Saturday, February 11, 2012

Latest from: CleanTechnica

Latest from: CleanTechnica

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Stanford Engineers Weld Nanowires with Light

Posted: 11 Feb 2012 07:00 AM PST

 
By Andrew Myers

One area of intensive research at the nanoscale is the creation of electrically conductive meshes made of metal nanowires. Promising exceptional electrical throughput, low cost and easy processing, engineers foresee a day when such meshes are common in new generations of touch-screens, video displays, light-emitting diodes, and thin-film solar cells.

Standing in the way, however, is a major engineering hurdle: In processing, these delicate meshes must be heated or pressed to unite the crisscross pattern of nanowires that form the mesh, damaging them in the process.

In a paper just published in the journal Nature Materials, a team of engineers at Stanford has demonstrated a promising new nanowire welding technique that harnesses plasmonics to fuse the wires with a simple blast of light.

Self-limiting

At the heart of the technique is the physics of plasmonics, the interaction of light and metal in which the light flows across the surface of the metal in waves, like water on the beach.

"When two nanowires lie crisscrossed, we know that light will generate plasmon waves at the place where the two nanowires meet, creating a hot spot. The beauty is that the hot spots exist only when the nanowires touch, not after they have fused. The welding stops itself. It's self-limiting," explained Mark Brongersma, an associate professor of materials science engineering at Stanford and an expert in plasmonics. Brongersma is one of the study's senior authors.

"The rest of the wires and, just as importantly, the underlying material are unaffected," noted Michael McGehee, a materials engineer and also senior author of the paper. "This ability to heat with precision greatly increases the control, speed and energy efficiency of nanoscale welding."

In before-and-after electron-microscope images, individual nanowires are visually distinct prior to illumination. They lie atop one another, like fallen trees in the forest. When illuminated, the top nanowire acts like an antenna of sorts, directing the plasmon waves of light into the bottom wire and creating heat that welds the wires together. Post-illumination images show X-like nanowires lying flat against the substrate with fused joints.

Transparency

In addition to making it easier to produce stronger and better performing nanowire meshes, the researchers say that the new technique could open the possibility of mesh electrodes bound to flexible or transparent plastics and polymers.

To demonstrate the possibilities, they applied their mesh on Saran wrap. They sprayed a solution containing silver nanowires in suspension on the plastic and dried it. After illumination, what was left was an ultrathin layer of welded nanowires.

"Then we balled it up like a piece of paper. When we unfurled the wrap, it maintained its electrical properties," said co-author Yi Cui, an associate professor materials science and engineering. "And when you hold it up, it's virtually transparent."

This could lead to inexpensive window coatings that generate solar power while reducing glare for those inside, the researchers said.

"In previous welding techniques that used a hotplate, this would never have been possible," said lead author, Erik C. Garnett, PhD, a post-doctoral scholar in materials science who works with Brongersma, McGehee and Cui. "The Saran wrap would have melted far sooner than the silver, destroying the device instantly."

"There are many possible applications that would not even be possible in older annealing techniques," said Brongersma. "This opens some interesting, simple and large-area processing schemes for electronic devices — solar, LEDs and touch-screen displays, especially."

This research was supported by the Center for Advanced Molecular Photovoltaics (CAMP) at Stanford University, funded by King Abdullah University of Science and Technology (KAUST).

Andrew Myers is associate director of communications at the School of Engineering.

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U.S Navy Joins Biofuels with Battleship: The [Green] Movie

Posted: 11 Feb 2012 06:21 AM PST

US Navy will sail Green Strike Group in RIMPAC 2012The new green economy sure is heading into some strange territory these days. Just consider Battleship: The Movie, a summer blockbuster due for release in May. The slam-bang Hollywood actioner features the U.S. Navy battling some rather aggressive seagoing critters and if it’s a hit, audiences around the world won’t just be rooting for the Navy — they’ll be cheering for the Navy and biofuels all summer long. Say, what?

The U.S. Navy and Biofuels

The makers of Battleship: The Movie might not have envisioned the biofuel scenario when the movie went into production a few years ago, but the U.S. Navy has been thoroughly engaged in a rapid transition to alternative energy, including solar power at Navy bases as well as biofuels at sea. As a sea-based service, the Navy has been straightforward about expressing the effects of global warming on its operations including humanitarian missions. That goes right to the top: Navy Secretary Ray Mabus has been a prominent, cut-to-the-chase spokesperson for the science of climate change.

