US Researchers Hope to Tap Ocean Flows for Electricity

Posted on May 24, 2008 by Rashid Faridi

The projects in Florida are the latest efforts to find alternative forms of energy to reduce the nation’s dependence on oil and other fossil fuels. VOA’s Brian Wagner has more in this Searching for Solutions report.

The same energy that drives ocean waves and currents may be a rich source of electrical power. Researchers in Florida say even gentle flows of two or three knots are enough to drive a propeller attached to an underwater turbine. Advocates say ocean power could be cheap and help replace oil or coal-based systems that are blamed for global warming.

Douglas Bedgood is president of Keys Hydro Power and says he wants to build a turbine farm in the Florida Keys, “We could upscale this to 10 feet [three meters] across and it would be perfect.”

The goal is to harness the energy produced by the rise and fall of waters during the tidal cycle. His group is working on a test turbine that it plans to submerge in a site about nine meters under water between two islands.

“By the end of 2008 or early 2009, we will have several [turbines] just to see how we can manage them as a group. Then another year after, it will be several hundred,” Bedgood said.

The first step, however, is to show authorities that the groundbreaking project will not damage wildlife or coastal resources in the popular tourist area. Bedgood says marine life should be unharmed. “For manatees and turtles, our turbines will be mounted up off the [ocean] floor, so they can maneuver through them. And the leading edges of any moving part will have foam rubber cushions on them,” he explains.

Alternative energy projects like this one aim to reduce existing strains on the earth’s resources, but they do raise concern about causing new problems. Kenny Broad is a professor at the Rosenstiel School for Marine and Atmospheric Science near Miami. He says new initiatives should proceed with caution.

“Take small steps at first, try to favor things that are reversible, as opposed to just going for it,” recommends Broad. “We are all attracted to clean technologies, and we need to develop and promote clean technologies, but in a responsible way.”

Similar projects are planned in Europe and other U.S. cities. Just 300 kilometers from Key West, researchers at Florida Atlantic University want to tap the powerful Gulf Stream current that brings warm water north into the Atlantic Ocean.

“So it is a significant velocity with the equivalent energy of some of the world’s richest energy sites,” says Rick Driscoll, who is head of the university’s Center for Ocean Energy Technology. He says one of the biggest challenges is developing equipment that can withstand the intense forces of the current. “It is a lot more challenging to put something in the ocean, and certainly any energy system to go in there has to work and be competitive with existing land-based technologies,” notes Driscoll.

He says more investment is needed for new technologies. “There is a lot of significant potential, but there is a limited supply of money out there right now,” he adds.

Driscoll says federal and state funding could help U.S. researchers perfect the new technologies and bring the benefits to other countries around the world.
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Water Pollution

Posted on May 24, 2008 by Rashid Faridi

When toxic substances enter lakes, streams, rivers, oceans, and other water bodies, they get dissolved or lie suspended in water or get deposited on the bed. This results in the pollution of water whereby the quality of the water deteriorates, affecting aquatic ecosystems. Pollutants can also seep down and affect the groundwater deposits.

Water pollution has many sources. The most polluting of them are the city sewage and industrial waste discharged into the rivers. The facilities to treat waste water are not adequate in any city in India. Presently, only about 10% of the waste water generated is treated; the rest is discharged as it is into our water bodies. Due to this, pollutants enter groundwater, rivers, and other water bodies. Such water, which ultimately ends up in our households, is often highly contaminated and carries disease-causing microbes. Agricultural run-off, or the water from the fields that drains into rivers, is another major water pollutant as it contains fertilizers and pesticides.

