Entries categorized as ‘sustainable energy’
alternatives to wind turbines
March 27, 2008 · 1 Comment
I discovered on the site “Popular Science” the following alternatives to wind turbines and wanted to share them since this topic comes up a lot in class:
“One common complaint about wind turbines is that they blemish the scenic countrysides and coastlines where they perch. Now an architect in London has an attractive solution. The “wind dam,” a giant swath of fabric connected to a turbine, looks more like a Christo art installation than a power generator.
The biggest inefficiency of current wind technology, says Laurie Chetwood, founder of the architectural firm Chetwood Associates, is that more wind passes around turbines than through their rotors. So he hit upon the idea of boosting productivity by capturing high-speed winds with a massive spinnaker sail—like those that yachts deploy to pick up extreme speed—anchored to cliffs on either side of a valley and funneling those winds through a central turbine. Based on a computer model of the dam, he expects it to produce up to 120 megawatts per year, enough to power about 35 homes.
But the design has drawn some criticism. Stephen Connors, a wind-energy expert at the Massachusetts Institute of Technology Energy Initiative doesn’t think the dam could stand up to winds gusting in multiple directions. And, because wind hitting the sail would create turbulence, the dam could struggle to concentrate wind on the turbine. Even if it did, Connors says, the wind would lose significant speed on its way to the rotors.
Chetwood is working on these problems—the sail will probably be conical to limit turbulence, and the architects will build in areas with winds that blow predominantly in one direction to reduce stress on the dam. He has teamed with a Finnish engineering firm and is seeking permission to build a privately financed $5-million, 17,000-square-foot Kevlar wind dam in a valley close to Lake Ladoga, near the Baltic Sea, as soon as 2009. After that, he may modify the design to fit on a bridge or skyscraper, where at the very least it would give passersby something colorful to look at.
How it Would Work
Two aluminum legs support the 17,000-square-foot Kevlar sail, which is anchored to cliffs in a valley near Lake Ladoga. The conical shape of the sail directs air to three in-line turbines, which are enclosed in a tube. The wind spins each turbine’s blades and turns an axle that runs into its gearbox. The gearbox steps up the rotational speed of a shaft that spins magnets around a wire inside the generator to transform the movement into electricity through electromagnetic induction.”
Here are two other models developing on this concept:
A student at Arizona State University has proposed overpass-mounted turbines that, based on windspeeds of at least 10 mph kicked up by cars, could each produce enough electricity to power one small home.
The floating Superturbine can be moored farther offshore than traditional turbines. Multiple high-speed rotors increase energy output, and a carbon-fiber frame and flexing mechanisms help it survive storms.
Categories: sustainable energy
talks and events related to the Sustainable Energy class – part II
March 25, 2008 · Leave a Comment
- WATCH
http://www.filmlinc.com/wrt/onsale/green_garbage.html
“If you create your own electricity, heating and water systems, you create your own politics. Maybe that’s what they’re afraid of.” — Michael Reynolds
- Garbage Warrior tells the story of Michael Reynolds, a renegade environmental architect striving to build sustainable off-the-grid housing communities. Using beer cans, abandoned auto tires and disposable water bottles, among other materials, Reynolds creates environmental “earthships,” but not without conflict with the mainstream architectural bureaucracy. But after the catastrophic tsunami and Hurricane Katrina in 2005, the need for self-sufficient housing is all the more pressing. Reynolds and director Oliver Hodge will join us for a Q&A.
The film is screening with *The Story of Stuff*, an exploration of the global materials economy and its impact on government, environment and health.
- Garbage Warrior
Oliver Hodge, UK, 2006; 85m
- screening with*The Story of Stuff*
Louis Fox, US, 2007; 21m
Garbage Warrior Green Screens Tuesday, March 25, 2008 at 6:30 pm Walter Reade Theater, Lincoln Center, plaza level 65th Street between Broadway & Amsterdam to buy tickets: http://www.filmlinc.com/wrt/onsale/green_garbage.html
- WATCH
Movie: “The Power of Community: How Cuba Survived Peak Oil,” followed by facilitated discussion.
When: Friday, March 28, 7 PM
Where: 6th Street Community Center 638 East 6th Street, Manhattan (between Avenues B and C)
A second screening of the film is also planned for:
Thursday April 10, 7 PM 15th Street Friends Meeting House 15 Rutherford Place, Manhattan, (15th Street between 2nd & 3rd Avenues)
suggested donation $5
When the Soviet Union collapsed in 1990 and imports of oil were reduced 50% and food 80%, Cuba was faced with instant peak oil. This film tells of the hardships and struggles, as well as the community and creativity, of the Cuban people during this difficult time. Cubans share how during “The Special Period” they transitioned from a highly mechanized, industrial agricultural system to local, urban gardens using organic methods of farming.
