'Fish Technology' Draws Renewable Energy From Slow Water Currents; 'Vortex Induced Vibrations'

Underwatertimes.com News ServiceNovember 22, 2008 16:33 EST

Anne Arbor, Michigan -- Slow-moving ocean and river currents could be a new, reliable and affordable alternative energy source. A University of Michigan engineer has made a machine that works like a fish to turn potentially destructive vibrations in fluid flows into clean, renewable power.
The machine is called VIVACE. A paper on it is published in the current issue of the quarterly Journal of Offshore Mechanics and Arctic Engineering.
-->
window.google_render_ad();
VIVACE is the first known device that could harness energy from most of the water currents around the globe because it works in flows moving slower than 2 knots (about 2 miles per hour.) Most of the Earth's currents are slower than 3 knots. Turbines and water mills need an average of 5 or 6 knots to operate efficiently.
VIVACE stands for Vortex Induced Vibrations for Aquatic Clean Energy. It doesn't depend on waves, tides, turbines or dams. It's a unique hydrokinetic energy system that relies on "vortex induced vibrations."
Vortex induced vibrations are undulations that a rounded or cylinder-shaped object makes in a flow of fluid, which can be air or water. The presence of the object puts kinks in the current's speed as it skims by. This causes eddies, or vortices, to form in a pattern on opposite sides of the object. The vortices push and pull the object up and down or left and right, perpendicular to the current.
These vibrations in wind toppled the Tacoma Narrows bridge in Washington in 1940 and the Ferrybridge power station cooling towers in England in 1965. In water, the vibrations regularly damage docks, oil rigs and coastal buildings.
"For the past 25 years, engineers---myself included---have been trying to suppress vortex induced vibrations. But now at Michigan we're doing the opposite. We enhance the vibrations and harness this powerful and destructive force in nature," said VIVACE developer Michael Bernitsas, a professor in the U-M Department of Naval Architecture and Marine Engineering.
Fish have long known how to put the vortices that cause these vibrations to good use. "VIVACE copies aspects of fish technology," Bernitsas said. "Fish curve their bodies to glide between the vortices shed by the bodies of the fish in front of them. Their muscle power alone could not propel them through the water at the speed they go, so they ride in each other's wake."
This generation of Bernitsas' machine looks nothing like a fish, though he says future versions will have the equivalent of a tail and surface roughness a kin to scales. The working prototype in his lab is just one sleek cylinder attached to springs. The cylinder hangs horizontally across the flow of water in a tractor-trailer-sized tank in his marine renewable energy laboratory. The water in the tank flows at 1.5 knots.
Here's how VIVACE works: The very presence of the cylinder in the current causes alternating vortices to form above and below the cylinder. The vortices push and pull the passive cylinder up and down on its springs, creating mechanical energy. Then, the machine converts the mechanical energy into electricity.
Just a few cylinders might be enough to power an anchored ship, or a lighthouse, Bernitsas says. These cylinders could be stacked in a short ladder. The professor estimates that array of VIVACE converters the size of a running track and about two stories high could power about 100,000 houses. Such an array could rest on a river bed or it could dangle, suspended in the water. But it would all be under the surface.
Because the oscillations of VIVACE would be slow, it is theorized that the system would not harm marine life like dams and water turbines can.
Bernitsas says VIVACE energy would cost about 5.5 cents per kilowatt hour. Wind energy costs 6.9 cents a kilowatt hour. Nuclear costs 4.6, and solar power costs between 16 and 48 cents per kilowatt hour depending on the location.
"There won't be one solution for the world's energy needs," Bernitsas said. "But if we could harness 0.1 percent of the energy in the ocean, we could support the energy needs of 15 billion people."
The researchers recently completed a feasibility study that found the device could draw power from the Detroit River. They are working to deploy one for a pilot project there within the 18 months.

