power plant in the world, providing enough energy to power 140,000 homes. And it is pretty much smack in the middle of nowhere.

The appeal of building solar powerplants in deserts like Ivanpah’s Mojave is obvious, especially when the mind-blowing statistics get thrown around, such as: The world’s deserts receive more energy beamed down from the sun in six hours than humankind uses in a year. Or, try this one: Cover around 4 percent of all deserts with solar panels, and you generate enough electricity to power the world. In other words, if we’re looking for energy – and of course, we are – those sandy sunny spots are a good place to start.

But statistics are one thing, building a few thousand gigawatts of solar power is quite another. Deserts are dusty, windblown and remote. So far, only a few hundred megawatts of utility-scale desert solar power have been built. Most projects are in the American Southwest, with a few in the Middle East and north Africa as well. Though progress has been slow and significant technical challenges remain, experts and industry leaders seem to agree that engineering difficulties alone are not holding us back from a big desert solar build-out. “From the technical side, I think we can do it. In fact, I know we can do it,” says Seth Darling, a solar researcher at Argonne National Laboratory near Chicago. “I don’t know that we can do it from a policy side, but I sure hope we can.”

Water and dust
On the engineering side, though, Darling says that there are one or two challenges that still could be “deal breakers,” at least for some technologies. The big one is water. Concentrating solar power (CSP) plants, like traditional power plants, need to be cooled to run, and cooling takes water – lots of it. And of course, if water were abundant in the desert, it wouldn’t be the desert. At Ivanpah, on-site wells supply the plant with water, but that solution won’t always be feasible. “I can’t think of any technical way around that unless a dry cooling technology that’s effective and affordable is developed,” Darling says. “No one has really come up with a way to do that.”
For photovoltaics (PV), water is only needed to clean the panels, which brings up the second large problem with desert solar: dust. Solar panels and mirrors need to be cleaned almost daily if efficiencies are to stay where they need to be. Dust is not transparent, so even just one gram of dust per square meter of solar panel area can reduce efficiency by around 40 percent. At that rate, it doesn’t take long in a dusty desert for the problem to become intractable.

In the desert near Abu Dhabi in the United Arab Emirates the Middle East’s first large CSP plant recently faced down the dust issue. In order to reach the 100-megawatt-capacity goal of the Shams 1 plant, developers had to add substantially more mirrors to the plant than planned due to dust in the atmosphere. Scott Burger, an analyst at Greentech Media’s GTM Research who focuses on the region, said the plant probably ended up costing three times the initial estimate, thanks in part to dealing with that dust. And now that it is built, Shams 1 sends a series of trucks up and down the lines of 250,000 mirrors every day, using robot arms to spray that precious water and clean away the dust.

http://www.scientificamerican.com/article.cfm?id=challenges-for-desert-solar-power

I’d start by looking at all the ways life in the desert has evolved to deal with dust. Do the spines and wax of a cactus keep the dust away, for example?

Posted in Alt Energy, Technology | 1 Comment »

Scientists Built a Mini Laser Gun That Generates Anti-Matter

Posted by Anonymous on June 30, 2013

Antimatter, created naturally above storm clouds, has now been created by device that uses magnets and tabletop lasers fired at a gold sheet through helium gas.

A team of physicists working at the University of Michigan just published a paper about their device in Physical Review Letters. But basically, it’s small enough to sit on a table and can create positrons – anti-electrons – like its big,big brother, the particle accelerator at CERN. Positrons, if you aren’t familiar, are found around black holes and pulsars.

PhysOrg explains the process in more detail:

The team fired a petawatt laser at a sample of inert helium gas. Doing so caused the creation of a stream of electrons moving at very high speed. Those electrons were directed at a very thin sheet of metal foil which caused them to smash into individual metal atoms. Those collisions resulted in a stream of electron and positron emissions – the two were then separated using magnets.

The researchers report that each blast of their gun lasts just 30 femtoseconds, but each firing results in the production of quadrillions of positrons – a density level comparable to those produced at CERN.

For scale: petawatt is one quadrillion watts, a femtosecond is a one quadrillionth of a second, and a quadrillion is 1,000,000,000,000,000.

