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MendoCoastCurrent, July 26, 2010

The Technology Strategy Board funding follows the support given earlier this month to AWS Ocean Energy by the Scottish Government’s WATERS programme (Wave and Tidal Energy: Research, Development and Demonstration Support).

Funding will further develop AWS Ocean Energy’s AWS-III, a ring-shaped multi-cell surface-floating wave power system.

The funding from the Technology Strategy Board is part of a £7m million funding package awarded to 9 wave and tidal stream research and development projects.

Simon Grey, Chief Executive of AWS Ocean Energy, says: “This latest funding is very welcome as we continue to develop our AWS-III wave energy device.

“Our trials on Loch Ness will restart in September for a 6 week period and thereafter a detailed assessment of the trial results will be undertaken before we start building and then deploy a full-scale version of one of the wave absorption cells.”

A single utility-scale AWS-III, measuring around 60 m in diameter, will be capable of generating up to 2.5 MW of continuous power.

AWS Ocean Energy says it is seeking industrial and utility partners to enable the launching of a 12-cell, 2.5 MW pre-commercial demonstrator in 2012 and subsequent commercialisation of the technology.

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The Engineer UK, July 6 2010

Aquamarine Power and AWS Ocean Energy today secured approximately £4.39m to continue development of their wave energy devices.

The WATERS fund (Wave and Tidal Energy: Research, Development and Demonstration Support) has provided Aquamarine Power with more than £3m to develop its 2.4MW Oyster demonstration project in Scotland while AWS Ocean Energy received £1.39m to develop its AWS-III surface-floating wave power device.

Phased installation of the Oyster 2 project will begin at the European Marine Energy Centre (EMEC) in Orkney in Summer 2011. In-depth coverage of Oyster from The Engineer’s 2009 Awards Supplement can be read here.

The Oyster demonstration project will consist of three 800kW hinged flaps, each measuring 26m by 16m. The flaps are moved by the motion of near shore waves, which in turn drive two hydraulic pistons that push high-pressure water onshore to drive a conventional hydro-electric turbine.

Oyster 2 Wave Energy Converter

Aquamarine Power claims each flap will deliver 250 per cent more power than the original Oyster prototype, which was successfully deployed at EMEC in 2009.

The three devices will be linked to a single onshore 2.4MW hydro-electric turbine. The new devices incorporate modifications that are expected to facilitate the production of more energy, be simpler to install and easier to maintain.

AWS Ocean Energy will use its funding to further develop the AWS-III device, a ring-shaped, multi-cell, surface-floating wave power system.

It is claimed that a single utility-scale AWS-III, measuring around 60m in diameter, will be capable of generating up to 2.5MW of continuous power.

Scale testing of the AWS-III on Loch Ness is currently being carried out to provide design data and confirm the AWS-III’s commercial potential.

The £15m WATERS scheme, which is run and administered by Scottish Enterprise, has been designed to support the construction and installation of pre-commercial full-scale wave and tidal stream device prototypes in Scottish waters.

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BBC News, June 11, 2010

A renewable energy company has gone “back to the future” to develop a device to harness power from waves.

AWS Ocean Energy chief executive Simon Grey said its prototype AWS-III on Loch Ness had evolved from “forgotten” technology first seen in 1985.

He said the device could eventually be used in the Northern Isles.

The technology was also tested on Loch Ness in the 1980s, but the Conservative government of the time suspended the wave energy programme.

Highlands Liberal Democrat MP and chief secretary to the Treasury, Danny Alexander, has visited the test site.

He said the progress being made by the company was impressive.

Mr Grey said Inverness-based AWS Ocean Energy was exploring the idea of a machine which had rubber rather than steel components.

Further research led to staff uncovering the similar concept from the 1980s.

He said: “We discovered that the work done in 1985 was rated as the most promising by the Department of Energy at the time.

“We have since taken that design and evolved it further so it is more cost effective in terms of producing power.”

