NREL: Semiconducting Single-Walled Carbon Nanotubes in Solar Energy Harvesting


National Renewable Energy Laboratory, Golden, Colorado 

Semiconducting single-walled carbon nanotubes (s-SWCNTs) represent a tunable model one-dimensional system with exceptional optical and electronic properties. 

High-throughput separation and purification strategies have enabled the integration of s-SWCNTs into a number of optoelectronic applications, including photovoltaics (PVs). In this Perspective, we discuss the fundamental underpinnings of two model PV interfaces involving s-SWCNTs. 

We first discuss s-SWCNT–fullerene heterojunctions where exciton dissociation at the donor–acceptor interface drives solar energy conversion. Next, we discuss charge extraction at the interface between s-SWCNTs and a photoexcited perovskite active layer. 

In each case, the use of highly enriched semiconducting SWCNT samples enables fundamental insights into the thermodynamic and kinetic mechanisms that drive the efficient conversion of solar photons into long-lived separated charges. 

These model systems help to establish design rules for next-generation PV devices containing well-defined organic semiconductor layers and help to frame a number of important outstanding questions that can guide future studies.

Cheap Catalysts turn Sunlight and Carbon Dioxide into Fuel – Sustainable & Abundant Energy


Photosynthesis NREL iStock-503352336_16x9Thanks to a new catalyst, sunlight has been converted into chemical energy with a record 13.4% efficiency.

Scientists have long dreamed of mimicking photosynthesis, by using the energy in sunlight to knit together hydrocarbon fuels from carbon dioxide (CO2) and water. Now, a cheap new chemical catalyst has carried out part of that process with record efficiency, using electricity from a solar cell to split CO2 into energy-rich carbon monoxide (CO) and oxygen. The conversion isn’t yet efficient enough to compete with fossil fuels like gasoline. But it could one day lead to methods for making essentially unlimited amounts of liquid fuels from sunlight, water, and CO2, the chief culprit in global warming.

A bright idea

A new catalyst made from copper and tin oxides uses electric current from a solar cell to split water (H2O) and carbon dioxide (CO2), creating energy-rich carbon monoxide (CO) that can be further refined into liquid fuels.

 

NREL I downloadThe new work is “a very nice result,” says John Turner, a renewable fuels expert at the National Renewable Energy Laboratory in Golden, Colorado.

The transformation begins when CO2 is broken down into oxygen and CO, the latter of which can be combined with hydrogen to make a variety of hydrocarbon fuels. Adding four hydrogen atoms, for example, creates methanol, a liquid fuel that can power cars. Over the last 2 decades, researchers have discovered a number of catalysts that enable that first step and split CO2 when the gas is bubbled up through water in the presence of an electric current. One of the best studied is a cheap, plentiful mix of copper and oxygen called copper oxide. The trouble is that the catalyst splits more water than it does CO2, making molecular hydrogen (H2), a less energy-rich compound, says Michael Graetzel, a chemist at the Swiss Federal Institute of Technology in Lausanne, whose group has long studied these CO2-splitting catalysts.

Last year, Marcel Schreier, one of Graetzel’s graduate students, was looking into the details of how copper oxide catalysts work. He put a layer of them on a tin oxide–based electrode, which fed electrons to a beaker containing water and dissolved CO2. Instead of splitting mostly water—like the copper oxide catalyst—the new catalyst generated almost pure CO. “It was a discovery made by serendipity,” Graetzel says.

The tin, Graetzel adds, seems to deactivate the catalytic hot spots that help split the water. As a result, almost all the electric current went into making the more desirable CO. Armed with the new insight, Graetzel’s team sought to speed up the catalyst’s work. To do so, they remade their electrode from copper oxide nanowires, which have a high surface area for carrying out the CO2-breaking reaction, and topped them with a single atom-thick layer of tin. As Graetzel’s team reports this week in Nature Energy, the strategy worked, converting 90% of the CO2 molecules into CO, with hydrogen and other byproducts making up the rest. They also hooked their setup to a solar cell and showed that a record 13.4% of the energy in the captured sunlight was converted into the CO’s chemical bonds. That’s far better than plants, which store energy with about 1% efficiency, and even tops recent hybrid approaches that combine catalysts with microbes to generate fuel.