The thought is that we can use gadgets like this to study positrons more easily than ever and learn more about those gaping black holes in space and other things like them. … [PhysOrg]

http://www.gizmodo.co.uk/2013/06/scientists-built-a-mini-laser-gun-that-generates-anti-matter/

From the Wikipedia antimatter bomb page:

An antimatter weapon is a hypothetical device using antimatter as a power source, a propellant, or an explosive for a weapon. Antimatter weapons do not currently exist due to the cost of production and the limited technology available to produce and contain antimatter in sufficient quantities for it to be a useful weapon. The United States Air Force, however, has been interested in military uses — including destructive applications — of antimatter since the Cold War, when it began funding antimatter-related physics research. The primary theoretical advantage of such a weapon is that antimatter and matter collisions convert a greater fraction of the weapon’s mass into explosive energy when compared to a fusion reaction, which is only on the order of 0.7%. There is considerable skepticism within the physics community about the viability of antimatter weapons. According to CERN laboratories, which regularly produces antimatter, “There is no possibility to make antimatter bombs for the same reason you cannot use it to store energy: we can’t accumulate enough of it at high enough density. (…) If we could assemble all the antimatter we’ve ever made at CERN and annihilate it with matter, we would have enough energy to light a single electric light bulb for a few minutes.”, but this would be a considerable feat because the accumulated antimatter would weigh less than one billionth of a gram.

If those scientists at the University of Michigan made just 12 grams of antimatter they’d have enough energy to light all 12 billion lightbulbs in the world for a few minutes.

Universe Today has this to say:

Antimatter is powerful. Even a tiny amount would create a devastating explosion. Just a kilogram of antimatter would release the same amount of energy as a 20 megaton thermonuclear bomb.

But here’s the problem. Generating antimatter is an incredibly expensive process. It’s been estimated that if you took all of the antimatter ever created in all the particle colliders in the world, you would only have enough to power a lightbulb for a few minutes. To create antimatter on an industrial scale to create an antimatter bomb would require the collective resources of the entire planet. Furthermore, there’s no easy way to store antimatter once you create it, since it will explode with even the slightest touch with regular matter.

There’s no risk of an antimatter bomb ever being created. Perhaps in the distant future, hundreds of years from now, but not any time soon. …

Read more: http://www.universetoday.com/39957/antimatter-bomb/

1 kilogram is 1,000 grams so we can estimate roughly that 1 gram of antimatter has the power of a 20 kiloton nuclear bomb. That’s more powerful than the bomb dropped on Hiroshima (13 to 18 kilotons).

Scaled up and put to good use this invention might solve world energy problems… unless it takes more energy to generate, separate and store the antimatter than could be recovered using it as a fuel.

Storage is tricky:

“Trapping antihydrogen proved to be much more difficult than creating antihydrogen,” says ALPHA team member Joel Fajans, a scientist in Berkeley Lab’s Accelerator and Fusion Research Division (AFRD) and a professor of physics at UC Berkeley. “ALPHA routinely makes thousands of antihydrogen atoms in a single second, but most are too ‘hot’”—too energetic—“to be held in the trap. We have to be lucky to catch one.”

The ALPHA collaboration succeeded by using a specially designed magnetic bottle called a Minimum Magnetic Field Trap. The main component is an octupole (eight-magnetic-pole) magnet whose fields keep anti-atoms away from the walls of the trap and thus prevent them from annihilating. Fajans and his colleagues in AFRD and at UC proposed, designed, and tested the octupole magnet, which was fabricated at Brookhaven. ALPHA team member Jonathan Wurtele of AFRD, also a professor of physics at UC Berkeley, led a team of Berkeley Lab staff members and visiting scientists who used computer simulations to verify the advantages of the octupole trap….

http://newscenter.lbl.gov/news-releases/2010/11/17/antimatter-atoms/

Posted in Alt Energy, Physics | Leave a Comment »

Testing artificial photosynthesis

Posted by Anonymous on June 11, 2013

 

With the daily mean concentrations of atmospheric carbon dioxide having reached 400 parts-per-million for the first time in human history, the need for carbon-neutral alternatives to fossil fuel energy has never been more compelling. With enough energy in one hour’s worth of global sunlight to meet all human needs for a year, solar technologies are an ideal solution. However, a major challenge is to develop efficient ways to convert solar energy into electrochemical energy on a massive-scale. A key to meeting this challenge may lie in the ability to test such energy conversion schemes on the micro-scale.