EIGHTIES REVISITED

  • AWS Ocean Energy is updating technology first tested in 1985
  • The Conservatives were also in government at the time
  • Government was funding “green” energy projects then as it is today
  • The film Back to the Future was released in 1985

Mr Grey said the wave energy programme in the 1980s was fully funded by the UK government but the work was later suspended.

He said: “When interest in wave energy re-emerged people assumed that because it hadn’t happened in the past then those ideas wouldn’t work and they had to find new ideas.”

The chief executive said AWS-III was a re-working of a concept people had “forgotten about”.

The ring-shaped machine on Loch Ness is one tenth of the size of the device that could eventually be generating electricity on a commercial scale.

Full-scale machines could be deployed in the sea around Orkney and Shetland following further tests in 2012.

Investment of £2.3m was secured from the Scottish government to develop the AWS-III.

In 2008, AWS Ocean Energy said it had set its sights on winning the world’s largest prize for marine energy innovation.

It said it planned to double its workforce in 12 months, in part to improve its chances of securing the Scottish government’s Saltire Prize.

Following a visit to the test site on Loch Ness, Mr Alexander said: “Power from our seas can make a significant contribution to our energy security and the future of our environment.”

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PETER BROWN, EnergyCurrent.com, February 16, 2009

stromnessOn a Monday morning in May last year, the Atlantic tide set a turbine in motion on the seabed off Orkney, and the energy captured was connected to the national grid. It was, said Jim Mather, Scotland’s Minister for Enterprise, Energy and Tourism, a “massive step forward”.

The amount of electricity generated may have been tiny, but for marine engineers the significance was huge. Their industry had stopped paddling and started to swim.

For small companies trying to get wave or tide devices off the drawing board and into the sea, many problems lie in wait. All turbines, whether they sit on the seabed or float, must withstand that once-in-a-century wave that could be a thousand times more powerful than the average. Conditions vary with the seasons and the seabed. A device that works in a fjord might not function in a firth. Rigorous, long-term testing is therefore vital.

“There are parallels with wind,” says Alan Mortimer, head of renewables policy at Scottish Power. “Many different types of turbine were proposed in the early Eighties. They boiled down to a small number of successful concepts. The same needs to happen with marine devices, but the difference is that they need to be full- size just to be tested.

“To get a reasonable number of prototypes into the water costs millions. What these small companies need is capital support.”

That, however, is hard to find. The Wave and Tidal Energy Support Scheme (Wates), which put GBP13.5 million into promising technologies, is now closed. Last year the Scottish Government offered the 10m Saltire Prize for a commercially viable scheme, but the Institution of Mechanical Engineers (IMechE), in its recent report Marine Energy: More Than Just a Drop in the Ocean?, called on the Government to provide another 40m.

This would go towards schemes to be tested at EMEC, the European Marine Energy Centre, which has two supported sites, with grid access, at Orkney. It was there that an Irish company, OpenHydro, made the grid breakthrough last year. “It’s desperately important that we grasp the nettle now,” says William Banks, IMechE’s president. “We have the micro-systems in place and I’d like to see them developed to the macro stage. However, unless we do that step by step, we’ll be in trouble.”

An estimated 50 teams are working around the world on marine energy. The danger is that Britain, and Scotland in particular, could lose the race, even though, as Alex Salmond, Scotland’s First Minister, says, “Scotland has a marine energy resource which is unrivalled in Europe.”

Scotland has a quarter of Europe’s tidal resources and a tenth of its wave potential.

Around 1,000 people work in Scottish marine energy, but that figure could billow. “You’re talking about an exercise that could transform the marine industry into something equivalent to oil and gas,” says Martin McAdam, whose company, Aquamarine Power, is growing fast.

Among his rivals in Scotland are AWS Ocean Energy, based near Inverness, with Archimedes, a submerged wave machine; Hammerfest UK, which wants to develop three 60MW tidal sites and is working with Scottish Power; Pelamis Wave Power, who are based in Edinburgh; and Scotrenewables, based in Orkney, who are currently developing a floating tidal turbine.

Politicians need to be educated about marine energy’s potential, says Banks. Indeed, IMechE has highlighted the need for sustained political leadership if what many see as the biggest problem – that of the grid – is to be solved. Why bring energy onshore if it can’t then reach homes?

