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Posts Tagged ‘Tidal Turbines’

NAO NAKANISHI, Reuters, October 5, 2009

PelamisWaveFarm_PelamisWavePowerA first attempt fell victim to the crisis: now in the docks of Scotland’s ancient capital, a second-generation scarlet Sea Snake is being prepared to harness the waves of Britain’s northern islands to generate electricity.

Dwarfed by 180 metres of tubing, scores of engineers clamber over the device, which is designed to dip and ride the swelling sea with each move being converted into power to be channelled through subsea cables.

Due to be installed next spring at the European Marine Energy Centre (EMEC) in Orkney, northern Scotland, the wave power generator was ordered by German power company E.ON, reflecting serious interest in an emerging technology which is much more expensive than offshore wind.

Interest from the utility companies is driven by regulatory requirements to cut carbon emissions from electricity generation, and it helps in a capital-intensive sector.

Venture capitalists interested in clean tech projects typically have shorter horizons for required returns than the 10-20 years such projects can take, so the utilities’ deeper pockets and solid capital base are useful.

“Our view … is this is a 2020 market place,” said Amaan Lafayette, E.ON’s marine development manager. “We would like to see a small-scale plant of our own in water in 2015-2017, built on what we are doing here. It’s a kind of generation we haven’t done before.”

The World Energy Council has estimated the market potential for wave energy at more than 2,000 terawatt hours a year — or about 10% of world electricity consumption — representing capital expenditure of more than 500 billion pounds ($790 billion).

Island nation Britain has a leading role in developing the technology for marine power, which government advisor the Carbon Trust says could in future account for 20% of the country’s electricity. The government is stepping up support as part of a 405 million pound investment in renewable energy to help its ambition of cutting carbon emissions by 80% by 2050 from 1990 levels, while securing energy supply. (The challenge is more about getting to a place where we are comparable with other renewable technologies… We want to get somewhere around offshore wind,” said Lafayette.)

Britain’s Crown Estate, which owns the seabed within 12 nautical miles of the coast, is also holding a competition for a commercial marine energy project in Pentland Firth in northern Scotland.

Besides wave power, Britain is testing systems to extract the energy from tides: private company Marine Current Turbines Ltd (MCT) last year opened the world’s first large-scale tidal turbine SeaGen in Northern Ireland.

DEVELOPING LIKE WIND

wave_power_pelamis“We are often compared to the wind industry 20 years ago,” said Andrew Scott, project development manager at Pelamis Wave Power Ltd, which is developing the Sea Snake system, known as P2. Standing beside the train-sized serpent, Pelamis’ Scott said wave power projects are taking a variety of forms, which he said was similar to the development of the wind turbine. “You had vertical axis, horizontal axis and every kind of shapes before the industry consolidated on what you know as acceptable average modern day turbines.”

The Edinburgh Snake follows a pioneering commercial wave power project the company set up in Portugal last September, out of action since the collapse of Australian-based infrastructure group Babcock & Brown which held a majority share. “It’s easy to develop your prototypes and models in the lab, but as soon as you put them in water, it swallows capital,” said John Liljelund, CEO of Finnish wave energy firm AW-Energy, which just received $4.4 million from the European Union to develop its WaveRoller concept in Portugal.

At present, industry executives say marine power costs about double that from offshore wind farms, which require investment of around 2-3 million euros per megawatt. Solar panels cost about 3-4 million per megawatt, and solar thermal mirror power about 5 million.

UTILITY ACTION

Other utility companies involved in wave power trials include Spain’s Iberdrola, which has a small experimental wave farm using floating buoys called “Power Take- offs” off the coast of northern Spain. It is examining sites for a subsea tidal turbine project made by Norwegian company Hammerfest Strom.

Countries developing the technology besides Britain include Portugal, Ireland, Spain, South Korea and the United States: about 100 companies are vying for a share of the market, but only a handful have tested their work in the ocean.

Privately owned Pelamis has focussed on wave energy since 1998, has its own full-scale factory in Leith dock and sees more orders for the second generation in prospect.

Lafayette said E.ON examined more than 100 devices since 2001 before picking Sea Snake for its first ocean project, a three-year test: “They have a demonstrable track record … and commercial focus and business focus.”

A single Sea Snake has capacity of 750 kilowatts: by around 2015, Pelamis hopes each unit will have capacity of 20 megawatts, or enough to power about 30,000 homes.

Neither Pelamis nor E.ON would elaborate on the cost of the Sea Snake, but they said the goal is to bring it down to the level of offshore wind farms.