Berkeley Lab researchers, working at the Joint Center for Artificial Photosynthesis (JCAP), have developed the first fully integrated microfluidic test-bed for evaluating and optimizing solar-driven electrochemical energy conversion systems. This test-bed system has already been used to study schemes for photovoltaic electrolysis of water, and can be readily adapted to study proposed artificial photosynthesis and fuel cell technologies.

“We’ve demonstrated a microfluidic electrolyzer for water splitting in which all functional components can be easily exchanged and tailored for optimization,” says Joel Ager, a staff scientist with Berkeley Lab’s Materials Sciences Division. “This allows us to test on a small scale strategies that can be applied to large scale systems.”

Ager is one of two corresponding authors of a paper in the journal Physical Chemistry Chemical Physics (PCCP) titled “Integrated microfluidic test-bed for energy conversion devices.” Rachel Segalman, also with Berkeley Lab’s Materials Sciences Division is the other corresponding author. Other co-authors are Miguel Modestino, Camilo Diaz-Botia, Sophia Haussener and Rafael Gomez-Sjoberg.

For more than two billion years, nature has employed photosynthesis to oxidize water into molecular oxygen. An artificial version of photosynthesis is regarded as one of the most promising of solar technologies. JCAP is a multi-institutional partnership led by the California Institute of Technology (Caltech) and Berkeley Lab with operations in Berkeley (JCAP-North) and Pasadena (JCAP-South). The JCAP mission is to develop an artificial version of photosynthesis through specialized membranes made from nano-engineered materials that can do what nature does only much more efficiently and for the purpose of producing storable fuels such as hydrogen or hydrocarbons (gasoline, diesel, etc.).

“The operating principles of artificial photosynthetic systems are similar to redox flow batteries and fuel cells in that charge-carriers need to be transported to electrodes, reactants need to be fed to catalytic centers, products need to be extracted, and ionic transport both from the electrolyte to catalytic centers and across channels needs to occur,” Ager says. “While there have been a number of artificial photosynthesis demonstrations that have achieved attractive solar to hydrogen conversion efficiencies, relatively few have included all of the operating principles, especially the chemical isolation of the cathode and anode.”

The microfluidic test-bed developed by Ager and his colleagues at JCAP-N allows for different anode and cathode materials to be integrated and electrically accessed independently through macroscopic contacts patterned in the outside of the microfabricated chip. The transport of charge-carriers occurs through an ion conducting polymer membrane, and electrolysis products can be evolved and collected in separated streams. This general design provides selective catalysis at the cathode and anode, minimization of cross-over losses, and managed transport of the reactants. Virtually any photoelectrochemical component, including those made of earth-abundant elements, can be incorporated into the test-bed.

Says Modestino, the lead author of the PCCP paper, “In our experimental realization of the design, a series of 19 parallel channels were fabricated in each device, with a total active area of eight square millimeters. As the microfabricated chips are relatively easy to make, we can readily change dimensions and materials to optimize performance.” …

via Testing artificial photosynthesis.

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New Process Generates Hydrogen From Aluminum Alloy To Run Engines, Fuel Cells

Posted by Anonymous on May 28, 2013

A Purdue University engineer has developed a method that uses an aluminum alloy to extract hydrogen from water for running fuel cells or internal combustion engines, and the technique could be used to replace gasoline.

The method makes it unnecessary to store or transport hydrogen – two major challenges in creating a hydrogen economy, said Jerry Woodall, a distinguished professor of electrical and computer engineering at Purdue who invented the process.

“The hydrogen is generated on demand, so you only produce as much as you need when you need it,” said Woodall, who presented research findings detailing how the system works during a recent energy symposium at Purdue.

The technology could be used to drive small internal combustion engines in various applications, including portable emergency generators, lawn mowers and chain saws. The process could, in theory, also be used to replace gasoline for cars and trucks, he said.

