Posts Tagged ‘electricity’
FYI: Can Wireless Electricity Kill People?
Tesla’s experiment proved that the Earth itself could be used to conduct electricity, no wires necessary. He also experimented with electromagnetic induction, a phenomenon discovered 70 years before Tesla’s experiments by the English scientist Michael Faraday. In electromagnetic induction, an oscillating magnetic field around an electromagnet produces a current in a nearby conductor—in effect, the current jumps the gap. While it is airborne, electric energy exists as a magnetic field. Magnetic induction is used today in the contact plates on electric toothbrushes, transmitting a charge from the plastic-wrapped charging station to the battery inside the brush.
In 2006, Marin Soljacic, a physics professor at the Massachusetts Institute of Technology, sent wireless electricity across a room to light a 60-watt bulb. Soljacic used electromagnetic induction, but with a twist. By tuning the sending and receiving coils in his electromagnetic field to resonate at the same frequency and engage only at that frequency (the way glass will shatter when struck by sound waves of just the right pitch), the current is focused and bypasses everything else, humans included. Resonant coupling, as Soljacic’s process is known, is far more efficient than Tesla’s attempts, and safer too.
Soljacic has , and he can now send 3,000 watts across a room—or a garage, since 3,000 watts can charge an electric car.
Have a science question you've always wondered about? Send an email to fyi@popsci.com
Single-Molecule Motor Runs on Electricity, Could Be Used for Single-Cell Surgery
Past single-molecule motors tended to be triggered with light, like this . But light tends to also affect lots of other molecules nearby, and sometimes has an unpredictable effect. This new one (the molecule in question is an 18-atom molecule which, , "gives brandy its distinctive smell." More importantly, it can be controlled by a stream of electrons shot from a Scanning Tunneling Microscope, which not only triggers the molecule to start spinning, it also enables viewing of the event.
That microscope is so precise that it can direct a beam of electrons at individual butyl methyl sulfide molecules (which are about one nanometer in size--for comparison, a human hair is 60,000 nanometers thick), causing one to turn without affecting any others.
There are caveats, of course; the experiments are being performed at excessively cold temperatures, about 5 degrees Kelvin, to try to slow down the movement. At that temperature, the molecule spins about 120 times per second. At 100 degrees Kelvin--about -279 degrees Fahrenheit--that jumps to over a million, which is as you can imagine pretty difficult to monitor.
Still, there are lots of possible uses for such a tiny motor, from nanorobots that can perform surgery on a single cell to providing power for tiny nanoscale sensors. Those might be "several decades away," but at least the Guinness Book is convinced that this is the world's smallest motor. (Not that .)
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Inside the World’s Largest Fusion Reactor
Hot fusion might be the answer to energy demands
At the forefront of the effort to realize fusion-based power is , an international collaboration to build the world’s largest fusion reactor. At the heart of the project is a tokamak, a doughnut-shaped vessel that contains the fusion reaction. In this vessel, magnetic fields confine a plasma composed of deuterium and tritium, two isotopes of hydrogen, while particle beams, radio waves and microwaves heat it to 270 million degrees Fahrenheit, the temperature needed to sustain the fusion reaction. During the reaction, the deuterium and tritium nuclei fuse, producing helium and a neutron. In a fusion power plant, those energetic neutrons would heat a structure, called a blanket, in the tokamak and that heat would be used to turn a turbine to produce electricity.
The ITER reactor will be the largest tokamak ever made, producing 500 megawatts of power, about the same output as a coal-fired power plant. But ITER won’t generate electricity; it’s just a gigantic physics experiment, albeit one with very high potential benefits. A mere 35 thousandths of an ounce of deuterium-tritium fuel could produce energy equivalent to 2,000 gallons of heating oil. And ITER’s process is “inherently safe,” says Richard Pitts, a senior scientific officer on the project. “It can never, ever be anything like what you see in the fission world--in Chernobyl or Fukushima--and this is why it is so attractive.”