Nate Lewis, a chemist at the California Institute of Technology in Pasadena, says the new result comes on the heels of other recent improvements that use different catalysts to turn CO2 into fuels. “Together, they show we’re making progress,” Lewis says. But he also cautions that current efforts to turn CO2into fuel remain squarely in the realm of basic research, because they can’t generate fuel at a price anywhere near to that of refining oil.

Still, exploding supplies of renewable electricity now occasionally generate more power than the grid can handle. So scientists are looking for a viable way to store the excess electricity. That’s likely to drive further progress in storing energy in chemical fuels, Graetzel says.

 

Posted in: DOI: 10.1126/science.aan6935

Energy from the sun, stored in a liquid – and released on demand OR … Solar to Hydrogen Fuel … And the Winner Is?


Liquid Solar Sweeden large_RkeCoGI3VB0jjnprwamEX8rEU6kapTZ8SQd-0sN5fzs

“The solar energy business has been trying to overcome … challenge for years. The cost of installing solar panels has fallen dramatically but storing the energy produced for later use has been problematic.”

Solar Crash I solar-and-wind-energy“In a single hour, the amount of power from the sun that strikes the Earth is more than the entire world consumes in an year.” To put that in numbers, from the US Department of Energy 

 

 

Each hour 430 quintillion Joules of energy from the sun hits the Earth. That’s 430 with 18 zeroes after it! In comparison, the total amount of energy that all humans use in a year is 410 quintillion JoulesFor context, the average American home used 39 billion Joules of electricity in 2013.

HOME SOLAR-master675Read About: What are the Most Efficient Solar Panels on the Market?

 

Clearly, we have in our sun “a source of unlimited renewable energy”. But how can we best harness this resource? How can we convert and  “store” this energy resource on for sun-less days or at night time … when we also have energy needs?

Now therein lies the challenge!

Would you buy a smartphone that only worked when the sun was shining? Probably not. What it if was only half the cost of your current model: surely an upgrade would be tempting? No, thought not.

The solar energy business has been trying to overcome a similar challenge for years. The cost of installing solar panels has fallen dramatically but storing the energy produced for later use has been problematic.

 

Now scientists in Sweden have found a new way to store solar energy in chemical liquids. Although still in an early phase, with niche applications, the discovery has the potential to make solar power more practical and widespread.

Until now, solar energy storage has relied on batteries, which have improved in recent years. However, they are still bulky and expensive, and they degrade over time.

Image: Energy and Environmental Science

Trap and release solar power on demand

A research team from Chalmers University of Technology in Gothenburg made a prototype hybrid device with two parts. It’s made from silica and quartz with tiny fluid channels cut into both sections.

 

The top part is filled with a liquid that stores solar energy in the chemical bonds of a molecule. This method of storing solar energy remains stable for several months. The energy can be released as heat whenever it is required.

The lower section of the device uses sunlight to heat water which can be used immediately. This combination of storage and water heating means that over 80% of incoming sunlight is converted into usable energy.

Suddenly, solar power looks a lot more practical. Compared to traditional battery storage, the new system is more compact and should prove relatively inexpensive, according to the researchers. The technology is in the early stages of development and may not be ready for domestic and business use for some time.

 

From the lab to off-grid power stations or satellites?

The researchers wrote in the journal Energy & Environmental Science: “This energy can be transported, and delivered in very precise amounts with high reliability(…) As is the case with any new technology, initial applications will be in niches where [molecular storage] offers unique technical properties and where cost-per-joule is of lesser importance.”

