Posts Tagged ‘power’
MIT’s Tiny Energy-Harvester Makes Electricity From Low-Frequency Vibrations
Wireless are used for all kinds of things, from monitoring factory machines and oil pipelines to keeping track of pollution. While the efficiency of their energy consumption has improved, the sensors' batteries still need to be changed occasionally. MIT's device, a microelectromechanical system (we prefer the term energy-harvester) makes electricity from the vibrations of foot traffic and other low-power energy sources from the environment, potentially removing the need for batteries completely.
The quarter-sized energy-harvester has improved on the designs of by taking inspiration from the bridges themselves. MIT's energy-harvester consists of a microchip with a bridge-like structure anchored at either end. On the bridge is a weight sitting on one layer of , which naturally gathers electric charge when faced with mechanical stress. Other devices use a cantilever beam instead of a bridge to pick up vibrations, which is much less efficient. MIT's design picks up a wider range of vibrations and produces 100 times more energy than any other harvester available.
The next step for the project is to get the device to pick up lower-frequency vibrations and generate at least 100 microwatts of power, a target that would be able to power a whole network of wireless sensors.
[MIT]
Are We Prepared for a Catastrophic Solar Storm?
A solar disaster isn't a question of if, but when--and it looks like soon
Curious about what a CME would mean for us?
Within weeks, backup generators at nuclear power plants would have run down, and the electric pumps that supply water to cooling ponds, where radioactive spent fuel rods are stored, would shut off. Multiple meltdowns would ensue. “Imagine 30 Chernobyls across the U.S.,” says electrical engineer John Kappenman, an expert on the grid’s vulnerability to space weather. A CME big enough to take out a chunk of the grid is what scientists and insurers call a high-consequence, low-frequency event. Many space-weather scientists say the Earth is due for one soon. Although CMEs can strike anytime, they are closely correlated to highs in the 11-year sunspot cycle. The current cycle will peak in July 2013.
The most powerful CME in recorded history occurred during a solar cycle with a peak similar to the one scientists are predicting in 2013. During the so-called Carrington Event in 1859, electrical discharges in the U.S. shocked telegraph operators and set their machines on fire. A CME in 1921 disrupted radio across the East Coast and telephone operations in most of Europe. In a 2008 National Academy of Sciences report, scientists estimated that a 1921-level storm could knock out 350 transformers on the American grid, leaving 130 million people without electricity. Replacing broken transformers would take a long time because most require up to two years to manufacture.
"We need to build protection against 100-year solar storms."Once outside power is lost, nuclear plants have diesel generators that can pump water to spent-fuel cooling pools for up to 30 days. The extent of the meltdown threat is well-documented. A month before the Fukushima plant in Japan went offline in March, the Foundation for Resilient Societies, a committee of engineers, filed a petition with the U.S. Nuclear Regulatory Commission recommending the augmentation of nuclear plants’ emergency backup systems. The petition claims that a severe solar storm would be far worse than a 9.0-magnitude quake and could leave about two thirds of the country’s nuclear plants without power for one to two years.
Preventing a surge from a CME would be costly. With enough warning (at least a few hours, probably), power companies could shut transformers off entirely, turning them back on after the storm. But shutting down the grid on such a large scale would cost billions. To confidently do so, forecasting must be accurate.
Last October, NASA scientists announced its Solar Shield program to monitor solar eruptions and predict storms. Though a good step, the system uses a satellite that was launched in 1997 and designed to run just five years. No other country has anything similar, or as advanced.
Our backup systems aren’t in place yet, either. The Department of Homeland Security is funding the development of an emergency replacement transformer, but it won’t be field-ready for several years. Kappenman has developed a $100,000 capacitor to block storm-induced surges, but these are unproven in emergency situations. “A massive solar storm is a ‘low probability’ event the same way a 100-year flood is,” Thomas Popik, the author of the NRC petition, says. “Just as we build levees to protect against 100-year floods, we need to build protection against 100-year solar storms.”
World’s Most Powerful Laser Gets Government Go-Ahead
The Extreme Light Infrastructure will be built in Eastern Europe
The lasers will be the first to operate in the exawatt scale--a quintillion watts. That’s about a million times more powerful than 10 billion 100-watt lightbulbs. And a fourth superlaser should be forthcoming, one with beams twice the power of these three. This is the laser that was theorized to be the .
The list of implications for this never-before-seen technology is long, reaching into cancer diagnosis and treatment, elimination of nuclear waste, broadening of the technology industry, and expansion of nanoscience and molecular chemistry research.