The film opens with a short history of peak oil, a term for the time in our history when world oil production will reach its all-time peak and begin to decline forever. Cuba, the only country that has faced such a crisis – the massive reduction of fossil fuels – is an example of options and hope. World peak oil production is expected to peak by 2015. http://www.powerofcommunity.org/cm/index.php
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Sierra Club NYC’s new report Sustainable Energy Independence for NYC calls on city officials to form an energy volatility task force, as has been done in San Francisco and Portland, Oregon, to prepare for volatile energy supply and price. It sets out recommendations to step up NYC’s sustainability initiatives in transportation, buildings, agriculture and electricity generation. Get the report at www.beyondoilnyc.org.
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Sponsored by: Sierra Club NYC Group http://www.nyc.sierraclub.org/ Oil Awareness Meetup http://oilawareness.meetup.com/36/ Neighborhood Energy Network http://neighborhoodenergynetwork.org/ Tristate Food Not Lawns http://www.tristatefoodnotlawns.org/ 6th Street Community Center http://www.sixthstreetcenter.org/ 15th Street Meeting House: Friends in Unity with Nature www.funquakers.org/ & 15th Street Arts Committee
Categories: sustainable energy
talks and events related to the sustainable energy class
February 28, 2008 · Leave a Comment
- ENERGY TALK & FILM
Future Visions movie and moderated discussion series: Crude Awakening: The Oil Crash
Friday, February 29, 7 PM
6th Street Community Center 638 East 6th Street, Manhattan (between Avenues B and C) Suggested donation $5
SPONSORS: Sierra Club NYC Group http://www.nyc.sierraclub.org/
Tristate Food Not Lawns http://www.tristatefoodnotlawns.org/
Neighborhood Energy Network http://neighborhoodenergynetwork.org/
6th Street Community Center http://www.sixthstreetcenter.org/
NYC Oil Awareness Meetup http://oilawareness.meetup.com/36
Crude Awakening: the Oil Crash, produced and directed by award-winning European journalists and filmmakers Basil Gelpke and Ray McCormack, tells the story of how our civilization’s addiction to oil puts it on a collision course with geology. The film features conversations with some of the world’s top experts and delivers a startling, but logical conclusion – our industrial society, built on cheap and readily available oil, must be completely re-imagined and overhauled. World oil production is expected to peak and begin permanent decline by 2015 or before. Increasing volatility in fuel price and supply is inevitable. Many observers think it may overtake climate change as a topic of public concern, although the solutions for the two challenges overlap, and both must be solved at the same time.
The film includes in-depth, thought-provoking interviews with Colin Campbell, Matt Simmons, Roscoe Bartlett, David Goodstein, Matt Savinar, Terry Lynn Karl, Fadhil Chalabi, Robert Ebel and many others. Shot on location at oil fields in Azerbaijan, Venezuela, the Middle East and Texas, with original music by Daniel Schnyder and Philip Glass, the film provides not only questions but possible solutions to the most perplexing and important economic, environmental and public policy issue of our time. http://www.oilcrashmovie.com/
Sierra Club NYC Group’s new report explains how preparing for fuel depletion and higher fuel prices will accelerate our response to climate change. “Sustainable Energy Independence for NYC” calls for city officials to follow San Francisco and Portland, OR by forming an energy volatility task force, and sets out recommendations to step up NYC’s sustainability initiatives in transportation, buildings, agriculture and electricity generation. Get the report at www.beyondoilnyc.org.
- WATCH
http://www.pbs.org/wgbh/nova/solar/ “Saved by the Sun: Is it time to take Solar Energy seriously?” Airing on PBS Tuesday, March 18 at 8 pm
- WATCH
There will be a movie premiere of a documentary with exceptional reviews by many environmental activists. This documentary, “Burning the Future: Coal in America” premieres at the Landmark Sunshine Theater this Friday, February 29! Here is a short synopsis of the film:
“In Burning the Future: Coal in America, writer/director David Novack examines the explosive forces that have set in motion a groundswell of conflict between the coal industry and residents of West Virginia. Confronted by an emerging coal-based US energy policy, local activists watch the nation praise coal without regard to the devastation caused by its extraction. Faced with toxic ground water, the obliteration of 1.4 million acres of mountains, and a government that appeases industry, our heroes demonstrate a strength of purpose and character in their improbable fight to arouse the nation’s help in protecting their mountains, saving their families, and preserving their way of life.”
