CAMBRIDGE, Massachusetts — Engineers at the Massachusetts Institute of Technology say they have made a major breakthrough in lithium-ion battery technology, one that may enable an electric vehicle to be recharged in as little time as it takes to fill the tank at the gas pump.

 

"MIT engineers have created a kind of beltway that allows for the rapid transit of electrical energy through a well-known battery material, an advance that could usher in smaller, lighter batteries — for cell phones and other devices — that could recharge in seconds rather than hours," said MIT in a statement on Wednesday on its Web site.

Currently, electric vehicles, such as the upcoming Chevrolet Volt, are expected to take an overnight period to recharge.

MIT said the researchers believe the technology could "make it into the marketplace within two to three years" because the battery material used isn't new — the only change is in the way it's made. The only limitation thus far to the new technique is the amount of power available to a homeowner through the electric grid, according to researchers.

The breakthrough is reported in the March 12 issue of Nature.

"The ability to charge and discharge batteries in a matter of seconds rather than hours may open up new technological applications and induce lifestyle changes," say the researchers in their Nature paper.

University of Miami physicist develops battery using new source of energy

His discovery is a 'proof of principle' of the existence of a 'spin battery'

CORAL GABLES, FL. (March 11, 2009)—Researchers at the University of Miami and at the Universities of Tokyo and Tohoku, Japan, have been able to prove the existence of a "spin battery," a battery that is "charged" by applying a large magnetic field to nano-magnets in a device called a magnetic tunnel junction (MTJ). The new technology is a step towards the creation of computer hard drives with no moving parts, which would be much faster, less expensive and use less energy than current ones. In the future, the new battery could be developed to power cars. The study will be published in an upcoming issue of Nature and is available in an online advance publication of the journal.

The device created by University of Miami Physicist Stewart E. Barnes, of the College of Arts and Sciences and his collaborators can store energy in magnets rather than through chemical reactions. Like a winding up toy car, the spin battery is "wound up" by applying a large magnetic field --no chemistry involved. The device is potentially better than anything found so far, said Barnes.

"We had anticipated the effect, but the device produced a voltage over a hundred times too big and for tens of minutes, rather than for milliseconds as we had expected," Barnes said. "That this was counterintuitive is what lead to our theoretical understanding of what was really going on."

The secret behind this technology is the use of nano-magnets to induce an electromotive force. It uses the same principles as those in a conventional battery, except in a more direct fashion. The energy stored in a battery, be it in an iPod or an electric car, is in the form of chemical energy. When something is turned "on" there is a chemical reaction which occurs and produces an electric current. The new technology converts the magnetic energy directly into electrical energy, without a chemical reaction. The electrical current made in this process is called a spin polarized current and finds use in a new technology called "spintronics."

The new discovery advances our understanding of the way magnets work and its immediate application is to use the MTJs as electronic elements which work in different ways to conventional transistors. Although the actual device has a diameter about that of a human hair and cannot even light up an LED (light-emitting diode--a light source used as electronic component), the energy that might be stored in this way could potentially run a car for miles. The possibilities are endless, Barnes said.

"There are magnets hidden away in many things, for example there are several in a mobile telephone, many in a car, and they are what keeps your refrigerator closed," he said. "There are so many that even a small change in the way we understand of how they work, and which might lead to only a very small improvement in future machines, has a significant financial and energetic impact."

Hydrogen: Could A High-Tech Sponge Boost Hydrogen Use?

There are many arguments for and against the use of hydrogen as a fuel for vehicles. One of the biggest obstacles that has prevented the gas from becoming commonplace is storage. As a gas, hydrogen is very energy dense but requires heavy, thick-walled tanks to contain it. Liquified, its energy density plummets to a quarter of that of petrol. Scientists think the solution lies in nano-engineered sponges.

The US Department of Energy set scientists a challenge five years ago, to develop a material that could hold 6% of its own weight in hydrogen. Researchers at the University of Crete have beaten that target, coming up with a theoretical material that can hold 6.1% of its weight in the gas.

