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perovskite solar cell

Perovskites Become More Stable

Solar cells based on perovskite crystals have made unparalleled advances in performance in the past decade, but most research on these devices has neglected the question of how stable they might be outdoors for long periods of time. Now two research groups have come up with different ways to improve perovskite solar cell stability, findings detailed in two papers in the journal Science.

One approach added rubidium cations to perovskite. "We believe this may help to relax lattice strain, resulting in a more defect-free overall crystal," says Michael Saliba, lead author of that study and a solar cell researcher at the Swiss Federal Institute of Technology in Lausanne.

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a perovskite solar cell made of many layers

Perovskite Solar Cells Grow Better With a Dash of Acrylic Glass

The conversion efficiency of solar cells based on perovskite crystals has shot up from 3.8 to 22.1 percent in less than a decade, an unprecedented rise in the field of photovoltaics. "Perovskites have rocked the whole photovoltaic community," says Michael Grätzel, director of the École Polytechnique Fédérale de Lausanne’s Laboratory of Photonics and Interfaces. Trying to keep the progress going, he and his colleagues have found a way to grow bigger, better performing perovskite cells—by growing with ordinary acrylic glass.

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Map of Asia Super Grid

Trio of Nations Aims to Hook Asia Super Grid to Grids of the World

Northeast Asia, the region encompassing China, South Korea, and Japan, has not yet gotten around to connecting its electricity grids together. But that’s not stopping these countries from promoting the Asia Super Grid, calculated to become the center of a global energy grid providing abundant, cheap electricity based on renewable energy. 

In Japan, the idea emerged following the 2011 Tohoku earthquake and subsequent Fukushima Daiichi nuclear plant disaster. The possibility of a nuclear disaster so shocked Masayoshi Son, founder and head of the telecom and Internet giant SoftBank Group, that he established the Renewable Energy Institute soon after to help develop and promote renewable energy.

“I was a total layman (in renewable energy) at the time of the earthquake,” Son told a packed audience attending a symposium celebrating the fifth anniversary of the institute in Tokyo last Friday.

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A patch of energy harvesting fabric combines solar-cell threads and triboelectric energy generator fibers

Walk Around in the Sun to Power Wearables With This Cloth

A new wearable fabric that generates electricity from both sunlight and motion could let you power your cell phone or smart watch by walking around outside. Researchers made the textile by weaving together plastic fiber solar cells and fiber-based generators that produce electricity when rubbed against each other.

The 0.32-millimeter-thick fabric is lightweight, flexible, breathable, and uses low-cost materials, its creators say. It could be integrated into clothes, tents, and curtains, turning them into power sources when they flap or are exposed to the sun. By harvesting solar and mechanical energy, the power-generating cloth could work day and night, its inventors say.

“The hybrid power textile could be extensively applied not only to self-powered electronics but also possibly to power generation on a larger scale,” Zhong Lin Wang at Georgia Tech, Xing Fan at Chongqing University in Chongqing, China, and their colleagues write in a research published today in the journal Nature Energy.

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Tapiwa M. Chiwewe is a research scientist at IBM Research in Johannesburg, South Africa, where he and colleagues are expanding the company's machine learning technology to predicting air quality.

Tackling Air Quality Prediction in South Africa With Machine Learning

Machine learning is nipping at the heels of conventional physical modeling of air quality predictions in more and more places. The latest is Johannesburg, South Africa, where computer engineer Tapiwa M. Chiwewe at the newly opened IBM Research lab is adapting IBM’s air quality prediction software to local needs and adding new capabilities. The work is an expansion of the so-called Green Horizons initiative, in which IBM researchers partnered with Chinese government researchers and officials, starting two years ago.

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A transient battery hooked to a multimeter by alligator clips shows an output of 2.5 volts.

This Battery Will Self-Destruct in 30 Minutes

Electronics that self-destruct over time could be the key to military applications to help keep secrets out of enemy handsmedical implants that don't need surgical removal, and environmental sensors that melt away when no longer needed. Now scientists at Iowa State University say they have developed the first practical transient battery to power them.

Recently, scientists have developed a wide range of transient electronics that can perform a variety of functions until exposure to light, heat, or liquids triggers their self-destruction. Until now, however, these devices largely relied on external power sources that were not transient themselves.

Early research into transient batteries led to devices with limited power, stability, and shelf life. They were also slow to destroy themselves, says Reza Montazami, a materials scientist at Iowa State University who led the effort to invent a better transient battery. Now Montazami and his colleagues have developed a transient battery that can power a desktop calculator for about 15 minutes and destroy itself in about 30 minutes.

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A schematic of the device

Electrochemical Cell Makes Electricity and Chemicals From CO2

Using aluminum and oxygen, new technology can convert carbon dioxide into useful chemicals and also generate substantial amounts of electrical energy, researchers say.

