From Science Alert: “A Brilliant New Kind of Solar Tech Could Provide Electricity And Clean Water to Millions”

From Science Alert

(shansekala/iStock)

10 JUL 2019
MIKE MCRAE

A compact device that uses waste heat shed by solar cells to purify water could one day change the lives of hundreds of millions of people around the globe.

The new spin on old technology from King Abdullah University of Science and Technology in Saudi Arabia promises to ease increasing pressures on the nexus point between water and energy that threatens our future.

These two resources are conveniences many of us take for granted. But more than 780 million people around the world currently lack easy access to clean water. Even more people don’t have electricity at the flick of a switch.

Missing out on water and electricity not only puts communities at direct risk of illness through contamination, it makes it harder to grow crops, raise livestock, or maintain stocks of food and medicine.

Perhaps even more importantly, there’s the Catch-22 relationship between clean water and electricity we rarely give much thought to.

Limited access to relatively fresh water makes it impossible to efficiently generate the steam required for power on an appreciable scale. And without a convenient source of power, water can be harder to decontaminate or even reach in the first place.

Fields of solar panels can bring electricity to populations in remote, dry places. But hosing them down with water is a good way to keep them clear of dust, which is not easily done in such arid locations.

With two birds to kill, researchers behind this latest project realised they could solve both problems by creating a photovoltaic cell that uses sunlight as both a means to generate electricity and distill water.

Unsurprisingly, linking photovoltaics with water decontamination isn’t novel. A US-based start-up called Zero Mass Water uses solar energy to condense liquid water absorbed straight out of atmosphere, for instance.

To be useful, though, such devices need to be compact and affordable, leaving plenty of room for improvement.

The engineers of this latest device designed their cell with efficiency in mind, folding the components for distillation under a fairly standard silicon photovoltaic cell in a way that doesn’t impact on the cell’s energy output.

Just over 10 percent of the sunlight collected by their photovoltaic cell on a clear day goes towards generating an electrical current, an efficiency that isn’t too far behind conventional solar technology.

A fraction of the remaining solar radiation becomes thermal energy, which would usually go to waste. That heat is instead absorbed by a pancake-like stack of hydrophobic membranes shuffled between materials selected to assist evaporation and condensation.

Heat forces water to turn into vapour as with any solar still. But as it condenses, the heat energy is passed down into lower membranes for the process to repeat, making for a higher rate of distillation.

By stacking the membranes this way, the researchers found they could improve on conventional solar stills, potentially producing about five times the amount of clean water.

Schematic illustration of the device. (Wang et al., Nature Communications, 2019)

Just a single square metre of this multi-stage membrane distillation device was shown to distil more than 1.6 litres of seawater per hour, all without compromising the amount of electricity being produced by the photovoltaic cell on top.

Last year, solar energy accounted for more than 500 gigawatts of the world’s electricity. By 2025, the researchers think we might come close to doubling this figure.

That’s good news, but to achieve it we’re going to need around 4 billion square metres of land. Doubling it up with distillation membranes could theoretically clean the equivalent of 10 percent of 2017’s drinking water.

It’s an exciting idea, if it scales. The next step for the research team is to investigate ways to push the boundaries on the device’s efficiency and affordability.

The interdependence between energy and water wages a heavy price on technologies that can potentially solve the problems of communities in need.

For example, desalination also has the potential to service large populations, but only if the energy is available. In 2016, sea water contributed 3 percent of the freshwater in Middle Eastern nations, but required 5 percent of its electricity to make palatable.

What’s more, the power required to separate out that salt demands a fraction of the very fresh water it produces.

With the US looking down the barrel of major water shortages in coming decades, the water-energy nexus will hit home like never before.

This kind of technology can’t come soon enough.

This research was published in Nature Communications.

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From University of Toronto: “U of T research looks at how to take the ‘petro’ out of the petrochemicals industry” Phil De Luna

From University of Toronto

Phil De Luna is the lead author of an article in Science that analyzes how green electricity and carbon capture could displace fossil fuels in the production of everything from fertilizer to textiles (photo by Tyler Irving)

April 30, 2019
Tyler Irving

Fossil fuels are the backbone of the global petrochemicals industry, which provides the world’s growing population with fuels, plastics, clothing, fertilizers and more. A new research paper, published last week in Science, charts a course for how an alternative technology – renewable electrosynthesis – could usher in a more sustainable chemical industry and ultimately enable us to leave much more oil and gas in the ground.

Phil De Luna, a PhD candidate in the Faculty of Applied Science & Engineering, is the paper’s lead author. His research involved designing and testing catalysts for electrosynthesis, and last November he was named to the Forbes 30 under 30 list of innovators in the category of Energy. He and his supervisor, Professor Ted Sargent, collaborated on the paper with an international team of researchers from Stanford University and TOTAL American Services, Inc.

Writer Tyler Irving sat down with De Luna to learn more about how renewable electrosynthesis could take the “petro” out of petrochemicals.

Can you describe the challenge you’re trying to solve?

Our society is addicted to fossil fuels – they’re in everything from the plastics in your phone to the synthetic fibres in your clothes. A growing world population and rising standards of living are driving demand higher every year.