Commission: Europe's Seas and Coasts Under Threat from Climate Change and Pollution

Underwatertimes.com News ServiceMarch 22, 2007 11:54 EST






Brussels, Belgium -- Protecting the delicate ecosystem of Europe's seas and coastal regions was the subject of a recent hearing in Parliament. A Commission Green paper last year identified the threat to Europe's coast of rising sea levels, pollution and over fishing. This is not a small problem - the EU has a coastline longer than Africa and the EU's sea area (territorial waters of members) is larger than its land mass. The hearing on 20 March brought together MEPs, experts and the EU's Fisheries Commissioner.
Emissions trading for ships
-->
window.google_render_ad();
The 27 countries of the European Union are surrounded by four seas and two oceans. If world temperatures continue to increase this will bring rising sea levels - the impact of which could be serious for Europe. Ironically, emissions from ships (like aircraft) are not covered by the Kyoto protocol on pollution. In fact, since 1990 emissions from marine transport have risen 45%. As Jorgo Chatzimarkakis of the Liberal ALDE group remarked at the hearing "so far we have been ignoring the fact that sea transport – while it is true that it accounts for a greater amount of transported goods– emits more CO2 than air traffic". Socialist Willi Piecyk, rapporteur for the transport committee, said that "we have to consider emissions trading even for ships and vessels."
Fishermen: friend or foe of Europe's coasts?
Simon Cripps of the World Wide Fund for Nature was unequivocal on this point at the hearing. He said that commercial fisheries had put the whole ecosystem at risk and that “illegal, unreported and unregulated fishing is a significant threat to maritime biodiversity."
Peter Mortensen, a former chair of the "Social Dialogue Committee for Maritime Fisheries" said that "there are a number of paragraphs in the Green Paper that seem to be more concerned with fish than with fishermen”. He pointed out that working conditions for fishermen are very difficult and that wages are very low. In total 5 million jobs in the EU are linked to marine activity of one kind or another.
Town planning for the seas
One solution could be "Marine Spatial Planning", a kind of town planning for the seas. This approach identifies different areas and recommends what activities would be best suited for the region. It also could be used find "at risk" zones.
This could have an impact on the possible development of an anti-global warming policy of "CO2 sequestering". This involves hiding CO2 by pumping it underground. Frederico Cardicos of the Azores regional administration warned however that this could "endanger a largely unknown ecosystem".
Seán Ó'Neachtain of the Union of Europe for the Nations Group warned against strict EU legislation. He said that existing regulation was impinging on communities of sparsely populated coastal regions and that “people are not taken into the equation”.
However, no matter what approach the EU takes all speakers were agreed that without international cooperation the welfare of the world's oceans cannot be guaranteed. As Karin Roth, Parliamentary State Secretary for the German Presidency put it: "the sea is globally connected. There won’t be the division into "clean EU-sea and the non-European-Sea".
What happens next?
The hearing brought together five of Parliament's Committees: Transport, Environment, Industry, Fisheries and Regional Development. On 4-5 June the Transport Committee will consider a draft report on this subject and the Plenary session of 18-21 June will vote on the report if it is ready. The Commission's consultation with interested parties is open until the end of June. Before the end of 2007 the Commission will address a Communication to the Council and Parliament summarising the results of the consultation process and proposing the way forward.