And since this is the national premiere of the movie, there will be Q & A sessions with David Novack after the early evening showings on Friday and Saturday, and after the matinees on Sunday. You can look up the movie times on the Landmark Sunshine Cinemas website at https://tickets.landmarktheatres.com/Landmark.aspx?TheatreID=256 This sounds like a really neat opportunity to educate yourself on the environmental and sociological consequences of coal mining. Hope some of you can make it! It is only showing in New York for a week, so see it while you can.
More info: http://www.burningthefuture.org/ Landmark Sunshine Cinema is located on East Houston between 1st and 2nd aves.
Think about this: Every eleven and one-half days, the explosive equivalent of the Hiroshima atomic bomb is unleashed upon the mountains of southern West Virginia and eastern Kentucky–for coal.
Categories: sustainable energy
lightning
February 23, 2008 · 3 Comments
Lightning is an electrical discharge, it can occur during thunderstorms, volcanic eruptions, nuclear reactions, forest fires where the dust creates a static charge or it can be triggered in a lab. Lightning is the sudden release of built-up charge stored in an electric field, though exactly what triggers it remains a mystery. There are many different types of lightning:
* cloud-to-ground, this is the archetypal lightning bolt, one that arcs out of the sky and strikes the ground with a flash of light.
* cloud discharge, this is lightning that occurs within a thundercloud, between two thunderclouds, or from a thundercloud to the air. Cloud discharges are certainly more common than the cloud-to-ground variety: 10 or more cloud flashes may occur before the first one that strikes the earth.
* ball lightning, there are not many scientific documentations such as videos, or other recordings of ball lightning, so experts have had to rely on eyewitness accounts, which have been numerous. Judging from such accounts, balls of lightning are typically between a golfball and a basketball in size, about as bright as a 60-watt light bulb, and often red, orange, or yellow in color. Observed shooting through the air, across the ground, and or even into houses, they are fleeting, generally lasting a few seconds before vanishing gradually or abruptly.
*blue jet, blue jets shoot upward from the tops of thunderclouds. This remoteness, and the fact that they last but a few hundred milliseconds at most, perhaps accounts for why they were not discovered until 1994. The color of sapphires, they are cone-shaped in structure and extend for many miles. Like sprites and elves, blue jets provide a mechanism for energy transfer from lightning and thunderstorms to regions of the atmosphere between thunderclouds and the lower ionosphere.
*red sprites, red sprites occur above large thunderstorm systems and are generally associated with larger positive cloud-to-ground flashes far below. They are most luminous very high up in the atmosphere, between altitudes of about 25 and 55 miles. Yet even at their most luminous, they are very hard to see, in part because they last for only a few thousandths of a second. Red in color and often bearing faint bluish tendrils extending downward, sprites come in several shapes, designated by colorful names like “carrot,” “angel,” and “columniform.”
*elves, like celestial halos, elves are circles of light that appear some 50 miles or more above thunderstorms. Triggered by lightning flashes far below, these ephemeral discs spread out radially across the bottom of the ionosphere in the briefest instant, expanding up to hundreds of miles in diameter in less than a millisecond. Experts believe elves are caused by lightning processes that accelerate electrons in the lower ionosphere.
* volcanic lightning, lightning-like discharges are sometimes observed during volcanic eruptions, with no thunderstorm anywhere nearby. Hundreds or even thousands of feet in length, these bolts can flash to the ground or remain entirely within the ash cloud above the volcano. Here, lightning flashes during an eruption of Japan’s Sakurajima Volcano in 1991.
How lightning initially forms is still a matter of debate. Scientists have studied root causes ranging from atmospheric perturbations, wind, humidity, atmospheric pressure, to the impact of solar wind and accumulation of charged solar particles. Ice inside a cloud is thought to be a key element in lightning development, and may cause a forcible separation of positive and negative charges within the cloud, thus assisting in the formation of lightning.
Of course, most lightning occurs inside thunderclouds but there are three parts to a storm – above, within and below a storm, and while scientists have been able to measure above and below a storm, it is still a mystery what happens within the strom – within the cloud. Several ideas have been suggested, including colliding raindrops, localized regions of concentrated charge, and avalanches of high-energy electrons initiated by cosmic rays from outer space.