“Grids were built to connect large power stations to cities. Now you’re going to have electricity generated all over the countryside. It’s a huge challenge,” says McAdam.

“We have had meetings with Ofgen and the national grid companies and we’re outlining the need to have grids to support at least 3,000MW of energy by 2020. That is definitely possible.” McAdam adds: “A European undersea grid is also being promoted and we’re very supportive of that.”

Such a system would help to overcome a frequent objection to renewables – their fickleness. If waves were strong in Scotland, Finland or France could benefit, and vice versa.

Another challenge is the cost of installation. “At the moment we’re competing with oil and gas for boats,” says McAdam. “We need to move away from using heavy-lift, jack-up vessels.” The answer might be devices that can be floated into position and then weighted down.

The race between suppliers is speeding up. Permission for a 4MW station at Siadar, off Lewis in the Western Isles, has just been granted to Wavegen, based in Inverness, and Npower Renewables. It could power about 1,500 homes, creating 70 jobs.

Among the success stories are the three 140-metre, red tubes developed by Pelamis (named after a sea serpent) which already float off the northern Portuguese coast at Aguadoura. More Pelamis turbines are to be installed at EMEC, along with Aquamarine’s wave device Oyster.

Oyster is basically a giant flap which feeds wave energy onshore to be converted to electricity. It has already been made, at a former oil and gas plant at Nigg, north of Inverness. A high- pressure pipeline was completed in December and a hydro-electric station will be installed this spring. In the summer, Oyster will finally be bolted to piles hammered into the seabed.

Unlike wave energy, tidal power needs a channel between two land masses – and in the roaring Pentland Firth, between Caithness and Orkney, Scotland has what has been called “the Saudi Arabia of marine power”, Europe’s largest tidal resource. To exploit it, a GBP2 million contract to build Aquamarine’s tidal power device, Neptune, was awarded last month. It will be tested at EMEC.

Elsewhere, SeaGen, an “underwater windmill” developed by a Bristol company, has just generated 1.2MW near the mouth of Strangford Lough, Northern Ireland.
But the most controversial of Britain’s tidal energy schemes is, of course, in the Severn Estuary, where a barrage could provide around 5% of Britain’s energy. Environmentalists fear irreparable damage to marshes and mudflats, but the Government is known to prefer the barrage to other, smaller options. The decision it takes next year is sure to be eagerly watched in Scotland.

Somewhat overshadowed by the Severn plan is Wave Hub, a project to build a wave-power station 10 miles off St Ives, on Cornwall’s north coast, using both Pelamis and a sea-bed device developed by ORECon of Plymouth. An application to create a safety area around it has just been submitted, part of the meticulous planning that precedes any marine trial.

“We have to have environmentalists looking at the impact on fisheries, flora and fauna,” says McAdam. “And we have to be completely open with the communities we’re going into. But most people realise that climate change and energy security are real things. We want to minimalise our environmental impact and give the country a means of isolating itself from the volatility of oil and gas.”

In theory, marine energy could generate a fifth of the UK’s electricity needs, but that would require a multitude of stations. Bill Banks believes nuclear power will be needed. “But we also need a variety of renewables,” he says. “Marine will take its place along with bio, hydro and wind energy. It’s available, it’s there at the moment, and if we get our act together I think we can lead Europe. We need a synergy of activity.”

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Guardian.co.uk, December 3, 2008

wave-ocean-blue-sea-water-white-foam-photoWay back in Napoleonic Paris, a Monsieur Girard had a novel idea about energy: power from the sea. In 1799, Girard obtained a patent for a machine he and his son had designed to mechanically capture the energy in ocean waves. Wave power could be used, they figured, to run pumps and sawmills and the like.

These inventors would disappear into the mists of history, and fossil fuel would instead provide an industrializing world with almost all its energy for the next two centuries. But Girard et fils were onto something, say a growing number of modern-day inventors, engineers, and researchers. The heave of waves and the tug of tides, they say, are about to begin playing a significant role in the world’s energy future.

