Largest tidal power device unveiled

A device thought to be the largest tidal energy turbine to be built in the world has been described by its developer as "simple and robust".

Atlantis Resources unveiled its AK-1000 at Invergordon ahead of it being shipped to a European Marine Energy Centre test site off Eday, Orkney.

Chief executive Tim Cornelius said it was designed to survive in a harsh marine environment.

The device stands 22.5m (73ft) tall and weighs 130 tonnes.

It has two sets of blades to harness ebb and flood tides and could provide electricity for about 1,000 homes.

BBC NEWS  12 Aug 2010

Bids sought for Pentland Firth tidal energy site

A giant tidal energy scheme which the government is counting on to meet ambitious new green energy targets set this week should not be built because it would be so ecologically destructive, the chair of the Environment Agency has warned ministers.

The government's roadmap to a low-carbon UK called for a 34% cut in emissions by 2020, with the power sector contributing the bulk of that saving. The Weston barrage, running 10 miles across the Severn estuary between Weston-super-Mare and Cardiff, is by far the largest of four tidal power schemes being considered by government and would be the centrepiece of the nation's renewable energy plan.

It could generate 8.6 gigawatts of zero-carbon electricity from the Severn – the equivalent of eight large coal-fired power stations – and would be the single largest renewable energy project in Europe.

But the £5bn flagship scheme would permanently flood nearly 35,000 hectares (86,000 acres) of internationally protected wetlands. It would also destroy some of Britain's most important fisheries in the Severn, Wye and Usk catchment areas, said Lord Smith in an interview with the Guardian ...

Guardian 17 July 2009

Britain's environmental movement was yesterday presented with its starkest choice yet: whether or not to support the world's largest-ever renewable energy project which will result in unprecedented ecological damage to one of our most important natural habitats.

The giant £20bn Severn barrage, which would stretch 10 miles from Lavernock Point near Cardiff to Brean Down near Weston-super-Mare, would harness the tides to generate up to 5 per cent of the UK's electricity needs – the equivalent of eight typical coal-fired power stations. This is crucially important in the fight against climate change.

But environmentalists fear that by blocking the Severn estuary completely, the barrage would destroy vast areas of mudflats and mashes, which are vital feeding grounds for tens of thousands of wading birds, and prevent migratory fish such as salmon and eels from ascending rivers to spawn. Other environmentalists think such a large project would divert resources away from other key renewable technologies such as wind power.

Yesterday the barrage appeared on a shortlist of five renewable energy schemes for the Severn estuary indicating that the project, which the Government is known to favour, is moving closer to formal acceptance ...

The Independent 27 January 2009

Row breaks out over UK's biggest renewables project

A tough choice between energy and the environment

Huge barrage plan makes estuary shortlist

Environmentalists react angrily to shortlisted projects for Severn estuary

Government consultants have been accused of miscalculating the costs of a project to generate vast amounts of green electricity in the Severn estuary, promoting a 10 mile-long tidal barrier strongly backed by ministers in preference to a scheme that engineers and environmentalists say is far less damaging.

The US engineering firm Parsons Brinckerhoff has been hired by the Department of Energy and Climate Change (Decc) to assess technologies that could meet, from the Severn estuary, up to 7% of the electricity consumption of England and Wales. Its feasibility study for the estuary, which has the second highest tidal range in the world, has been sent to ministers, who will soon announce a shortlist of potential schemes based on the assessment ...

Sources in Decc say the firm favourite is the 10-mile barrier, which would span the entire estuary and is costed at about £14bn. Parsons Brinckerhoff (PB) said the barrier could generate between 5GW and 8.6GW of renewable electricity at a cost of about 3p/kWh, but that it would impede shipping and lead to permanent flooding over more than 100 miles of shoreline ...

... correspondence seen by the Guardian shows that a row erupted between PB and a company promoting a scheme that environmental groups and other engineers claim would be far less damaging, as well as cheaper and more efficient.

Tidal Electric wants to generate electricity by using tidal lagoons built on the estuary floor from rock. Up to 13 lagoons would be dotted around the Severn estuary, not across it. These would trap water at high tide and release it later through electricity-generating turbines.