In theory, the material would consist of atom-thick carbon sheets called graphene (see photo above). These sheets would be separated by carbon nanotube pillars just 1.2-nanometers tall. The sponge would be coated, or "doped", with positively charged lithium ions which would enhance its hold on the gas.
The sponge would be capable of storing hydrogen at normal temperature and pressure, without the need for a heavy-duty storage tank. This is a crucial factor if we hope to use hydrogen in smaller applications such as home heating, or even to power our gadgets.

High-temperature solar collectors to date, anyway have suffered from a built in Achilles' heel: Materials capable of absorbing great amounts of sunlight readily are usually just as capable of losing that absorbed energy through the emission of infrared radiation. The very qualities which make a collector surface a good absorber, in other words, also make it a good radiator.

Conversely, materials which do not lose energy readily through emission usually do not absorb it readily either. Tungsten, for instance, has long been regarded as both a poor absorber and a poor emitter of radiation.

Thus, IBM research scientists were understandably surprised a few months ago when they noted that a laboratory-grown tungsten film seemed to act as an unusually good absorber of light. They were even more interested to find that the same tungsten surface appeared to be a very bad emitter of infrared radiation.

Closer examination of the "vapor-deposited" tungsten revealed that the extraordinary film was covered with hundreds of thousands of tiny vertical spear like structures known as dendrites. The little spikes range from 1/2,500th to 1/5,000th

of an inch in diameter and separation between individual dendrites may be as small as 1/50,000th of an inch (which is comparable to the wavelengths of visible light). "Large" dendrites may be as tall as 1/500th of an inch and separated from one another, on the average, by approximately the same distance. Interspersed among these "big ones" is a dense "undergrowth" of smaller dendrites that range downward to as little as 1/2,500th inch in height.

Apparently (as the semi-schematic drawing above shows) rays of light oriented within about 15 degrees of the dendrites' vertical axes can enter this maze quite easily. The rays, however, then have their angles changed by repeated reflection and-once those angles are changed-only about 4% of the trapped light energy is able to escape. Result: The new solar-absorber is able to maintain an operating temperature in the range of 500° C (932° F). Which as any knowledgeable experimenter with high temperature solar collectors can tell you is BIG NEWS.

It's almost a sure bet, then, that we're all going to be hearing more about vapor-deposited tungsten and dendrites in the future.

Note: You can read debates on the article and make comments here, and read Shawyer’s theory paper here (pdf format).

The trip from London to Havant on the south coast of England is like travelling through time. I sit in an air-conditioned train, on tracks first laid 150 years ago, passing roads that were known to the Romans. At one point, I pick out a canal boat, queues of cars and the trail from a high-flying jet - the evolution of mechanised travel in a single glance.

But evolution has a habit of springing surprises. Waiting at my destination is a man who would put an end to mechanised travel. Roger Shawyer has developed an engine with no moving parts that he believes can replace rockets and make trains, planes and automobiles obsolete. "The end of wings and wheels" is how he puts it. It's a bold claim. (Too bold? See the later feedback here and here)

Of course, any crackpot can rough out plans for a warp drive. What they never show you is evidence that it works. Shawyer is different. He has built a working prototype to test his ideas, and as a respected spacecraft engineer he has persuaded the British government to fund his work. Now organisations from other parts of the world, including the US air force and the Chinese government, are beating a path to his tiny company.

The device that has sparked their interest is an engine that generates thrust purely from electromagnetic radiation - microwaves to be precise - by exploiting the strange properties of relativity. It has no moving parts, and releases no exhaust or noxious emissions. Potentially, it could pack the punch of a rocket in a box the size of a suitcase. It could one day replace the engines on almost any spacecraft. More advanced versions might allow cars to lift from the ground and hover. It could even lead to aircraft that will not need wings at all. I can't help thinking that it sounds too good to be true.

When I meet Shawyer, he turns out to be reassuringly normal. His credentials are certainly impressive. He worked his way up through the aerospace industry, designing and building navigation and communications equipment for military and commercial satellites, before becoming a senior aerospace engineer at Matra Marconi Space (later part of EADS Astrium) in Portsmouth, near where he now lives. He was also a consultant to the Galileo project, Europe's satellite navigation system, which engineers are now testing in orbit and for which he negotiated the use of the radio frequencies it needed.