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JAMES RICKMAN, Seeking Alpha, June 8, 2009

wave-ocean-blue-sea-water-white-foam-photoOceans cover more than 70% of the Earth’s surface. As the world’s largest solar collectors, oceans generate thermal energy from the sun. They also produce mechanical energy from the tides and waves. Even though the sun affects all ocean activity, the gravitational pull of the moon primarily drives the tides, and the wind powers the ocean waves.

Wave energy is the capture of the power from waves on the surface of the ocean. It is one of the newer forms of renewable or ‘green’ energy under development, not as advanced as solar energy, fuel cells, wind energy, ethanol, geothermal companies, and flywheels. However, interest in wave energy is increasing and may be the wave of the future in coastal areas according to many sources including the International Energy Agency Implementing Agreement on Ocean Energy Systems (Report 2009).

Although fewer than 12 MW of ocean power capacity has been installed to date worldwide, we find a significant increase of investments reaching over $2 billion for R&D worldwide within the ocean power market including the development of commercial ocean wave power combination wind farms within the next three years.

Tidal turbines are a new technology that can be used in many tidal areas. They are basically wind turbines that can be located anywhere there is strong tidal flow. Because water is about 800 times denser than air, tidal turbines will have to be much sturdier than wind turbines. They will be heavier and more expensive to build but will be able to capture more energy. For example, in the U.S. Pacific Northwest region alone, it’s feasible that wave energy could produce 40–70 kilowatts (kW) per meter (3.3 feet) of western coastline. Renewable energy analysts believe there is enough energy in the ocean waves to provide up to 2 terawatts of electricity.

Companies to Watch in the Developing Wave Power Industry:

Siemens AG (SI) is a joint venture partner of Voith Siemens Hydro Power Generation, a leader in advanced hydro power technology and services, which owns Wavegen, Scotland’s first wave power company. Wavegen’s device is known as an oscillating water column, which is normally sited at the shoreline rather than in open water. A small facility is already connected to the Scottish power grid, and the company is working on another project in Northern Spain.

Ocean Power Technologies, Inc (OPTT) develops proprietary systems that generate electricity through ocean waves. Its PowerBuoy system is used to supply electricity to local and regional electric power grids. Iberdrola hired the company to build and operate a small wave power station off Santona, Spain, and is talking with French oil major Total (TOT) about another wave energy project off the French coast. It is also working on projects in England, Scotland, Hawaii, and Oregon.

Pelamis Wave Power, formerly known as Ocean Power Delivery, is a privately held company which has several owners including various venture capital funds, General Electric Energy (GE) and Norsk Hydro ADR (NHYDY.PK). Pelamis Wave Power is an excellent example of Scottish success in developing groundbreaking technology which may put Scotland at the forefront of Europe’s renewable revolution and create over 18,000 green high wage jobs in Scotland over the next decade. The Pelamis project is also being studied by Chevron (CVX).

Endesa SA ADS (ELEYY.PK) is a Spanish electric utility which is developing, in partnership with Pelamis, the world’s first full scale commercial wave power farm off Aguçadoura, Portugal which powers over 15,000 homes. A second phase of the project is now planned to increase the installed capacity from 2.25MW to 21MW using a further 25 Pelamis machines.

RWE AG ADR (RWEOY.PK) is a German management holding company with six divisions involved in power and energy. It is developing wave power stations in Siadar Bay on the Isle of Lewis off the coast of Scotland.

Australia’s Oceanlinx offers an oscillating wave column design and counts Germany’s largest power generator RWE as an investor. It has multiple projects in Australia and the U.S., as well as South Africa, Mexico, and Britain.

Alstom (AOMFF.PK) has also announced development in the promising but challenging field of capturing energy from waves and tides adding to the further interest from major renewable power developers in this emerging industry.

The U.S. Department of Energy has announced several wave energy developments including a cost-shared value of over $18 million, under the DOE’s competitive solicitation for Advanced Water Power Projects. The projects will advance commercial viability, cost-competitiveness, and market acceptance of new technologies that can harness renewable energy from oceans and rivers. The DOE has selected the following organizations and projects for grant awards:

First Topic Area: Technology Development (Up to $600,000 for up to two years)

Electric Power Research Institute, Inc (EPRI) (Palo Alto, Calif.) Fish-friendly hydropower turbine development & deployment. EPRI will address the additional developmental engineering required to prepare a more efficient and environmentally friendly hydropower turbine for the commercial market and allow it to compete with traditional designs.