Changing the system requires a massive global transformation. In some areas, we have alternatives – for example, electric vehicles can replace internal combustion engines. Renewable electrosynthesis could do something similar for the petrochemical industry.

What is renewable electrosynthesis?

Think about what the petrochemical industry does: It takes heavy, long-chain carbon molecules and uses high heat and pressure to break them down into basic chemical building blocks. Then, those building blocks get reassembled into plastics, fertilizers, fibres, etc.

Imagine that instead of using fossil fuels, you could use CO2 from the air. And instead of doing the reactions at high temperatures and pressures, you could make the chemical building blocks at room temperature using innovative catalysts and electricity from renewable sources, such as solar or hydro power. That’s renewable electrosynthesis.

Once we do that initial transformation, the chemical building blocks fit into our existing infrastructure, so there is no change in the quality of the products. If you do it right, the overall process is carbon neutral or even carbon negative if powered completely by renewable energy.

Plants also take CO2 from the air and make it into materials such as wood, paper and cotton. What is the advantage of electrosynthesis?

The advantages are speed and throughput. Plants are great at turning CO2 into materials, but they also use their energy for things like metabolism and reproduction, so they aren’t very efficient. It can take 10 to 15 years to grow a tonne of usable wood. Electrosynthesis would be like putting the CO2 capture and conversion power of 50,000 trees into a box the size of a refrigerator.

Why don’t we do this today?

It comes down to cost. You need to prove that the cost to make a chemical building block via electrosynthesis is on par with the cost of producing it the conventional way.

Right now there are some limited applications. For example, most of the hydrogen used to upgrade heavy oil comes from natural gas, but about four per cent is now produced by electrolysis – that is, using electricity to split water into hydrogen and oxygen. In the future, we could do something similar for carbon-based building blocks.

What did your analysis find?

We determined that there are two main factors: The first is the cost of electricity itself, and the second is the electrical-to-chemical conversion efficiency.

In order to be competitive with conventional methods, electricity needs to cost less than four cents per kilowatt-hour, and the electrical-to-chemical conversion efficiency needs to be 60 per cent or greater.

How close are we?

There are some places in the world where renewable energy from solar can cost as little as two or three cents per kilowatt-hour. Even in a place like Quebec, which has abundant hydro power, there are times of the year where electricity is sold at negative prices, because there is no way to store it. So, from an economic potential perspective, I think we’re getting close in a number of important jurisdictions.

Designing catalysts that can raise the electrical-to-chemical conversion efficiency is harder, and it’s what I spent my thesis doing. For ethylene, the best I’ve seen is about 35 per cent efficiency, but for some other building blocks, such as carbon monoxide, we’re approaching 50 per cent.

Of course, all this has been done in labs – it’s a lot harder to scale that up to a plant that can make kilotonnes per day. But I think there are some applications out there that show promise.

Can you give an example of what renewable electrosynthesis would look like?

Let’s take ethylene, which is by volume the world’s most-produced petrochemical. You could in theory make ethylene using CO2 from the air – or from an exhaust pipe – using renewable electricity and the right catalyst. You could sell the ethylene to a plastic manufacturer, who would make it into plastic bags or lawn chairs or whatever.

At the end of its life, you could incinerate this plastic – or any other carbon-intensive form of waste – capture the CO2, and start the process all over again. In other words, you’ve closed the carbon loop and eliminated the need for fossil fuels.

What do you think the focus of future research should be?

I’ve actually just taken a position as the program director of the clean energy materials challenge program at the National Research Council of Canada. I am building a $21 million collaborative research program, so this is something I think about a lot.

We’re currently targeting parts of the existing petrochemical supply chain that could easily be converted to electrosynthesis. There is the example I mentioned above, which is the production of hydrogen for oil and gas upgrading using electrolysis.

Another good building block to target would be carbon monoxide, which today is primarily produced from burning coal. We know how to make it via electrosynthesis, so if we could get the efficiency up, that would be a drop-in solution.

How does renewable electrosynthesis fit into the large landscape of strategies to reduce emissions and combat climate change?

I’ve always said that there’s no silver bullet. Instead, I think what we need is what I call a “silver buckshot” approach. We need recycled building materials, we need more efficient LEDs for lighting, we need better solar cells and better batteries.

But even if emissions from the electricity grid and the transportation network dropped to zero tomorrow, it wouldn’t do anything to help the petrochemical industry that supplies so many of the products we use every day. If we can start by electrifying portions of the supply chain, that’s the first step to building an alternative system.

See the full article here .

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From École Polytechnique Fédérale de Lausanne: “Record solar hydrogen production with concentrated sunlight”

From École Polytechnique Fédérale de Lausanne

4.29.19
Laure-Anne Pessina

Saurabh Tembhurne, Sophia Haussener and Fredy Nandjou© Marc Delachaux / 2019 EPFL

EPFL researchers have created a smart device capable of producing large amounts of clean hydrogen. By concentrating sunlight, their device uses a smaller amount of the rare, costly materials that are required to produce hydrogen, yet it still maintains a high solar-to-fuel efficiency. Their research has been taken to the next scale with a pilot facility installed on the EPFL campus.