Dangerous idea

With that pedigree, you'd imagine Shawyer would be someone the space industry would have listened to. Far from it. While at Astrium, Shawyer proposed that the company develop his idea. "I was told in no uncertain terms to drop it," he says. "This came from the very top."

What Shawyer had in mind was a replacement for the small thrusters conventional satellites use to stay in orbit. The fuel they need makes up about half their launch weight, and also limits a satellite's life: once it runs out, the vehicle drifts out of position and must be replaced. Shawyer's engine, by contrast, would be propelled by microwaves generated from solar energy. The photovoltaic cells would eliminate the fuel, and with the launch weight halved, satellite manufacturers could send up two craft for the price of one, so you would only need half as many launches.

So why the problem? Shawyer argues that for companies investing billions in rockets and launch sites, a new technology that leads to fewer launches and longer-lasting satellites has little commercial appeal. By the same token, a company that offers more for less usually wins in the end, so Shawyer's idea may have been seen as too speculative. Whatever the reason, in 2000, he resigned to go it alone.

Surprisingly, Shawyer's disruptive technology rests on an idea that goes back more than a century. In 1871 the physicist James Clerk Maxwell worked out that light should exert a force on any surface it hits, like the wind on a sail. This so-called radiation pressure is extremely weak, though. Last year, a group called The Planetary Society attempted to launch a solar sail called Cosmos 1 into orbit. The sail had a surface area of about 600 square metres. Despite this large area, about the size of two tennis courts, its developers calculated that sunlight striking it would produce a force of 3 millinewtons, barely enough to lift a feather on the surface of the Earth. Still, it would be enough to accelerate a craft in the weightlessness of space, though unfortunately the sail was lost after launch. NASA is also interested in solar sails, but has never launched one. Perhaps that shouldn't be a surprise, as a few millinewtons isn't enough for serious work in space.

But what if you could amplify the effect? That's exactly the idea that Shawyer stumbled on in the 1970s while working for a British military technology company called Sperry Gyroscope. Shawyer's expertise is in microwaves, and when he was asked to come up with a gyroscopic device for a guidance system he instead came up with the idea for an electromagnetic engine. He even unearthed a 1950s paper by Alex Cullen, an electrical engineer at University College London, describing how electromagnetic energy might create a force. "It came to nothing at the time, but the idea stuck in my head," he says.

In his workshop, Shawyer explains how this led him to a way of producing thrust. For years he has explored ways to confine microwaves inside waveguides, hollow tubes that trap radiation and direct it along their length. Take a standard copper waveguide and close off both ends. Now create microwaves using a magnetron, a device found in every microwave oven. If you inject these microwaves into the cavity, the microwaves will bounce from one end of the cavity to the other. According to the principles outlined by Maxwell, this will produce a tiny force on the end walls. Now carefully match the size of the cavity to the wavelength of the microwaves and you create a chamber in which the microwaves resonate, allowing it to store large amounts of energy.

What's crucial here is the Q-value of the cavity - a measure of how well a vibrating system prevents its energy dissipating into heat, or how slowly the oscillations are damped down. For example, a pendulum swinging in air would have a high Q, while a pendulum immersed in oil would have a low one. If microwaves leak out of the cavity, the Q will be low. A cavity with a high Q-value can store large amounts of microwave energy with few losses, and this means the radiation will exert relatively large forces on the ends of the cavity. You might think the forces on the end walls will cancel each other out, but Shawyer worked out that with a suitably shaped resonant cavity, wider at one end than the other, the radiation pressure exerted by the microwaves at the wide end would be higher than at the narrow one.

Key is the fact that the diameter of a tubular cavity alters the path - and hence the effective velocity - of the microwaves travelling through it. Microwaves moving along a relatively wide tube follow a more or less uninterrupted path from end to end, while microwaves in a narrow tube move along it by reflecting off the walls. The narrower the tube gets, the more the microwaves get reflected and the slower their effective velocity along the tube becomes. Shawyer calculates the microwaves striking the end wall at the narrow end of his cavity will transfer less momentum to the cavity than those striking the wider end (see Diagram). The result is a net force that pushes the cavity in one direction. And that's it, Shawyer says.