A view of solar panels, set up on what will be the biggest integrated solar panel roof of the world, in a farm in Weinbourg, Eastern France February 12, 2009. Bright winter sun dissolves a blanket of snow on barn roofs to reveal a bold new sideline for farmer Jean-Luc Westphal: besides producing eggs and grains, he is to generate solar power for thousands of homes. Picture taken February 12.         To match feature FRANCE-FARMER/SOLAR              REUTERS/Vincent Kessler  (FRANCE) - RTXC0A6     Image: REUTERS: Kessler

The team now plans to test the real-world performance of the technology and estimate how much it will cost. Initially, the device could be used in off-grid power stations, extreme environments, and satellite thermal control systems.

 

Editor’s Note: As Solomon wrote in  Ecclesiastes 1:9:What has been will be again, what has been done will be done again; there is nothing new under the sun.”

Storing Solar Energy chemically and converting ‘waste heat’ has and is the subject of many research and implementation Projects around the globe. Will this method prove to be “the one?” This writer (IMHO) sees limited application, but not a broadly accepted and integrated solution.

Solar Energy to Hydrogen Fuel

So where does that leave us? We have been following the efforts of a number of Researchers/ Universities who are exploring and developing “Sunlight to Hydrogen Fuel” technologies to harness the enormous and almost inexhaustible energy source power-house … our sun! What do you think? Please leave us your Comments and we will share the results with our readers!

Read More

We have written and posted extensively about ‘Solar to Hydrogen Renewable Energy’ – here are some of our previous Posts:

Sunlight to hydrogen fuel 10-scientistsusScientists using sunlight, water to produce renewable hydrogen power

 

 

Rice logo_rice3Solar-Powered Hydrogen Fuel Cells

Researchers at Rice University are on to a relatively simple, low-cost way to pry hydrogen loose from water, using the sun as an energy source. The new system involves channeling high-energy “hot” electrons into a useful purpose before they get a chance to cool down. If the research progresses, that’s great news for the hydrogen […]

HyperSolar 16002743_1389245094451149_1664722947660779785_nHyperSolar reaches new milestone in commercial hydrogen fuel production

HyperSolar has achieved a major milestone with its hybrid technology HyperSolar, a company that specializes in combining hydrogen fuel cells with solar energy, has reached a significant milestone in terms of hydrogen production. The company harnesses the power of the sun in order to generate the electrical power needed to produce hydrogen fuel. This is […]

riceresearch-solar-water-split-090415 (1)Rice University Research Team Demonstrates Solar Water-Splitting Technology: Renewable Solar Energy + Clean – Low Cost Hydrogen Fuel

Rice University researchers have demonstrated an efficient new way to capture the energy from sunlight and convert it into clean, renewable energy by splitting water molecules. The technology, which is described online in the American Chemical Society journal Nano Letters, relies on a configuration of light-activated gold nanoparticles that harvest sunlight and transfer solar energy […]

NREL I downloadNREL Establishes World Record for Solar Hydrogen Production

NREL researchers Myles Steiner (left), John Turner, Todd Deutsch and James Young stand in front of an atmospheric pressure MDCVD reactor used to grow crystalline semiconductor structures. They are co-authors of the paper “Direct Solar-to-Hydrogen Conversion via Inverted Metamorphic Multijunction Semiconductor Architectures” published in Nature Energy. Photo by Dennis Schroeder.   Scientists at the U.S. […]

NREL CSM Solar Hydro img_0095NREL & Colorado School of Mines Researchers Capture Excess Photon Energy to Produce Solar Fuels

Photo shows a lead sulfide quantum dot solar cell. A lead sulfide quantum dot solar cell developed by researchers at NREL. Photo by Dennis Schroeder.

Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) have developed a proof-of-principle photo-electro-chemical cell capable of capturing excess photon energy normally lost to generating heat. Using quantum […]

What is up with the U.S. ‘Solar Industry’? Is There and Impending US Solar Energy Crash?