Domestic sewage refers to waste water that is discarded from households. Also referred to as sanitary sewage, such water contains a wide variety of dissolved and suspended impurities. Biochemical oxygen demand, or BOD

The amount of organic material that can rot in the sewage is measured by the biochemical oxygen demand. BOD is the amount of oxygen required by micro-organisms to decompose the organic substances in sewage. Therefore, the more organic material there is in the sewage, the higher the BOD. It is among the most important parameters for the design and operation of sewage treatment plants. BOD levels of industrial sewage may be many times that of domestic sewage. Dissolved oxygen is an important factor that determines the quality of water in lakes and rivers. The higher the concentration of dissolved oxygen, the better the water quality. When sewage enters a lake or stream, micro-organisms begin to decompose the organic materials. Oxygen is consumed as micro-organisms use it in their metabolism. This can quickly deplete the available oxygen in the water. When the dissolved oxygen levels drop too low, many aquatic species perish. In fact, if the oxygen level drops to zero, the water will become septic. When organic compounds decompose without oxygen, it gives rise to the undesirable odours usually associated with septic or putrid conditions.

It amounts to a very small fraction of the sewage by weight. But it is large by volume and contains impurities such as organic materials and plant nutrients that tend to rot. The main organic materials are food and vegetable waste, plant nutrient come from chemical soaps, washing powders, etc. Domestic sewage is also very likely to contain disease-causing microbes. Thus, disposal of domestic waste water is a significant technical problem. Sewage generated from the urban areas in India has multiplied manifold since 1947.

Today, many people dump their garbage into streams, lakes, rivers, and seas, thus making water bodies the final resting place of cans, bottles, plastics, and other household products. The various substances that we use for keeping our houses clean add to water pollution as they contain harmful chemicals. In the past, people mostly used soaps made from animal and vegetable fat for all types of washing. But most of today’s cleaning products are synthetic detergents and come from the petrochemical industry. Most detergents and washing powders contain phosphates, which are used to soften the water among other things. These and other chemicals contained in washing powders affect the health of all forms of life in the water.

Agricultural Run off
Eutrophication

When fresh water is artificially supplemented with nutrients, it results in an abnormal increase in the growth of water plants. This is known as eutrophication. The discharge of waste from industries, agriculture, and urban communities into water bodies generally stretches the biological capacities of aquatic systems. Chemical run-off from fields also adds nutrients to water. Excess nutrients cause the water body to become choked with organic substances and organisms. When organic matter exceeds the capacity of the micro-organisms in water that break down and recycle the organic matter, it encourages rapid growth, or blooms, of algae. When they die, the remains of the algae add to the organic wastes already in the water; eventually, the water becomes deficient in oxygen. Anaerobic organisms (those that do not require oxygen to live) then attack the organic wastes, releasing gases such as methane and hydrogen sulphide, which are harmful to the oxygen-requiring (aerobic) forms of life. The result is a foul-smelling, waste-filled body of water. This has already occurred in such places as Lake Erie and the Baltic Sea, and is a growing problem in freshwater lakes all over India. Eutrophication can produce problems such as bad tastes and odours as well as green scum algae. Also the growth of rooted plants increases, which decreases the amount of oxygen in the deepest waters of the lake. It also leads to the death of all forms of life in the water bodies.

The use of land for agriculture and the practices followed in cultivation greatly affect the quality of groundwater. Intensive cultivation of crops causes chemicals from fertilizers (e.g. nitrate) and pesticides to seep into the groundwater, a process commonly known as leaching. Routine applications of fertilizers and pesticides for agriculture and indiscriminate disposal of industrial and domestic wastes are increasingly being recognized as significant sources of water pollution.

The high nitrate content in groundwater is mainly from irrigation run-off from agricultural fields where chemical fertilizers have been used indiscriminately.

Industrial effluents

Waste water from manufacturing or chemical processes in industries contributes to water pollution. Industrial waste water usually contains specific and readily identifiable chemical compounds. During the last fifty years, the number of industries in India has grown rapidly. But water pollution is concentrated within a few subsectors, mainly in the form of toxic wastes and organic pollutants. Out of this a large portion can be traced to the processing of industrial chemicals and to the food products industry. In fact, a number of large- and medium-sized industries in the region covered by the Ganga Action Plan do not have adequate effluent treatment facilities. Most of these defaulting industries are sugar mills, distilleries, leather processing industries, and thermal power stations. Most major industries have treatment facilities for industrial effluents. But this is not the case with small-scale industries, which cannot afford enormous investments in pollution control equipment as their profit margin is very slender.

