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Chemical Battery Can Recharge Itself With Light

Batteries, by definition, convert chemical energy into electricity. Once you’ve sucked them dry, you have to reverse the process to convert electricity into chemical energy, and for that, you need a source of electricity. It’s not like it’s hard to do this, but it is certainly a minor annoyance that could do with a fix.

Researchers at the Indian Institute of Science Education and Research (IISER) in Pune, India, have skipped the annoying step by developing a battery that charges directly from light. We’re not talking about a battery with a solar panel on it: it’s a “photo battery” where the anode itself is made of titanium nitride and ambient light.   

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Doping Lithium-ion Batteries to Make Them Safer

Fires resulting from the catastrophic failure of lithium-ion batteries could be prevented with chemical additives, say researchers at Stanford University.

When lithium-ion batteries overheat, they can burn through internal pockets, burst into flames, and even explode. One reason such damage can occur is the formation of dendrites—finger-like deposits of lithium that can grow long enough to pierce the barrier between a lithium-ion battery's halves and cause it to short out.

Dendrites form when a battery electrode degrades and metal ions deposit onto the electrode's surface. Previously, scientists at Stanford developed a lithium-ion battery that can detect when dendrites start to puncture the barrier between its halves and warn that it needs to be replaced.

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Project Will Make Clothes Cool So You Don't Need the AC

Researchers from the University of California at San Diego are developing a smart fabric capable of helping the wearer maintain a comfortable body temperature. The aim: reducing the need for building-level air conditioning.

According to the U.S. Department of Energy, five percent of all the electricity produced in the United States is used by air conditioners. This isn't just reflected in billions of dollars, but also in hundreds of millions of tons of carbon dioxide released into the air each year. The U.S. isn't alone. In India for example, the total power consumption for air-conditioning is projected to climb by an order of magnitude over the coming decade.

Although developing more power-efficient air conditioners and building greener homes and offices can help cut energy costs and reduce pollution, finding ways to live and work without air conditioners might prove to have an even larger impact in the long run.

The achieve this ambitious goal, the Department of Energy’s Advanced Research Projects Agency (ARPA-E) has been financing several initiatives including one called ATTACH (Adaptive Textiles Technology with Active Cooling and Heating).

The goal of this three-year project, led by UC San Diego nanoengineering professor Joseph Wang, is to create personal, wearable heating and cooling technology for office occupants in order to reduce the energy consumption of a building's HVAC (heating, ventilating and air conditioning) system. Unlike other advanced fabric technologies, which are designed to work outdoors (in either very cold climates or a very warm ones), ATTACH is designed for indoor use at temperatures ranging from 19 °C to 26 °C. Garments using the technology can help reduce and in some cases even eliminate the need for HVAC.

According to ATTACH team member Renkun Chen, "The project's goal is to achieve a comfortable skin temperature of 93 degrees [Fahrenheit]." The technology under development is based on adaptive textiles that will automatically increase or decrease their insulation value (porosity and thickness) when the ambient temperature decreases or increases, respectively. That part of the mechanism would be purely passive, consuming no power. In addition to that, the team plans to add integrated heating and cooling elements, using printed thermoelectric devices and batteries.

According to Wang, his team is looking at different innovative ways of powering the active components. Among these are a flexible biofuel cell (already demonstrated by Wang's team in previous research) that uses sweat as a fuel source, and printable, flexible low-cost batteries.

ATTACH is still in the early stages of development, with different teams working on individual components. If all goes according to plan, these components will be integrated into a single wearable fabric prototype in three years time.​

Evaporation Can Drive Engines and Generate Electricity

Evaporating water can generate electricity, a clean renewable energy source that could help power robots, sensors, and vehicles, researchers say.

Biology regularly uses evaporation as a source of energy. For instance, redwood trees rely on evaporation to pull water from the ground to their crowns. Now scientists at Columbia University and their colleagues have developed two new engines that generate power from evaporation.

The researchers previously found that when bacterial spores expand and shrink with changing humidity, they can push and pull other objects very forcefully, packing more energy gram for gram than many other materials.

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The Forgotten History of How Bird Poop Cripples Power Lines

Bird poop once crippled the most wide-ranging power grid in the world, a new historical study reveals.

In 1913, two 386-kilometer-long electric lines, the longest in the world at the time, began carrying power from the Big Creek hydroelectric dams in the Sierra Nevada mountains southward to customers in Los Angeles. In 1923, the lines were upgraded to carry 220,000 volts, making them among the world's highest voltage lines at the time and pushing the limits of what was thought to be possible with the technology of the day.

However, unexplained short circuits that cropped up in the months after the expensive upgrade threatened to turn this marvel of engineering into a failure. The rate of disruptive flashovers—arcs of electric current that sometimes leapt from the wires to the steel towers and into the earth—jumped dramatically, leading to power interruptions seconds to minutes long every two or three days on average.

