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Posts Tagged ‘Sea Turbine’

Ocean Energy Council, March 17, 2009

fauResearchers in Dania Beach, Fla., landed almost $1.2 million in a federal grant to continue working on an underwater turbine prototype that will use ocean currents to generate power.

Researchers at Florida Atlantic University’s (FAU) Center for Ocean Energy Technology (COET) joined Rep. Ron Klein, D-Fla., today to announced the funding at the SeaTech campus in Dania Beach. The grant is part of the $410 billion spending bill signed by President Barack Obama. This is the first time the project has received federal funds.

The money will help pay for testing and possibly expanding the staff as the Center moves toward making the turbines a commercial product that can be used in offshore areas around the country. Scientists and engineers say these underwater turbines can power buildings along the coastline and eventually become a major energy source.

All the testing to date has been on land while the FAU Center studies underwater conditions and seeks federal and state permits to put the first prototype in the water, possibly this summer.

The Center expects to raise its national profile and get more funding for this and other renewable ocean energy projects, including ocean thermal energy (OTEC) and deep seawater cooling for air conditioning. “This [money] puts us on the radar screen at the federal level,” said Susan Skemp, executive director of the Center.

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DAVID FOGARTY, Reuters Climate Change Correspondent, February 5, 2009

ceto-overview1For millennia, Australia’s rugged southern coast has been carved by the relentless action of waves crashing ashore.

The same wave energy could soon be harnessed to power towns and cities and trim Australia’s carbon emissions.

“Waves are already concentrated solar energy,” says Michael Ottaviano, who leads a Western Australian firm developing a method to turn wave power into electricity.

“The earth has been heated by the Sun, creating wind, which created the swells,” he told Reuters from Perth, saying wave power had the potential to supply all of Australia’s needs many times over.

Ottaviano heads Carnegie Corp, which has developed a method of using energy captured from passing waves to generate high-pressure sea water. This is piped onshore to drive a turbine and to create desalinated water.

A series of large buoys are tethered to piston pumps anchored in waters 15 to 50 metres deep (49 to 131 feet). The rise and fall of passing waves drives the pumps, generating water pressures of up to 1,000 pounds per square inch (psi).

This drives the turbine onshore and forces the water through a membrane that strips out the salt, creating fresh water in a process that normally requires a lot of electricity.

The CETO (named after a mythical Greek sea creature) pumps and buoys are located under water, differing from some other wave power methods, for example, those that sit on the surface.

The CETO concept was invented in the 1970s by a Western Australian businessman Alan Burns and initial development began in 1999, followed by completion of a working prototype by 2005.

Ottaviano says the company, which works in partnership with British-based wind farm developer Renewable Energy Holdings and French utility EDF, is in the process of selecting a site for its first commercial demonstration plant in Australia.

The 50 megawatt plant, enough to power a large town, would cost between A$300 million to A$400 million ($193 million to $257 million) and cover about 5 hectares (12.5 acres) of seabed.

Funding could be raised from existing or new shareholders, he believes.

Several sites in Western Australia, including Albany in the south and Garden Island off Perth, looked promising.

“There’s significant interest in these sorts of projects, even in the current financial environment,” he added.

And a 50 MW plant was just a drop in the ocean.

He pointed to a study commissioned by the company that said wave power had the potential to generate up to 500,000 MW of electricity along the southern half of Australia’s coast at depths greater than 50 metres (165 feet).

At shallower depths, the potential was 170,000 MW, or about four times Australia’s installed power generation capacity.

Interest in renewable energy in Australia and elsewhere is being driven by government policies that enshrine clean energy production targets as well as state-backed funding programmes for emerging clean-tech companies.

“Australia is going to be one of those markets because of what the government is doing to drive investment in this sector. For starters, there’s quite a bit of direct government funding for projects like this,” he said.

The federal government has also set a renewable energy target of 20% by 2020, which is expected to drive billions of dollars worth of investment in Australia over the next decade, with much of it going into wind farms.

A second company, BioPower Systems, is developing underwater wave and tidal power systems and expects to complete pilot projects off northern Tasmania this year.

The company’s bioWAVE system is anchored to the sea bed and generates electricity through the movement of buoyant blades as waves pass, in a swaying motion similar to the way sea plants, such as kelp, move.

Tidal power, in which electricity is generated by turbines spinning to the ebb and flow of tides, has not taken off in Australia, partly because of cost, but is expected to be a big provider of green power in Britain in coming years.