Hang on a minute, though. If the cavity is to move, it must be pushed by something. A rocket engine, for example, is propelled by hot exhaust gases pushing on the rear of the rocket. How can photons confined inside a cavity make the cavity move? This is where relativity and the strange nature of light come in. Since the microwave photons in the waveguide are travelling close to the speed of light, any attempt to resolve the forces they generate must take account of Einstein's special theory of relativity. This says that the microwaves move in their own frame of reference. In other words they move independently of the cavity - as if they are outside it. As a result, the microwaves themselves exert a push on the cavity.

"How can photons confined inside a cavity make the cavity move? This is where relativity and the strange nature of light come in"

Each photon that a magnetron fires into the cavity creates an equal and opposite reaction - like the recoil force on a gun as it fires a bullet. With Shawyer's design, however, this force is minuscule compared with the forces generated in the resonant cavity, because the photons reflect back and forth up to 50,000 times. With each reflection, a reaction occurs between the cavity and the photon, each operating in its own frame of reference. This generates a tiny force, which for a powerful microwave beam confined in the cavity adds up to produce a perceptible thrust on the cavity itself.

Shawyer's calculations have not convinced everyone. Depending on who you talk to Shawyer is either a genius or a purveyor of snake oil. David Jefferies, a microwave engineer at the University of Surrey in the UK, is adamant that there is an error in Shawyer's thinking. "It's a load of bloody rubbish," he says. At the other end of the scale is Stepan Lucyszyn, a microwave engineer at Imperial College London. "I think it's outstanding science," he says. Marc Millis, the engineer behind NASA's programme to assess revolutionary propulsion technology accepts that the net forces inside the cavity will be unequal, but as for the thrust it generates, he wants to see the hard evidence before making a judgement.

Thrust from a box

Shawyer's electromagnetic drive - emdrive for short - consists in essence of a microwave generator attached to what looks like a large copper cake tin. It needs a power supply for the magnetron, but there are no moving parts and no fuel - just a cord to plug it into the mains. Various pipes add complexity, but they are just there to keep the chamber cool. And the device seems to work: by mounting it on a sensitive balance, he has shown that it generates about 16 millinewtons of thrust, using 1 kilowatt of electrical power. Shawyer calculated that his first prototype had a Q of 5900. With his second thruster, he managed to raise the Q to 50,000 allowing it to generate a force of about 300 millinewtons - 100 times what Cosmos 1 could achieve. It's not enough for Earth-based use, but it's revolutionary for spacecraft.

One of the conditions of Shawyer's £250,000 funding from the UK's Department of Trade and Industry is that his research be independently reviewed, and he has been meticulous in cataloguing his work and in measuring the forces involved. "It's not easy because the forces are tiny compared to the weight of the equipment," he says.

Optimising the cavity is crucial, and it's as much art as science. Energy leaks out in all kinds of ways: microwaves heat the cavity, for example, changing its electrical characteristics so that it no longer resonates. At very high powers, microwaves can rip electrons out of the metal, causing sparks and a dramatic loss of power. "It can be a very fine balancing act," says Shawyer.

To review the project, the UK government hired John Spiller, an independent space engineer. He was impressed. He says the thruster's design is practical and could be adapted fairly easily to operate in space. He points out, though, that the drive needs to be developed further and tested by an independent group with its own equipment. "It certainly needs to be flown experimentally," he says.

Armed with his prototypes, the test measurements and Spiller's review, Shawyer is now presenting his design to the space industry. The reaction in China and the US has been markedly more enthusiastic than that in Europe. "The European Space Agency knows about it but has not shown any interest," he says. The US air force has already paid him a visit, and a Chinese company has attempted to buy the intellectual property associated with the thruster. This month, he will be travelling to both countries to visit interested parties, including NASA.

"A Chinese company has tried to buy rights to the microwave thruster"

To space and beyond

His plan is to license the technology to a major player in the space industry who can adapt the design and send up a test satellite to prove that it works. If all goes to plan, Shawyer believes he could see the engine tested in space within two years. He estimates that his thruster could save the space industry $15 billion over the next 10 years. Spiller is more cautious. While the engine could certainly reduce the launch weight of a satellite, he doubts it will significantly increase its lifetime since other parts will still wear out. The space industry might not need to worry after all.