Hydrogen will play a key role in reducing our dependence on fossil fuels. It can be sustainably produced by using solar energy to split water molecules. The resulting clean energy can be stored, used to fuel cars or converted into electricity on demand. But making it reliably on a large scale and at an affordable cost is a challenge for researchers. Efficient solar hydrogen production requires rare and expensive materials – for both the solar cells and the catalyst – in order to collect energy and then convert it.

Scientists at EPFL’s Laboratory of Renewable Energy Science and Engineering (LRESE) came up with the idea of concentrating solar irradiation to produce a larger amount of hydrogen over a given area at a lower cost. They developed an enhanced photo-electrochemical system that, when used in conjunction with concentrated solar irradiation and smart thermal management, can turn solar power into hydrogen with a 17% conversion rate and unprecedented power and current density. What’s more, their technology is stable and can handle the stochastic dynamics of daily solar irradiation.

The results of their research have just been published in Nature Energy. “In our device, a thin layer of water runs over a solar cell to cool it. The system temperature remains relatively low, allowing the solar cell to deliver better performance,” says Saurabh Tembhurne, a co-author of the study. “At the same time, the heat extracted by the water is transferred to catalysts, thereby improving the chemical reaction and increasing the hydrogen production rate,” adds Fredy Nandjou, a researcher at the LRESE. Hydrogen production is therefore optimized at each step of the conversion process.

The scientists used the LRESE’s unique solar simulator to demonstrate the stable performance of their device. The results from the lab-scale demonstrations were so promising that the device has been upscaled and is now being tested outdoors, on EPFL’s Lausanne campus. The research team installed a 7-meter diameter parabolic mirror that concentrates solar irradiation by a factor of 1,000 and drives the device. The first tests are under way.

Hydrogen stations

The scientists estimate that their system can run for over 30,000 hours – or nearly four years – without any part replacements, and up to 20 years if some parts are replaced every four years. Their solar concentrator turns and follows the sun across the sky in order to maximize its yield. Sophia Haussener, the head of the LRESE and the project lead, explains: “In sunny weather, our system can generate up to 1 kilogram of hydrogen per day, which is enough fuel for a hydrogen-powered car to travel 100 to 150 kilometers.”

For distributed, large-scale hydrogen generation, several concentrator systems could be used together to produce hydrogen at chemical plants or for hydrogen stations. Tembhurne and Haussener are planning to take their technology from the lab to industry with a spin-off company called SoHHytec.

Open source software

Thanks to an open interface, it will be possible to monitor the instantaneous performance of the system.
As part of their research, the scientists also performed a technological and economic feasibility study and developed an open-source software program called SPECDO (Solar PhotoElectroChemical Device Optimization, http://specdo.epfl.ch). This program can help engineers design components for low-cost photoelectrochemical systems for producing solar hydrogen. Additionally, they provided a dynamic benchmarking tool called SPECDC (Solar PhotoElectroChemical Device Comparison), for the comparison and assessment of all photoelectrochemical system demonstrations.
Funding

This research is being funded by the NanoTera project SHINE and the SNFS Starting Grant SCOUTS; the scale-up is being funded by SNSF-Bridge, the Swiss Federal Office of Energy and EPFL.

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From Geospatial World: “Google and DeepMind predict wind energy output using AI”

From Geospatial World

03/04/2019
Aditya Chaturvedi

Image Courtesy: Unsplash

Google has announced in its official blog post that it has enhanced the feasibility of wind energy by using AI software created by its UK subsidiary DeepMind.

Renewable energy is the way towards lowering carbon emissions and sustainability, so it is imperative that we focus on yielding optimum energy outputs from renewable energy.

Renewable technologies will be at the forefront of climate change mitigation and addressing global warming, however, the complete potential is yet to be harnessed owing to a slew of obstructions. Wind energy has emerged as a crucial source of renewable energy in the past decade due to a decline in the cost of turbines that has led to the gradual mainstreaming of wind power. Though, unpredictability in delivering power at set time frame continues to remain a daunting challenge before the sector.

Google and DeepMind project will change this forever by overcoming this limitation that has hobbled wind energy adoption.

With the help of DeepMind’s Machine Learning algorithms, Google has been able to predict the wind energy output of the farms that it uses for its Green Energy initiatives.

“DeepMind and Google started applying machine learning algorithms to 700 megawatts of wind power capacity in the central United States. These wind farms—part of Google’s global fleet of renewable energy projects—collectively generate as much electricity as is needed by a medium-sized city”, the blog says.

Google is optimistic that it can accurately predict and schedule energy output, which certainly would have an upper hand over non-time based deliveries.

Image Courtesy: Google/ DeepMind

Taking a neural network that makes uses of weather forecasts and turbine data history, DeepMind system has been configured to predict wind power output 36 hours in advance.

Taking a cue from these predictions, the advanced model recommends the best possible method to fulfill, and even exceed, delivery commitments 24 hrs in advance. Its importance can be estimated from the fact that energy sources that deliver a particular amount of power over a defined period of time are usually more vulnerable to the grid.

Google is working to make the algorithm more refined so that any discrepancy that might occur could be nullified. Till date, Google claims that Machine Learning algorithms have boosted wind energy generated by 20%, ‘compared to the to the baseline scenario of no time-based commitments to the grid’, the blog says.