Several countries competed for the honor of hosting the laser. ELI's most important research laser will find its home in the Czech Republic while the other two will reside in Hungary and Romania.
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How Nuclear Reactors Work, And How They Fail
Several of Japan's nuclear power plants are experiencing serious damage from the earthquake and ensuing tsunami. Here's what you need to know to understand the news, as it happens
What Is a Nuclear Reaction?
A nuclear reaction is at its most basic nothing more than a reaction process that occurs in an atomic nucleus. They typically take place when a nucleus of an atom gets smacked by either a subatomic particle (usually a "free neutron," a short-lived neutron not bound to an existing nucleus) or another nucleus. That reaction produces atomic and subatomic products different from either of the original two particles. To make the kind of nuclear reaction we want, a fission reaction (in which the nucleus splits apart), those two original particles have to be of a certain type: One has to be a very heavy elemental isotope, typically some form of uranium or plutonium, and the other has to be a very light "free neutron." The uranium or plutonium isotopes are referred to as "fissile," which means we can use them to induce fission by bombarding them with free neutrons.
In a fission reaction, the light particle (the free neutron) collides with the heavy particle (the uranium or plutonium isotope) which splits into two or three pieces. That fission produces a ton of energy in the form of both kinetic energy and electromagnetic radiation. Those new pieces include two new nuclei (byproducts), some photons (gamma rays), but also some more free neutrons, which is the key that makes nuclear fission a good candidate to generate energy. Those newly produced free neutrons zoom around and smack into more uranium or plutonium isotopes, which in turn produces more energy and more free neutrons, and the whole thing keeps going that way--a nuclear fission chain reaction.
Nuclear fission produces insane amounts of energy, largely in the form of heat--we're talking several million times more energy than you'd get from a similar mass of a more everyday fuel like gasoline.
Getting Usable Energy From Fission
There are several types of nuclear fission reactors in Japan, but we're going to focus on the Fukushima Naiishi plant, the most hard-hit facility in the country. Fukushima, run by the Tokyo Electric Power Company (TEPCO), has six separate reactor units, although numbers 4, 5, and 6 were shut down for maintenance at the time of the earthquake (and more importantly, the subsequent tsunami). Numbers 1, 2, and 3 are all "boiling water reactors," made by General Electric in the early- to mid-1970s. A boiling water reactor, or BWR, is the second-most-common reactor type in the world.
A BWR contains thousands of thin, straw-like tubes 12 feet in length, known as fuel rods, that in the case of Fukushima are made of a zirconium alloy. Inside those fuel rods is sealed the actual fuel, little ceramic pellets of uranium oxide. The fuel rods are bundled together in the core of the reactor. During a nuclear fission chain reaction, the tubes heat up to extremely high temperatures, and the way to keep them safe turns out to also be the way to extract useful energy from them. The rods are kept submerged in demineralized water, which serves as a coolant. The water is kept in a pressurized containment vessel, so it has a boiling point of around 550 °F. Even at such a high boiling point, the burning hot fuel rods produce large amounts of steam, which is actually what we want from this whole complicated arrangement—the high-pressure steam is used to turn the turbines on dynamos, producing electricity.
Safety
Since lots of heat is being produced, as well as the production and use of lots of pretty nasty radioactive materials, nuclear plants employ a variety several safety efforts beyond simply the use of the cooling water (which itself is backed up by redundant diesel generators--more on that later). The plant's core, the fuel rods and the water, is encased in a steel reactor vessel. That reactor vessel is in turn encased in a giant reinforced concrete shell, which is designed to prevent any radioactive gases from escaping.
Isn't There an "Off" Switch?
Sure! But needless to say, safely shutting down and controlling a nuclear reactor is not at all as simple as unplugging a rogue kitchen appliance. This is due to the extreme heat still present well after fission has subsided--mostly due to chemical reactions inherent in the fission reaction.
A functioning fission plant employs a system of control rods, essentially structures that limit the rate of fission inside the fuel rods by absorbing roaming free neutrons. The rate of fission can be controlled--even stopped--by inserting and removing the control rods in the reactor. At the time of the quake, the Fukushima reactors' control rods functioned normally, shutting down the fission reaction. But even with the fission reaction stopped, the fuel rods remain at extremely high temperatures and require constant cooling.
Which isn't typically a problem, so long as the cooling system (and, failing that, its diesel-powered backup) is still intact. But after losing main power in the quake, the subsequent tsunami wave also destroyed Fukushima's diesel backup generators. Which is a serious problem; even though the fission had stopped, coolant is still very much required to keep the plant safe.