Verdant Power Inc. (New York, N.Y.) Improved structure and fabrication of large, high-power kinetic hydropower systems rotors. Verdant will design, analyze, develop for manufacture, fabricate and thoroughly test an improved turbine blade design structure to allow for larger, higher-power and more cost-effective tidal power turbines.

Public Utility District #1 of Snohomish County (SnoPUD) (Everett, Wash.) Puget Sound Tidal Energy In-Water Testing and Development Project. SnoPUD will conduct in-water testing and demonstration of tidal flow technology as a first step toward potential construction of a commercial-scale power plant. The specific goal of this proposal is to complete engineering design and obtain construction approvals for a Puget Sound tidal pilot demonstration plant in the Admiralty Inlet region of the Sound.

Pacific Gas and Electric Company – San Francisco, Calif. WaveConnect Wave Energy In-Water Testing and Development Project. PG&E will complete engineering design, conduct baseline environmental studies, and submit all license construction and operation applications required for a wave energy demonstration plant for the Humboldt WaveConnect site in Northern California.

Concepts ETI, Inc (White River Junction, Vt.) Development and Demonstration of an Ocean Wave Converter (OWC) Power System. Concepts ETI will prepare detailed design, manufacturing and installation drawings of an OWC. They will then manufacture and install the system in Maui, Hawaii.

Lockheed Martin Corporation (LMT) – Manassas, Va., Advanced Composite Ocean Thermal Energy Conversion – “OTEC”, cold water pipe project. Lockheed Martin will validate manufacturing techniques for coldwater pipes critical to OTEC in order to help create a more cost-effective OTEC system.

Second Topic Area, Market Acceleration (Award size: up to $500,000)

Electric Power Research Institute (Palo Alto, Calif.) Wave Energy Resource Assessment and GIS Database for the U.S. EPRI will determine the naturally available resource base and the maximum practicable extractable wave energy resource in the U.S., as well as the annual electrical energy which could be produced by typical wave energy conversion devices from that resource.

Georgia Tech Research Corporation (Atlanta, Ga.) Assessment of Energy Production Potential from Tidal Streams in the U.S. Georgia Tech will utilize an advanced ocean circulation numerical model to predict tidal currents and compute both available and effective power densities for distribution to potential project developers and the general public.

Re Vision Consulting, LLC (Sacramento, Calif.) Best Siting Practices for Marine and Hydrokinetic Technologies With Respect to Environmental and Navigational Impacts. Re Vision will establish baseline, technology-based scenarios to identify potential concerns in the siting of marine and hydrokinetic energy devices, and to provide information and data to industry and regulators.

Pacific Energy Ventures, LLC (Portland, Ore.) Siting Protocol for Marine and Hydrokinetic Energy Projects. Pacific Energy Ventures will bring together a multi-disciplinary team in an iterative and collaborative process to develop, review, and recommend how emerging hydrokinetic technologies can be sited to minimize environmental impacts.

PCCI, Inc. (Alexandria, Va.) Marine and Hydrokinetic Renewable Energy Technologies: Identification of Potential Navigational Impacts and Mitigation Measures. PCCI will provide improved guidance to help developers understand how marine and hydrokinetic devices can be sited to minimize navigational impact and to expedite the U.S. Coast Guard review process.

Science Applications International Corporation (SAI) – San Diego, Calif., International Standards Development for Marine and Hydrokinetic Renewable Energy. SAIC will assist in the development of relevant marine and hydrokinetic energy industry standards, provide consistency and predictability to their development, and increase U.S. industry’s collaboration and representation in the development process.

Third Topic Area, National Marine Energy Centers (Award size: up to $1.25 million for up to five years)

Oregon State University, and University of Washington – Northwest National Marine Renewable Energy Center. OSU and UW will partner to develop the Northwest National Marine Renewable Energy Center with a full range of capabilities to support wave and tidal energy development for the U.S. Center activities are structured to: facilitate device commercialization, inform regulatory and policy decisions, and close key gaps in understanding.

University of Hawaii (Honolulu, Hawaii) National Renewable Marine Energy Center in Hawaii will facilitate the development and implementation of commercial wave energy systems and to assist the private sector in moving ocean thermal energy conversion systems beyond proof-of-concept to pre-commercialization, long-term testing.

Types of Hydro Turbines

There are two main types of hydro turbines: impulse and reaction. The type of hydropower turbine selected for a project is based on the height of standing water— the flow, or volume of water, at the site. Other deciding factors include how deep the turbine must be set, efficiency, and cost.