Last week, Britain announced five possible projects to generate power from a large tidal area in south-west England. The largest of the projects could generate 8,600 MW and cost 21 billion pounds ($29 billion).

CONSTANT

Ottaviano believes wave power is one of the few green technologies that can provide steady, or baseload power.

Wind and solar photovoltaic panels can only operate at 25 to 30% efficiencies because neither the wind nor the sun are permanently available.

Government policies should promote the development of technologies that delivered large-scale, high-availability clean power competitively, he said.

“If you look from an outcome point of view and leave it up to the market to work out how that is going to be achieved, it comes down to geothermal certainly being one of the potential technologies because (of) its high availability and also potentially cost-competitive and harnessable at large scale,” Ottaviano said.

Australia has large geothermal potential in remote central and northern areas.

“Wave is another logical one because it is high availability. It is 90 to 100% available in most sites around southern Australia.”

“You could power the country 10 times over.”

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ALOK JHA, Guardian UK, January 5, 2009

Tidal Energy's DeltaStream

Tidal Energy's DeltaStream

Propellers on ships have been tried and tested for centuries in the rough and unforgiving environment of the sea: now this long-proven technology will be used in reverse to harness clean energy from the UK’s powerful tides.

The tides that surge around the UK’s coasts could provide up to a quarter of the nation’s electricity, without any carbon emissions. But life in the stormy seas is harsh and existing equipment – long-bladed underwater wind turbines – is prone to failure.  A Welsh renewable energy company has teamed up with ship propulsion experts to design a new marine turbine which they believe is far more robust.

Cardiff-based Tidal Energy Limited will test a 1MW tidal turbine off the Pembrokeshire coast at Ramsey Sound, big enough to supply around 1,000 homes. Their DeltaStream device, invented by marine engineer Richard Ayre while he was installing buoys in the marine nature reserve near Pembrokeshire, will be the first tidal device in Wales and become fully operational in 2010.

To ensure the propeller and electricity generation systems were as tough as possible, the tidal turbine’s designers worked with Converteam, a company renowned for designing propulsion systems for ships. “They’ve put them on the bottom of the Queen Mary … and done work for highly efficient destroyers, which is exactly the same technology that we’re looking at here,” said Chris Williams, development director of DeltaStream.

DeltaStream’s propellers work in reverse to a ship’s propulsion system – the water turns the blades to generate electricity – but the underlying connections between blades and power systems are identical to those on the ship.

Tidal streams are seen as a plentiful and predictable supply of clean energy, as the UK tries to reduce its greenhouse gas emissions. Conservative estimates suggest there is at least 5GW of power, but there could be as much as 15GW – 25% of current national demand.

A single DeltaStream unit has three propeller-driven generators that sit on a triangular frame. It weighs 250 tonnes, but is relatively light compared with other tidal systems which can be several times heavier. The unit is simple to install and can be used in closely packed units at depths of at least 20m. Unlike other tidal turbine systems, which must be anchored to the sea floor using piles bored into the seabed, DeltaStream’s triangular structure simply sits on the sea floor.

Duncan Ayling, head of offshore at the British Wind Energy Association and a former UK government adviser on marine energy, said that one of the biggest issues facing all tidal-stream developers is ease of installation and maintenance of their underwater device. “Anything you put under the water becomes expensive to get to and service. The really good bit of the DeltaStream is that they can just plonk it in the water and it just sits there.”

Another issue that has plagued proposed tidal projects is concern that the whirling blades could kill marine life. But Williams said: “The blades themselves are thick and slow moving in comparison to other devices, so minimising the chance of impact on marine life.”

The device also has a fail-safe feature when the water currents become too powerful and threaten to destroy the turbines by dragging them across the sea floor – the propellers automatically tilt their orientation to shed the extra energy.

Pembrokeshire businessman and sustainability consultant Andy Middleton said: “People are increasingly recognising how serious global warming really is, and in St David’s we are keen to embrace our responsibility to minimise climate change. DeltaStream is developing into a perfect example of the technology that fills the need for green energy and has the added benefit of being invisible and reliable.”

The country’s first experimental tidal turbine began generating electricity in Strangford Lough, Northern Ireland last year, built by Bristol-based company Marine Current Turbines. SeaGen began at about 150kW, enough for around 100 homes, but has now reached 1,200kW in testing. It had a setback early in its test phase, with the tidal streams breaking one of the blades in July.