Hydrogen is generated spontaneously when water is added to pellets of the alloy, which is made of aluminum and a metal called gallium. The researchers have shown how hydrogen is produced when water is added to a small tank containing the pellets. Hydrogen produced in such a system could be fed directly to an engine, such as those on lawn mowers.

They use gallium to dope silicon substrates for semiconductors. It’s not benign stuff, unfortunately. “Gallium is a chemical element in the periodic table that has the symbol Ga and atomic number 31. A rare, soft silvery metallic poor metal, gallium is a brittle solid at low temperatures but liquefies slightly above room temperature and indeed will melt in the hand. It occurs in trace amounts in bauxite and zinc ores. An important application is in the compound gallium arsenide, used as a semiconductor, most notably in light-emitting diodes (LEDs).” en.wikipedia.org/wiki/Gallium …

http://www.sciencedaily.com/releases/2007/05/0705181631…

What has happened with this research in the past 6 years?

Posted in Alt Energy | 2 Comments »

Solar plane sets distance record on US tour

Posted by Anonymous on May 24, 2013


The first manned aircraft that can fly day and night powered only by solar energy set a new distance record Thursday when it landed after the second leg of a cross-country US tour.

The Solar Impulse project, founded and led by two Swiss pilots, aims to showcase what can be accomplished without fossil fuels, and has set its “ultimate goal” as an around-the-world flight in 2015.

Solar Impulse landed in Dallas-Fort Worth, Texas at 1:08 am (0608 GMT) after an 18 hour and 21 minute flight from Phoenix, Arizona, a distance of 1,541 kilometers (950 miles), organizers said in a statement.

“This leg was particularly challenging because of fairly strong winds at the landing. It also was the longest flight — in terms of distance — ever flown by a solar airplane,” the plane’s pilot Andre Borschberg said.

“You have to understand that the pilot needs to stay awake for more than 20 hours without any autopilot,” added Borschberg, who holds the record for the longest solar-powered flight, at 26 hours.

The previous distance record was attained by Solar Impulse one year ago on a 1,116 kilometer (693 mile) flight from Switzerland to Spain.

The first leg of Solar Impulse’s US tour took place on May 3, when Swiss aviator Bertrand Piccard flew the aircraft from the San Francisco, California area to Phoenix.

On the first leg the plane — which has a slim body and four electric engines attached to enormous wings — flew quietly at an average speed of about 30 miles (49 kilometers) per hour.

Energy provided by 12,000 solar cells powered the plane’s propellers.

The plane can fly at night by reaching a high elevation of 27,000 feet (8,230 meters) and then gently gliding downward, using almost no power until the sun comes up to begin recharging the solar cells.

The US itinerary allows for up to 10 days at each stop in order to showcase the plane’s technology to the public. Another stop is planned in the US capital Washington before the trip concludes in New York in early July.

The stopovers will allow Piccard and Borschberg to share duties and rest between flights.

A dashboard showing the live speed, direction, battery status, solar generator and engine power, along with cockpit cameras of both Piccard and his view from the plane, are online at live.solarimpulse.com.

via Solar plane sets distance record on US tour | GlobalPost.

Congratulations to Captain’s Piccard and Borschberg!

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Compressing air for renewable energy storage

Posted by Anonymous on May 21, 2013

 

Enough Northwest wind energy to power about 85,000 homes each month could be stored in porous rocks deep underground for later use, according to a new, comprehensive study. Researchers at the Department of Energy’s Pacific Northwest National Laboratory and Bonneville Power Administration identified two unique methods for this energy storage approach and two eastern Washington locations to put them into practice.

Compressed air energy storage plants could help save the region’s abundant wind power – which is often produced at night when winds are strong and energy demand is low – for later, when demand is high and power supplies are more strained. These plants can also switch between energy storage and power generation within minutes, providing flexibility to balance the region’s highly variable wind energy generation throughout the day.

“With Renewable Portfolio Standards requiring states to have as much as 20 or 30 percent of their electricity come from variable sources such as wind and the sun, compressed air energy storage plants can play a valuable role in helping manage and integrate renewable power onto the Northwest’s electric grid,” said Steve Knudsen, who managed the study for the BPA.