Image Courtesy: Google

Completely doing away with wind variability is next to impossible, but Google claims that Machine Learning and AI would indeed make wind power more predictable and hence more useful.

This unique approach would surely open up new avenues and make wind farm data more reliable and precise. When the productivity of wind power farms in greatly increased and their output can be predicted as well as calculated, wind will have the capability to match conventional electricity sources.

Google is hopeful that the power of Machine Learning and AI would boost the mass adoption of wind power and turn it into a popular alternative to traditional sources of electricity over the years.

See the full article here .

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From Science Alert: “14-Year-Old Kid Has Reportedly Become The Youngest Person to Achieve Nuclear Fusion”

From Science Alert

22 FEB 2019
CARLY CASSELLA

(Fox News)

We might have a new contender for the youngest person to ever achieve nuclear fusion.

Tennessee teenager Jackson Oswalt is not your average 14-year-old. While other kids are playing video games or watching TV, he’s been busy putting together a nuclear laboratory in an old playroom in his house.

The budding nuclear engineer has been working on this project since he was 12, and on 19 January 2018, just hours before his 13th birthday, he reportedly achieved his mission.
Using 50,000 volts of electricity, Oswalt was reportedly able to combine two atoms of deuterium gas, successfully fusing the nuclei in his reactor’s plasma core.

(Jackson Oswalt)

After conducting some further tests over the following months, Oswalt became more convinced than ever that he had achieved fusion.

“For those that haven’t seen my recent posts, it will come as a major surprise that I would even consider believing I had achieved fusion,” he wrote on the Fusor.net forum recently.

“However, over the past month I have made an enormous amount of progress resulting from fixing major leaks in my system. I now have results that I believe to be worthy.”

To be clear, these claims have not been peer reviewed as yet – until they’re replicated and the results are published in a peer-review journal, we need to take all of this with a very, very big grain of salt.

But Oswalt is not the only one who thinks he’s been successful.

The Open Source Fusor Research Consortium has also verified Oswalt’s results. According to Jason Hull, an administrator on the website, Oswalt has now been added to the hobbyist group’s list of successful fusioneers.

“Good work. Nice system. You have put some money into this,” Hull wrote, applauding Oswalt’s work.

He’s not wrong. While Oswalt’s nuclear reactor is considered a “tiny volume fusor”, setting it up in an old playroom in his parents’ house cost something like $10,000 (£7,700).

What’s even crazier is that Oswalt isn’t the only young teen working on ambitious projects like this.

If Oswalt’s results are peer-reviewed or verified by a scientific organisation, he will have officially ousted the former record holder, a 14-year-old named Taylor Wilson, as the youngest person to ever achieve nuclear fusion.

See the full article here .

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From Horizon The EU Research and Innovation Magazine: “Record-breaking solar cells get ready for mass production”

From Horizon The EU Research and Innovation Magazine

21 November 2018
Benedict O’Donnell

Researchers in Europe are trying to work out how record-breaking solar cells contacts can be mass-produced. BedZed Eco village. Image credit: Flickr- Bioregional International, licensed under CC.

Sandwiching an oxygen-rich layer of silicon between a solar cell and its metal contact has allowed researchers in Europe to break performance records for the efficiency with which silicon solar cells convert sunlight into electricity. But the challenge now is how to make these so-called passivating contacts suitable for mass production.

‘There is currently a lot of excitement about passivating contacts among the solar cell community,’ said Dr Byungsul Min at the Institute for Solar Energy Research in Hamelin (ISFH), Germany. This year, the technology allowed his laboratory to set a new record efficiency of 26.1% for the kind of solar cells the kind that dominates the photovoltaics market. Commercial solar panels currently operate with an efficiency of around 20%.

Passivating contacts consist of two thin layers of oxidised and crystallised silicon sandwiched between a solar cell and its metal contact. Speaking to a packed hall this September at the European Photovoltaics Solar Energy Conference in Brussels, Belgium, Dr Min said that the layers work by healing broken atomic bonds on the silicon surface and reducing the risk of electric charges getting trapped as they flow out of the solar cell.

The design was developed in 2013 by ISFH and the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, Germany. In recent years, it has driven the energy conversion efficiency of silicon photovoltaics above 25% – a ceiling that had limited the efficiency that researchers could achieve in the lab for over a decade.

Mass fabrication

Still, Dr Min says that few manufacturers have so far adopted passivating contacts in industry. As part of a project called DISC, he is now coordinating work with research institutes and equipment manufacturers across Europe to streamline their design for mass fabrication.

Making record-setting solar cells with passivating contacts has so far required costly materials and complex laboratory techniques that Dr Min says cannot be adopted in factory assembly lines. However, by getting rid of these sophisticated approaches and substituting them with tools that are already common in the solar cell industry, the DISC consortium expects to bring down manufacturing costs for the technology.

ISFH has notably replaced an expensive and highly conductive indium-containing layer that is deposited on the cell surface to better collect electrical charges out of the passivating contact. By fine-tuning pressure and temperature conditions during production, Dr Min can now form a zinc-containing layer that presents comparable physical properties while using abundant materials.