ITER's magnets produce fields at least 1,000 times as strong as the magnets stuck to your refrigerator.To fully commercialize tokamak-based fusion, developers must overcome several challenges. First is the matter of breeding the tritium; there are only about 50 pounds of it in the world at any given time because it is not naturally occurring and decays quickly. (Deuterium is not radioactive and can be distilled from water.) Although ITER may use tritium produced by nuclear power plants, a full-scale fusion plant will need to produce its own supply--neutrons from the fusion reaction could be used to convert a stash of lithium into tritium. In addition, physicists must also determine which materials can best withstand the by-products of the fusion reaction, which will wear down the tokamak’s walls. Finally, residual radioactivity in the device will pose maintenance problems because people won’t be able to work safely within the vessel. ITER scientists must develop robots capable of replacing parts that can weigh up to 10 tons.
ITER will begin experiments in 2019 in France. If those are successful, the data produced by the project will aid the ITER team in the design of DEMO, a proposed 2,000- to 4,000-megawatt demonstration fusion power plant that will be built by 2040.
(Click the above image for more information.)
After Thousands of Years of Research, We’re Still Trying to Figure Out Static Electricity
Static electricity has been under investigation for a few millennia now, with research dating back to the ancient Greeks. But the Northwestern team wasn’t convinced that everything was as it seemed. So they applied to the problem, which allowed them to see the varying levels of charge distributed unevenly across the surface of objects.
What they found is that these charges are far less uniform than previously thought, and that clumps of positive and negative charge are strewn unevenly across surfaces. It’s these clumps that are transferred between objects when they come in contact, not just the charges.
In normal human language, that means that when you rub a balloon on your hair to make it stand up, there is a small exchange of matter--tiny bits of balloon actually adhere to the hair, disrupting the electrical patchwork on the balloon and causing that strange attraction between it and other objects that we all know as static electricity.
That matter exchange is proven pretty definitively by this research, but like most discoveries, this one begets more questions. Why do these negative and positive clumps exist, and does knowing that they do exist fully explain the static phenomenon? Scientists still aren’t sure. And that, boys and girls, is why we never stop learning.
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Federal Study of Power Grid Might Disrupt The Nation’s Clocks
Once they’re programmed, electrically powered clocks tell time based on the rate of the electric current that feeds them, as an explains. Electrical utilities keep the current’s frequency stable in part to keep clocks precise, the AP says. But utilities could save energy and money by allowing for greater frequency variation, so the Federal Energy Regulatory Commission is considering allowing the change.
Joe McClelland, head of electric reliability for FERC, wondered whether anyone really uses the grid to tell time.
“Let’s see if anyone complains if we eliminate it,” he said.
Renewable energy is one primary reason FERC cares about frequency variation. Power sources like wind and solar energy will ramp up and drop off with great variability, inducing spikes and valleys in the energy flowing through the nation’s electrical grid. Adjusting for those differences is expensive, and can be wasteful, according to FERC. Forgetting about it would just be easier — unless all the nation’s clocks are suddenly off.
With a more variable current, wall clocks and appliance clocks, like the one that’s programmed to brew your coffee every morning, will become less accurate every second, a phenomenon that can get much worse over time. One trade group that has studied the potential effects says East Coast clocks could run 20 minutes fast over a year, and timepieces on the West Coast clocks would be off by about 8 minutes.
Officials from FERC said they are tentatively planning to test a more variable frequency in mid-July, AP said.
It’s a good thing we have atomic clocks to keep us all on track.
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Concepts & Prototypes: Two Next-Gen Nukes
Nuclear power is the most efficient emissions-free energy available. But can it be made safe? Two new reactor designs do just that
One nuclear plant with a footprint of one square mile provides the energy equivalent of 20 square miles of solar panels, 1,200 windmills or the entire Hoover Dam. If the country wants to significantly reduce its dependence on carbon-based energy, it will need to build more nuclear power plants. The question is how to do so safely.
