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Posts Tagged ‘battery tech’

The problem here, of course, is that buried nuclear waste has to be completely sealed, meaning there can’t be any ductwork allowing wires to run from the surface to the inside of the containment facility. If there were water might get in or radioactivity might get out, negating the whole point of burying the waste in the first place.

But how to power sensors underground 100 years after they are buried? Conventional chemical batteries would long since have lost their charges. This answer entails a handful of magnets and a copper coil--the basis of a simple generator--and a 100-year timer.

The gist: two powerful neodymium magnets are set opposite each other about 15 centimeters apart, connected by a carbon fiber rod. A third doughnut-shaped magnet is wrapped around the rod, free to move along it in either direction. The end magnets would be polarized such that both repel this third magnet. The whole array is surrounded by a copper coil.

To set the battery, one would simply trap the doughnut-shaped magnet against one of the larger end magnets with a latch set to a 100-year timer; a century on, the timer releases the doughnut-shaped magnet, which is thrust along the rod to the other end where it is repelled by that magnet and pushed back toward the first magnet, and so on. Eventually the magnet comes to rest in the middle of the carbon fiber rod between the two repelling forces, but by then it has made several passes along the length of the copper coil, creating enough juice to charge the various sensors and transmitters necessary to get temperature and radioactivity data to the surface.

Of course, that raises the obvious problem of creating a 100-year timer to release the magnet. Researchers think such a latch could be triggered externally, perhaps by a radio signal. Because a 100-year mechanical clock would take a really, really long time to wind.

[New Scientist]

The batteries were fabricated by materials scientists at Stanford by depositing a thin film of carbon nanotubes followed by another thin film of metal-containing lithium compound on top of the nanotube layer. These thin bilayer films are layered onto both sides of a piece of ordinary paper, which serves as both the structural support of the battery as well as the electrode separator. The lithium serves as electrodes, while the nanotube layers are current collectors.

The result is a working battery just 300 micrometers thick – that’s 300 millionths of a meter – that is flexible, super-thin, and more energy dense than other thin-bodied batteries. It’s also durable; over a 300-cycle recharge test, performance remained satisfactory. It’s also fairly easy to fabricate, making it far more commercially viable than other methods of downsizing battery technology.

Such batteries aren’t ideal for every application, but they could be extremely useful in future incarnations of smart packaging, RFID sensing, and electronic paper products.

[Chemical & Engineering News]

The technology is actually as old as the beginnings of life itself, but the research represents the first working fuel cell that produces power in such a way. The new biofuel cell borrows from the mitochondria that power our bodies' own cells. Mitochondria, you'll remember from high school biology, are the powerhouses of the cell, converting sugars or fats into adenosine triphosphate -- or ATP -- which stores the energy until the cell needs to burn it.

The new fuel cell is still in prototype, but the researchers have demonstrated it in the lab. It essentially consists of a thin layer of mitochondria pressed between two electrodes, one of which is gas-permeable. In tests, cooking oil byproducts and sugar both produced electricity.

Naturally, such a power source would be useful in myriad applications. Less likely than fueling up laptops with energy drinks are uses like powering small wireless sensors. Besides, Red Bull is more expensive by the gallon than gasoline.

MetalCell was designed with militaries in mind; on the modern battlefield, soldiers rely on a growing array of electronics to execute their missions, but when operating in remote areas or cut off from support, those devices can run out of juice at inopportune moments. But MetalCell can sit in the back of a Humvee, in a remote bunker, or in a locker at a forward operating base for years, waiting to power up electrical devices in a pinch.

The rugged little boxes are similar to the so-called Baghdad batteries dating to the early centuries A.D. that some researchers believe were the first voltage-creating devices. Fitted with magnesium plates inside, the MetalCell can be charged up with nothing more than the addition of saltwater. The sodium in the salt reacts with the magnesium to create a dose of low-voltage power that can power up laptop, a flashlight, night vision specs, etc. when no other source is available. The output can keep a laptop humming for more than four hours and can be recharged with fresh saltwater until the magnesium begins to deteriorate.

Soldiers can pool salt from their Meals, Ready-to-Eat (MREs) to create the a proper sodium solution, but failing that, soldiers could also charge up the MetalCell with their urine (and given the blandness of MREs, they might opt to). That's an energy-rich resource a grunt can always lay his hands on.

[National Defense]

The battery consists of two large silos filled with crushed rock. Electricity generated by the turbine heats and pressurizes argon gas and feeds it into the first silo. The gravel is heated to more than 900 degrees as the hot, pressurized argon passes through, though by the time the argon leaves the chamber it has cooled to ambient temperature.

The argon is then fed into the second silo where it returns to normal atmospheric pressure, initiating a cooling effect that chills the gas and rock to -256 degrees. Thus, the electricity is stored as a temperature difference between the two chambers. If the wind ceases to blow, the process is reversed, feeding the cold gas back into silo number one, powering a generator as it makes the transition back to hot from cold.

The process isn't a perfect closed energy loop, but Isentropic claims a complete trip through the cycle retains up to 80 percent of the original electricity. Even better, gravel is cheap; the cost per kilowatt-hour falls somewhere between $10 and $55, depending on the costs of other materials. Isentropic also claims the batteries are highly durable; according to the company's founder, a 164-foot tall silo with an equal diameter would retain half its energy even if left untouched for three years.

All that sounds pretty good, but Isentropic has yet to fully prove out the idea. The vast temperature differences generated by the argon sound quite drastic, and the director of the UK Energy Research Centre points out, gravel isn't the ideal material to have inside of machine with moving parts. As such, Isentropic is designing a pilot plant that could store 16 megawatt-hours in two silos just 23 feet tall by 23 feet in diameter. That's enough to cover a pretty big neighborhood during a long, windless stretch. The company is also in talks with an unnamed utility to build a larger demonstration facility.

[Guardian, Isentropic]