In the first commercial scale signal of that, last October a trio of articulated, cylinder-shaped electricity generators began undulating in the waves off the coast of Portugal. The devices look like mechanical sea snakes. (In fact, their manufacturer, Scotland’s Pelamis Wave Power Ltd., takes its name from a mythical ancient Greek sea serpent.) Each Pelamis device consists of four independently hinged segments. The segments capture wave energy like the handle of an old fashioned water pump captures the energy of a human arm: as waves rock the segments to and fro, they pump a hydraulic fluid (biodegradable, in case of spills) powerfully through a turbine, spinning it to generate up to 750,000 watts of electricity per unit. Assuming the devices continue to perform well, Portuguese utility Energis expects to soon purchase another 28 more of the generators.

The completed “wave farm” would feed its collective power onto a single high voltage sea-floor cable, adding to the Portuguese grid about 21 megawatts of electricity. That’s enough to power about 15,000 homes.

In a world where a single major coal or nuclear plant can produce more than 1,000 megawatts of electricity, it’s a modest start. But from New York’s East River to the offshore waters of South Korea, a host of other projects are in earlier stages of testing. Some, like Pelamis, rely on the motion of waves. Others operate like underwater windmills, tapping the power of the tides.

Ocean-powered technologies are in their infancy, still technologically well behind such energy alternatives as wind and solar. Necessarily designed to operate in an inherently harsh environment, the technologies remain largely unproven and — unless subsidized by governments — expensive. (Portugal is heavily subsidizing the Pelamis project, with an eye to becoming a major European exporter of clean green power in the future.) Little is known about the effects that large wave or tide farms might have on marine ecosystems in general.

Despite the uncertainties, however, proponents say the potential advantages are too striking to ignore. Eight hundred times denser than air, moving water packs a huge energy wallop. Like solar and wind, power from moving seas is free and clean. But sea power is more predictable than either wind or solar. Waves begin forming thousands of miles from coastlines and days in advance; tides rise and fall as dependably as the cycles of the moon. That predictability makes it easier to match supply with demand.

Roger Bedard, who leads ocean energy research at the U.S. utility-funded Electric Power Research Institute (EPRI) in Palo Alto, says there’s plenty of reason for optimism about the future of what he calls “hydrodynamic” power. Within a decade, he says, the U.S. could realistically meet as much as 10% of its electricity needs from hydrodynamic power. As a point of reference, that’s about half of the electricity the U.S. produces with nuclear power today. Although he acknowledges that initial sea-powered generation projects are going to be expensive, Bedard believes that as experience grows and economies of manufacturing scale kick in, hydrodynamic power will follow the same path toward falling costs and improving technologies as other alternatives.

“Look at wind,” he says. “A kilowatt hour from wind cost fifty cents in the 1980s. Now it’s about seven cents.” (That’s about the same as producing electricity with natural gas, and only about three cents more than coal, the cheapest — and dirtiest — U.S. energy choice. Any future tax on carbon emissions could narrow that gap even more, as would additional clean-power subsidies.)

For some nations, wave and tide power could pack an even bigger punch. Estimates suggest, for instance, that the choppy seas surrounding the United Kingdom could deliver as much as 25% of its electricity. British alternative energy analyst Thomas W. Thorpe believes that on a worldwide basis, waves alone could produce as much as 2,000 terawatt hours of electricity, as much as all the planet’s major hydroelectric plants generate today.

Although none are as far along as Pelamis, most competing wave-power technologies rely not on the undulations of mechanical serpents, but instead on the power captured by the vertical bobbing of large buoys in sea swells. Ocean Power Technologies (OPT), based in New Jersey, drives the generators in its PowerBuoy with a straightforward mechanical piston. A stationary section of the mostly submerged, 90-foot buoy is anchored to the ocean floor; a second section simply moves up and down with the movement of sea swells, driving pistons that in turn drive an electrical generator. The Archimedes Wave Swing, a buoy-based system developed by Scotland’s AWS Ocean Energy, harnesses the up-and-down energy of waves by pumping air to spin its turbines. Vancouver-based Finavera Renewables uses seawater as its turbine-driving hydraulic fluid.