Solar Crash I solar-and-wind-energy

After nice stretch of sunny weather, the last few months have clouded over for big solar. Declining prices for photovoltaic cells are hurting panel manufacturers and stressing solar installation businesses.

This situation was in sharp relief this week in Tesla’s (TSLA Tesla Motors Inc TSLA 307.19 -0.38%) earnings, as its solar installation business, SolarCity, disclosed a big slowdown in builds. SolarCity commands 41 percent of the residential solar installation market, according to GTM. In its latest earnings, the firm revealed that it had installed 150 MW of panels in the first quarter, down nearly 39 percent y/y.

“Rather than prioritizing the growth of MW of solar deployed at any cost, we are selectively deploying projects that have higher margin and generate cash up front. Consequently, solar energy generation deployments in Q1 2017 declined year-over-year, but had better financial results,” said the earnings release.

The Curious Logic of the Solar Market

Industry body Solar Energy Industries Association (SEIA) reports that installations for the past year actually went up. In 2016, the U.S. saw 14.8GW solar capacity installed with a new installation taking place every 84 seconds.

There are companies that are doing well. First Solar (FSLR First Solar In FSLR 35.15 +1.77%) just reported strong earnings while Vivint Solar (VSLR Vivint Solar Inc VSLR 3.00+1.70%) announced is expansion into Rhode Island and is expected to announce financial results next week. However, the list of struggling companies in the sector is longer.

SunPower Corp. (SPWR) reported its sixth consecutive quarter of losses and laid off 25 percent of its workforce. Verengo Solar filed for bankruptcy last year, while Sungevity and Suninva did the same earlier this year.

But if solar energy is seeing such high demand, why are the companies feeling the heat?

The Price Is Not Right

The cost of the production and installation of solar panels has dropped dramatically and that is driving demand. According to SEIA, the cost to install solar capacity dropped 29 percent in the final quarter of 2016, compared to the same period last year. Over the past 10 years, installation costs have come down by nearly 60 percent.

There is more than one reason for price suppression in the solar industry.

“Driving the cost reductions were lower module and inverter prices, increased competition, lower installer and developer overheads, improved labor productivity, and optimized system configurations,” a National Renewable Energy Laboratory report states.

At home, the government tried to promote solar energy to consumers by making it affordable. One such initiative was the Solar Investment Tax Credit for residential and business solar installations, adopted in 2006 and extended in 2015.

In the international arena, U.S. solar companies blame declining panel prices on foreign imports, especially from countries like China, Mexico and Canada. Suniva recently implored President Trump for protectionist policies for the sector.

However, as the big ones struggled, someone made hay as the sun shone. According to GTM research’s U.S. Residential Solar Update 2017, many of the larger firms struggled to do well while smaller, local companies thrived.

More Insights: Investopedia http://www.investopedia.com/news/solar-industry-slowdown-catches-solarcity/#ixzz4gWsv7IYa

NREL’s Advanced Atomic Layer Deposition Enables Lithium-Ion Battery Technology


Forge Nano II batterypower-669x272

NREL’s Agreement with Forge Nano helps fundamentally enhance lithium-ion battery safety, durability, and lifetime

The U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) has entered into an exclusive license agreement with Forge Nano to commercialize NREL’s patented battery materials and systems capable of operating safely in high-stress environments. A particular feature of the technology is the encapsulation of materials with solid electrolyte coatings that can be designed to meet the increasingly demanding needs of any battery application.

These lithium-ion batteries feature a hybrid solid-liquid electrolyte system, in which the electrodes are coated with a solid electrolyte layer. This layer minimizes the potential for the formation of an internal short circuit between electrodes to prevent “thermal runaway,” or the uncontrolled increase in battery cell temperature that can result in a fire or an explosion.