Dutch equipment provider Meco is swapping complex lithography steps with plating techniques that can metallise the electrical contacts of passivating contact solar cells in throughputs high enough for factory assembly lines.

Over the past year, DISC samples have shuttled across France, Germany, Switzerland and the Netherlands as partners play their part in an international supply line. Each laboratory adds a layer of silicon or other materials in which it specialises, gradually building up the stack of semiconductors into a functioning solar cell.

‘This August, we completed our first industry-sized solar cells,’ said Dr Min. ‘They have already reached energy conversion efficiencies above 21%.’ This falls within the range of solar cells on the market today.

Over the coming year, Dr Min expects that fine-tuning the layers in these factory-friendly devices will help edge their performance above that of the competition. In an industry where a difference of just half a percentage can make or break companies, a technology with a proven potential of over 25% efficiency in the laboratory offers enticing prospects for manufacturers.

‘We have to go to higher solar cell efficiencies,’ agreed Dr Martin Hermle, one of the pioneers of passivating contacts at Fraunhofer ISE. His research group is now developing industrial deposition methods for the solar cells produced in DISC, and developing ways of further boosting their energy conversion efficiency in another project called Nano-Tandem.

‘The cost of solar panels is largely dictated by their surface area. If you can make cells with 30% efficiency instead of 20% or 15%, that really helps reduce the overall cost of solar energy.’

Technology developed by two German institutes set a new record efficiency for solar cells of 26.1%. Image credit: Institute for Solar Energy Research in Hamelin.

33% efficiency

Earlier this year, Fraunhofer ISE produced a solar cell that reached a staggering 33% efficiency. Researchers stacked a silicon solar cell that incorporated passivating contacts with two additional solar cells made of more exotic materials, based on elements in the third and fifth group of the periodic table.

‘These top cells are good at absorbing blue shades of light, but they are made of comparatively rare elements, like gallium or indium, that are also slower to assemble than conventional silicon solar cells,’ said Dr Hermle. ‘If you want to compete on the mass market, you have to bring the cost of the material deposition down by about two orders of magnitude.’

One solution Nano-Tandem is exploring is to use less of them. Fraunhofer ISE has shipped silicon solar cells with passivating contacts to IBM Research Zürich, where project partners are placing solar cells on top of them not as solid layers, but as carpets of wires barely 1000 atoms wide. Startup Sol Voltaics and Lund University in Sweden are developing a potentially cheaper way of manufacturing the nanowires, assembling them from gas molecules as they fly through a tube furnace.

Nano-Tandem coordinator Professor Lars Samuelson at Lund University says that the raw materials used are expensive, but that photonic effects in them could turn their economics around. He says that, assembled wisely, manufacturers could in principle use 90% less material without much impact on the efficiency or light absorption of their solar cells.

This is the kind of innovative edge that Dr Hermle describes as crucial in keeping European research institutes at the head of solar cell technology. As the market for solar cells skyrockets into 11-digit annual figures, Asian competition is increasingly muscling European manufacturers out of business.

Dr Hermle says that passivating contacts offer an example of how European industry can remain relevant in the face of global competition. ‘This is a technology that really came from Europe to the solar cell market,’ he said.

The research in this article was funded by the EU. If you liked this article, please consider sharing it on social media.

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From Stanford University: “Stanford researchers develop a rooftop device that can make solar power and cool buildings”

From Stanford University

November 8, 2018
Tom Abate, Stanford Engineering
(650) 736-2245,
tabate@stanford.edu

Professor Shanhui Fan and postdoctoral scholar Wei Li atop the Packard Electrical Engineering building with the apparatus that is proving the efficacy of a double-layered solar panel. The top layer uses the standard semiconductor materials that go into energy-harvesting solar cells; the novel materials on the bottom layer perform the cooling task. (Image credit: L.A. Cicero)

Stanford electrical engineer Shanhui Fan wants to revolutionize energy-producing rooftop arrays.

Today, such arrays do one thing – they turn sunlight into electricity. But Fan’s lab has built a device that could have a dual purpose – generating electricity and cooling buildings.

“We’ve built the first device that one day could make energy and save energy, in the same place and at the same time, by controlling two very different properties of light,” said Fan, senior author of an article appearing Nov. 8 in Joule.

The sun-facing layer of the device is nothing new. It’s made of the same semiconductor materials that have long adorned rooftops to convert visible light into electricity. The novelty lies in the device’s bottom layer, which is based on materials that can beam heat away from the roof and into space through a process known as radiative cooling.

In radiative cooling, objects – including our own bodies – shed heat by radiating infrared light. That’s the invisible light night-vision goggles detect. Normally this form of cooling doesn’t work well for something like a building because Earth’s atmosphere acts like a thick blanket and traps the majority of the heat near the building rather allowing it to escape, ultimately into the vast coldness of space.

Holes in the blanket

Fan’s cooling technology takes advantage of the fact that this thick atmospheric blanket essentially has holes in it that allow a particular wavelength of infrared light to pass directly into space. In previous work, Fan had developed materials that can convert heat radiating off a building into the particular infrared wavelength that can pass directly through the atmosphere. These materials release heat into space and could save energy that would have been needed to air-condition a building’s interior. That same material is what Fan placed under the standard solar layer in his new device.