Although Pelamis beat all of these companies out of the commercialization gate, OPT appears to be right behind, with plans to install North America’s first commercial-scale wave power array of buoys off the coast of Oregon as early as next year. That array — occupying one square-mile of ocean and, like other wave power installations, located far from shipping lanes — would initially produce 2 megawatts of power. OPT also announced last September an agreement to install a 1.4-megawatt array off the coast of Spain. An Australian subsidiary is in a joint venture to develop a 10-megawatt wave farm off the coast of Australia.

Meanwhile, Pelamis Wave Power plans to install more of its mechanical serpents — three megawatts of generating capacity off the coast of northwest Scotland, and another five-megawatt array off Britain’s Cornwall coast.

The Cornwall installation will be one of four wave power facilities plugged into a single, 20-megawatt underwater transformer at a site called “Wave Hub.” Essentially a giant, underwater version of a socket that each developer can plug into, Wave Hub — which will be connected by undersea cable to the land-based grid — was designed as a tryout site for competing technologies. OPT has won another of the four Wave Hub berths for its buoy-based system.

Other innovators are trying to harness the power of ocean or estuarine tides. Notably, in 2007, Virginia’s Verdant Power installed on the floor of New York’s East River six turbines that look, and function, much like stubby, submerged windmills, their blades — which are 16 feet in diameter — turning at a peak rate of 32 revolutions per minute. The East River is actually a salty and powerful tidal straight that connects Long Island Sound with the Atlantic Ocean. Although the “underwater windmills” began pumping out electricity immediately, the trial has been a halting one. The strong tides quickly broke apart the turbines’ first- (fiberglass and steel) and second- (aluminum and magnesium) generation blades, dislodging mounting bolts for good measure.

Undeterred, in September Verdant Power began testing new blades made of a stronger aluminum alloy. If it can overcome the equipment-durability problems, the company hopes to install as many as 300 of its turbines in the East River, enough to power 10,000 New York homes.

A scattering of similar prototype “underwater windmill” projects have been installed at tidal sites in Norway, Northern Ireland, and South Korea. (In addition, interest in moving into freshwater sites is growing. Verdant itself hopes to install its turbines on the St. Lawrence River. At least one other company, Free Flow Power of Massachusetts, has obtained Federal Energy Regulatory Commission permits to conduct preliminary studies on an array of sites on the Mississippi River south of St. Louis.)

The environmental benefits of hydrodynamic power seem obvious: no carbon dioxide or any other emissions associated with fossil-fuel-based generation. No oil spills or nuclear waste. And for those who object to wind farms for aesthetic reasons, low-profile wave farms are invisible from distant land; tidal windmill-style turbines operate submerged until raised for maintenance.

There are, however, environmental risks associated with these technologies.

New York state regulators required Verdant Power to monitor effects of their its turbines on fish and wildlife. So far, sensors show that fish and water birds are having no trouble avoiding the blades, which rotate at a relatively leisurely 32 maximum revolutions per minute. In fact the company’s sensors have shown that fish tend to seek shelter behind rocks around the channel’s banks and stay out of the central channel entirely when tides are strongest.

But a host of other questions about environment effects remain unanswered. Will high-voltage cables stretching across the sea from wave farms somehow harm marine ecosystems? Will arrays of hundreds of buoys or mechanical serpents interfere with ocean fish movement or whale migrations? What effect will soaking up large amounts of wave energy have on shoreline organisms and ecosystems?

“Environmental effects are the greatest questions right now,” EPRI’s Bedard says, “because there just aren’t any big hydrodynamic projects in the world.”

Projects will probably have to be limited in size and number to protect the environment, he says – that’s a big part of the reason he limits his “realistic” U.S. estimate to 10% of current generation capacity. But the only way to get definitive answers on environmental impact might be to run the actual experiment — that is, to begin building the water-powered facilities, and then monitor the environment for effects.

Bedard suggests that the way to get definitive answers will be to build carefully on a model like Verdant’s: “Start very small. Monitor carefully. Build it a little bigger and monitor some more. I’d like to see it developed in an adaptive way.”