Effects of water pollution

The effects of water pollution are not only devastating to people but also to animals, fish, and birds. Polluted water is unsuitable for drinking, recreation, agriculture, and industry. It diminishes the aesthetic quality of lakes and rivers. More seriously, contaminated water destroys aquatic life and reduces its reproductive ability. Eventually, it is a hazard to human health. Nobody can escape the effects of water pollution.

The individual and the community can help minimize water pollution. By simple housekeeping and management practices the amount of waste generated can be minimized.

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Space Travels in Geology: Jupiter’s Moon Io: A Different Kind of Hell

Posted on May 23, 2008 by Rashid Faridi

Space Travels in Geology: Io: A Different Kind of Hell
Mary Caperton Morton
NASA/USGS/Tammy Becker and Paul Geissler
A mosaic basemap of Io was produced by compositing images from the Voyager 1 and Galileo missions.

In 1610, using one of the world’s first telescopes, Galileo discovered Jupiter’s moons: Io, Europa, Ganymede and Callisto. For the next several hundred years, astronomers assumed the four moons were similar to our own — icy, cold, pockmarked and geologically dead. But then in 1979, the Voyager probe flew by Io, the closest moon to Jupiter, and returned images of volcanic eruptions hundreds of kilometers high, larger than any ever seen in the solar system. In the 30 years since then, a series of observations has revealed Io to be an inferno more volatile than Dante himself imagined.

Io, a sulfurous rock about the size of Earth’s moon, is bursting with volcanoes. With more than 400 active vents spewing red-hot lava, the moon is by far the most geologically active body in our solar system. Some of Io’s most spectacular eruptions eject plumes of debris nearly 500 kilometers into outer space. Io’s surface churns so vigorously that the landscape is devoid of the impact craters that characterize our moon or planets such as Mars. Instead, Io’s tumultuous surface is covered with vast calderas the size of Texas, huge sulfurous lakes and extensive lava flows.

Io’s volcanism is driven by a different mechanism than Earth’s. While Earth’s internal heat comes from radioactive isotope decay, Io’s main source comes from friction generated by the strong gravitational pull of massive Jupiter and nearby moons Europa and Ganymede. As Io rotates, gravity’s pull creates tidal bulges that are similar to ocean tides, but act instead on waterless Io’s crustal rocks. These bulges can be 100 meters high and they move as the moon spins. Such extreme flexing of the crust creates enormous friction and heat, which has melted most of Io’s interior mantle and iron sulfide core. Known as tidal heating, scientists estimate that this friction generates heat 10 times greater than is found in Earth’s core.


NASA’s Galileo spacecraft captured this image of a volcanic eruption on Io in 2000. The dark areas are lava flows.

Tidal heating on Io produces the hottest lava found anywhere in the solar system. Infrared measurements have shown vent temperatures in excess of 1,725 degrees Celsius. That’s nearly the hottest temperature in our solar system, second only to the surface of the sun. These blistering vents are probably basaltic, while temperatures at some of Io’s cooler volcanoes are likely to extrude molten sulfur as well, according to Alfred McEwan of the University of Arizona in Tucson and colleagues who reported on the moon’s makeup in Science in 1998.