Zhen Chen, who led the experiments as a postdoctoral scholar in Fan’s lab, said the researchers built a prototype about the diameter of a pie plate and mounted their device on the rooftop of a Stanford building. Then they compared the temperature of the ambient air on the rooftop with the temperatures of the top and bottom layers of the device. The top layer device was hotter than the rooftop air, which made sense because it was absorbing sunlight. But, as the researchers hoped, the bottom layer of the device was significant cooler than the air on the rooftop.

“This shows that heat radiated up from the bottom, through the top layer and into space,” said Chen, who is now a professor at the Southeast University of China.

What they weren’t able to test is whether the device also produced electricity. The upper layer in this experiment lacked the metal foil, normally found in solar cells, that would have blocked the infrared light from escaping. The team is now designing solar cells that work without metal liners to couple with the radiative cooling layer.

“We think we can build a practical device that does both things,” Fan said.

Shanhui Fan is the director of the Edward L. Ginzton Laboratory, a professor of electrical engineering, a senior fellow at the Precourt Institute for Energy and a professor, by courtesy, of applied physics. Postdoctoral scholars Wei Li of Stanford and Linxiao Zhu of the University of Michigan, Ann Arbor, also co-authored the paper.

The research was supported by the Stanford University Global Climate and Energy Project, the National Science Foundation and the National Natural Science Foundation of China.

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From MIT News: “New battery gobbles up carbon dioxide”

From MIT News

September 21, 2018
David L. Chandler

This scanning electron microscope image shows the carbon cathode of a carbon-dioxide-based battery made by MIT researchers, after the battery was discharged. It shows the buildup of carbon compounds on the surface, composed of carbonate material that could be derived from power plant emissions, compared to the original pristine surface (inset). Courtesy of the researchers

Scanning transmission electron microscope Wikipedia

Lithium-based battery could make use of greenhouse gas before it ever gets into the atmosphere.

A new type of battery developed by researchers at MIT could be made partly from carbon dioxide captured from power plants. Rather than attempting to convert carbon dioxide to specialized chemicals using metal catalysts, which is currently highly challenging, this battery could continuously convert carbon dioxide into a solid mineral carbonate as it discharges.

While still based on early-stage research and far from commercial deployment, the new battery formulation could open up new avenues for tailoring electrochemical carbon dioxide conversion reactions, which may ultimately help reduce the emission of the greenhouse gas to the atmosphere.

The battery is made from lithium metal, carbon, and an electrolyte that the researchers designed. The findings are described today in the journal Joule, in a paper by assistant professor of mechanical engineering Betar Gallant, doctoral student Aliza Khurram, and postdoc Mingfu He.

Currently, power plants equipped with carbon capture systems generally use up to 30 percent of the electricity they generate just to power the capture, release, and storage of carbon dioxide. Anything that can reduce the cost of that capture process, or that can result in an end product that has value, could significantly change the economics of such systems, the researchers say.

However, “carbon dioxide is not very reactive,” Gallant explains, so “trying to find new reaction pathways is important.” Generally, the only way to get carbon dioxide to exhibit significant activity under electrochemical conditions is with large energy inputs in the form of high voltages, which can be an expensive and inefficient process. Ideally, the gas would undergo reactions that produce something worthwhile, such as a useful chemical or a fuel. However, efforts at electrochemical conversion, usually conducted in water, remain hindered by high energy inputs and poor selectivity of the chemicals produced.

Gallant and her co-workers, whose expertise has to do with nonaqueous (not water-based) electrochemical reactions such as those that underlie lithium-based batteries, looked into whether carbon-dioxide-capture chemistry could be put to use to make carbon-dioxide-loaded electrolytes — one of the three essential parts of a battery — where the captured gas could then be used during the discharge of the battery to provide a power output.

This approach is different from releasing the carbon dioxide back to the gas phase for long-term storage, as is now used in carbon capture and sequestration, or CCS. That field generally looks at ways of capturing carbon dioxide from a power plant through a chemical absorption process and then either storing it in underground formations or chemically altering it into a fuel or a chemical feedstock.

Instead, this team developed a new approach that could potentially be used right in the power plant waste stream to make material for one of the main components of a battery.

While interest has grown recently in the development of lithium-carbon-dioxide batteries, which use the gas as a reactant during discharge, the low reactivity of carbon dioxide has typically required the use of metal catalysts. Not only are these expensive, but their function remains poorly understood, and reactions are difficult to control.

By incorporating the gas in a liquid state, however, Gallant and her co-workers found a way to achieve electrochemical carbon dioxide conversion using only a carbon electrode. The key is to preactivate the carbon dioxide by incorporating it into an amine solution.

“What we’ve shown for the first time is that this technique activates the carbon dioxide for more facile electrochemistry,” Gallant says. “These two chemistries — aqueous amines and nonaqueous battery electrolytes — are not normally used together, but we found that their combination imparts new and interesting behaviors that can increase the discharge voltage and allow for sustained conversion of carbon dioxide.”

They showed through a series of experiments that this approach does work, and can produce a lithium-carbon dioxide battery with voltage and capacity that are competitive with that of state-of-the-art lithium-gas batteries. Moreover, the amine acts as a molecular promoter that is not consumed in the reaction.