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The Economist, June 5, 2008

You only have to look at waves pounding a beach, inexorably wearing cliffs into rubble and pounding stones into sand, to appreciate the power of the ocean. As soaring oil prices and concern over climate change give added urgency to the search for new, renewable sources of energy, the sea is an obvious place to look. In theory the world’s electricity needs could be met with just a tiny fraction of the energy sloshing around in the oceans.

Alas, harnessing it has proved to be unexpectedly difficult. In recent years wind farms have sprouted on plains and hilltops, and solar panels have been sprinkled across rooftops and deserts. But where the technology of wind and solar power is established and steadily improving, that of wave power is still in its infancy. The world had to wait until October 2007 for the first commercial wave farm, consisting of three snakelike tubes undulating with the Atlantic swell off the coast of Portugal.

In December Pacific Gas & Electric, an American utility, signed an agreement to buy electricity from a wave farm that is to be built off the coast of California and is due to open in 2012. Across the world many other wave-power schemes are on the drawing board. The story of wave power, however, has been one of trials and tests followed by disappointment and delays. Of the many devices developed to capture wave energy, none has ever been deployed on a large scale. Given wave power’s potential, why has it been so hard to get the technology to work—and may things now be about to change?

The first patents for wave-power devices were issued in the 18th century. But nothing much happened until the mid-1970s, when the oil crisis inspired Stephen Salter, an engineer at the University of Edinburgh, in Scotland, to develop a wave generator known as Salter’s Duck. His design contained curved, floating canisters, each the size of a house, that would be strung together and then tethered to the ocean floor. As the canisters, known as Ducks, were tossed about by the waves, each one would rock back and forth. Hydraulics would convert the rocking motion to rotational motion, which would in turn drive a generator. A single Duck was calculated to be capable of generating 6 megawatts (MW) of electricity—enough to power around 4,000 homes. The plan was to install them in groups of several dozen.

Initial estimates put the cost of generating electricity in this way at nearly $1 per kilowatt hour (kWh), far more than nuclear power, the most expensive electricity at the time. But as Dr Salter and his team improved their design, they managed to bring the cost-per-kWh down to the cost of nuclear power. Even so, the research programme was shut down by the British government in 1982. The reasons for this were not made public, but it is widely believed to have happened after lobbying by the nuclear industry. In testimony to a House of Lords committee in 1988, Dr Salter said that an accurate evaluation of the potential of new energy sources would be possible only when “the control of renewable energy projects is completely removed from nuclear influences.”

Salter’s Duck never took to the seas, but it sparked interest in the idea of wave power and eventually helped to inspire other designs. One example is the Pelamis device, designed by some of Dr Salter’s former students, who now work at Pelamis Wave Power, a firm based in Scotland. Three such devices, each capable of generating up to 750kW, have been deployed off the coast of Portugal, and dozens more are due to be installed by 2009. There are also plans for installations off Orkney in Scotland and Cornwall in England.

As waves travel along the 140-metre length of the snakelike Pelamis, its hinged joints bend both up and down, and from side to side. This causes hydraulic rams at the joints to pump hydraulic fluid through turbines, turning generators to produce electricity. Pelamis generators present only a small cross-section to incoming waves, and absorb less and less energy as the waves get bigger. This might seem odd, but most of the time the devices will not be operating in stormy seas—and when a storm does occur, their survival is more important than their power output.

Oh Buoy

The Aquabuoy, designed by Finavera Renewables of Vancouver, takes a different approach. (This is the device that Pacific Gas & Electric hopes to deploy off the California coast.) Each Aquabuoy is a tube, 25-metres long, that floats vertically in the water and is tethered to the sea floor. Its up-and-down bobbing motion is used to pressurise water stored in the tube below the surface. Once the pressure reaches a certain level, the water is released, spinning a turbine and generating electricity.

