Slideshow." data-pin-do="buttonBookmark">
TIDAL TURBINE: Verdant Power's kinetic hydropower underwater turbines are designed to generate electricity from the water currents of tides, rivers and man-made channels.
For more images, view our Extreme Tech Slideshow.
Image: Courtesy of Verdant Power
-
The Best Science Writing Online 2012
Showcasing more than fifty of the most provocative, original, and significant online essays from 2011, The Best Science Writing Online 2012 will change the way...
Read More »
Additional images of tidal and wave energy technologies can be found in our Extreme Tech Slideshow.
Thirty feet (nine meters) below Manhattan's East River, next to Roosevelt Island, six turbines—each 16 feet (five meters) in diameter, churning at a peak rate of 32 revolutions per minute—stand at attention on the riverbed. The turbines—which belong to New York City-based Verdant Power, Inc., —are built on a swiveling platform that keeps their nose cones facing the tide, whether it's coming in or going out. Resembling an underwater wind farm, these kinetic hydropower systems use gearboxes and speed increasers—which convert the slower rotating rotor into a faster rotating generator—to transform each turbine's mechanical power into electricity.
Verdant's turbines require tides that move at least six feet per second in order to generate enough energy for them to be cost-effective, and the East River is more than obliging. "The East River is a good tidal channel that links the Long Island Sound to the ocean," says Trey Taylor, the company's president and head of market development. "Plus, New York is an expensive place to buy power, so it would be easier here to prove that this could help."
A few dozen feet away from the closest turbine, an onshore control room gets a feed of the energy created by the entire cluster. To prove that this energy could be usable for local businesses, Verdant last year sent a test transmission of electricity to a supermarket and parking garage on Roosevelt Island that were willing to participate in the Roosevelt Island Tidal Energy project.
The Earth's oceans, pushed by wind and tugged by the moon and sun, ebb and flow over more than 70 percent of the planet, but only recently has technology emerged to finally harness some of that kinetic energy as usable power for us landlubbers. Underwater turbines, submerged "wind" farms and wave-riding electrical generators are being tested around the world, with new advances in technology promising relief for overworked energy utilities. "We consider wave energy to be more predictable than wind," says Phil Metcalf, CEO of Edinburgh-based Pelamis Wave Power, Ltd., a company taking a different approach than Verdant in developing ocean power–utilizing devices. "You look at the ocean 1,000 miles out, you'll get a good idea of what to expect over the next 24 to 48 hours. We think it's actually going to be easier to dispatch to the grid."
Pelamis's devices are big red tubes, each 426.5 feet (130 meters) long, 13 feet (about four meters) in diameter, weighing around 750 tons (635 metric tons), and with a life expectancy of up to 20 years. They flex as the ocean swells around them. The wave-induced motion of the tubes' joints is resisted by hydraulic rams, which pump high-pressure fluid through hydraulic motors that drive electrical generators to produce electricity. Power from all the joints is fed down a single umbilical cable to a junction on the seabed. Three of the tubes, which work best at a depth of 165 to 230 feet (50 to 70 meters) and roughly 3.7 miles (six kilometers) from the shore, can produce up to 2.25 megawatts.
Pelamis—which until September had been called Ocean Power Delivery—has taken its prototype through about 2,000 hours of testing at the European Marine Energy Center's wave test site near Scotland's Orkney Islands. Three additional machines will form the initial phase of Agucadoura, the world's first commercial wave farm, in April off the coast of Portugal, a project developed by Portuguese utility Enersis, a subsidiary of Babcock and Brown. Pelamis is negotiating with other utilities and governments as well, with future deployments depending on how well the Portuguese project is able to turn waves of water into currents of electricity.
See what we're tweeting about
13 Comments
Add CommentI think there is a mistake where it says "That said, a rough cost estimate for Verdant's marine renewable energy technology is up to $3,600 per kilowatt hour"
Reply | Report Abuse | Link to this$3,600 is 1000* more than other sources cost.
The problem with this energy source is not only the cost ($3600/kw), but also the maintainability/longevity of an undersea generator. The longevity is short (20 years estimated in article)compared to normal hydroelectric power plants (70 - 100 years +); and underwater maintenance would be quite expensive.
Reply | Report Abuse | Link to thisNormal hydroelectric plants are a renewable energy source that costs $800 - $1200/kw to build. Canada produces 65% of its electric energy using normal hydroelectric power; the U.S. produces only 10%. Why can't we produce more normal hydroelectric power in the U.S.