In addition, coating of the electrode materials reduces the stress on traditional polymer separators that are currently necessary components in commercial lithium-ion batteries and can allow for thinner separators designed for higher power devices. This advancement has the potential to reduce both the cost and weight of the battery device, while substantially increasing safety and lifetime.

Lab-scale testing of NREL’s hybrid solid-liquid electrolyte system has shown increased electrode durability and reliability without compromised electrochemical performance. “The cells are less likely to fail, even in demanding, real-world conditions like high temperatures and fast recycle rates,” said Ahmad Pesaran, whose team of engineers in NREL’s Energy Storage group invented the technology.

Forge Nano 2017 AAEAAQAAAAAAAAdtAAAAJDgzZGI5OTYxLTcwYjUtNDdiMy05Yjc5LWFkZDZlOWU1OTg3YwForge Nano, formerly PneumatiCoat Technologies, is a Colorado-based company specializing in the scale-up and manufacturing of cost-effective Atomic Layer Deposition (ALD) encapsulated materials. Forge Nano presented its technology at the 2013 and 2017 NREL Industry Growth Forum, the nation’s premier clean energy investment event. A year later, NREL approached the company as a potential licensee after conducting a licensee search in the battery technology area.

“This license agreement will allow Forge Nano to offer further customized lithium-ion battery materials for high performance devices by utilizing our patented high-throughput ALD system that has already been successfully tested at the pilot scale and in large format pouch cells,” Paul Lichty, CEO of Forge Nano, said. “The incorporation of this technology into Forge Nano’s offering will lead to a substantial reduction in cost per unit energy of lithium-ion batteries.”

NREL has more than 800 technologies available for licensing. Companies interested in partnering to advance research on or commercialize renewable energy technologies can visit the EERE Energy Innovation Portal, which features descriptions of all renewable energy technologies funded by the Department of Energy’s Office of Energy Efficiency and Renewable Energy.

NREL is the U.S. Department of Energy’s primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for the Energy Department by The Alliance for Sustainable Energy, LLC.

Visit NREL online at www.nrel.gov

To learn more about Forge Nano visit: Forge Nano

NREL Wins Award for Isothermal Battery Calorimeters – Measuring Battery Heat Levels and Energy Efficiency with 98% Accuracy – Video


NREL engineer Matthew Keyser holds a A123 battery module over the calorimeter he designed and built with the help of his staff.

” …. The IBCs can determine heat levels and battery energy efficiency with 98% accuracy and provide precise measurements through complete thermal isolation.”

NREL’s R&D 100 Award-winning Isothermal Battery Calorimeters (IBCs) are the only calorimeters in the world capable of providing the precise thermal measurements needed for safer, longer-lasting, and more cost-effective electric-drive vehicle (EDV) batteries. In order for EDVs hybrids (HEVs), plug-in hybrids (PHEVs), and all-electric vehicles (EVs) to realize ultimate market penetration, their batteries need to operate at maximum efficiency, performing at optimal temperatures in a wide range of driving conditions and climates, and through numerous charging cycles.

ibc_rotator_1Cutaway showing battery in the test chamber, heat flux gauges, isothermal fluid surrounding the test chamber, and outside container with insulation holding the bath fluid and the test chamber. Image: Courtesy of NETZSCH

 

NREL’s IBCs make it possible to accurately measure the heat generated by electric-drive vehicle batteries, analyze the effects of temperature on battery systems, and pinpoint ways to manage temperatures for the best performance and maximum life. Three models, the IBC 284, the Module IBC, and the Large-Volume IBC, make it possible to test energy devices at a full range of scales.

The World’s Most Precise Battery Calorimeters

Development of precisely calibrated battery systems relies on accurate measurements of heat generated by battery modules during the full range of charge/discharge cycles, as well as determination of whether the heat was generated electrochemically or resistively. The IBCs can determine heat levels and battery energy efficiency with 98% accuracy and provide precise measurements through complete thermal isolation. These are the first calorimeters designed to analyze heat loads generated by complete battery systems.