The design is deliberately simple, with few moving parts. In theory, at least, there is very little to go wrong. But a prototype device failed last year when it sprang a leak and its bilge-pump malfunctioned, causing it to sink just as it was due to be collected at the end of a trial. Finavera has not released the results of the trial, which was intended to measure the Aquabuoy’s power output, among other things. The company has said, however, that Aquabuoy will be profitable only if each device can generate at least 250kW, and that it has yet to reach this threshold.

Similar bobbing buoys are also being worked on by AWS Ocean Energy, based in Scotland, and Ocean Power Technologies, based in Pennington, New Jersey, among others. The AWS design is unusual because the buoys are entirely submerged; the Ocean Power device, called the PowerBuoy, is being tested off the coast of Spain by Iberdrola, a Spanish utility.

The Oyster, a wave-power device from Aquamarine Power, another Scottish firm, works in an entirely different way. It is an oscillating metal flap, 12 metres tall and 18 metres wide, installed close to shore. As the waves roll over it, the flap flexes backwards and forwards. This motion drives pistons that pump seawater at high pressure through a pipe to a hydroelectric generator. The generator is onshore, and can be connected to lots of Oyster devices, each of which is expected to generate up to 600kW. The idea is to make the parts that go in the sea simple and robust, and to keep the complicated and delicate bits out of the water. Testing of a prototype off the Orkney coast is due to start this summer.

The logical conclusion of this is to put everything onshore—and that is the idea behind the Limpet. It is the work of Wavegen, a Scottish firm which is a subsidiary of Voith Siemens Hydro, a German hydropower firm. A prototype has been in action on the island of Islay, off the Scottish coast, since 2000. The Limpet is a chamber that sits on the shoreline. The bottom of the chamber is open to the sea, and on top is a turbine that always spins in the same direction, regardless of the direction of the airflow through it.

As waves slam into the shore, water is pushed into the chamber and this in turn displaces the air, driving it through the turbine. As the water recedes, air is sucked back into the chamber, driving the same turbine again. The Limpet on Islay has three chambers which generate an average of 100kW between them, but larger devices could potentially generate three times this amount, according to Wavegen. Limpets may be built into harbour breakwaters in Scotland and Spain.

Dozens of wave-energy technologies are being developed around the world: ideas, in other words, are not what has held the field back. So what has? Tom Thorpe of Oxford Oceanics, a consultancy, blames several overlapping causes. For a start, wave energy has lagged behind wind and solar, because the technology is much younger and still faces some big technical obstacles. “This is a completely new energy technology, whereas wind and photovoltaics have been around for a long time—so they have been developed, rather than invented,” says Mr Thorpe.

The British government’s decision to shut its wave-energy research programme, which had been the world’s biggest during the 1970s, set the field back nearly two decades. Since Britain is particularly well placed to exploit wave energy (which is why so many wave-energy companies come from there), its decision not to pursue the technology affected wave-energy research everywhere, says Mr Thorpe. “If we couldn’t do it, who could?” he says.

Once interest in wave power revived earlier this decade, practical problems arose. A recurring problem, ironically enough, is that new devices underestimate the power of the sea, and are unable to withstand its assault. Installing wave-energy devices is also expensive; special vessels are needed to tow equipment out to sea, and it can be difficult to get hold of them. “Vessels that could potentially do the job are all booked up by companies collecting offshore oil,” says Trevor Whittaker, an engineer at Queen’s University in Belfast who has been part of both the Limpet and Oyster projects. “Wave-generator installation is forced to compete with the high prices the oil industry can pay.”

Another practical problem is the lack of infrastructure to connect wave-energy generators to the power grid. The cost of establishing this infrastructure makes small-scale wave-energy generation and testing unfeasible; but large-scale projects are hugely expensive. One way around this is to build a “Wave Hub”, like the one due to be installed off the coast of Cornwall in 2010 that will provide infrastructure to connect up wave-energy arrays for testing.

Expect Flotations

But at last there are signs of change. Big utilities are taking the technology seriously, and are teaming up with wave-energy companies. Venture-capitalists are piling in too, as they look for new opportunities. Several wave-energy companies are thought to be planning stockmarket flotations in the coming months. Indeed, such is investors’ enthusiasm that Mr Thorpe worries that things might have gone too far. A big failure could tarnish the whole field, just as its prospects look more promising than ever.