Study: First Ever Evidence Of Natural Disease Resistance In Tropical Corals

Underwatertimes.com News ServiceNovember 21, 2008 18:33 EST

Researchers have found the first ever evidence of natural disease resistance in corals
Boston, Massachusetts -- In recent years, tropical coral reefs have become drastically altered by disease epidemics. In a new study published by PLoS ONE, lead author Steven V. Vollmer, assistant professor of biology at the Marine Science Center at Northeastern University, finds that acroporid corals listed on the US Endangered Species List due to epidemics of White Band Disease can recover because up to six percent of the remaining corals are naturally resistant to the disease. This is the first evidence of natural disease resistance in tropical reef corals.
The Carribean-wide mass die-offs of acroporid corals and urchins have been major contributors to the rapid decline of coral reefs. Reef-building corals have generally been susceptible to the global rise in marine diseases. As foundation species on tropical reefs, the impacts of White Band Disease (WBD) and other coral diseases have rippled throughout the ecosystem. Recuperation of these formerly dominant corals has been slow.
-->
window.google_render_ad();
Despite its extreme impacts, much about the causes and ecology of WBD remains poorly understood.
“Understanding disease resistance in these corals is a critical link to restoring populations of these once prevailing corals throughout their habitat,” said Vollmer. “Our study has shown that there are disease resistant corals, which means that these corals and thus the shallow water reefs of the Caribbean can be recovered.”
The study, titled “Natural Disease Resistance in Threatened Staghorn Corals” examines the potential for natural resistance to WBD in the staghorn coral. Using genotype information and field monitoring of WBD, the study found that six percent of staghorn coral genotypes are naturally resistant to WBD.
These resistant staghorn coral strains might explain why pockets of coral have been able to survive the WBD epidemic. Identifying, protecting and farming these disease resistant corals provides a clear avenue to recover these corals.

Beaked Whales Perform Extreme Dives To Hunt Deepwater Prey

A Cuvier's beaked whale breaches in the Ligurian Sea. (Photo courtesy of Natacha Aguilar de Soto, University of La Laguna, Spain)

ScienceDaily (Oct. 20, 2006) — A study of ten beaked whales of two poorly understood species shows their foraging dives are deeper and longer than those reported for any other air-breathing species. This extreme deep-diving behavior is of particular interest since beaked whales stranded during naval sonar exercises have been reported to have symptoms of decompression sickness. One goal of the study was to explore whether the extreme diving behavior of beaked whales puts them at a special risk from naval sonar exercises.