Hydrogen energy is too volatile(as in Hindenberg explosion), can an admixture of nitrogen in the right proportions solve the volitility issue without diluting the power thereof?
Reply | Report Abuse | Link to thisHow much energy would we save if everything shut down one day a week?
Reply | Report Abuse | Link to thisHow much more effective would the water turbines be if they adopted Tubercle Technology, which is more than just another blade design: It is a fundamental advance in fluid dynamics which will transform a host of machines built on that challenging science. for wind power it doubles the power at 17 mph. Developed from the whale fin design, it should work as well in the water, particularly where low water speeds are encountered. Just when the world needs it most, Tubercle Technology offers new options. Turbines, compressors, pumps and fans. http://www.whalepower.com/drupal/
Reply | Report Abuse | Link to thisI'm surprised there was no mention of helical turbines developed by Prof. Alexander Gorlov of Boston's Northeastern University. He spent years designing and testing environment-friendly helical turbines to capture power from the Gulf Stream and other currents.
Reply | Report Abuse | Link to thisNear-shore ocean currents are a vast, untapped energy resource that could easily meet most of North America's power needs.
David M. Clemen posted:
Reply | Report Abuse | Link to this[i]"The problem with this energy source is not only the cost ($3600/kw), but also the maintainability/longevity of an undersea generator. The longevity is short (20 years estimated in article)compared to normal hydroelectric power plants (70 - 100 years +); and underwater maintenance would be quite expensive."[/i]
Do not try to compare land-based hydro turbines with those used in ocean or river currents. Underwater turbines would consist of a farm of much smaller, different design turbines that could be lifted out of the water for maintenance.
[i]"Normal hydroelectric plants are a renewable energy source that costs $800 - $1200/kw to build. Canada produces 65% of its electric energy using normal hydroelectric power; the U.S. produces only 10%. Why can't we produce more normal hydroelectric power in the U.S."[/i]
Because building new mega-dams to supply conventional hydro generation requires flooding of thousands of acres of land. It also disrupts riverine ecology. Costs to the environment is unconscionable, and it would be a social and political hot potato.
We must consider new technology that will permit us to operate power run-of-the-river turbines and ocean-based turbines with minimal ecological impact. It can be done for a fairly reasonable cost.
Think of the power of the Gulf Stream, the waters flowing in and out of San Francisco Bay and Puget Sound. That's where the future of power generation is!:-D
TimeTraveler
Reply | Report Abuse | Link to this1. If you don't compare them to land based hydro turbines for cost, exactly what do you compare them to for the cost to produce energy. In any case, the comment concerning short life (due to the underwater salt-water environment) and high maintenance costs (compared to any present day generation source) are valid.
2. Presently, you have 80,000 existing dams in the U.S. (Reference Hydro Review magazine, Sept 2007, "National Inventory of Dams), and only 3% of these dams are used to produce electrical power. An additional 20% of the "existing" dams could be used to generate over 30,000 MW (about 30 nuclear plants). We do not have to build new, large dams.
3. I was involved in over 10 "small" hydro projects (not large dams) that the local communities were overjoyed to have. Four were built on existing dams (municipal water suppies, irrigation, flood control), two were on existing lock & dams on the Ohio River, and the remainder were run of river in up state New York. More of these small projects should be advocated.
What is your problem, if any, with these types of hydroelectric generation. They don't require the building of large dams; and they don't interrupt river systems. Moreover, land based hydro plants are the most efficient "renewable" energy source (potential energy of water to electrical energy efficieny exceeds 80%) whereas the free flow turbines are limited by the Betz coefficien (59.6%) unless they have shrouds.
"timetrvlr"
Reply | Report Abuse | Link to thisyou are talking about stupid economics, read SCIAM article "economist has no clothes"
then talk about real costs.
You obviously meant $3600/kw, not kw-hr.
Reply | Report Abuse | Link to thisThese turbines turn at variable speed, generating DC at variable voltage. You fail to mention the problem of converting this to constant voltage, constant frequency AC power - store the DC in batteries, from which AC generators are driven, or what? . Is this really economically viable?
Reply | Report Abuse | Link to thisWe have in La Guajira, north o Colobia S.A. near the Caribean Cost a wind plant producen wind-energy with great succes. Is a private service Company with german or netherland equipments, Is the only pwind plant in this Country.
Reply | Report Abuse | Link to thisThere is a wind plant in La Guajira north o Colombia S.A near the Caribean Cost that is managed by e private Company with very good result in cost an energy. Around them is a big desert without water or hidraulic energu sources.
Reply | Report Abuse | Link to this