Whether one wave-energy device will dominate, or different devices will suit different conditions, remains to be seen. But wave energy’s fortunes have changed. “We have to be prepared for some spectacular failures,” says Mr Thorpe, “but equally some spectacular successes.”

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IMC Brokers, October 23, 2007

Generating Renewable Energy from Ocean Waves

Wave power refers to the energy of ocean surface waves and the capture of that energy to do useful work – including electricity generation, desalination, and the pumping of water (into reservoirs). Wave power is a form of renewable energy. Though often co-mingled, wave power is distinct from the diurnal flux of tidal power and the steady gyre of ocean currents. Wave power generation is not a widely employed technology, and no commercial wave farm has yet been established (although development for the first commercial wind farm in the Orkneys are well under way).

Below you will find a selection of technologies used to convert wave energy into electricity.


Pelamis Wave Energy Converter: The Pelamis is a semi-submerged, articulated structure composed of cylindrical sections linked by hinged joints. The wave-induced motion of these joints is resisted by hydraulic rams, which pump high-pressure oil through hydraulic motors via smoothing accumulators. The hydraulic motors drive electrical generators to produce electricity. Power from all the joints is fed down a single umbilical cable to a junction on the sea bed. Several devices can be connected together and linked to shore through a single seabed cable.


Finavera’s AquabuOY: The AquaBuOY is a floating buoy structure that converts the kinetic energy of the vertical motion of oncoming waves into clean electricity. It utilizes a cylindrical buoy as the displacer and the reactor is a large water mass enclosed by a long vertical tube underneath the buoy.

[Youtube=http://www.youtube.com/watch?v=xu6_Em1LfBg”]
Aegir Dynamo: The Aegir Dynamo™ functions in a unique fashion by generating electrical current from the motion of the prime mover in one phase via a direct mechanical conversion and the use of a bespoke buoyancy vessel.

[YouTube=http://www.youtube.com/watch?v=r7-EPR8Ss6M”]Wave Dragon: Wave Dragon is a floating, slack-moored energy converter of the overtopping type that can be deployed in a single unit or in arrays of Wave Dragon units in groups resulting in a power plant with a capacity comparable to traditional fossil based power plants.

[YouTube=http://www.youtube.com/watch?v=cGD20eObcF8″]OWC Pico Power Plant: Wave enters in the “hydro-pneumatic chamber” (resembling a cave with entry below the waterline). Up-and down- movement of water column inside chamber makes air flow to and from the atmosphere, driving an air turbine. The turbine is symmetric and is driven indifferently in which direction the air flows.

AWS Wave Energy Converter
AWS Wave Energy Converter: The AWS (Archimedes Wave Swing) wave energy converter is a cylinder shaped buoy, moored to the seabed. Passing waves move an air-filled upper casing against a lower fixed cylinder, with up and down movement converted into electricity.
As a wave crest approaches, the water pressure on the top of the cylinder increases and the upper part or ‘floater’ compresses the gas within the cylinder to balance the pressures. The reverse happens as the wave trough passes and the cylinder expands. The relative movement between the floater and the lower part or silo is converted to electricity by means of a hydraulic system and motor-generator set.

Open-Centre Tidal Turbine
OpenHydro: The company’s vision is to deploy farms of open-centre tidal turbines under the world’s oceans – silently and invisibly generating electricity at no cost to the environment. OpenHydro’s technology enables the ocean’s immense energy to be harnessed for the benefit of all. The Open-Centre Turbine, with just one moving part and no seals, is a self-contained rotor with a solid state permanent magnet generator encapsulated within the outer rim, minimising maintenance requirements.

SPERBOY
SPERBOY: Developed and patented by Embley Energy, is a floating wave energy converter based on the ‘oscillating water column’ principle. Air displaced by the oscillating water column is passed through turbine-generators. Designed to be deployed in large arrays 8 to 12 miles off shore SPERBOYTM provides large-scale energy generation at a competitive cost.

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