In the 30 years since regulators last approved the construction of a new nuclear plant in the U.S., engineers have . (You can see some of the older, not-so-safe ones in .) The newest designs, called Generation III+, are just beginning to come online. (Generation I plants were early prototypes; Generation IIs were built from the 1960s to the 1990s and include the facility at Fukushima; and Generation IIIs began operating in the late 1990s, though primarily in Japan, France and Russia.)
Unlike their predecessors, most Generation III+ reactors have layers of passive safety elements designed to stave off a meltdown, even in the event of power loss. Construction of the first Generation III+ reactors is well under way in Europe. China is also in the midst of building at least 30 new plants. In the U.S., the Southern Company recently broke ground on the nation’s first Generation III+ reactors at the Vogtle nuclear plant near Augusta, Georgia. The first of two reactors is due to come online in 2016.
(Click the above image for more details.)
Like many of the 20 or so pending Generation III+ facilities in the U.S., the Vogtle plant will house Westinghouse AP1000 reactors. A light-water reactor, the AP1000 prompts uranium-235 into a chain reaction that throws off high-energy neutrons. The particles heat water into steam, which then turns a turbine that generates electricity.
The greatest danger in a nuclear plant is a meltdown, in which solid reactor fuel overheats, melts, and ruptures its containment shell, releasing radioactive material. (Want more information? Check out our explainer on .) Like most reactors, the AP1000 is cooled with electrically powered water pumps and fans, but it also has a passive safety system, which employs natural forces such as gravity, condensation and evaporation to cool a reactor during a power outage.
The U.S. has 104 nuclear reactors operating at 65 sites in 31 states, all of them approved before 1980.A central feature of this system is an 800,000-gallon water tank positioned directly above the containment shell. The reservoir’s valves rely on electrical power to remain closed. When power is lost, the valves open and the water flows down toward the containment shell. Vents passively draw air from outside and direct it over the structure, furthering the evaporative cooling.
Depending on the type of emergency, an additional reservoir within the containment shell can be manually released to flood the reactor. As water boils off, it rises and condenses at the top of the containment shell and streams back down to cool the reactor once more. Unlike today’s plants, most of which have enough backup power onsite to last just four to eight hours after grid power is lost, the AP1000 can safely operate for at least three days without power or human intervention.
Even with their significant safety improvements, Generation III+ plants can, theoretically, melt down. Some people within the nuclear industry are calling for the implementation of still newer reactor designs, collectively called Generation IV. The thorium-powered molten-salt reactor (MSR) is one such design. In an MSR, liquid thorium would replace the solid uranium fuel used in today’s plants, a change that would make meltdowns all but impossible
(Click the above image for more details.)
MSRs were developed at Tennessee’s Oak Ridge National Laboratory in the early 1960s and ran for a total of 22,000 hours between 1965 and 1969. “These weren’t theoretical reactors or thought experiments,” says engineer John Kutsch, who heads the nonprofit Thorium Energy Alliance. “[Engineers] really built them, and they really ran.” Of the handful of Generation IV reactor designs circulating today, only the MSR has been proven outside computer models. “It was not a full system, but it showed you could successfully design and operate a molten-salt reactor,” says Oak Ridge physicist Jess Gehin, a senior program manager in the lab’s Nuclear Technology Programs office.
One pound of thorium produces as much power as 300 pounds of uranium--or 3.5 million pounds of coal.The MSR design has two primary safety advantages. Its liquid fuel remains at much lower pressures than the solid fuel in light-water plants. This greatly decreases the likelihood of an accident, such as the hydrogen explosions that occurred at Fukushima. Further, in the event of a power outage, a frozen salt plug within the reactor melts and the liquid fuel passively drains into tanks where it solidifes, stopping the fission reaction. “The molten-salt reactor is walk-away safe,” Kutsch says. “If you just abandoned it, it had no power, and the end of the world came--a comet hit Earth--it would cool down and solidify by itself.”