Engineers at power company Southern California Edison proposed a variety of causes for this mysterious problem, including lightning storms, moisture on spider webs, and "rivers of ions" in the air, but none could fully solve the puzzle. After a few desperate months of investigation, researchers finally discovered the culprit—vast amounts of bird excrement, historian of science Etienne Benson at the University of Pennsylvania explains in a new study in the journal Environmental Humanities.

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Senegalese-American Chart-topper Akon Looks to Light Up Africa

Senegalese-American musician and record producer Akon is well known for lighting up the stage and the music charts. But now he’s set his sights on a more important mission than delighting music fans: supplying electricity to 600 million Africans who currently lack access to the grid. He has started an initiative called Akon Lighting Africa. Its first project is the launch of a Solar Academy in Bamako, Mali. The faculty at the academy, which is scheduled to open this summer, will help African engineers and entrepreneurs develop skills that will enable them to produce solar-powered microgrids and make it easier to acquire the necessary equipment.

Africa has the lowest percentage of inhabitants with access to national grids, but has the benefit of 320 days of sun each year on average. Harnessing that solar energy will not only allow Africans to use electronic gadgets, but also create a new category of tech jobs that could boost the standard of living across the continent. “We expect the Africans who graduate from this center to devise new, innovative, technical solutions,” Thione Niang, one of Akon Lighting Africa’s cofounders, told Reuters. “With this academy, we can capitalize on Akon Lighting Africa and go further.”

The group announced the launch of the academy late last month at the second United Nations Sustainable Energy for All Forum, in New York City.

Law Loosens an Efficiency Standard But Boosts Grid Stability

The Energy Improvement Act of 2015, which went into effect last month, brought a change that might seem incongruous with the name of the legislation. You see, it loosened  the U.S. Department of Energy’s newest energy-efficiency standards for electric waters heaters, which came into force just this past April.

The DOE standards had called for large electric waters heaters—ones with a capacity in excess of 210 liters—to meet very stringent efficiency ratings, ones that would in practice require them to use heat pumps rather than simple electrical-resistance heating elements. The new law relaxes that requirement and allows some very large (in excess of 285 L) water heaters to be sold even though they warm water the old-fashioned way, with simple resistance heating elements.

So what gives? Was Congress unduly influenced by a bunch of K Street lobbyists working for entrenched interests in the water-heater industry?

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StoreDot Wants to Charge Your EV in 5 Minutes

Israeli startup StoreDot announced last month at Microsoft's ThinkNext conference in Tel-Aviv that it had started working on a technology that will enable future electric vehicles to fully charge in only 5 minutes. The hours it typically takes now to tank up an EV’s battery is considered a major inconvenience and contributes to drivers’ dreaded "range anxiety" fears. Knowing they can get a five-minute fill-up, StoreDot is betting, might make a big difference to drivers.

Last year, StoreDot demonstrated a smartphone battery that charges in just 30 seconds, but in order to scale that up to work for an EV, it had to develop what it calls a multifunction electrode (MFE). The MFE is a combination of a conductive polymer and metal oxide. The polymer part allows the battery to receive the charge extremely quickly, while the metal oxide part is used to trickle the Lithium ions into the electrode. Trickle charging is important because it prevents the electrode from cracking and shorting out the battery, a real danger when trying to fast charge an ordinary Li-ion battery.

When it comes to battery life, one of the biggest problems plaguing today’s fast charging lithium battery technology is heat, which destroys the electrodes over time. Indeed, existing quick chargers reduce the life of a battery by half—from around 500-600 charges of a fresh lithium ion battery to approximately 250-300 charge cycles. StoreDot developed new organic materials with very low resistance that produce almost no heat. This technology is capable of more than three times as many charge cycles as a normal lithium ion battery (around 1500-2000 charges, according to the company), while at the same time achieving a charging rate about one order of magnitude faster than the best existing battery technology.

To accomplish this, StoreDot doesn't simply take an existing Lithium ion battery and change an electrode. Taking on charge super quickly calls for the replacement of every one of the battery’s components—including the anode, cathode, electrolyte, and separator—with new components optimized for super-fast charging.

This reengineering isn't a small task, so the company raised over US $42 million in 2014 to create a pilot production line that will demonstrate how to manufacture batteries using its technology. StoreDot is estimating that about 80 percent of its manufacturing process will be very similar to the way lithium batteries are being manufactured today.

Of course, the battery is just one part of what’s needed to make super-fast charging a reality.