That's due to the heat that remains in the nuclear core, both from the recently-disabled but still-hot fuel rods and from the various byproducts of the fission process. Those byproducts include radioactive iodine and caesium, both of which produce what's called "decay heat"--residual heat that is very slow to dissipate. If the core isn't continuously cooled, there's still more than enough heat to cause a meltdown long after it's been "turned off."
In the case of the Fukushima plant, with both the main and backup coolant systems down for the count, TEPCO was forced to rig a method to flood the core with seawater laced with boric acid (the boric acid to stave off another fission reaction if one were to restart due to a meltdown--more on that below). That's a bad sign--it's a last-ditch effort to prevent catastrophe, as the salt in the seawater will corrode the machinery. It's also a temporary fix: TEPCO will need to pump thousands of gallons of seawater into the core every day, until they can get the coolant system back online. Without it, the seawater method might have to go on for weeks, even up to a year, as the decay heat slowly subsides.
The Dreaded Meltdown
First of all, a "meltdown" is not a precisely defined term, which makes it fairly useless as an indicator of what's going on. Even the terms "full meltdown" and "partial meltdown" are pretty unhelpful, which is partly why we've written this guide--you'll be able to understand what's actually happening without relying on spurious terms that the experts themselves are often loathe to use.
Anyway, let's start at some of the less severe (though still unsettling) things that can happen when the coolant liquid is no longer present in the core. When the fuel rods are left uncovered by water, they'll get far too hot--we're talking thousands of degrees Celsius here--and begin to oxidize, or rust. That oxidation will react with the water that's left, producing highly explosive hydrogen gas. This has already happened in reactor No. 1 at Fukushima (see the video below). The hydrogen gas can be vented in smallish doses into the containment building, but if they can't vent it fast enough, it'll explode, which is exactly what happened at reactor No. 1. Keep in mind, this is not a nuclear reaction, but a simple chemical explosion that often (as in this case) results in little or no radioactive material being leaked into the outside world.
TEPCO has announced that after the explosion, radiation levels in the area around the plant were still within "normal" parameters. This is an important distinction--not to say that a hydrogen explosion at a nuclear plant is particularly fun news, but it is not nearly as panic-inducing as a meltdown.
What people mean when they say "meltdown" can refer to several different things, all likely coming after a hydrogen explosion. A "full meltdown" has a more generally accepted definition than, say, a "partial meltdown." A full meltdown is a worst-case scenario: The zirconium alloy fuel rods and the fuel itself, along with whatever machinery is left in the nuclear core, will melt into a lava-like material known as corium. Corium is deeply nasty stuff, capable of burning right through the concrete containment vessel thanks to its prodigious heat and chemical force, and when all that supercharged nuclear matter gets together, it can actually restart the fission process, except at a totally uncontrollable rate. A breach of the containment vessel could lead to the release of all the awful radioactive junk the containment vessel was built to contain in the first place, which could lead to your basic Chernobyl-style destruction.
The problem with a full meltdown is that it's usually the end result of a whole boatload of other chaos--explosions, fires, general destruction. Even at Chernobyl, which (unbelievably, in retrospect) had no containment building at all, the damage was caused mostly by the destruction of the plant by explosion and a graphite fire which allowed the corium to escape to the outside world, not the physical melting of the nuclear core.
Over the weekend, Chief Cabinet Secretary Yukio Edano somewhat hesitatingly confirmed a "partial" meltdown. What does that mean? Nobody knows! The that a "partial" meltdown doesn't actually need to have any melting involved to qualify it as such--it could simply mean the fuel rods have been un-cooled long enough to corrode and crack, which given the hydrogen explosion, we know has already happened. But we'd advise against putting too much stock in any term relating to "meltdown"--it'll be much more informative to find out what's actually going on, rather than relying on a vague blanket term.
As TEPCO grapples with the damage the earthquake and tsunami did to the nuclear system, there's going to be lots of news--there could be more explosions, mass evacuations, and more "meltdowns" of one kind or another. All we can do is learn about what's going on, think calmly about the situation, and hope that TEPCO can eventually regain control of the plants.
How the Empire State Building Is Pioneering the Future of Energy Efficiency
Greening the world’s most iconic skyscraper
Now, a sweeping $13.4 million energy retrofit is slashing the Empire State Building’s energy consumption by nearly 40 percent and reducing greenhouse gas emissions by 105,000 metric tons over the next 15 years while trimming $4.4 million from annual energy costs. We took a firsthand look at what such a massive and meaningful project looks like, starting in a nondescript corner of the fifth floor where the Empire State Building is turning two-decade-old glass into future dollars.