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GLOBE-NET NEWS, May 29, 2008

Forever moving – our restless oceans have enough energy to power the world. As long as the Earth turns and the moon keeps its appointed cycle, the oceans will absorb and dissipate vast amounts of kinetic energy – a renewable energy resource of enormous potential. But harnessing this resource has proven more difficult than first thought. In this the latest installment of the GLOBE-Net Series on Renewable Energy – we look at how the power of the oceans might eventually find its place among other forms of renewable energy.

Ocean Energy – What is it?

According to the United Nations, 44% of the world’s population lives within 150 km of an ocean coast. In Canada and Australia the number is much higher at 80%. In the United States 53% of the population lives in close proximity to an ocean.

Thus it is only natural that many countries look to the oceans as a source of energy to be harnessed. How they seek to exploit this resource varies according to factors of geography and available technologies.

The two main forms of energy associated with our oceans are tidal power and wave power – born of the same source, but different in how they turn energy into electricity.

Tidal Power

Tidal power coverts the energy of tides into electricity utilizing the rise and fall of the ocean tides. The stronger the tide, either in water level height or tidal current velocities, the greater the potential for tidal electricity generation.

Tidal generators act in much the same way as do wind turbines, however the higher density of water (832 times that of air) means that a single generator can provide significant power at velocities much lower than those associated`with the wind power generators.

Tidal power can be classified into two main types; Tidal Stream Systems and Barrages.

Barrages are similar to hydro-electric dams but are placed in an estuary bay or river mouth, where they act as barriers that create artificial tidal lagoons. When water levels outside the lagoon changes relative to water levels inside, turbines in the barrages are able to produce electrical power. There are only three such structures in the world: the Rance River in France, Canada’s Bay of Fundy, and Kislaya Guba, Russia.

Tidal stream systems make use of the kinetic energy of moving water to power turbines. This technology simply relies on individual turbines which are placed in the water column; moored to be suspended, floating or anchored to the ocean floor. As the tide flows in or out, electrical energy is produced as water moves through the turbine.

Tidal power boasts several advantages over other types of renewable energy technology, because tides are more predictable and reliable than wind energy or sunny days for solar power. Tidal energy has an efficiency ratio of approximately 80% in terms of converting the potential energy of the water into electricity. Tidal stream system turbines are only a third the diameter of wind rotors of the same power output.

As with wind power, location is important factor in terms of being able to harness the earth’s natural energy. Tidal stream systems must be located in areas with fast currents where natural flows are concentrated between natural obstructions, for example at the entrances to bays and rivers, around rocky points or headlands, or between islands and other land masses.

Wave Power

Ocean surface waves are also a considerable source of energy potential, but energy that is not as restricted in terms of location as tidal energy systems. Typically wave energy is captured using buoys which generate mechanical energy as they oscillate vertically from wave motion.

Terminator devices extend perpendicular to the direction of wave travel and capture or reflect the power of the wave. Water enters through a subsurface opening into a chamber with air trapped above it and wave action causes the captured water column to move up and down like a piston to force the air though an opening connected to a turbine.

A point absorber is a floating structure with components that move relative to each other due to wave action (e.g., a floating buoy inside a fixed cylinder). The relative motion is used to drive electromechanical or hydraulic energy converters.

Attenuators are long multi-segment floating structures oriented parallel to the direction of the waves. The differing heights of waves along the length of the device causes flexing where the segments connect, and this flexing is connected to hydraulic pumps or other converters.

Overtopping devices have reservoirs that are filled by incoming waves to levels above the average surrounding ocean. The water is then released, and gravity causes it to fall back toward the ocean surface. The energy of the falling water is used to turn hydro turbines.

Wave power varies considerably in different parts of the world, and wave energy can’t be harnessed effectively everywhere. According to the Ocean Renewable Energy Group, a Vancouver based organisation that promotes the development of ocean energy in Canada, regions considered to have “good” wave energy resources are generally those found within 40 to 60 degrees of latitude, where the strongest winds are found. Wave-power rich areas of the world include the western coasts of Scotland, northern Canada, southern Africa, Australia, and the northwestern coasts of the United States.

Projects Underway

Ocean energy company Clean Current Power Systems estimates a potential global market for 67,000 Megawatts (MW) of tidal and wave action equipment worth $200 billion. At 20 cents/kW hour, the market for tidal electricity could be $27 billion annually. According to Finavera, world-wide wave energy could provide up to 2,000 TWh/year, 10% of world electricity consumption.

It comes as no surprise then, that interest in ocean energy has been building momentum in the past few years as these nations scramble to meet renewable energy targets.