Shouting out the Green Biofuel Message

The Navy is also not shy about broadcasting the impact of a precarious and dwindling supply of fossil fuels on national security. Its one-pager on energy security goals states:

“The United States Navy and Marine Corps rely far too much on petroleum, a dependency that degrades the strategic position of our country and the tactical performance of our forces. The global supply of oil is finite, it is becoming increasingly difficult to find and exploit, and over time cost continues to rise.”

The Navy’s Green Strike Group

The one-pager outlines five goals, one of which is to float an entire “Green Fleet” powered by alternative energy by 2016. As an interim step, this year the Navy has been testing biofuels on enough fighter jets, helicopters and ships to send a Green Strike Group out to sea. Though the group will be anchored by a nuclear-powered carrier, every member of the fleet will be powered with the help of non-petroleum fuels.

The Green Strike Group and RIMPAC

The Green Strike Group will debut at this summer’s Rim of the Pacific (RIMPAC) international maritime exercise, the largest of its kind in the world. RIMPAC has taken place every other summer since the 1970′s and this year it is scheduled for late June, coincidently just a few weeks after Battleship: The Movie opens on May 28 (also coincidentally, World Environment Day takes place on June 5, barely a week after the movie’s opening).

Battleship: The Movie, Biofuels and RIMPAC

This is where it starts to get really interesting. The setting for Battleship: The Movie is RIMPAC itself – you can catch it right at the beginning of the Battleship trailer. The movie even features footage from film that was shot during RIMPAC 2010. That’s right, the real-life international showcase for the Navy’s alternative energy program is the setting for a movie that aims to reach millions of viewers all over the world.

Mainstreaming the New Green Economy

The display of green firepower in Battleship: The Movie is a bit off-message from the ideal of a sustainable future, and for that matter most movie-goers won’t be aware that they’re seeing a time-shifted version of the Navy’s Green Strike Group. However, the underlying fact is clear: the

new green economy is rapidly becoming part of the mainstream landscape and we are all a part of it, whether it’s the work we do, the goods we buy, or a brief escape from reality in a darkened movie theater.

Image: U.S. Navy, USS Thatch. License Attribution Some rights reserved by Official U.S. Navy Imagery.

Follow Tina Casey on Twitter: @TinaMCasey.

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Stanford Engineers’ Nanoshell Whispering Galleries Improve Thin Solar Panels

Posted: 11 Feb 2012 04:30 AM PST

 
By Andrew Myers

Visitors to Statuary Hall in the U.S. Capitol Building may have experienced a curious acoustic feature that allows a person to whisper softly at one side of the cavernous, half-domed room and for another on the other side to hear every syllable. Sound whisks around the semi-circular perimeter of the room almost without flaw. The phenomenon is known as a whispering gallery.

In a paper published in Nature Communications, a team of engineers at Stanford describes how it has created tiny hollow spheres of photovoltaic nanocrystalline-silicon and harnessed physics to do for light what whispering galleries do for sound. The results, say the engineers, could dramatically cut materials usage and processing cost.

“Nanocrystalline-silicon is a great photovoltaic material. It has a high electrical efficiency and is durable in the harsh sun,” said Shanhui Fan, an associate professor of electrical engineering at Stanford and co-author of the paper. “Both have been challenges for other types of thin solar films.”

The downfall of nanocrystalline-silicon, however, has been its relatively poor absorption of light, which requires thick layering that takes a long time to manufacture.

A scanning electron microscope image of a single layer of nanocrystalline-silicon shells. The hollow shell structure improves light absorption while reducing the cost and weight of the device. (Photo: Yan Yao / Stanford University)

Whispering Galleries

The engineers call their spheres nanoshells. Producing the shells takes a bit of engineering magic. The researchers first create tiny balls of silica – the same stuff glass is made of – and coat them with a layer of silicon. They then etch away the glass center using hydrofluoric acid that does not affect the silicon, leaving behind the all-important light-sensitive shell. These shells form optical whispering galleries that capture and recirculate the light.

“The light gets trapped inside the nanoshells,” said Yi Cui, an associate professor of materials science engineering at Stanford and a senior author of the paper. “It circulates round and round rather than passing through and this is very desirable for solar applications.”

The researchers estimate that light circulates around the circumference of the shells a few times, during which energy from the light gets absorbed gradually by the silicon. The longer the shells can keep the light in the material, the better the absorption will be.