Scientists from the Woods Hole Oceanographic Institution (WHOI) teamed with colleagues from the University of La Laguna in Spain, the University of Aarhus in Denmark, Bluwest and the NATO Undersea Research Centre in Italy. The team studied Cuvier’s beaked whales (Ziphius cavirostris) and Blainville’s beaked whales (Mesoplodon densirostris) in Italian and Spanish waters using a non-invasive digital archival tag or D-tag developed at WHOI by one of the authors, engineer Dr. Mark Johnson. Their findings are reported in the current online issue of the Journal of Experimental Biology.
The D-tag, about the size of a sandal, has a variety of sensors to record sounds and movements, and is attached to the animals with four small suction cups using a handheld pole. It is programmed to release from the animal within a day and is recovered with help from a VHF radio beacon in the tag. The 3-6 Gbytes of audio and sensor data are then off-loaded to a computer for anaylsis.
Dr. Peter Tyack, a senior scientist in the WHOI Biology Department and lead author of the study, says they found some similarities with the much better studied sperm whales and elephant seals, but also some major differences. “These two beaked whale species make long, very deep dives to find food, and then make shallow dives and rest near the surface. By contrast, sperm whales and elephant seals can make a series of deep dives without the need for prolonged intervals between deep dives. We think that beaked whales return to the surface after deep dives with an oxygen debt and need to recover before their next deep dive."
Tyack said the team's analysis suggests that the normal deep diving behavior of beaked whales does not pose a decompression risk. "Rather, it appears that their greatest risk of decompression sickness would stem from an atypical behavioral response involving repeated dives at depths between 30 and 80 meters (roughly100 to 250 feet)," Tyack said. "The reason for this is that once the lungs have collapsed under pressure, gas does not diffuse from the lungs into the blood. Lung collapse is thought to occur shallower than 100 meters (330 feet), so deeper parts of the dive do not increase the risk of decompression problems. However, if beaked whales responded to sonars with repeated dives to near 50 meters (165 feet), this could pose a risk.”
The Cuvier’s beaked whales were tagged in June 2003 and 2004 in the Ligurian Sea off Italy, while the Blainville’s beaked whales were tagged in October 2003 and 2004 off the island of El Hierro in the Canary Islands. Both field sites were in deep water, between 700 and 2,000 meters (2,300 to 6,500 feet) with steep bottom topography. Tags were attached to seven Cuvier’s beaked whales and three Blainville’s beaked whales, and they remained attached to the whales for an average of 8 hours and 12 hours, respectively.
“Although this study was limited to ten animals, it provides the first detailed information available about the diving, acoustic, and movement behavior of two species of beaked whales,” Tyack said. “Shallow dives seem to be performed between deep dives, and both species dive very deep to hunt for prey. They seem to spend equal time ascending and descending in shallow dives, but take longer to ascend from deep dives.”
The slow ascent from deep dives is a major mystery. “Why don’t they stay longer at depth to feed, and then come up more rapidly?” Tyack said. “Avoidance of decompression problems by slow ascent, as in scuba divers, cannot account for this behavior if the lungs of these breathhold diving marine mammals are collapsed at depths greater than 100 meters (330 feet).”
Very little is known about these two species of beaked whales since they spend little time on the surface and it is difficult to tag them. The much better studied sperm whale can dive for more than one hour to depths greater than 1,200 meters (roughly 4,000 feet), but typically dives for 45 minutes to depths of 600-1,000 meters (1,968 to 3,280 feet). Elephant seals, another well known deep diver, can spend up to two hours in depths over 1,500 meters (nearly 5,000 feet), but typically dive for only 25-30 minutes to depths of about 500 meters (1,640 feet). Marine mammals seem to have adapted to the effects of diving deep and optimizing their oxygen supplies.
The Cuvier’s beaked whales dove to maximum depths of nearly 1,900 meters (about 6,230 feet) with a maximum duration of 85 minutes, while the Blainville’s beaked whales dove to a maximum depth of 1,250 meters (4,100 feet) and 57 minutes in duration. The dives near 1,900 meters constitute the deepest confirmed dives reported from any air-breathing animal. While people often focus on the maximum dives of breathhold diving animals, breathhold divers are not at a track meet and it is the average of the deep foraging dives that is more important. Regular echolocation clicks and buzzes and echoes of what appears to be prey were recorded on the tags, suggesting the whales were hunting for food on the deep dives. The average foraging dive for Cuvier’s beaked whale went to a depth of 1,070 meters (about 3,500 feet) with a duration of 58 minutes, while the Blainville’s beaked whales dove to an average depth of 835 meters (2,740 feet) and 46.5 minutes in duration. These represent the deepest and longest average dives reported for any breathhold-diving animal.
These two beaked whale species have been reported to mass strand during naval sonar exercises in the area. It is unclear how these beaked whale species respond to the sonar sounds and whether their responses cause physiological changes that increase the risk that they will strand and die. This study suggests the paradoxical result that even though beaked whales are extreme divers, their normal diving behavior does not seem to put them at greater physiological risk for sonar exposure. Rather it suggests that physiological risk would stem from a specific behavioral response to the sonars.
“No matter what the precise cause of the strandings is, we need to develop effective mitigation strategies to reduce the accidental exposure of beaked whales to bay sonar,” Tyack said. “The information in this study provides critical data to design efficient acoustic and visual detection methods for these at-risk species of marine mammals.”
Funding for the tag development was provided by a Cecil H. and Ida M. Green Technology Innovation Award at WHOI and the U.S. Office of Naval Research. Funding for field work was provided by the Strategic Environmental Research and Development Program (SERDP), the National Ocean Partnership Program, the Packard Foundation, the Canary Islands Government, and the Spanish Ministry of Defense. Fieldwork support was provided by BluWest, NATO Undersea Research Center, and the Government of El Hierro.

Ecologists Home In On How Sperm Whales Find Their Prey

ScienceDaily (May 29, 2006) — Ecologists have at last got a view of sperm whales' behaviour during their long, deep dives, thanks to the use of recently developed electronic "dtags". According to new research published in the British Ecological Society's Journal of Animal Ecology, sperm whales – like bats – use echolocation consistently to track down their prey at depth.