All compressed air energy storage plants work under the same basic premise. When power is abundant, it’s drawn from the electric grid and used to power a large air compressor, which pushes pressurized air into an underground geologic storage structure. Later, when power demand is high, the stored air is released back up to the surface, where it is heated and rushes through turbines to generate electricity. Compressed air energy storage plants can re-generate as much as 80 percent of the electricity they take in.

The world’s two existing compressed air energy storage plants – one in Alabama, the other in Germany – use man-made salt caverns to store excess electricity. The PNNL-BPA study examined a different approach: using natural, porous rock reservoirs that are deep underground to store renewable energy.

Interest in the technology has increased greatly in the past decade as utilities and others seek better ways to integrate renewable energy onto the power grid. About 13 percent, or nearly 8,600 megawatts, of the Northwest’s power supply comes from of wind. This prompted BPA and PNNL to investigate whether the technology could be used in the Northwest.

To find potential sites, the research team reviewed the Columbia Plateau Province, a thick layer of volcanic basalt rock that covers much of the region. The team looked for underground basalt reservoirs that were at least 1,500 feet deep, 30 feet thick and close to high-voltage transmission lines, among other criteria.

They then examined public data from wells drilled for gas exploration or research at the Hanford Site in southeastern Washington. Well data was plugged into PNNL’s STOMP computer model, which simulates the movement of fluids below ground, to determine how much air the various sites under consideration could reliably hold and return to the surface.

Analysis identified two particularly promising locations in eastern Washington. One location, dubbed the Columbia Hills Site, is just north of Boardman, Ore., on the Washington side of the Columbia River. The second, called the Yakima Minerals Site, is about 10 miles north of Selah, Wash., in an area called the Yakima Canyon.

But the research team determined the two sites are suitable for two very different kinds of compressed air energy storage facilities. The Columbia Hills Site could access a nearby natural gas pipeline, making it a good fit for a conventional compressed air energy facility. Such a conventional facility would burn a small

The Yakima Minerals Site, however, doesn’t have easy access to natural gas. So the research team devised a different kind of compressed air energy storage facility: one that uses geothermal energy. This hybrid facility would extract geothermal heat from deep underground to power a chiller that would cool the facility’s air compressors, making them more efficient. Geothermal energy would also re-heat the air as it returns to the surface.

“Combining geothermal energy with compressed air energy storage is a creative concept that was developed to tackle engineering issues at the Yakima Minerals Site,” said PNNL Laboratory Fellow and project leader Pete McGrail. “Our hybrid facility concept significantly expands geothermal energy beyond its traditional use as a renewable baseload power generation technology.”

The study indicates both facilities could provide energy storage during extended periods of time. This could especially help the Northwest during the spring, when sometimes there is more wind and hydroelectric power than the region can absorb. The combination of heavy runoff from melting snow and a large amount of wind, which often blows at night when demand for electricity is low, can spike power production in the region. …

via Not just blowing in the wind: Compressing air for renewable energy storage.

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The solar-powered plane Solar Impulse prepares for flight around the world

Posted by Anonymous on April 26, 2013

Solar Impulse pilots Bertrand Piccard (L) and Andre Borschberg at Moffett Field in Mountain View, California

The solar-powered plane Solar Impulse is preparing for a journey around the world scheduled to begin on May 1. It is powered by about 12,000 photovoltaic cells that cover its massive wings. They allow it to charge its batteries and enable it to fly day and night without jet fuel. Above, the Solar Impulse glides over the Golden Gate Bridge in San Francisco.

via The solar-powered plane Solar Impulse prepares for flight around the world – Telegraph.

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‘Artificial leaf’ gains the ability to self-heal damage and produce energy from dirty water

Posted by Anonymous on April 22, 2013

Another innovative feature has been added to the world’s first practical “artificial leaf,” making the device even more suitable for providing people in developing countries and remote areas with electricity, scientists reported here today. It gives the leaf the ability to self-heal damage that occurs during production of energy.

Daniel G. Nocera, Ph.D., described the advance during the “Kavli Foundation Innovations in Chemistry Lecture” at the 245th National Meeting & Exposition of the American Chemical Society.