“This is a new approach to broadband light absorption. The use of whispering-gallery resonant modes inside nanoshells is very exciting,” said Yan Yao, a post-doctoral researcher in the Cui Lab and a co-lead author of the paper. “It not only can lead to better solar cells, but it can be applied in other areas where efficient light absorption is important, such as solar fuels and photo-detectors.”

Through Thick and Thin

In measuring light absorption in a single layer of nanoshells, the research showed significantly more absorption over a broader spectrum of light than a flat layer of the silicon deposited side-by-side with the nanoshells.

“The nanometer spherical shells really hit a sweet spot and maximize the absorption efficiency of the film. The shells both allow light to enter the film easily and they trap it to enhance the absorption in a way larger-scale counterparts cannot. That is the power of nanotechnology,” said Jie Yao, a post-doctoral researcher in Cui's lab and co-lead author of the paper.

Further, by depositing two or even three layers of nanoshells atop one another, the team teased the absorption higher still. With a three-layer structure, they were able to achieve total absorption of 75 percent of light in certain important ranges of the solar spectrum.

Clever Structure

Having demonstrated improved absorption, the engineers went on to show how their clever structure will pay dividends beyond the mere trapping of light.

First, nanoshells can be made quickly. “A micron-thick flat film of solid nanocrystalline-silicon can take a few hours to deposit, while nanoshells achieving similar light absorption take just minutes,” said Yan.

The nanoshell structure, likewise, uses substantially less material, one-twentieth that of solid nanocrystalline-silicon.

“A twentieth of the material, of course, costs one-twentieth and weighs one-twentieth what a solid layer does,” said Jie. “This might allow us to cost-effectively produce better-performing solar cells of rare or expensive materials.”

“The solar film in our paper is made of relatively abundant silicon, but down the road, the reduction in materials afforded by nanoshells could prove important to scaling up the manufacturing of many types of thin-film cells, such as those which use rarer materials like tellurium and indium,” said Vijay Narasimhan, a doctoral candidate in the Cui Lab and co-author of the paper.

Finally, the nanoshells are relatively indifferent to the angle of incoming light and the layers are thin enough to bend and twist without damage. These characteristics might open up an array of new applications in situations where achieving the optimal incoming angle of the sun is not always possible. Imagine solar sails on the high seas or photovoltaic clothing for mountain climbing.

“This new structure is just the beginning and demonstrates some of the exciting potentials for using advanced nanophotonic structures to improve solar cell efficiency,” said Shanhui Fan.

The Center on Nanostructuring for Efficient Energy Conversion (CNEEC) at Stanford University and the U.S. Department of Energy funded this research.

Andrew Myers is associate director of communications at the School of Engineering.

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Independent Report: DOE Loan Program Working, Could Be Improved

Posted: 10 Feb 2012 01:29 PM PST

 

An independent review of the U.S. Department of Energy's (DOE) loan guarantee program (LGP) finds that the program is working, but recommends several strategies to better protect government investments from failure.

Overall, the program was found to be a success. LGP funding has leveraged $40 billion in direct private investment into the U.S. economy, according to the review. In addition, the review states the LGP has $2.9 billion of risk on its books, which is about a third of the risk Congress allotted for the program when enacted on a bipartisan basis in 2005.

However, the report also calls on DOE to create a "Management Information Reporting System" (MIRS) to monitor market and regulatory trends that could impact LGP projects. In addition, the report urges DOE to monitor the status of loans, borrowers, contractors, and off-take parties that could affect loan recipients.

The report also urges DOE to create a Chief Risk Officer to lead a Risk Management unit that houses all DOE oversight functions. Combined with the MIRS, this early warning system would identify problems with the loans before they could reach bankruptcy.

The White House ordered the review in October 2011 at the height of Republican criticism of DOE's loan program after Solyndra filed for bankruptcy protection. Herb Allison, a former Treasury Department official during the Bush Administration who also oversaw the Troubled Asset Relief Program (TARP), was tasked with conducting the review.

Allison reviewed 30 loans issued by DOE, including five for advanced vehicle technology, totaling about $24 billion dollars. Only $8.3 billion of these loans, has been drawn down. Notably, the report did not analyze the DOE loans to Solyndra or Beacon Power, both of which filed for bankruptcy. While Solyndra has not found a buyer, Beacon Power recently announced it had been bought and would return 70 percent of the DOE loan.