For instance, in November 2007, British company Lunar Energy announced that it would be building the world’s first deep-sea tidal-energy farm off the coast of Pembrokshire in Wales. Eight underwater turbines, each 25 metres long and 15 metres high will provide electricity for 5,000 homes. Construction is due to start in the summer of 2008 and the proposed tidal energy turbines, described as “a wind farm under the sea”, should be operational by 2010.

Plans for a ten-mile barrage across the River Severn, which could generate 5% of the UK’s electricity needs, are currently under development. According to the UK Sustainable Development Commission, a barrage across the Severn would produce clean and sustainable electricity for 120 years. This would have a capacity of 8,640MW and an estimated output of 17 terawatt hours a year.

Scotland boasts roughly 25% of the entire European Union’s tidal power potential and 10% of its wave energy potential and could produce more than 1,300 megawatts by 2020, enough to power a city the size of Seattle. In 2007, Scotland announced $26 million worth of funding packages to develop marine power in the nation. So far $8 million has been procured to develop 3 MW of tidal power.

UK based Marine Current Turbines is developing a tidal stream system off the coast of Ireland. The 1.2-megawatt turbine will be tested for 12 weeks before feeding power into the Northern Ireland grid where it will operate for up to 20 hours per day, producing enough electricity to power 1,000 homes.

Both Scotland and England are planning wave energy projects. Scotland will be developing a 3MW array and England will be developing a 20 MW Wave Hub off the north coast of Cornwall, England. The Cornwall project will power up to 7,500 homes.

Canada has the world’s longest coastline and has always been serious about harnessing ocean energy. In early 2008 the Government of Nova Scotia gave the green light to three tidal energy testing projects in the Bay of Fundy to help establish a permanent tidal energy farm (see GLOBE-Net Article Nova Scotia to fund tidal power research). Irving Oil is also studying 11 potential sites in the Bay of Fundy to develop tidal energy farms.

The Government of British Columbia estimates there are more than 6,000 megawatts of potential wave energy that have been identified so far in the province and projects are already underway to develop wave energy systems. In 2006 Vancouver based Clean Current Power Systems began developing a pilot tidal power project near Victoria to demonstrate the potential for tidal power.

PG&E and Vancouver-based Finavera Renewables is developing America’s first commercial wave power plant off the coast of Northern California. The plant is scheduled to begin operating in 2012, generating a maximum of 2 megawatts of electricity.

In March, 2008, the U.S. Department of Energy announced would be offering up to $7.5 million in grants for hydro-kinetic energy such as wave and tidal power. The department is seeking partnerships with companies and universities to develop the technologies and plans to award up to 17 grants.

Portugal is planning the world’s first commercial wave farm, the Aguçadora Wave Park near Póvoa de Varzim. If successful, a further 70 million euro is likely to be invested before 2009 on a further 28 machines to generate 72.5 MW.

The Challenges

Despite the enormous potential of ocean energy, there remain many pitfalls (if such a word can be used in a watery context) that have proven difficult to overcome, and which explains why ocean energy remains the least developed of all forms renewable energy. Problems still exist regarding cost, maintenance, environmental concerns and our still imperfect understanding of how power from the oceans will impact on the world’s energy infrastructure.

For example, turbines are susceptible to bio-fouling; the growth of aquatic life on or in the turbine. This can severely inhibit the efficiency of energy production and is both costly and difficult to remove. Turbines are also prone to damage from ocean debris.

In the Bay of Fundy, project developers are particularly concerned with ice floes the size of small apartments, and cobblestones the size of watermelons constantly being tossed across the Bay’s terrain by the power of the Bay’s water flows.

Turbines may also be hazardous to marine life and the impacts on marine life are still largely unknown, but concern is warranted.

Barrage systems are affected by problems of high initial infrastructure costs associated with construction and the resulting environmental problems. For example, independent research on the economics of building the proposed Severn Barrage in the UK revealed that, taking environmental costs into account, the structure could cost as much as $12 billion to create – $4 billion more than previously estimated.

Barrage impacts include a decrease in the average salinity and turbidity within a barrage, significantly altering associated ecosystems.

Wave power systems present their own set of challenges. Most electric generators operate at higher speeds, and most turbines require a constant, steady flow. Unfortunately wave energy is slow and ocean waves oscillate at varying frequencies.

The rough realities of the marine environment have also proven difficult to deal with, especially for companies seeking to remain cost-effective. Constructing wave devices that can survive storm damage and saltwater corrosion add to development costs.