Nocera, leader of the research team, explained that the “leaf” mimics the ability of real leaves to produce energy from sunlight and water. The device, however, actually is a simple catalyst-coated wafer of silicon, rather than a complicated reproduction of the photosynthesis mechanism in real leaves. Dropped into a jar of water and exposed to sunlight, catalysts in the device break water down into its components, hydrogen and oxygen. Those gases bubble up and can be collected and used as fuel to produce electricity in fuel cells.

“Surprisingly, some of the catalysts we’ve developed for use in the artificial leaf device actually heal themselves,” Nocera said. “They are a kind of ‘living catalyst.’ This is an important innovation that eases one of the concerns about initial use of the leaf in developing countries and other remote areas.”

Nocera, who is the Patterson Rockwood Professor of Energy at Harvard University, explained that the artificial leaf likely would find its first uses in providing “personalized” electricity to individual homes in areas that lack traditional electric power generating stations and electric transmission lines. Less than one quart of drinking water, for instance, would be enough to provide about 100 watts of electricity 24 hours a day. Earlier versions of the leaf required pure water, because bacteria eventually formed biofilms on the leaf’s surface, shutting down production.

“Self-healing enables the artificial leaf to run on the impure, bacteria-contaminated water found in nature,” Nocera said. “We figured out a way to tweak the conditions so that part of the catalyst falls apart, denying bacteria the smooth surface needed to form a biofilm. Then the catalyst can heal and re-assemble.” …

via ‘Artificial leaf’ gains the ability to self-heal damage and produce energy from dirty water.

Posted in Alt Energy, Technology | 1 Comment »

New solar-cell coating could boost efficiency

Posted by Anonymous on April 18, 2013

Band Gap EfficiencyThroughout decades of research on solar cells, one formula has been considered an absolute limit to the efficiency of such devices in converting sunlight into electricity: Called the Shockley-Queisser efficiency limit, it posits that the ultimate conversion efficiency can never exceed 34 percent for a single optimized semiconductor junction.

Now, researchers at MIT have shown that there is a way to blow past that limit as easily as today’s jet fighters zoom through the sound barrier — which was also once seen as an ultimate limit. …

in the new technique, each photon can instead knock two electrons loose. This makes the process much more efficient: In a standard cell, any excess energy carried by a photon is wasted as heat, whereas in the new system the extra energy goes into producing two electrons instead of one.

While others have previously “split” a photon’s energy, they have done so using ultraviolet light, a relatively minor component of sunlight at Earth’s surface. The new work represents the first time this feat has been accomplished with visible light, laying a pathway for practical applications in solar PV panels.

This was accomplished using an organic compound called pentacene in an organic solar cell. While that material’s ability to produce two excitons from one photon had been known, nobody had previously been able to incorporate it within a PV device that generated more than one electron per photon.

“Our whole project was directed at showing that this splitting process was effective,” says Baldo, who is also the director of the Center for Excitonics, sponsored by the U.S. Department of Energy. “We showed that we could get through that barrier.”

The theoretical basis for this work was laid long ago, says Congreve, but nobody had been able to realize it in a real, functioning system. “In this system,” he says, “everyone knew you could, they were just waiting for someone to do it.”

Since this was just a first proof of principle, the team has not yet optimized the energy-conversion efficiency of the system, which remains less than 2 percent. But ratcheting up that efficiency through further optimization should be a straightforward process, the researchers say. “There appears to be no fundamental barrier,” Thompson says.

While today’s commercial solar panels typically have an efficiency of at most 25 percent, a silicon solar cell harnessing singlet fission should make it feasible to achieve efficiency of more than 30 percent, Baldo says — a huge leap in a field typically marked by slow, incremental progress. In solar cell research, he notes, people are striving “for an increase of a tenth of a percent.”

Solar panel efficiencies can also be improved by stacking different solar cells together, but combining solar cells is expensive with conventional solar-cell materials. The new technology instead promises to work as an inexpensive coating on solar cells.

The work made use of a known material, but the team is now exploring new materials that might perform the same trick even better. “The field is working on materials that were chanced upon,” Baldo says — but now that the principles are better understood, researchers can begin exploring possible alternatives in a more systematic way. …

via New solar-cell coating could boost efficiency.

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