Working in the Atlantic, the Gulf of Mexico and the Ligurian Sea, scientists from Woods Hole Oceanographic Institution and the University of St Andrews attached acoustic recording tags to the dorsal surface of sperm whales with suction cups. The whales were then tracked acoustically with a towed hydrophone array.
The researchers used the tags to record the sounds that sperm whales produce while foraging. As sperm whales descended from the surface, they emitted a regular series of "clicks". When the whales reach the bottom of their dive, these clicks are emitted more often, eventually merging together to form "buzzes" of sound. This pattern reflects the whales homing in on cephalopods such as squid, with the buzzes reflecting the animals' final approach when detailed information on the squid's position and movement are required, the researchers believe.
Dr Stephanie Watwood and colleagues found that sperm whales produced buzzes on every deep dive they made, in all three locations, suggesting that they are highly successful at locating prey in the dark ocean depths.
The sperm whale is the world's largest deep-diving toothed whale, feeding mainly on squid, but until now little has been known about the timing of prey detection and capture during dives.
"Due to the difficulty of observing sperm whales during their long, deep dives, little has been known about their subsurface behaviour, giving rise to an array of speculations on how sperm whales find prey, including luring, touch, passive listening, echolocation and vision. Recording vocalisations of diving sperm whales presents a non-invasive opportunity to document feeding activity." says Watwood.

Scientists Discover New Life In Antarctic Deep Sea

This carnivorous moonsnail lives in the Antarctic deep sea. It can detect food from a wide distance and will moved towards it. Polyps, covering its shell, use the moonsnail as transport to food sources. (Credit: Image courtesy of British Antarctic Survey)

ScienceDaily (May 17, 2007) — Scientists have found hundreds of new marine creatures in the vast, dark deep-sea surrounding Antarctica. Carnivorous sponges, free-swimming worms, crustaceans, and molluscs living in the Weddell Sea provide new insights into the evolution of ocean life.

Reporting this week in the journal Nature, scientists describe how creatures in the deeper parts of the Southern Ocean - the source for much of the deep water in the world ocean -- are likely to be related to animals living in both the adjacent shallower waters and in other parts of the deep ocean.
A key question for scientists is whether shallow water species colonised the deep ocean or vice versa. The research findings suggest the glacial cycle of advance and retreat of ice led to an intermingling of species that originated in shallow and deep water habitats.
Lead author Professor Angelika Brandt from the Zoological Institute and Zoological Museum, University Hamburg says,
"The Antarctic deep sea is potentially the cradle of life of the global marine species. Our research results challenge suggestions that the deep sea diversity in the Southern Ocean is poor. We now have a better understanding in the evolution of the marine species and how they can adapt to changes in climate and environments."
Dr Katrin Linse, marine biologist from British Antarctic Survey, says,
"What was once thought to be a featureless abyss is in fact a dynamic, variable and biologically rich environment. Finding this extraordinary treasure trove of marine life is our first step to understanding the complex relationships between the deep ocean and distribution of marine life."
Three research expeditions, as part of the ANDEEP project (Antarctic benthic deep-sea biodiversity), onboard the German research ship Polarstern took place between 2002 and 2005. An international team from 14 research organisations investigated the seafloor landscape, its continental slope rise and changing water depths to build a picture of this little known region of the ocean. They found over 700 new species.

Sounds From the Sea Acoustical Oceanographers Record Noises in the Deep

July 1, 2006 — Manmade and natural sounds, from boat engines to rainfall, sound different below the sea surface. To study their impact of noise on marine life, scientists are submerging devices called Passive Aquatic Listeners, or PALs, at depths of up to hundreds of meters deep in oceans around the globe. PALs could also help track whales and other marine life.