Impulse Turbines

The impulse turbine generally uses the velocity of the water to move the runner and discharges to atmospheric pressure. The water stream hits each bucket on the runner. There is no suction on the down side of the turbine, and the water flows out the bottom of the turbine housing after hitting the runner. An impulse turbine, for example Pelton or Cross-Flow is generally suitable for high head, low flow applications.

Reaction Turbines

A reaction turbine develops power from the combined action of pressure and moving water. The runner is placed directly in the water stream flowing over the blades rather than striking each individually. Reaction turbines include the Propeller, Bulb, Straflo, Tube, Kaplan, Francis or Kenetic are generally used for sites with lower head and higher flows than compared with the impulse turbines.

Types of Hydropower Plants

There are three types of hydropower facilities: impoundment, diversion, and pumped storage. Some hydropower plants use dams and some do not.

Many dams were built for other purposes and hydropower was added later. In the United States, there are about 80,000 dams of which only 2,400 produce power. The other dams are for recreation, stock/farm ponds, flood control, water supply, and irrigation. Hydropower plants range in size from small systems for a home or village to large projects producing electricity for utilities.

Impoundment

The most common type of hydroelectric power plant (above image) is an impoundment facility. An impoundment facility, typically a large hydropower system, uses a dam to store river water in a reservoir. Water released from the reservoir flows through a turbine, spinning it, which in turn activates a generator to produce electricity. The water may be released either to meet changing electricity needs or to maintain a constant reservoir level.

The Future of Ocean and Wave Energy

Wave energy devices extract energy directly from surface waves or from pressure fluctuations below the surface. Renewable energy analysts believe there is enough energy in the ocean waves to provide up to 2 terawatts of electricity. (A terawatt is equal to a trillion watts.)

Wave energy rich areas of the world include the western coasts of Scotland, northern Canada, southern Africa, Japan, Australia, and the northeastern and northwestern coasts of the United States. In the Pacific Northwest alone, it’s feasible that wave energy could produce 40–70 kilowatts (kW) per meter (3.3 feet) of western coastline. The West Coast of the United States is more than a 1,000 miles long.
In general, careful site selection is the key to keeping the environmental impacts of wave energy systems to a minimum. Wave energy system planners can choose sites that preserve scenic shorefronts. They also can avoid areas where wave energy systems can significantly alter flow patterns of sediment on the ocean floor.

Economically, wave energy systems are just beginning to compete with traditional power sources. However, the costs to produce wave energy are quickly coming down. Some European experts predict that wave power devices will soon find lucrative niche markets. Once built, they have low operation and maintenance costs because the fuel they use — seawater — is FREE.

The current cost of wave energy vs. traditional electric power sources?

It has been estimated that improving technology and economies of scale will allow wave generators to produce electricity at a cost comparable to wind-driven turbines, which produce energy at about 4.5 cents kWh.

For now, the best wave generator technology in place in the United Kingdom is producing energy at an average projected/assessed cost of 6.7 cents kWh.

In comparison, electricity generated by large scale coal burning power plants costs about 2.6 cents per kilowatt-hour. Combined-cycle natural gas turbine technology, the primary source of new electric power capacity is about 3 cents per kilowatt hour or higher. It is not unusual to average costs of 5 cents per kilowatt-hour and up for municipal utilities districts.

Currently, the United States, Brazil, Europe, Scotland, Germany, Portugal, Canada and France all lead the developing wave energy industry that will return 30% growth or more for the next five years.

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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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JENNY HAWORTH, Scotman.com, February 12, 2009

na910MORE than three dozen energy companies from across the world are hoping to install wave energy devices in a stretch of sea off the north of Scotland. The renewable energy firms all have their sights on the Pentland Firth, which is considered one of the best locations in the world for generating electricity from the power of the tides.

Yesterday, the Crown Estate, which owns the seabed and will authorize any offshore  wave energy project, announced it had invited 38 companies to submit detailed plans for schemes in the Pentland Firth.

This is the first stretch of water off the UK to be opened up for development of marine renewables, meaning successful companies will be building among the first marine wave energy projects in the world.

Each company hopes to install dozens, or even hundreds of wave energy devices, such as tidal turbines, in the ocean.

Alex Salmond, the First Minister, hopes it will help Scotland become a world leader in renewable energy, saying “the fact that so many companies have already registered their interest in developing wave and tidal energy projects in the Pentland Firth and surrounding waters is extremely encouraging.”