This video describes NREL’s R&D 100 Award-winning Isothermal Battery Calorimeters, the only calorimeters in the world capable of providing the precise thermal measurements needed for safer, longer-lasting, and more cost-effective electric-drive vehicle batteries.

Calorimeter Specifications
Specifications IBC 284 (Cell) Module IBC Large-Volume IBC (Pack)
Maximum Voltage (Volts) 50 500 600
Sustained Maximum Current (Amps) 250 250 450
Excursion Currents (Amps) 300 300 1,000
Volume (liters) 9.4 14.7 96
Maximum Dimensions (cm) 20.3 x 20.3 x 15.2 35 x 21 x 20 60 x 40 x 40
Operating Temperature (C) -30 to 60 -30 to 60 -40 to 100
Maximum Constant Heat Generation (W) 50 150 4,000

Working with Industry to Fine-Tune Energy Storage Designs

The IBCs’ capabilities make it possible for battery developers to predict thermal performance before installing batteries in vehicles. Manufacturers use these metrics to compare battery performance to industry averages, troubleshoot thermal issues, and fine-tune designs.

NREL in partnership with NETSCH Instrument North America and with support from the U.S. Department of Energy is using IBCs to help industry design better thermal management systems for EDV battery cells, modules, and packs. The U.S. Advanced Battery Consortium (USABC) and its partners rely on NREL for precise measurement of energy storage devices’ heat generation and efficiency under different states of charge, power profiles, and temperatures.

Experts Outline Pathway for Generating Up to Ten (10) Terawatts of Power from Sunlight by 2030: NREL – GA SERI


NREL IV energy-resources-renewables-fossil-fuel-uranium

The annual potential of solar energy far exceeds the world’s energy consumption, but the goal of using the sun to provide a significant fraction of global electricity demand is far from being realized.

Scientists from the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL), their counterparts from similar institutes in Japan and Germany, along with researchers at universities and industry, assessed the recent trajectory of photovoltaics and outlined a potential worldwide pathway to produce a significant portion of the world’s electricity from solar power in the new Science paper, Terawatt-Scale Photovoltaics: Trajectories and Challenges.NREL I download

Fifty-seven experts met in Germany in March 2016 for a gathering of the Global Alliance of Solar Energy Research Institutes (GA-SERI), where they discussed what policy initiatives and technology advances are needed to support significant expansion of solar power over the next couple of decades.

“When we came together, there was a consensus that the global PV industry is on a clear trajectory to reach the multi-terawatt scale over the next decade,” said lead author Nancy Haegel, director of NREL’s Materials Science Center. “However, reaching the full potential for PV technology in the global energy economy will require continued advances in science and technology. Bringing the global research community together to solve challenges related to realizing this goal is a key step in that direction.”

NREL III pv global

Photovoltaics (PV) generated about 1 percent of the total electricity produced globally in 2015 but also represented about 20 percent of new installation. The International Solar Alliance has set a target of having at least 3 terawatts – or 3,000 gigawatts (GW) – of additional solar power capacity by 2030, up from the current installed capacity of 71 GW. But even the most optimistic projections have under-represented the actual deployment of PV over the last decade, and the GA-SERI paper discusses a realistic trajectory to install 5-10 terawatts of PV capacity by 2030.

Reaching that figure should be achievable through continued technology improvements and cost decreases, as well as the continuation of incentive programs to defray upfront costs of PV systems, according to the Science paper, which in addition to Haegel was co-authored by David Feldman, Robert Margolis, William Tumas, Gregory Wilson, Michael Woodhouse, and Sarah Kurtz of NREL.

GA-SERI’s experts predict 5-10 terawatts of PV capacity could be in place by 2030 if these challenges can be overcome:

  • A continued reduction in the cost of PV while also improving the performance of solar modules
  • A drop in the cost of and time required to expand manufacturing and installation capacity
  • A move to more flexible grids that can handle high levels of PV through increased load shifting, energy storage, or transmission
  • An increase in demand for electricity by using more for transportation and heating or cooling
  • Continued progress in storage for energy generated by solar power.