The new report's findings largely track with other independent analyses, including a Bloomberg Government report from December 2001. The Bloomberg analysis found 87 percent of the LGP loans were "low-risk" and the controversy over Solyndra was "not proportional to its impact" because it equaled roughly .00051 percent of the federal government's outstanding loan commitments.

Earlier this week, DOE Secretary Steven Chu defended the program, saying the DOE improved the program before and after Solyndra's bankruptcy. "There's a lot going forward that the Department of Energy has to be on top of and make sure that these taxpayer investments are protected as much as possible while trying to help these companies," said Chu.

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HUGE Push to Save Renewable Energy Subsidies (Wind, Solar, Geothermal, Biomass, & Hydro)

Posted: 10 Feb 2012 12:42 PM PST

 
Sign the two letters to Congress below to help prolong key renewable energy industry incentives that will continue to create tens of thousands of U.S. jobs!

Every renewable energy industry in the country—wind, hydro, solar, geothermal, biomass,…—are working hard right now to get some critical government subsidies continued. It’s quite odd that this clean energy industry has to work so hard for government support the fossil fuel industry has had for over a century.

There are a couple of key policies these renewable energy industries are pushing and you can help them do so here:

  • a renewable energy production tax credit (PTC) — send a short message to your congresspeople via that link
  • the 1603 Treasury Grant Program — same deal–contact your congresspeople about this important renewable energy program via the link.. all the cool kids are doing it!

Here’s more info a few statements on these programs:

wind energy subsidies

Wind

The PTC is the primary policy tool to promote wind energy development and manufacturing in the United States,” the American Wind Energy Association (AWEA) writes. While it is set to expire at the end of 2012, the wind industry's long lead times to develop projects and order wind turbines from manufacturers means that the credit has already effectively expired for the industry. Congress has a choice to make: extend the PTC this month, and keep the wind industry on track to employ 500,000 people, or halve the work force, including tens of thousands of manufacturing jobs that will not return to this country.”

“America needs homegrown energy resources to power the nation, and with our economy struggling, we're in dire need of American jobs. Wind energy delivers in both of these areas. The renewable energy production tax credit (PTC) is an effective tool to keep electricity prices low and encourage development of proven clean energy projects. However, the PTC expiration is looming and we need to act fast to protect wind industry jobs.”

geothermal energy subsidies

Geothermal, Hydro, Biomass

This week, “executives from the hydropower, geothermal and biomass power industries called on Congressional leaders to extend the production tax credit through 2016 for hydropower, geothermal and biomass,” a joint letter on the Geothermal Energy Association’s website states. “The three industries operate in parts of the country not often associated with renewable energy – particularly the Southeast and Mountain West – and company and trade association leaders expressed concern for a looming crisis that has put thousands of jobs in these states at risk. The call comes as opponents of renewable energy tax policy place the future of these industries in jeopardy.”

“The group called for the immediate passage of H.R. 3307: American Renewable Energy Production Tax Credit Extension Act of 2011, which covers all renewable technologies, and is sponsored by Rep. Dave Reichert [R-WA8] and Rep. Earl Blumenauer [D-OR3] with over 60 bipartisan cosponsors, including 16 Republicans.”

"The geothermal industry has added over $1 billion in new power projects to the grid since the Congress extended the PTC to geothermal energy in 2005, bringing several thousand drilling, construction and operating jobs to often rural areas with high unemployment,” said Karl Gawell, Executive Director, Geothermal Energy Association notes. ”But with a project lead time of 4 years or more, the geothermal industry has already reached its so-called tax credit cliff, even if the legal deadline is 2013. This is not just undermining projects in 16 states with new geothermal power projects, it is also costing vendors lost orders in over 46 states that supply geothermal projects. It is more critical than ever for Congress to adopt a longer time frame for geothermal incentives. We urge action now to extend the tax deadline from 2013 to at least 2016."

Much more on this, from these three industries above, in the letter linked above.

Solar

The solar energy industry is working to extend a separate incentive, the 1603 Treasury Program. From the Solar Energy industry Association (SEIA):

The 1603 program is hands-down one of the most successful policies ever enacted to deploy clean energy.  In only two years, it has generated over $22 billion in private sector investment to jump-start more than 22,000 renewable energy projects across the country. This has created tens of thousands of new American jobs.”

Again, you can contact your senators in Congress on SEIA’s site.