The exact arrangement of charge in the clouds has not been determined, but one model hypothesizes that the upper regions of the clouds have a strong positive charge, the center has a strong negative charge, and the lower regions have a weak positive charge. This is based on the idea that heavier and larger particles tend to gain a negative charge while lighter particles tend to gain a positive charge in collisions. The charged particles then separate due to the differences in size and density, moving to certain levels of the cloud system. This model has been demonstrated consistently in laboratory simulations of the inside of a thunderhead. The amount of total charge and polarity is also affected by the temperature in the layer of the cloud, the content of the water particles, and several other conditions. This theory is the most widely accepted, although it is just one of many which attempt to explain the properties of the charge buildup in electrical storms.
The thunderstrom configeration of a positive charge above negative charge, is called a positive dipole. Wilson (1920) proposed a current flowing from the tops of thunderstorms to the upper atmosphere to supply the ‘fair weather current’ – fair weather is when the electrical state of the lower to middle atmosphere is in quasi-static equilibrium, meaning that the charge moving into a region equals the charge leaving the region – a simplified definition of fair weather would mean no thunderstorms around. Above the tops of the storms, a net positive current flows towards the electrosphere. Blakeslee (1989) discovered conduction currents averaging 1.7 A, with a maximum of 3.7 A.
Thunderclouds are a consequence of atmospheric instability and develop as warm, moist air near the earth rises and displaces the colder, denser air above. Thunderclouds are large atmospheric heat-engines with water vapour as the primary heat-transfer agent. They increase the local stability of the atmosphere and are believed to maintain the atmosphere’s electrical potential relative to the earth.
Earth has a magnetic field that permeates the atmosphere and extends above the atmosphere into space. The ionosphere is the region in the upper atmosphere where there are enough electrons and ions to make the atmosphere a reasonably good conductor. Solar radiation at extreme ultraviolet frequenceies is absorbed into the ionosphere through the process of photoionization. In fair weather the electrical state of the lower to middle atmosphere is in quasi-static equilibrium (the charge moving into a region equals the charge leaving the region).
Coulumb (1795) discovered that air is conductive. Peltier (1842) stated that the Earth is negativeley charged. Finally, Wilson (1920) completed the circuit concept by proposing that “a thunder-cloud or shower-cloud is the seat of an electromagnetic force which must cause a current to flow through the cloud between Earth’s surface and the upper atmosphere.” Positive and negative ions move in opposite directions under the influence of an electric field, so current flows in the atmosphere whenever an electric field is present. In fair weather atmosphere the relationship between currents and electric fields is given by Ohm’s law:
- where J, the current density, equals conductivity times the electric field.
In order to get a conventional spark, the kind that a spark plug makes, the electric field needs to surpass the conventional breakdown field, the point at which air loses its insulating properties and becomes capable of conducting electricity. For air, this is about 70,000 volts per inch at sea level. Thunderstorms can also generate big voltages.The voltages produced by the resulting charge separation are impressive, sometimes exceeding 100,000,000 volts.
The leader of a bolt of lightning can travel at speeds of 60,000 m/s, and can reach temperatures approaching 30,000 °C, 54,000 °F.
Lightning produces current that can be divided into those that directly transfer charge to Earth via ground flashes and those that are internal to the strom generator via cloud flashes. Livingston and Krider (1978) estimated that ground strikes produced an average current density of 3 nA m-2, resulting in a current of 3.5 A. Krehbiel (1981) estimated each cloud flash involves about 50-100 nA m-2 or a total current of 0.1-0.7 A.
There are over 16 million lightning storms every year.
At any time there are 1,000 thunderclouds continuously in progress over the surface of the earth. Solar heating warms the surface of the earth with a thermal input of 1kW m-2 and as the earth rotates around the sun new thunderclouds from in the subsolar area so that a wave of thunderstorms move westward every day.
Geological evidence of thunderstorms dates back 250 million years and scientists belive that thunderstorm activity has been taking place since the devlopment of the earth’s atmosphere – in fact lightning played a significant role in the modification of the early atmosphere and to the origin of life on the planet.
Active thunderclouds can extend from 3km in diameter to greater than 50km. Distrubances have lasted more than 48 hours and moved more than 2,000Km. The distance (in kilometres) to a lightning flash may be estimated by dividing the time delay (in seconds) between the flash and the thunder by 3. (If you hear thunder where the time delay is less than 30 seconds, you should find shelter.)
Because scientist are not yet sure how lightning gets started, I have included below one theory that speculates that incoming cosmic rays from outer space serve as the trigger.
Sources:
http://www.pbs.org/wgbh/nova/sciencenow/3214/02.html
The Electrical Nature of Storms, Donald MacDormand – Oxford University Press, USA
Lightning, Rudolf Golde
Categories: sustainable energy