Meanwhile Shawyer is looking ahead to the next stage of his project. He wants to make the thrusters so powerful that they could make combustion engines obsolete, and that means addressing the big problem with conventional microwave cavities - the amount of energy they leak. The biggest losses come from currents induced in the metal walls by the microwaves, which generate heat when they encounter electrical resistance. This uses up energy stored in the cavity, reduces the Q, and the thrust generated by the engine drops.

Fortunately particle accelerators use microwave cavities too, so physicists have done a lot of work on reducing Q losses inside them. The key, says Shawyer, is to make the cavity superconducting. Without electrical resistance, currents in the cavity walls will not generate heat. Engineers in Germany working on the next generation of particle accelerators have achieved a Q of several billion using superconducting cavities. If Shawyer can match that performance, he calculates that the thrust from a microwave engine could be as high as 30,000 newtons per kilowatt - enough to lift a large car.

This raises another question. Why haven't physicists stumbled across the effect before? They have, says Shawyer, and they design their cavities to counter it. The forces inside the latest accelerator cavities are so large that they stretch the chambers like plasticine. To counteract this, engineers use piezoelectric actuators to squeeze the cavities back into shape. "I doubt they've ever thought of turning the force to other uses," he says.

No doubt his superconducting cavities will be hard to build, and Shawyer is realistic about the problems he is likely to meet. Particle accelerators made out of niobium become superconducting at the temperature of liquid helium - only a few degrees above absolute zero. That would be impractical for a motor, Shawyer believes, so he wants to find a material that superconducts at a slightly higher temperature, and use liquid hydrogen, which boils at 20 kelvin, as the coolant. Hydrogen could also power a fuel cell or turbine to generate electricity for the emdrive.

In the meantime, he wants to test the device with liquid nitrogen, which is easier to handle. It boils at 77 kelvin, a temperature that will require the latest generation of high-temperature ceramic superconductors. Shawyer hasn't yet settled on the exact material, but he admits that any ceramic will be tricky to incorporate into the design because of its fragility. It will have to be reliably bonded to the inside of a cavity and mustn't crack or flake when cooled. There are other problems too. The inside of the cavity will still be heated by the microwaves, and this will possibly quench the superconducting effect. "Nobody has done this kind of work," Shawyer says. "I'm not expecting it to be easy."

Then there is the issue of acceleration. Shawyer has calculated that as soon as the thruster starts to move, it will use up energy stored in the cavity, draining energy faster than it can be replaced. So while the thrust of a motionless emdrive is high, the faster the engine moves, the more the thrust falls. Shawyer now reckons the emdrive will be better suited to powering vehicles that hover rather than accelerate rapidly. A fan or turbine attached to the back of the vehicle could then be used to move it forward without friction. He hopes to demonstrate his first superconducting thruster within two years.

What of the impact of such a device? On my journey home I have plenty of time to speculate. No need for wheels, no friction. Shawyer suggested to me before I left that a hover car with an emdrive thruster cooled and powered by hydrogen could be a major factor in converting our society from a petrol-based one to one based on hydrogen. "You need something different to persuade people to make the switch. Perhaps being able to move in three dimensions rather than two would do the trick."

What about aircraft without wings? I'm aware that my feeling of scepticism is being replaced by a more dangerous one of unbounded optimism. In five minutes of blue-sky thinking you can dream up a dozen ways in which the emdrive could change the world. I have an hour ahead of me. The end of wings and wheels. Now there's a thought.

Chinese researchers claim they've confirmed the theory behind an "impossible" space drive, and are proceeding to build a demonstration version. If they're right, this might transform the economics of satellites, open up new possibilities for space exploration –- and give the Chinese a decisive military advantage in space.