“Please take a few moments to contact your Senators TODAY.  We need to stand together to let Congress know that extending the 1603 Program is critical to keep America working,” SEIA writes. It’s true—we do. The fossil fuel industry has the money. But we have the people power. We can be sure the fossil fuel industry will continue investing in Congresspeople in order to get a nice return in subsidies of various kinds. We have to show up online and elsewhere to make sure renewable energy gets at least equal treatment.

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Hertz Tests Wireless EV Charging in the U.S.

Posted: 10 Feb 2012 10:53 AM PST

 
Hertz Tests Plugless Power's Wireless Charging

Electric cars need to be charged – they run on rechargeable batteries. But taking a long cord and plugging it into an actual outlet seems so… so… 20th-century. Enter Nissan and its wireless charging stations, soon followed by Infiniti and Karabag. Car rental company Hertz is now joining the ranks of those involved in wireless EV charging, partnering with Evatran for its fleet of EVs and PHVs.

Hertz is the first company to make EVs and PHVs available for rental (which is great for the consumer, since it's much cheaper to rent an electric car and drive it for a day as a test than to lease one for a month or actually buy one). Customers in the U.S. (New York, DC, and San Francisco), the U.K. (London), and China (Shanghai) can all get electric vehicles from Hertz now, and customers in London can rent electric bicycles!

Plugs? We Don't Need Plugs!

The EVs, of course, need a charging network, and that's where Evatran comes in. Evatran is a Virginia-based company making charging systems for electric vehicles, and the product Hertz is using is called Plugless Power (yep, we’ve covered it a couple times). It uses inductive power transfer (similar to Nissan's wireless system) and is completely hands-free.

Plugless Power is currently a pilot program in its trial phase, the first of its kind in the world. The trial will follow Hertz (and five other participants) as they test Plugless Power on their vehicles. During the trial, Hertz will be expected to provide feedback – how the product is used on a daily basis, how the user interface does (or doesn't!) work, and any other issues (good or bad) that may arise.

All installation work is scheduled to be finished this month, after which the trial may commence. Hertz and Evatran hope the pilot program will help establish the US as an EV market leader. I also hope the trial goes well; EVs have the potential to be much, much greener than almost any other type of transportation, and anything that goes well for electric cars is probably okay in my book.

More information about Evatran and the Plugless Power trial are available on the Plugless Power website. Questions or opinions? Let us know in the comments below!

Source: PR Newswire | Image: Plugless Power

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World’s Largest Concentrating Solar Power Plant Hits Milestone (VIDEO)

Posted: 10 Feb 2012 10:41 AM PST

 

America's first commercial-scale concentrating solar power (CSP) facility took a major step forward this week with completion of the project's 540-foot tower.

When complete, the Crescent Dunes Solar Energy Project, located near Tonopah, Nevada, will feature 110-megawatts of new solar capacity with fully integrated energy storage, and be the largest CSP facility in the world.

Crescent Dunes has secured a 25-year power purchase agreement (PPA) with NV Energy, and will supply 480,000 megawatt-hours annually – enough to power 75,000 homes. The project is being built on federal land operated by the Bureau of Land Management, and is expected to be operational by the end of 2013.

"Our U.S.-developed technology has the ability to store energy for 10-15 hours and solves the issue of intermittent power generation to the grid," said Kevin Smith, SolarReserve CEO. "We can deliver electricity 'on demand' the same way a coal, natural gas or nuclear-fueled plant does."

Here’s a time-lapse video and discussion of the tower’s construction, worth a quick watch (more info following the video):

The CSP process means electricity can be generated from solar power any time of the day – even at night. A large circular field of 10,000 billboard-sized sun-tracking mirrors will focus sunlight to the central receiver tower. Liquid salt will be circulated through the receiver, heated to 1050 degrees Fahrenheit by the sunlight, and stored for later use. When electricity is needed, the hot salt will produce steam and drive a conventional steam turbine cycle, and then be reused the next day.

Funding is a key issue for Crescent Dunes. SolarReserve raised $260 million in private equity and $737 in loan guarantees from the Department of Energy. Electricity from the plant is projected to cost 13.5 cents per kilowatt-hour and will rise one percent per year during the 25-year PPA.

The project will also have a significant economic impact. Facility construction began in 2011, and is expected to create more than 4,300 jobs throughout the U.S. Construction will create up to 500 on-site jobs, and up to 50 permanent jobs. Once operational, Crescent Dunes is expected to generate $47 million in total tax revenue through the first 10 years of operation.

Photo courtesy of the U.S. Department of Energy

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