Self-healing “artificial leaf” produces energy from dirty water
April 10, 2013
Back in 2011, scientists reported the creation of the “world’s first practical artificial leaf” that mimics the ability of real leaves to produce energy from sunlight and water. Touted as a potentially inexpensive source of electricity for those in developing countries and remote areas, the leaf’s creators have now given it a capability that would be especially beneficial in such environments – the ability to self heal and therefore produce energy from dirty water.
While the leaf mimics a real leaf’s ability to produce energy from sunlight and water, it doesn’t mimic the method real leaves rely on, namely photosynthesis. Instead, as described by Daniel G. Nocera, Ph.D. who led the research team, the artificial leaf is actually a simple wafer of silicon coated in a catalyst that, when dropped into a jar of water and exposed to sunlight, breaks down water into its hydrogen and oxygen components. These gases can be collected as they bubble up through the water to be used for fuel to produce electricity in fuel cells.
Because bacteria can build up on the leaf’s surface and stop the energy production process, previous versions of the device required pure water. Now Nocera’s team has found that some of the catalysts developed for the artificial leaf actually heal themselves, meaning the process can work with dirty water.
“Self-healing enables the artificial leaf to run on the impure, bacteria-contaminated water found in nature,” Nocera said. “We figured out a way to tweak the conditions so that part of the catalyst falls apart, denying bacteria the smooth surface needed to form a biofilm. Then the catalyst can heal and re-assemble.”
Where similar devices are expensive to manufacture due to the use of rare and expensive metals and complex wiring, Nocera’s artificial leaf uses cheaper materials and a simple “buried junction” design that he says would make it cheaper to mass produce. Additionally, less than one liter (0.25 gal) of water is enough to produce around 100 watts of electricity 24 hours a day. And while it isn’t necessarily the most efficient form of electricity generation, Nocera likens the approach to “fast-food energy.”
“We’re interested in making lots of inexpensive units that may not be the most efficient, but that get the job done. It’s kind of like going from huge mainframe computers to a personal laptop. This is personalized energy.
“A lot of people are designing complicated, expensive energy-producing devices, and it is difficult to see them being adopted on a large scale,” he added. “Ours is simple, less expensive, and it works.”
Nocera believes the artificial leaf is likely to find its first use in individual homes in areas that lack traditional electric production and distribution systems. As well as being cheaper than solar panels, because the artificial leaf doesn’t directly generate electricity, but produces hydrogen and oxygen that can be stored, the electricity could be generated for use at night.
The research team hopes to integrate the artificial leaf with technology for converting the hydrogen into a liquid fuel to power everything from traditional portable electric generators to cars.
Nocera described the artificial leaf at the 245th National Meeting & Exposition of the American Chemical Society that is currently being held in New Orleans.
The Pentagon’s army of space-age robot warriors is getting a lot more real with the PETMAN robot
April 8, 2013
The Defense Advanced Research Projects Agency, or DARPA, has released video footage of a project that’s been long in the works and really starting to now take shape. The Protection Ensemble Test Mannequin — or “PETMAN,” for short — is the subject of the latest clip, and very well could be all it takes to scare off any insurgents once it’s ready for the battlefield.
PETMAN is a bipedal robot that has been displayed during previous tests as having the ability to climb stairs and even do pushups. In the latest video, though, the experimental project is showcased as being more lifelike than ever before.
Scientists at Boston Dynamics have released a video that shows PETMAN, clothed head-to-toe in full-on camouflage, jogging in place on a laboratory platform. But unlike earlier videos in which PETMAN appeared to be nothing more than a pile of wires enclosed in metal, the newest footage shows the science project at its all-time most humanness.
PETMAN isn’t being tasked with running like a human being for simply the sake of being creepy, though. Boston Dynamics have outfitted the robot in high-tech protective camo clothing that is designed to keep soldiers — real, cyborg or other — safe from hazardous chemicals. “PETMAN has sensors embedded in its skin that detect any chemicals leaking through the suit. The skin also maintains a micro-climate inside the clothing by sweating and regulating temperature,” explains Boston Dynamics.
The robot, adds the scientists, can balance itself, move freely, walk and do a variety of suit-stressing calisthenics — all while being exposed to chemical warfare agents. “Natural, agile movement is essential for PETMAN to simulate how a soldier stresses protective clothing under realistic conditions,” adds Boston Dynamics. “The robot will have the shape and size of a standard human, making it the first anthropomorphic robot that moves dynamically like a real person.”
And yeah, PETMAN can walk the walk — but he doesn’t stop there either. Scientists have programed the robot to “simulate human physiology,” so that when being exposed to chemical agents, researchers can send signals to the robot that forces it to mimic human sweating and switch its body temperature like a real-life soldier might do while on the field. So with PETMAN being able to do all of that and then some, what does DARPA have planned next? That’s likely top-secret, but critics of the US Defense Department’s science lab say projects like this will lend themselves to changing the face of war from a human one to a robotic one.
“It’s going to be used for chasing people across the desert, I would imagine. I can’t think of many civilian applications - maybe for hunting, or farming, for rounding up sheep,” Noel Sharkey, professor of artificial intelligence and robotics at the University of Sheffield, told the BBC previously in regards to DARPA’s robot creations.
“But of course if it’s used for combat, it would be killing civilians as well as it’s not going to be able to discriminate between civilians and soldiers,” he said.
Turtle En-route for the Holidays!
Our hatchling loggerhead sea turtle is getting the red-carpet treatment from the folks at US Airways.
A day after the turtle was bumped from his flight to Monterey from North Carolina, both turtle and Husbandry Curator Steve Vogel are scheduled for VIP treatment to get them home for the holidays – at 600 miles per hour, in a three-leg flight that will take most of Thursday to complete.
Andrew Christie with the communications staff at US Airways headquarters in Phoenix has arranged all the details, short of guaranteeing a favorable weather forecast. He’s made sure that everyone at US Airways – from staff at ticket counters and gates, to flight attendants and pilots – is aware that a Very Special Sea Turtle has the green light to travel with them today.
“Our reservations folks were kind enough to book [Steve] on all aisle seats to accommodate any need to…check and/or change the hot water bottle for the baby turtle,” Andrew added.
It’s service that’s can make a life-or-death difference, as our veterinarian, Dr. Mike Murray, notes.
“Thank you so very much for accommodating this little guy, the smallest passenger of the season,” he wrote. “I know it is a bit out of the ordinary, but your kindness and understanding are so very much appreciated. Being so small (only about 4 inches in length) the little turtle has a huge thermal disadvantage. He is not only cold blooded and can’t generate body heat, but the heat that we provide is lost quickly because of his high surface-area-to-body-weight ratio. Having Steve right there with him to monitor the temperature is so critical to the little turtle’s well being.”
You can follow their progress from New Bern, N.C. to Monterey on Twitter at #TravelingTurtle. We’ll post updates throughout the day.
It’s the most famous corkscrew in history. Now an electron microscope has captured the famous Watson-Crick double helix in all its glory.
This is an image of six or seven molecules of DNA wrapped around a core, taken with TEM (transmission electron microscopy). The team of scientists that published these images in Nanostructures this month used the hydrophobic nature of DNA molecules to suspend and stretch them between silicon pillars.
May I just say, gosh, helix, your beautiful!
(via kenobi-wan-obi)Source: newscientist.com