The key was developing the right electrolyte system, Khurram explains. In this initial proof-of-concept study, they decided to use a nonaqueous electrolyte because it would limit the available reaction pathways and therefore make it easier to characterize the reaction and determine its viability. The amine material they chose is currently used for CCS applications, but had not previously been applied to batteries.

This early system has not yet been optimized and will require further development, the researchers say. For one thing, the cycle life of the battery is limited to 10 charge-discharge cycles, so more research is needed to improve rechargeability and prevent degradation of the cell components. “Lithium-carbon dioxide batteries are years away” as a viable product, Gallant says, as this research covers just one of several needed advances to make them practical.

But the concept offers great potential, according to Gallant. Carbon capture is widely considered essential to meeting worldwide goals for reducing greenhouse gas emissions, but there are not yet proven, long-term ways of disposing of or using all the resulting carbon dioxide. Underground geological disposal is still the leading contender, but this approach remains somewhat unproven and may be limited in how much it can accommodate. It also requires extra energy for drilling and pumping.

The researchers are also investigating the possibility of developing a continuous-operation version of the process, which would use a steady stream of carbon dioxide under pressure with the amine material, rather than a preloaded supply the material, thus allowing it to deliver a steady power output as long as the battery is supplied with carbon dioxide. Ultimately, they hope to make this into an integrated system that will carry out both the capture of carbon dioxide from a power plant’s emissions stream, and its conversion into an electrochemical material that could then be used in batteries. “It’s one way to sequester it as a useful product,” Gallant says.

“It was interesting that Gallant and co-workers cleverly combined the prior knowledge from two different areas, metal-gas battery electrochemistry and carbon-dioxide capture chemistry, and succeeded in increasing both the energy density of the battery and the efficiency of the carbon-dioxide capture,” says Kisuk Kang, a professor at Seoul National University in South Korea, who was not associated with this research.

“Even though more precise understanding of the product formation from carbon dioxide may be needed in the future, this kind of interdisciplinary approach is very exciting and often offers unexpected results, as the authors elegantly demonstrated here,” Kang adds.

See the full article here .

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The mission of MIT is to advance knowledge and educate students in science, technology, and other areas of scholarship that will best serve the nation and the world in the twenty-first century. We seek to develop in each member of the MIT community the ability and passion to work wisely, creatively, and effectively for the betterment of humankind.

From University of Cambridge: “Scientists pioneer a new way to turn sunlight into fuel”

From University of Cambridge

03 Sep 2018
No writer credit

The quest to find new ways to harness solar power has taken a step forward after researchers successfully split water into hydrogen and oxygen by altering the photosynthetic machinery in plants.

Experimental two-electrode setup showing the photoelectrochemical cell illuminated with simulated solar light. Credit: Katarzyna Sokół

Photosynthesis is the process plants use to convert sunlight into energy. Oxygen is produced as a by-product of photosynthesis when the water absorbed by plants is ‘split’. It is one of the most important reactions on the planet because it is the source of nearly all of the world’s oxygen. Hydrogen which is produced when the water is split could potentially be a green and unlimited source of renewable energy.

A new study led by academics at the University of Cambridge, used semi-artificial photosynthesis to explore new ways to produce and store solar energy. They used natural sunlight to convert water into hydrogen and oxygen using a mixture of biological components and manmade technologies.

The research could now be used to revolutionise the systems used for renewable energy production. A new paper, published in [Nature Energy], outlines how academics at the Reisner Laboratory in Cambridge’s Department of Chemistry developed their platform to achieve unassisted solar-driven water-splitting.

Their method also managed to absorb more solar light than natural photosynthesis.

Katarzyna Sokół, first author and PhD student at St John’s College, said: “Natural photosynthesis is not efficient because it has evolved merely to survive so it makes the bare minimum amount of energy needed – around 1-2 per cent of what it could potentially convert and store.”

Artificial photosynthesis has been around for decades but it has not yet been successfully used to create renewable energy because it relies on the use of catalysts, which are often expensive and toxic. This means it can’t yet be used to scale up findings to an industrial level.

The Cambridge research is part of the emerging field of semi-artificial photosynthesis which aims to overcome the limitations of fully artificial photosynthesis by using enzymes to create the desired reaction.

Sokół and the team of researchers not only improved on the amount of energy produced and stored, they managed to reactivate a process in the algae that has been dormant for millennia.

She explained: “Hydrogenase is an enzyme present in algae that is capable of reducing protons into hydrogen. During evolution, this process has been deactivated because it wasn’t necessary for survival but we successfully managed to bypass the inactivity to achieve the reaction we wanted – splitting water into hydrogen and oxygen.”

Sokół hopes the findings will enable new innovative model systems for solar energy conversion to be developed.

She added: “It’s exciting that we can selectively choose the processes we want, and achieve the reaction we want which is inaccessible in nature. This could be a great platform for developing solar technologies. The approach could be used to couple other reactions together to see what can be done, learn from these reactions and then build synthetic, more robust pieces of solar energy technology.”

This model is the first to successfully use hydrogenase and photosystem II to create semi-artificial photosynthesis driven purely by solar power.