Click to launch the photo gallery
It’s here that 100 double-pane windows per day are ripped from their aging frames, put through a rigorous cleaning process, treated with a thin UV-resistant film, and pumped full of pressurized argon and krypton gasses that improve their insulation values. By the time the retrofit is complete, all 6,514 windows will have been refurbished at a cost more than $1,600 per window less expensive than replacing them would be.
The window rehab – and other projects like it – reduces the energy load on the building, which in turn allows the engineers behind the retrofit to find efficiencies elsewhere. It’s all part of an 8-point plan that will eventually reduce the building’s energy consumption by 38.4 percent and its expenses by a few million dollars each year. With a footprint the size of the Empire State Building’s, that’s game-changing not just for the building, but also for the city and the world.
“Eighty percent of the energy consumed in New York City is consumed by buildings,” says Malkin, who is president of Malkin Holdings, part-owner of the Empire State Building. “Not by cars, not by buses, not by taxis, not by subways, not by trains. Even more interestingly, 20 percent of the buildings consume 80 percent of that energy. So 64 percent of all energy consumed in New York City is consumed by 20 percent of the buildings. That really took me by surprise.”
The Empire State Building fell into that energy-sucking 20 percent, so perhaps it was no surprise that the Clinton Climate Initiative took an interest in the building. In 2007, a representative for CCI approached Malkin seeking a building in which to demonstrate the foundation’s green retrofit program. Malkin was in the midst of a massive renovation project spanning his company’s entire portfolio, so he offered up a building at Broadway and 35th street in Midtown Manhattan.
The CCI pressed for something bigger. If it could turn the world-renowned Empire State into a model for efficiency, the whole world would take notice. At the time, the Empire State Building consumed the same amount of energy as 40,000 single-family homes, a figure that is unfortunately not unique; 43 percent of office space in New York City was constructed before the end of World War II, much of it comprising that 20 percent of buildings consuming the majority of the city’s energy. Greening the Empire State Building and skyscrapers like it wouldn’t just benefit real estate owners and their tenants; it would significantly move the dial on the entire city’s energy consumption.
Malkin agreed for reasons both altruistic and self-interested. “This is all about making money,” Malkin says bluntly of the retrofit. “To me, the whole concept of ‘green’ is a misnomer. The world is getting greenwashed. If you can’t prove it economically, it doesn’t matter.”
Malkin and the CCI set out to prove not only that enhanced energy efficiency is a cost-effective means of controlling expenses, but to create an economically feasible model that can be implemented by any building anywhere.
“If we succeeded only at the Empire State Building, we failed,” Malkin says. “It had to be broadly adoptable and malleable, and it had to be quantitative."
To create a cost-effective retrofit regimen, the project would have to be carefully managed. Malkin and the Empire State Building brought in technology and management experts from Johnson Controls and real estate consultants Jones Lang Lasalle, as well as the green-thinkers at the Rocky Mountain Institute, to craft a suite of technologies that not only incrementally reduce energy consumption but that have a multiplying effect on one another that generates further efficiency.
For Paul Rode, business development director for building efficiency at Johnson Controls, this synergistic effect was crucial. The retrofit team considered more than 60 off-the-shelf technologies and practices. They came up with eight initiatives that together were more effective than the sum of their parts. “If we take any one of these items out, the overall reduction values of the others change disproportionately,” he says.
The technology package attacks the problem from three sides. First, the team found ways to reduce the existing load on the building’s infrastructure by rehabbing the windows, installing better insulation behind the more than 6,500 radiators in the building and outfitting offices with occupancy sensors, better lighting controls, and layouts that maximize natural daylight. They also improved the efficiency of existing systems, retrofitting (rather than replacing) the chiller plant and replacing old air handling equipment with fewer and more efficient units.
The third component entails smartly controlling energy use. New York City’s tallest building is now home to America’s largest wireless control system. Carbon dioxide sensors throughout the building determine exactly how much outside air needs to be brought into the building at a given time, cutting down on unnecessary circulation, and occupancy sensors allow the building to better allocate air and manage lighting. And the Empire State's wireless thermostat sensors, unlike the hard-wired variety, can be moved around an office space to ensure they are placed where the temperature is average (rather than, say, tucked behind the copier or coffee machine where they record a falsely warm ambient temperature).