When the Galileo space probe visited Io in 1995, it accidentally flew through one of the moon’s massive eruption plumes. The probe survived because the plume turned out to be composed of frozen sulfur dioxide snowflakes. Although Io’s volcanoes are scorching hot, because of its distance from the sun and a lack of atmosphere, Io’s surface is actually frigid. The plumes form when underground pools of liquid sulfur dioxide come into contact with hot zones and the sulfur explodes to the surface as a column of superheated gas, similar to Earth’s geysers. But upon contact with surface temperatures as low as minus 150 degrees Celsius, the gas condenses into sulfur snowflakes, which shoot, unimpeded by gravity or atmosphere, hundreds of kilometers above Io’s surface. The Galileo probe flew by Io 10 times during its seven-year visit with Jupiter and observed these sulfurous geysers erupting from as many as 80 vents, some for months at a time.
NASA/JPL
Two sulfurous eruptions are visible on Io in this composite image from Galileo. On the horizon, a bluish plume rises about 140 kilometers above the surface of a volcanic caldera. Near the night/day shadow line, the ring-shaped Prometheus plume rises about 75 kilometers. The Prometheus plume is visible in every image ever taken of the region dating back to the Voyager flybys in 1979.

Flying through the plume was the least of Galileo’s problems. The space probe’s mission was also fraught with technical problems that made it difficult to gather much information. Io orbits closer to Jupiter than our moon does to Earth, placing it within one of Jupiter’s most intense radiation belts. Debris from Io’s plumes and volcanoes is constantly stripped away by Jupiter, creating a cloud of ions around Jupiter that further inflate the colossal planet’s unusually large magnetic field. This interaction between Io and Jupiter generates an electric current of more than 1 trillion watts — high enough to severely limit the amount of time the Galileo probe could spend gathering information near the moon. After the difficulties of the last Galileo mission, NASA has no further plans to send another probe to explore Jupiter’s moons, so Io is now observed from Earth-based telescopes and by the Hubble Space Telescope.

In 2001, the Keck II telescope on the big island of Hawaii observed the largest recorded volcanic eruption anywhere in the solar system on Io. In an article published in Icarus, researcher Franck Marchis of the University of California at Berkeley called the eruption “the most energetic ever seen.” Fountains of fiery molten lava several kilometers high were observed and extensive surface flows dwarfed eruptions from Earth’s largest volcano, Mount Etna. The eruption changed the landscape of Io dramatically in a matter of days, creating new features that were appropriately named for places in Dante’s Inferno.
JPL


Though unknown, researchers have inferred Io’s interior characteristics from gravity fields and magnetic measurements. Io’s radius is 1,821 kilometers, similar to our moon, and it has a metallic (mostly iron and nickel) core. The core is surrounded by a rock shell (shown in brown) that is thought to extend to the surface.

The Hubble Space Telescope has also photographed Io, producing detailed images of the moon’s unique landscape. In addition to volcanoes, Io’s surface is also dotted with massive non-volcanic mountains. Unlike on Earth, Io’s mountains are not the result of tectonic activity. Instead, as the layers of new volcanic material extrude onto the moon’s surface, older deposits of lava are buried and as they sink are compressed. The compressive forces build up until the pressure is relieved through thrust faulting and uplift of large blocks of crustal rock, as reported in 1998 in Science by Paul Schenk of the Lunar and Planetary Institute in Houston, Texas, and Mark Bulmer of the Smithsonian National Air and Space Museum in Washington, D.C. Io’s tallest mountain, Euboea Montes, was created through such a process and, at 15.9 kilometers, it would tower over Earth’s tallest mountains. One Hubble image of Euboea Montes showed a massive landslide on the mountain’s northern flank that produced a Pennsylvania-sized debris apron, by far the largest recorded slide in the solar system.

For such a tiny place, Io holds a lot of solar system records: most volcanoes, hottest temperatures and biggest landslide. Exploration of Io over the past few decades has revealed an extreme, geologically unique world far different from Earth or anywhere else in the solar system. Given its volatility and extreme temperatures, maybe traveling there is best left to the imagination.
source:http://www.geotimes.org/may08/article.html?id=feature_io.html

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Sesmic Waves, Earthqukes and Interior of the Earth

Posted on May 22, 2008 by Rashid Faridi

What Is Seismology?