To say that the "Emdrive" (short for "electromagnetic drive") concept is controversial would be an understatement. According to Roger Shawyer, the British scientist who developed the concept, the drive converts electrical energy into thrust via microwaves, without violating any laws of physics. Many researchers believe otherwise. An article about the Emdrive in New Scientist magazine drew a massive volley of criticism. Scientists not only argued that Shawyer's work was blatantly impossible, and that his reasoning was flawed. They also said the article should never have been published.

"It is well known that Roger Shawyer's 'electromagnetic relativity drive' violates the law of conservation of momentum, making it simply the latest in a long line of 'perpetuum mobiles' that have been proposed and disproved for centuries," wrote John Costella, an Australian physicist. "His analysis is rubbish and his 'drive' impossible."

Shawyer stands by his theoretical work. His company, Satellite Propulsion Research (SPR), has constructed demonstration engines, which he says produce thrust using a tapering resonant cavity filled with microwaves. He is adamant that this is not a perpetual motion machine, and does not violate the law of conservation of momentum because different reference frames apply to the drive and the waves within it. Shawyer's big challenge, he says, has been getting people who will actually look into his claims rather than simply dismissing them.

 

Such extravagant claims are usually associated with self-taught, backyard inventors claiming Einstein got it all wrong. But Shawyer is a scientist who has worked with radar and communication systems and was a program manager at European space company EADS Astrium; his work rests entirely on Einstein being right. The thrust is the result of a relativistic effect and would not occur under simple Newtonian physics. Many have dismissed his work out of hand, and British government funding has ceased. He has had some interest from both the United States and China. Now the Chinese connection with the Northwestern Polytechnical University (NPU) in Xi'an seems to have paid off.

"NPU started their research program in June 2007, under the supervision of Professor Yang Juan. They have independently developed a mathematical simulation which shows unequivocally that a net force can be produced from a simple resonant tapered cavity," Shawyer tells Danger Room. "The thrust levels predicted by this simulation are similar to those resulting from the SPR design software, and the SPR test results."

What's more, Shawyer says, NPU is "currently manufacturing" a "thruster" based on this theoretical work.

"I could confirm that our mathematical simulation gives the results Dr. Roger Shawyer told you. Now we are submitting our result to a journal. It is now under the consideration of the editor," Professor Yang adds. "We also developed a tapered cavity and are preparing an experiment which will be completed at the end of this year."

Needless to say, independent confirmation is a big deal -- though many will want to see it published in a peer-reviewed journal. Even when it is, I doubt the controversy will subside. Prof. Yang has plenty of experience in this type of area, having previously done work on microwave plasma thrusters, which use a resonant cavity to accelerate a plasma jet for propulsion. While the theory behind the Emdrive is very different, the engineering principles of building the hardware are similar. The Chinese should be capable of determining whether the thruster really works or whether the apparent forces are caused by experimental errors.

The thrust produced is small, but significant. Shawyer compares a C-Band Emdrive with the existing NSTAR ion thruster used by NASA. The Emdrive produces 85 mN of thrust compared to 92 for the NSTAR (that's about one-third of an ounce), but the Emdrive only consumes a quarter of the amount of power and weighs less than 7 kilos, compared to over 30 kilos. The biggest difference is in propellant: NSTAR uses 10 grams per hour; the Emdrive uses none. As long as it has an electricity supply, the Emdrive will keep going.

The possibilities are phenomenal: Instead of going out of service when they run out of fuel, satellites would have greatly extended endurance and be able to move around at will. (We wouldn't have to shoot them down because of the risk from toxic fuel either.) Deep space probes could go further, faster –- and stop when they arrive. Shawyer calculates that a solar-powered Emdrive could take a manned mission to Mars in 41 days. Provided it works, of course.

What will China do with the technology? It may be relevant that professor Yang is not unknown in military circles, having published a paper called "Plasma Attack Against Low-Orbit Spy Satellites."

Meanwhile, what about the American interest? Shawyer told me that "the flight thruster program is on hold for the present. [O]nce the U.K. government had provided an export license for a U.S. military application, the major U.S. aerospace company we had been dealing with stopped talking to us. "

The company may have decided that the Emdrive could not work. If they're wrong, China has at least a year's head start in a technology that will dominate space and make previous satellites as obsolete as sailing ships in the age of steam.