The Fraunhofer Institute for Solar Energy (Germany), the National Institute of Advanced Industrial Science and Technology (Japan), and the National Renewable Energy Laboratory (United States) are the member institutes of GA-SERI, which was founded in 2012.

NREL is the U.S. Department of Energy’s primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for the Energy Department by The Alliance for Sustainable Energy, LLC.

NREL & Colorado School of Mines Researchers Capture Excess Photon Energy to Produce Solar Fuels



Photo shows a lead sulfide quantum dot solar cell. A lead sulfide quantum dot solar cell developed by researchers at NREL. Photo by Dennis Schroeder.




Scientists at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) have developed a proof-of-principle photoelectrochemical cell capable of capturing excess photon energy normally lost to generating heat.


Using quantum dots (QD) and a process called Multiple Exciton Generation (MEG), the NREL researchers
were able to push the peak external quantum efficiency for hydrogen generation to 114 percent.


The advancement could significantly boost the production of hydrogen from sunlight by using the cell to split water at a higher efficiency and lower cost than current photoelectrochemical approaches.

Details of the research are outlined in the Nature Energy paper Multiple exciton generation for photoelectrochemical hydrogen evolution reactions with quantum yields exceeding 100%, co-authored by Matthew Beard, Yong Yan, Ryan Crisp, Jing Gu, Boris Chernomordik, Gregory Pach, Ashley Marshall, and John Turner.

All are from NREL; Crisp also is affiliated with the Colorado School of Mines, and Pach and Marshall are affiliated with the University of Colorado, Boulder.




Beard and other NREL scientists in 2011 published a paper in Science that showed for the first time how MEG allowed a solar cell to exceed 100 percent quantum efficiency by producing more electrons in the electrical current than the amount of photons entering the solar cell.




“The major difference here is that we captured that MEG enhancement in a chemical bond rather than just in the electrical current,” Beard said.

“We demonstrated that the same process that produces extra current in a solar cell can also be applied to produce extra chemical reactions or stored energy in chemical bonds.”

The maximum theoretical efficiency of a solar cell is limited by how much photon energy can be converted into usable electrical energy, with photon energy in excess of the semiconductor absorption bandedge lost to heat.

The MEG process takes advantages of the additional photon energy to generate more electrons and thus additional chemical or electrical potential, rather than generating heat. QDs, which are spherical semiconductor nanocrystals (2-10 nm in diameter), enhance the MEG process.




In current report, the multiple electrons, or charge carriers, that are generated through the MEG process within the QDs are captured and stored within the chemical bonds of a H2 molecule.

NREL researchers devised a cell based upon a lead sulfide (PbS) QD photoanode. The photoanode involves a layer of PbS quantum dots deposited on top of a titanium dioxide/fluorine-doped tin oxide dielectric stack.

The chemical reaction driven by the extra electrons demonstrated a new direction in exploring high-efficiency approaches for solar fuels.

Funds for the research came from the Department of Energy’s Office of Science.

NREL is the U.S. Department of Energy’s primary national laboratory for renewable energy and energy efficiency research and development. NREL is operated for the Energy Department by The Alliance for Sustainable Energy, LLC.

Hydrogen Infrastructure Testing and Research Facility: Mountain Driving Demonstration: 175 Mile Loop + Two 11,000 foot Mountain Passes ~ ‘Colorado Cool!’