Seismology is the study of earthquakes and seismic waves that move through and around the earth. A seismologist is a scientist who studies earthquakes and seismic waves.

What Are Seismic Waves?

Seismic waves are the waves of energy caused by the sudden breaking of rock within the earth or an explosion. They are the energy that travels through the earth and is recorded on seismographs.

Types of Seismic Waves

There are several different kinds of seismic waves, and they all move in different ways. The two main types of waves are body waves and surface waves. Body waves can travel through the earth’s inner layers, but surface waves can only move along the surface of the planet like ripples on water. Earthquakes radiate seismic energy as both body and surface waves.

Body Waves

Traveling through the interior of the earth, body waves arrive before the surface waves emitted by an earthquake. These waves are of a higher frequency than surface waves.

P Waves

The first kind of body wave is the P wave or primary wave. This is the fastest kind of seismic wave, and, consequently, the first to ‘arrive’ at a seismic station. The P wave can move through solid rock and fluids, like water or the liquid layers of the earth. It pushes and pulls the rock it moves through just like sound waves push and pull the air. Have you ever heard a big clap of thunder and heard the windows rattle at the same time? The windows rattle because the sound waves were pushing and pulling on the window glass much like P waves push and pull on rock. Sometimes animals can hear the P waves of an earthquake. Dogs, for instance, commonly begin barking hysterically just before an earthquake ‘hits’ (or more specifically, before the surface waves arrive). Usually people can only feel the bump and rattle of these waves.

P waves are also known as compressional waves, because of the pushing and pulling they do. Subjected to a P wave, particles move in the same direction that the the wave is moving in, which is the direction that the energy is traveling in, and is sometimes called the ‘direction of wave propagation’.


Figure 1 – A P wave travels through a medium by means of compression and dilation. Particles are represented by cubes in this model. Image ©2000-2006 Lawrence Braile, used with permission.

S Waves

The second type of body wave is the S wave or secondary wave, which is the second wave you feel in an earthquake. An S wave is slower than a P wave and can only move through solid rock, not through any liquid medium. It is this property of S waves that led seismologists to conclude that the Earth’s outer core is a liquid. S waves move rock particles up and down, or side-to-side–perpindicular to the direction that the wave is traveling in (the direction of wave propagation).


Figure 2 – An S wave travels through a medium. Particles are represented by cubes in this model. Image ©2000-2006 Lawrence Braile, used with permission.

Surface Waves

Travelling only through the crust, surface waves are of a lower frequency than body waves, and are easily distinguished on a seismogram as a result. Though they arrive after body waves, it is surface waves that are almost enitrely responsible for the damage and destruction associated with earthquakes. This damage and the strength of the surface waves are reduced in deeper earthquakes.

Love Waves

The first kind of surface wave is called a Love wave, named after A.E.H. Love, a British mathematician who worked out the mathematical model for this kind of wave in 1911. It’s the fastest surface wave and moves the ground from side-to-side. Confined to the surface of the crust, Love waves produce entirely horizontal motion.


Figure 3 – A Love wave travels through a medium. Particles are represented by cubes in this model. Image ©2000-2006 Lawrence Braile, used with permission.

Rayleigh Waves

The other kind of surface wave is the Rayleigh wave, named for John William Strutt, Lord Rayleigh, who mathematically predicted the existence of this kind of wave in 1885. A Rayleigh wave rolls along the ground just like a wave rolls across a lake or an ocean. Because it rolls, it moves the ground up and down, and side-to-side in the same direction that the wave is moving. Most of the shaking felt from an earthquake is due to the Rayleigh wave, which can be much larger than the other waves.

Figure 4 – A Rayleigh wave travels through a medium. Particles are represented by cubes in this model. Image ©2000-2006 Lawrence Braile, used with permission.

links

http://www.geo.mtu.edu/UPSeis/waves.html

en.wikipedia.org/wiki/Seismic_wave

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