The same occupancy sensors that manage air allocation and lighting also tell the building’s management which offices are leaving the lights or the coffee maker on when no one is around. Offices are individually metered – and billed – and metering information is archived and provided to tenants online so they can see when and how they are using the most energy. That kind of meaningful information helps tenants manage thier behaviors to trim their own energy use – and expense. The Empire State Building's management is a partner in the entire process, helping each tenant figure out how it can reduce its load on the building.
“Tenants are drawn to us because tenants’ largest three expenses are salary, rent, and utilities,” Malkin says. “The ability to control expense is extremely important. The work that we are doing is not just from the perspective of our own building systems, but we’ve created a suite of services to help tenants achieve things that give them tremendous payback for their own spaces, their own investments.”
As for Malkin’s investment, he’s paying out $13.4 million incrementally for the retrofit, an investment that should save him $4.4 million per year. That means his capital investment in green tech will pay for itself in just three years, two years ahead of schedule. And by creating a competitive advantage for tenants, the building creates a monetary incentive for tenants to be conscious of their own energy consumption. Which, as Malkin is quick to point out, is how you really initiate change.
“It’s not just about doing the right thing for the sake of doing the right thing,” he says. “It’s about making money by doing the right thing.”
Coming Generation of Lasers May Be the Most Powerful Lasers That Will Ever Lase
The theoretical energy ceiling for lasers is approaching
That finite limit on how intense a laser can get is hypothesized to exist because, at sufficiently high energies, matter can be created out of light.
When a high-powered laser fires, causing photons to impact electrons at a tremendous velocity, it is possible for matter -- a positron-electron pair -- to be created by the impact, as was demonstrated in a Stanford experiment in 1997. When such matter is created with a sufficiently high energy, it in turn can emit photons that move fast enough that they create their own matter. This cascade effect can have as much energy as the laser itself does, and result in the destruction of the laser.
It is predicted that the effect will be visible in the ELI project and other lasers currently being built.
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Navy Submarine Runs Eternally on Thermal Power from Ocean Currents
SOLO-TREC is outfitted with a series of tubes full of waxy phase-change materials. As the float encounters warm temperatures near the ocean's surface, the materials expand; when it dives and the waters grow cooler, the materials contract. The expansion and contraction pressurizes oil, which drives a hydraulic motor. The motor generates electricity and recharges the batteries, which power a pump. The pump can change the float's buoyancy, allowing it to move up and down the water column.
"In theory what you have now is unlimited endurance for something that has this type of engine," said Thomas Swean Jr., team leader for ocean engineering and marine systems at the Office of Naval Research, which funded the project. "Other things can break, but as far as the energy source, it will only stop working if the ocean ran out of energy, which is unlikely to happen ... One of the Navy's goals is to have a persistent presence in the world's oceans. This is the type of technology that leads you to that."
NASA's Jet Propulsion Laboratory and the ONR designed the thermal engine, and the Scripps Institution of Oceanography at the University of California-San Diego designed the vessel, which weighs about 180 pounds and looks like a large scuba tank. Its batteries are charged by materials that change phases in the different temperature gradients found at various ocean depths.
The float made its first dives last November and was just approved for an extended research mission.
As of this week, SOLO-TREC has made 430 dives from the surface to about 500 meters (1,640 feet), and each time, it's produced about 1.6 watt-hours of power, more than enough to operate its science instruments, buoyancy pump, GPS receiver and communications devices. You can track its path through the ocean .
Future generations of thermal engines could harbor all kinds of scientific and surveillance instruments uninhibited by the need for replenished power. Swean said the next step is to put a thermal engine inside a sea glider, perhaps one like the "Scarlet Knight" unmanned glider that made a transatlantic trip last year.
"This type of an engine, as it matures, will find many types of applications. Gliders is one; traditional unmanned underwater vehicles is another," Swean said. "Essentially you have an unlimited energy supply and we've got an engine that is taking advantage of that."
Yi Chao, principal investigator at JPL, said a fleet of thermal-engine-powered floats could provide oceanographers with constant data about ocean salinity, pH, and other variables. Bigger floats could even accommodate hydrophones or cameras that can venture deep into the ocean, he said.
"For NASA, this is really complementary for our satellites, to what we see on the surface," he said.
Could it be used to study the oceans of Titan or Europa? Chao said maybe someday, as long as their oceans have enough temperature gradients.
But, he points out, there's plenty of research left to do right here.
"We know so little about the ocean. It would be nice to explore more of the deep sea," he said. "It would be a long time before we run out of science to do."