The large-scale adoption of carbon capture, utilization and sequestration (CCUS) technologies is currently limited in part by how much energy it can take to capture carbon. In addition, methods to make the most of carbon dioxide once it gets stored by converting it into useful chemicals and fuels have proven difficult to develop.

But recently, chemical engineer Lynden Archer and his colleagues at Cornell University investigated whether electrochemical cells could both capture carbon dioxide and generate power. Such electrochemical cells, they hypothesized, would use a metal as the anode and mixed streams of carbon dioxide and oxygen as the active ingredients of the cathode. The electrochemical reactions between the anode and the cathode would sequester the carbon dioxide into carbon-rich compounds while also producing electricity.

Archer and his colleague Wajdi Al Sadat detailed their findings in the 20 July online edition of the journal Science Advances.

Previous research used lithium, sodium, and magnesium as the anodes in such electrochemical cells. These converted carbon dioxide into carbonates, “which are not that useful,” Archer says. “It then occurred to us to use aluminum, which is the third most abundant element in Earth's crust.” Aluminum's abundance makes it cheap, and it is also less chemically reactive than lithium and sodium, which makes it safer to work with, Archer adds.

In the new device, the anode consists of aluminum foil, the cathode consists of a porous, electrically conductive material such as a stainless steel mesh that allows carbon dioxide and oxygen to pass through it, and the electrolyte bridging the anode and cathode is a liquid through which molecules can diffuse.

In experiments, the electrochemical cell could generate as much as 13 ampere-hours for each gram of carbon it captured, without the need for a catalyst or high temperatures. Moreover, it converted carbon dioxide into aluminum oxalate, which, in turn, is easily converted into oxalic acid, a chemical widely used in industry. “It's a versatile product that's a nice starting material for plastics and so forth,” Archer says. In theory, adding extra compounds to the cathode might help convert carbon dioxide to other useful chemicals, Archer adds.

Archer notes that the electrolyte in his group’s electrochemical cell does not work if exposed to water. This is a problem because the carbon dioxide emissions that this device might treat, such as those from factories or power plants, might be loaded with moisture. However, it might be possible to find an electrolyte that is much less sensitive to water, Archer says.

A box on a utility pole is a micro phasor measurement unit (microPMU), which could be a useful too in grid cybersecurity

Detecting Cybersecurity Threats by Taking the Grid's Pulse

Power quality expert Alex McEachern set out to build an advanced power sensor for utility distribution grids, and accidentally produced a promising tool to protect power grids from cyber attack. The equipment–developed by McEachern and collaborators at the University of California Berkeley and Lawrence Berkeley National Laboratory—is part of the starter pack for military installations competing in a $77 million power grid cyber security R&D contest that DARPA is kicking off next month. 

“What we’re trying to do is to take the most sensitive instruments that have ever been made for looking at the grid, and looking at what they might be able to see from inside military bases,” says McEachern, who is president of Alameda, Calif.-based power quality firm Power Standards Lab.

Defending against cyber attacks is a mission with new urgency following the Internet-based disruption of Ukraine’s power grid in December 2015—a sophisticated hack planned and executed over more than six months by what is widely thought to be a well-financed team within Russia. Cybersecurity experts called that attack a wake-up call for North American utilities, which are just beginning to invest in network monitoring and other active defenses for their industrial control systems. 

DARPA says it may take “many years” for U.S. utilities to mount effective defenses against what could be devastating attacks. "Beyond the severe domestic impacts, including economic and human costs, prolonged disruption of the grid would hamper military mobilization and logistics, impairing the government’s ability to project force or pursue solutions to international crises,” wrote the agency in a December 2015 release announcing its Rapid Attack Detection, Isolation, and Characterization Systems (RADICS) program.

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Simulated measurement of methane emissions from French Guyana's “Petit Saut” hydroelectric power plant

Satellite Tracks Carbon Polluters From Space

Attention greenhouse gas emitters: There’s a new eye in the sky that will soon be photographing your carbon footprint and selling the images to any and all. It’s a micro-satellite dubbed “Claire” (clear, bright, and clean in French) by its Montreal-based developer, GHGSat.

This microwave-oven-sized pollution paparazzo rocketed to a 512-kilometer-high orbit in mid-June care of the Indian Space Agency, with a mission to remotely measure the plumes of carbon dioxide and methane wafting up from myriad sources on Earth’s surface. Claire's targets include power plants, natural gas fracking fields, rice paddies, and much more—just about any emissions source that someone with a checkbook (corporations, regulators, activists) wants tracked, according to GHGSat president Stéphane Germain.

Germain says Claire’s data can improve compliance reporting to regulators and carbon markets, enable tracking of industrial efficiency, and provide competitive intelligence, among other uses. "Our vision is to be the global standard for emissions monitoring across the world. That’s ambitious, but we think it's attainable,” he says.

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