Published on Oct 10, 2016

Recently, researchers at the National Renewable Energy Laboratory wanted to know, how well does NREL’s hydrogen infrastructure support fueling multiple fuel cell electric vehicles (FCEVs) for a day trip to the Rocky Mountains?car-fc-3-nrel-download

The answer-great! NREL staff took FCEVs on a trip to demonstrate real-world performance and range in high-altitude conditions. To start the trip, drivers filled three cars at NREL’s hydrogen fueling station. The cars made a 175-mile loop crossing two 11,000+ foot mountain passes on the way. Back at NREL, the cars were filled up with hydrogen in ~5 minutes and ready to go again. Learn more at http://www.nrel.gov/hydrogen.

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Genesis Nanotechnology, Inc. ~ “Great Things from Small Things”

Solar Fuel Cell U of T energy_cycleRead More on Nano Enabled Fuel Cell Technologies for many more Energy Applications: Genesis Nanotechnology Fuel Cell Articles & Videos

NREL: Nanoscale confinement leads to new all-inorganic perovskite with exceptional solar cell properties – Using Quantum Dots to Create Increased Solar Cell Efficiency: Colorado School of Mines


confinement-for-qdots-100816-nanoscaleconAshley Marshall, Erin Sanehira and Joey Luther with solutions of all-inorganic perovskite quantum dots, showing intense photoluminescence when illuminated with UV light. Credit: National Renewable Energy Laboratory

Scientists with the Energy Department’s National Renewable Energy Laboratory (NREL) for the first time discovered how to make perovskite solar cells out of quantum dots and used the new material to convert sunlight to electricity with 10.77 percent efficiency.

The research, Quantum dot-induced phase stabilization of a-CsPbI3 perovskite for high-efficiency photovoltaics, appears in the journal Science. The authors are Abhishek Swarnkar, Ashley Marshall, Erin Sanehira, Boris Chernomordik, David Moore, Jeffrey Christians, and Joseph Luther from NREL. Tamoghna Chakrabarti from the Colorado School of Mines also is a co-author.co-school-of-mines-222925_original

In addition to developing quantum dot , the researchers discovered a method to stabilize a crystal structure in an all-inorganic perovskite material at room temperature that was previously only favorable at high temperatures. The crystal phase of the inorganic material is more stable in .

Most research into perovskites has centered on a hybrid organic-inorganic structure. Since research into perovskites for photovoltaics began in 2009, their efficiency of converting sunlight into electricity has climbed steadily and now shows greater than 22 percent power conversion efficiency. However, the organic component hasn’t been durable enough for the long-term use of perovskites as a solar cell.

NREL scientists turned to quantum dots-which are essentially nanocrystals-of cesium lead iodide (CsPbI3) to remove the unstable and open the door to high-efficiency quantum dot optoelectronics that can be used in LED lights and photovoltaics. NREL 20140609_buildings_26954_hp

The nanocrystals of CsPbI3 were synthesized through the addition of a Cs-oleate solution to a flask containing PbI2 precursor. The NREL researchers purified the nanocrystals using methyl acetate as an anti-solvent that removed excess unreacted precursors. This step turned out to be critical to increasing their stability.

Contrary to the bulk version of CsPbI3, the nanocrystals were found to be stable not only at temperatures exceeding 600 degrees Fahrenheit but also at room temperatures and at hundreds of degrees below zero. The bulk version of this material is unstable at , where photovoltaics normally operate and convert very quickly to an undesired crystal structure.

NREL scientists were able to transform the nanocrystals into a thin film by repeatedly dipping them into a methyl acetate solution, yielding a thickness between 100 and 400 nanometers. Used in a solar cell, the CsPbI3 nanocrystal film proved efficient at converting 10.77 percent of sunlight into electricity at an extraordinary high open circuit voltage. The efficiency is similar to record quantum dot solar cells of other materials and surpasses other reported all-inorganic perovskite solar cells.

Explore further: Rubidium pushes perovskite solar cells to 21.6 percent efficiency

More information: A. Swarnkar et al. Quantum dot-induced phase stabilization of -CsPbI3 perovskite for high-efficiency photovoltaics, Science (2016). DOI: 10.1126/science.aag2700