What do boats, whales and rainfall sound like from underneath the surface of the sea? How does it affect everything that lives down there?
Jeffrey Nystuen, a physical and acoustical oceanographer at University of Washington in Seattle developed PALs, or Passive Aquatic Listeners.
"By listening passively to the underwater sound field, we learn a lot about the environment," Nystuen tells DBIS.
Researchers submerge PALs from 10 to hundreds of meters below the sea's surface. They record a few seconds of sound about every 10 minutes. Nystuen says: "You can listen for bubbles. You can listen for whales. You can listen for ships and sonars."
PALs have been submerged at locations around the world and are in place for one year. The recordings can help scientists measure wind speed or rainfall at sea -- and learn more about the wildlife. They can also help biologists identify when and where there are large groups of whales and other marine life.
Other scientists say the impacts of man-made sounds on the marine environment are of a concern and passive acoustic monitoring is a valuable tool.
show background -->
BACKGROUND: Physical oceanographer Jeff Nyustuen is giving scientists and managers a way to sift through and identify the sounds present in various marine ecosystems. Passive Aquatic Listeners (PALS) are devices that sink ten to thousands of meters below the water surface and are set to listen for a few seconds every few minutes. PALs can identify sounds coming from such things as ships, whales, volcanic eruptions, rainfall and breaking waves. The result is a record of all the noise and its intensity in the ocean environment, which can help biologists sort out what levels of noise go unnoticed, or can cause harm to marine mammals, for example.
HOW IT WORKS: PALs don't try to record every single sound in the ocean. That would take too much memory. Instead, Nyusten is developing software that allows the PALs to sift through the racket, identify and sort sound sources by frequencies as they are received.
ABOUT SOUND: Sound waves are pressure waves: the result of a vibrating object that creates a disturbance in the surrounding air. For instance, when the telephone rings, the ringer vibrates very quickly, sending energy radiating outward through the air. These vibrations disturb the molecules that make up the air. The air molecules push closer together as the object moves one way ý an effect known as compression -- and then create a space between themselves and the vibrating object as it moves the other way, called rarefaction. The motion disturbs the neighboring molecules in turn, creating an outward ripple effect, much like a stone cast in a quiet pond will cause waves to ripple outward from the spot where the stone hit.
WHAT'S YOUR FREQUENCY? All sound waves have wavelength and frequency. The distance between compressions determines the wavelength. Objects that vibrate very quickly create short wavelengths because there is very little space between the compressions, creating a high-pitched sound. Objects that vibrate very slowly create long wavelengths because the compressions are spaced further apart. This creates a low-pitched sound. Frequency measures how many crests, or compressions, occur within one second; the measurement of this speed of vibration is called a Hertz, and 1 Hertz is equivalent to 1 vibration per second. Pitch simply means those frequencies within the range of human hearing (from about 20 Hertz to 20,000 Hertz). The faster the rate of vibration, the higher the pitch; the slower the rate of vibration, the lower the pitch.
SOUND SENSE: Bats emit a series of ultrasonic pulses that bounce off objects in its environment. How long it takes for the sound to be reflected back to the bat indicates how close (or far) a given object might be, enabling the bat to orient itself as it flies, and to detect food. Modern sonar technology is based on the same principle. The more feedback the bat receives, in terms of incoming reflections, the more accurately it can pinpoint a given object's location That's why the rate of the ultrasonic calls increases as the bat nears its prey, climaxing into a "feeding buzz" as the bat locks in on its target and prepares to strike. In contrast, whales appear to use sounds (or "songs") to communicate, emitting a complex sequence of low moans, high squeals and clicking noises that can last as long as 30 minutes. The songs appear to be related to mating cycles.
STOP THAT RACKET: Noise cancellation tries to block the unwanted sound at its source, rather than merely trying to prevent it from entering our ears. If we add two waves together, and the peaks of one line up with the valleys of the other, they will cancel each other out. Digital signal processors (DSPs) are microelectronic devices that determine which sound wave is required to cancel the unwanted sound wave (noise). It then creates that sound and amplifies it through speakers or headphones. The end result is near silence. Most cell phones, CD players, and hearing aids now contain one or more DSP devices.
The American Astronomical Society and the Acoustical Society of America contributed to the information contained in the video portion of this report.