To understand why, you first have to look at how StoreDot's charging technology will work and what its limitations are. To fully charge the battery of an electric vehicle in 5 minutes, you need a powerful electrical infrastructure. How powerful? According to Doron Myersdorf, StoreDot's CEO and co-founder, you will need to plug into a charging apparatus delivering at least 200 kilowatts of power for every 100 km you intend to drive between charges. So super-fast charging at home is out, unless you are living in a modern high-rise building with this level of power. And even if you do live in such a building, that level of current draw will prevent more than a single car from being charged at any given time.

A five-minute charge will also require a more direct connection to the battery than is found in today’s EVs.

StoreDot's goal for its car battery technology is to be able to provide the driver with a similar refueling experience to what he or she currently has: a 5 minute stop at a local refueling station for a full tank that can last for a few hundred kilometers. But that will mean connecting existing and future refueling stations to more than 200 kW power.

Tesla had a similar problem when it began building out its Supercharger network of 120 kW fast charging stations in the United States. A Supercharger can deliver enough energy to provide about 320 km (200 miles) of driving for a Tesla model S in 30 minutes. StoreDot's technology could charge a car much more rapidly, but doing so would require that the station be relatively close to a high-power transformer. So StoreDot believes that widespread deployment of this technology will come only with some sort of government support directing where new grid components are installed.

According to Myersdorf, the cost of a StoreDot car battery will be about 20 to 30 percent higher than today’s lithium-ion units, mostly due to the use of costly organic materials. However, when taking into consideration the fact that the technology allows for around three times as many charge-discharge cycles, the long term cost of ownership should actually be 50 percent lower. So the savings could be in the thousands of dollars.

StoreDot expects that we will see the first product based on its technology around the second half of 2016—but for the mobile market. The company says it should have a preliminary prototype of the vehicle battery in 2016 and a commercial prototype in 2017.

StoreDot has set for itself two extremely ambitious goals for a company that is less than three years old: to change the way we use our mobile electronic devices and the way we power our cars. Although the company still has to prove that it can deliver on its promises—especially in the complex ecosystem that is the vehicle market—success could mean a dramatic change in the way most of us operate on a daily basis.

Mud-Fueled Smart Sensors for the Bottom of the Ocean

If you put tiny electrodes in the mud on the ocean floor, you can harvest enough energy to power a tiny sensor platform that can monitor what’s going on at those depths.

So say researchers from the University of Michigan at Ann Arbor, in a recent issue of IEEE Transactions on Circuits and Systems I. Together with collaborators from Korea and California, they have designed a self-sustaining sensor platform for oceanic sensing applications that is powered entirely by small-scale benthic microbial fuel cells.

“We wanted a platform that could run off very small harvesting sources,” Michigan electrical engineering professor and IEEE Fellow David Blaauw tells IEEE Spectrum. “If you can get power consumption down enough, there are all sorts of things you can use. Even plants produce little bits of voltage,” he says.

When benthic bacteria are in an anaerobic environment, their metabolism produces electric current. “It’s been well studied,” says Blaauw, “but in the past, people have struggled to get enough current to run something.”

 According to Blaauw, laboratory experiments confirmed that if a microbial fuel cell sits in the sediment, with the cathode floating in a water column where it is exposed to oxygen, it can deliver enough energy to run the platform perpetually.

Though using electrodes with larger surface areas generates more power, the researchers say that it is more challenging to maintain the anaerobic environment with larger electrodes. “If the anode pops out, the whole thing stops working,” Blaauw says, adding that large-size microbial fuel cells also require human divers and sophisticated deployment equipment in order to be properly installed in the ocean floor.

But his team’s setup has very little in the way of complications. “We have much lower power requirements. Just shoot a small dart into the mud, wait a couple of days for the oxygen deprived environment to establish itself, and then you get current.”

Blaauw explains that the sensor platform features a microprocessor, a radio, and few kilobytes of memory. Its power management unit helps keep the draw from its battery to a minuscule 2 nanowatts.

“When the system is in standby mode, it retains data, but consumes little power,” he says. “Very low power timers allow it to wake up occasionally, take readings, then check, store, or transfer data. Low power consumption enables us to work with obscure, small harvesting sources. We can now deploy sensors in the oceanic floor easily and cheaply, and we don’t have to provide batteries that will run forever.”

Blaauw told Spectrum that the prototype system was designed to track changes in temperature, but that it’s easy to imagine it measuring other things such as changes in coral reefs suffering from decay due to pollution.

He explains that this platform is part of a broader portfolio of work focused on powering electronic systems with low energy sources. “These platforms could be used inside the human body, by oil companies investigating fissures in the ground, or by security systems where you need something unobtrusive that fits into the surrounding décor,” he says. “We’ve had interest from a university that wants to study snails, and another that is studying bees. Make a platform really small, and it opens up all sorts of new avenues.”

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