The Future

Modern advances in ocean energy technology may eventually see large amounts of power generated from the ocean, especially tidal currents using the tidal stream designs. The technology is still in its infant stage and most projects that exist or are that are in project development stages are mainly pilot projects. But the promise remains.

“It’s not as well-established as solar, thermal, wind and biomass, but it [ocean power] shows a lot of promise,” said Philip Jennings, professor of energy studies at Western Australia’s Murdoch University.

“As the technology develops and becomes more affordable, which it will over time, we can continue to expand pretty much anywhere where there is an ocean,” said Chief Executive Officer Phil Metcalf of Pelamis Wave Power.

The market potential for tidal power still remains unclear [says who?]. Sector analysts believe Initial Public Offerings (IPO) for wave and tidal power projects will be much harder to price than for comparable wind power projects, because wave firms cannot give exact estimates on the scale of benefits and few have technologies that are up and running.

Regardless, both ocean wave and tidal power have attracted growing interest from investors and power utilities looking for the next long-term play in renewable energy.

“Water covers more than 70 percent of the Earth’s surface,” said Andy Karsner, assistant secretary for energy efficiency and renewable energy at the DOE. “Using environmentally responsible technologies, we have a tremendous opportunity to harness energy produced from ocean waves, tides or ocean currents, free-flowing water in rivers and other water resources to…provide clean and reliable power.”

According to Jennings ocean power could not match fossil fuels for electricity production but could be competitive with other forms of renewable energy.

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NANEA KALANI, Pacific Business News, March 21, 2008

Australian technology company Oceanlinx is moving ahead with a wave energy project that would anchor large floating generators off Maui’s Pauwela Point and could power up to 2,500 homes.

A month after announcing the $20 million project, Oceanlinx has hired Honolulu-based Planning Solutions to conduct an environmental impact assessment, which could take up to a year.

Oceanlinx expects the project to be on line by the end of 2009, generating 2.7 megawatts of power that it would sell to Maui Electric Company.

The company’s patented turbine technology will harness air generated by rising and falling sea swells near the big wave surf spot known as Jaws. The air flow would spin the turbine’s blades, generating electricity.

State lawmakers are considering legislation to provide Oceanlinx with up to $20 million in special-purpose revenue bonds.

“For Maui, this will be one more link in a renewable energy chain that includes biomass and wind,” said Hawaiian Electric Co. spokesman Peter Rosegg. “As oil prices continue upward … clean, local renewables like solar, wind and wave power offer more stable prices and increased energy security in the long run.”

This month, the average Maui household will see an electric bill of $206.10 for 600 kilowatt-hours of electricity usage.

The wave energy project will add to the 30-megawatt wind farm above Maalaea, which MECO says accounts for about 9% of Maui’s electrical power.

The Oceanlinx project will involve anchoring two to three 450-ton floating generators a half-mile off of Pauwela Point in waters about 120 feet deep.

Each 25-foot-high platform is about the size of a basketball court — 90 feet long by 65 feet wide — but Oceanlinx says they will not be visible from the highway or any residences in the area.

Environmental groups on Maui say they don’t anticipate environmental issues with the project.

“We haven’t seen an EIS yet, and there’s some concern about the view plane, but so far we think this is a real project with potential,” said Lance Holter, chairman of the Maui Sierra Club. “The downside with visual issues is minimal compared to the upside of creating a new renewable energy source for Maui residents.”

Maui Tomorrow, the advocacy group that strongly opposed the Hawaii Superferry, says it also supports additional alternative energy options for Maui residents.

“The Oceanlinx group has been really proactive and engaged with the community, which is refreshing,” said Executive Director Irene Bowie. “We’ll reserve judgement until the environmental review is done, but we’re optimistic.”

Oceanlinx and MECO say the selected site on the northeastern coast of the island has no fishing, boating or surfing activity nearby. The site was chosen over another area in Kapalua past Honolua Bay.

The company will install underwater transmission cables that will run along the shoreline to Maliko Bay, where it will then feed into a utility substation on MECO’s grid.

The Maui units would be the 11-year-old company’s first commercial project. Oceanlinx also is in talks with energy companies in Rhode Island, Portugal, Namibia, Mexico and Australia.

The wave technology has yet to take off in the United States. Fewer than 50 so-called hydrokinetic projects have been permitted by the Federal Energy Regulatory Commission and none has been built.

FERC, which oversees energy industries, said in December it issued its first license for a wave energy project to be built off the coast of Washington state.

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