“The Scottish Government has recently launched the world’s greatest-ever single prize for innovation in marine energy, the £10 million Saltire Prize, and the opening of the Pentland Firth for development is a timely and crucial move.”

The Crown Estate invited initial expressions of interest in the Pentland Firth from renewables firms in November 2008. A spokeswoman said she could not reveal how many companies had shown an interest because of competition rules, but she confirmed 38 firms would be invited to the next stage – to tender for sites in the Pentland Firth.

They must now submit detailed applications, spelling out how many devices they want to install in the water, by the end of May.

The Crown Estate will decide which are suitable, and the companies will then have to apply for planning permission from the Scottish Government.

Calum Duncan, Scottish conservation manager for the Marine Conservation Society, welcomed renewable technologies, but said the possible impact of the devices on sensitive seabed habitats must be considered, including the likely affect on mussel beds and feeding areas for fish, basking sharks and seabirds.

Liam McArthur, the Liberal Democrat energy spokesperson and MSP for Orkney, also welcomed the strong interest but had reservations. “This energetic stretch of water will be a challenging resource to tame,” he said.

“We still know relatively little about the Pentland Firth and what will happen when we start putting devices in the water there.

“While the Pentland Firth is often described as the Saudi Arabia of tidal power, the challenges it presents also make it the Mount Everest.”

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RenewableEnergyWorld.com, January 27, 2009 

One Choice

One Option on the Shortlist

A shortlist of proposed plans to generate electricity from the power of the tides in the Severn estuary has been unveiled by the UK Department of Energy and Climate Change.

UK Energy and Climate Change Secretary Ed Miliband has also announced £500,000 [US $702,000] of new funding to further develop early-stage technologies like tidal reefs and fences. The progress of these technologies will be considered before decisions are taken whether to go ahead with a Severn tidal power scheme.

The tides in the Severn estuary are the second highest in the world. The largest proposal being taken forward has the potential to generate nearly 5% of the UK’s electricity from this domestic, low carbon and sustainable source.

Over the past year, the Government-led feasibility study has been investigating a list of ten options, gathering information on the costs, benefits and environmental challenges of using the estuary to generate power.

The proposed shortlist is includes:       

  • Cardiff Weston Barrage: A barrage crossing the Severn estuary from Brean Down, near Weston super Mare to Lavernock Point, near Cardiff. Its estimated capacity is over 8.6 gigawatts (GW).
  • Shoots Barrage: Further upstream of the Cardiff Weston scheme. Capacity of 1.05 GW, similar to a large fossil fuel plant.
  • Beachley Barrage: The smallest barrage on the proposed shortlist, just above the Wye River. It could generate 625 MW.
  • Bridgwater Bay Lagoon: Lagoons are radical new proposals which impound a section of the estuary without damming it. This plan is sited on the English shore between east of Hinkley Point and Weston super Mare. It could generate 1.36 GW.
  • Fleming Lagoon: An impoundment on the Welsh shore of the estuary between Newport and the Severn road crossings. It too could generate 1.36 GW.The proposed shortlist will now be subject to a three month public consultation which begins this week.

“Fighting climate change is the biggest long term challenge we face and we must look to use the UK’s own natural resources to generate clean, green electricity. The Severn estuary has massive potential to help achieve our climate change and renewable energy targets. We want to see how that potential compares against the other options for meeting our goals,” said UK Energy and Climate Change Secretary Ed Miliband.

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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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BBC News, December 18, 2008

_45310426_43017507A tidal turbine near the mouth of Strangford Lough has begun producing electricity at full capacity for the first time.  The SeaGen system now generates 1.2MW, the highest level of power produced by a tidal stream system anywhere in the world.

The system works like an “underwater windmill” but with rotors driven by tidal currents rather than the wind.

It has been undergoing commissioning trials since May.

SeaGen will now move towards full-operating mode for periods of up to 22 hours a day, with regular inspections and performance testing carried out.

The power generated by the system is being purchased by Irish energy company, ESB Independent, for its customers in Northern Ireland and the Republic.

The turbine has the capacity to generate power to meet the average electricity needs of around 1000 homes.

Martin Wright, managing director of SeaGen developers, Marine Current Turbines, said that having the system generating at full power was an important milestone.

“It demonstrates, for the first time, the commercial potential of tidal energy as a viable alternative source of renewable energy,” he said.

“As the first mover in tidal stream turbine development, we have a significant technical lead over all rival tidal technologies that are under development.

“There are no other tidal turbines of truly commercial scale; all the competitive systems so far tested at sea are quite small, most being less than 10% the rotor area of SeaGen.”

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