Although an MSR could also run on uranium or plutonium, using the less-radioactive element thorium, with a little plutonium or uranium as a catalyst, has both economic and safety advantages. Thorium is four times as abundant as uranium and is easier to mine, in part because of its lower radioactivity. The domestic supply could serve the U.S.’s electricity needs for centuries. Thorium is also exponentially more efficient than uranium. “In a traditional reactor, you’re burning up only a half a percent to maybe 3 percent of the uranium,” Kutsch says. “In a molten-salt reactor, you’re burning 99 percent of the thorium.” The result: One pound of thorium yields as much power as 300 pounds of uranium--or 3.5 million pounds of coal.
Because of this efficiency, a thorium MSR would produce far less waste than today’s plants. Uranium-based waste will remain hazardous for tens of thousands of years. With thorium, it’s more like a few hundred. As well, raw thorium is not fissile in and of itself, so it is not easily weaponized. “It can’t be used as a bomb,” Kutsch says. “You could have 1,000 pounds in your basement, and nothing would happen.”
One nuclear plant provides the energy equivalent of 1,200 windmills or 20 square miles of solar panels.Without the need for large cooling towers, MSRs can be much smaller than typical light-water plants, both physically and in power capacity. Today’s average nuclear power plant generates about 1,000 megawatts. A thorium-fueled MSR might generate as little as 50 megawatts. Smaller, more numerous plants could save on transmission loss (which can be up to 30 percent on the present grid). The U.S. Army is interested in using MSRs to power individual bases, Kutsch says, and Google, which relies on steady power to keep its servers running, held a conference on thorium reactors last year. “The company would love to have a 70- or 80-megawatt reactor sitting next door to a data center,” Kutsch says.
Even with military and corporate support, the transition to a new type of nuclear power generation is likely to be slow, at least in the U.S. Light-water reactors are already established, and no regulations exist to govern other reactor designs. Outside the U.S., the transition could come more quickly. In January the Chinese government launched a thorium reactor program. “The Chinese Academy of Sciences has approved development of an MSR with relatively near-term deployment--maybe 10 years,” says Gehin, who thinks the Chinese decision may increase work on the technology worldwide. Even after Fukushima, “there’s still interest in advanced nuclear,” he says. “I don’t see that changing.”
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Hooking a 9-Volt Battery To Your Brain Improves Your Video Game Skills, Researcher Finds
(But don't try this at home)
Neuroscientists at the University of New Mexico asked volunteers to play a video game called “DARWARS Ambush!”, developed to help train American military personnel. Half of the players received 2 milliamps of electricity to the scalp, using a device powered by a simple 9-volt battery, and they played twice as well as those receiving a much tinier jolt. The DARPA-funded study suggests direct current applied to the brain could improve learning.
This type of brain stimulation, called transcranial direct current stimulation (tDCS), is controversial but could show promise for treatment of various neurological disorders and cognitive impairments. Click through to for a thorough overview.
It’s different from , in which a magnetic coil running at high voltage is positioned close to the head. The magnets stimulate electrical responses in the brain. Transcranial direct current stimulation is just what it sounds, applying the current directly to the brain.
We’ve been hearing quite a lot about these methods lately, and the scientific literature indicates the fields — tDCS in particular — are experiencing a revival, Nature News points out. Scientists hope the methods could be used to treat depression, post-traumatic stress disorder, stroke and autism, as well as to improve learning by increasing the brain’s plasticity.
Researchers are beginning to understand how an external electrical current affects brain function, including by inducing changes to the flow of electricity across neurons and increasing the expression of certain synapse proteins.
Apparently, it takes very little electricity to do all this. But please, don’t start hooking up 9-volt batteries to your brain — leave that to the scientific studies.
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