Dr Erwin Reisner, Head of the Reisner Laboratory, a Fellow of St John’s College, University of Cambridge, and one of the paper’s authors described the research as a ‘milestone’.

He explained: “This work overcomes many difficult challenges associated with the integration of biological and organic components into inorganic materials for the assembly of semi-artificial devices and opens up a toolbox for developing future systems for solar energy conversion.”

See the full article here .

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The University of Cambridge (abbreviated as Cantab in post-nominal letters) is a collegiate public research university in Cambridge, England. Founded in 1209, Cambridge is the second-oldest university in the English-speaking world and the world’s fourth-oldest surviving university. It grew out of an association of scholars who left the University of Oxford after a dispute with townsfolk. The two ancient universities share many common features and are often jointly referred to as “Oxbridge”.

Cambridge is formed from a variety of institutions which include 31 constituent colleges and over 100 academic departments organised into six schools. The university occupies buildings throughout the town, many of which are of historical importance. The colleges are self-governing institutions founded as integral parts of the university. In the year ended 31 July 2014, the university had a total income of £1.51 billion, of which £371 million was from research grants and contracts. The central university and colleges have a combined endowment of around £4.9 billion, the largest of any university outside the United States. Cambridge is a member of many associations and forms part of the “golden triangle” of leading English universities and Cambridge University Health Partners, an academic health science centre. The university is closely linked with the development of the high-tech business cluster known as “Silicon Fen”.

From UCLA Newsroom: “Dual-layer solar cell developed at UCLA sets record for efficiently generating power”

From UCLA Newsroom

August 30, 2018
Matthew Chin

A solar cell developed by UCLA Engineering researchers converts 22.4 percent of incoming energy from the sun, a record for this type of cell. Oszie Tarula/UCLA

Materials scientists from the UCLA Samueli School of Engineering have developed a highly efficient thin-film solar cell that generates more energy from sunlight than typical solar panels, thanks to its double-layer design.

The device is made by spraying a thin layer of perovskite — an inexpensive compound of lead and iodine that has been shown to be very efficient at capturing energy from sunlight — onto a commercially available solar cell. The solar cell that forms the bottom layer of the device is made of a compound of copper, indium, gallium and selenide, or CIGS.

The team’s new cell converts 22.4 percent of the incoming energy from the sun, a record in power conversion efficiency for a perovskite–CIGS tandem solar cell. The performance was confirmed in independent tests at the U.S. Department of Energy’s National Renewable Energy Laboratory. (The previous record, set in 2015 by a group at IBM’s Thomas J. Watson Research Center, was 10.9 percent.) The UCLA device’s efficiency rate is similar to that of the poly-silicon solar cells that currently dominate the photovoltaics market.

The research, which was published today in Science, was led by Yang Yang, UCLA’s Carol and Lawrence E. Tannas Jr. Professor of Materials Science.

Qifeng Han, Yang Yang and Lei Meng. Oszie Tarula/UCLA

“With our tandem solar cell design, we’re drawing energy from two distinct parts of the solar spectrum over the same device area,” Yang said. “This increases the amount of energy generated from sunlight compared to the CIGS layer alone.”

Yang added that the technique of spraying on a layer of perovskite could be easily and inexpensively incorporated into existing solar-cell manufacturing processes.

The cell’s CIGS base layer, which is about 2 microns (or two-thousandths of a millimeter) thick, absorbs sunlight and generates energy at a rate of 18.7 percent efficiency on its own, but adding the 1 micron-thick perovskite layer improves its efficiency — much like how adding a turbocharger to a car engine can improve its performance. The two layers are joined by a nanoscale interface that the UCLA researchers designed; the interface helps give the device higher voltage, which increases the amount of power it can export.

And the entire assembly sits on a glass substrate that’s about 2 millimeters thick.

“Our technology boosted the existing CIGS solar cell performance by nearly 20 percent from its original performance,” Yang said. “That means a 20 percent reduction in energy costs.”

He added that devices using the two-layer design could eventually approach 30 percent power conversion efficiency. That will be the research group’s next goal.

The study’s lead authors are Qifeng Han, a visiting research associate in Yang’s laboratory, and Yao-Tsung Hsieh and Lei Meng, who both recently earned their doctorates at UCLA. The study’s other authors are members of Yang’s research group and researchers from Solar Frontier Corp.’s Atsugi Research Center in Japan.

The research was supported by the National Science Foundation and the Air Force Office of Scientific Research. Yang and his research group have been working on tandem solar cells for several years and their accomplishments include developing transparent tandem solar cells that could be used in windows.

See the full article here .

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For nearly 100 years, UCLA has been a pioneer, persevering through impossibility, turning the futile into the attainable.

We doubt the critics, reject the status quo and see opportunity in dissatisfaction. Our campus, faculty and students are driven by optimism. It is not naïve; it is essential. And it has fueled every accomplishment, allowing us to redefine what’s possible, time after time.

This can-do perspective has brought us 12 Nobel Prizes, 12 Rhodes Scholarships, more NCAA titles than any university and more Olympic medals than most nations. Our faculty and alumni helped create the Internet and pioneered reverse osmosis. And more than 100 companies have been created based on technology developed at UCLA.