Studies carried out by the engineers AS Atkins, for Tidal Electric, have suggested that the lagoons could generate twice as much power, per square mile impounded, than the barrage, and therefore generate about 25-40% more energy without damaging the shoreline.

However, the plan sent by PB to ministers says the tidal lagoon option would be eight times more expensive than the barrage scheme and would not generate as much power.

... Peter Ullman, chief executive of Tidal Electric, said: "PB has made huge miscalculations. They have submitted [to ministers] cost-numbers on power from tidal lagoons that are roughly 800% higher than all the previous studies of tidal lagoon power conducted by UK engineering giant WS Atkins and corroborated by AEA Technology, Ofgem and Rothschild Bank. They have arrived at their extraordinarily high numbers by ignoring the technology developer's design parameters and introducing their own design."

One key issue is that Tidal Electric plans to site the lagoons in shallow water, while PB assumes they would be built – at a higher cost – in deeper water ...

Guardian 05 January 2009

Britain's largest environment groups have strongly rejected plans for a massive £15bn tidal barrage across the Severn that would provide about 5% of the UK's annual electricity demand and help the government meet climate-change targets.

In the first shots of what is expected to become one of the fiercest environmental battles in years, the groups, which include the National Trust, the RSPB and WWF, but not Greenpeace, have challenged the government to find cheaper and less destructive ways of generating renewable electricity from the estuary.

Britain will need to generate nearly 40% of its electricity from renewable resources by 2020 to meet its EU targets, and a 10-mile long tidal barrage with 200 turbines between Cardiff and Weston-super-Mare is widely seen in government as one of the most attractive options. Plans for a barrage have been proposed for more than 100 years.

But the coalition of 10 groups, with a membership of more than 5 million people, says a barrage would be economically dubious and ecologically disastrous. It would, the coalition says, destroy nearly 86,486 acres (35,000 ha) of highly protected wetlands across the estuary. More power could be generated more cheaply by using other green technologies, the group says.

Their report, commissioned from the economics consultancy Frontier Economics, follows a study last year by the government's environmental advisers, the Sustainable Development Commission (SDC). ...

The land that would be submerged hosts about 68,000 birds in winter, including huge flocks of dunlins and shelducks, together with Bewick's swans, curlews, pintails, wigeons and redshanks. Breeding birds feeding on the estuary in summer include curlews, shelducks and oystercatchers. At least 30,000 salmon and tens of thousands of shads, lampreys and sea trout use the estuary to reach spawning grounds in the Usk and Wye rivers. Eels swim back down these rivers to reach spawning grounds at sea and millions of elvers return in the spring.

Guardian 12 June 2008

The justification for a barrage should flow from it being the least cost option amongst the range of options available to meet Government’s objectives.

This study examines one particular aspect of that least cost decision: a comparison of the individual costs of generating from different sources.

The analysis is based on a bottom-up calculation of generation costs that takes the specific characteristics of the different technologies into account.

In addition, it uses cost data from actual projects currently being commissioned.

This analysis suggests that:

• under a range of plausible scenarios, a large barrage on the Severn is expensive compared to alternative ways of generating renewable electricity; and

• there appears to be sufficient capacity to use other technologies to meet the barrage’s output and Government’s targets.

... the extent of the analysis, the in-built conservatism in the estimates used and range of sensitivity analysis undertaken suggests that considerable new evidence would be needed to make a large barrage in the Severn estuary an attractive option for meeting Government’s overall objectives ...

Frontier Economic June 2008

Summary Electricity-generating tidal lagoons located in the Severn Estuary could provide an economically attractive and environmentally acceptable way of supplying up to 7% of England and Wales’s electricity consumption with low-cost, low-carbon electricity.

There are a large range of potential environmental and economic benefits and disbenefits associated with siting lagoons or the proposed Severn Barrage in the Estuary. However, initial comparisons strongly suggest that lagoons could be significantly less extensive and environmentally damaging and more cost effective and powerful than the Barrage.

Lagoons would not directly impound the ecologically highly valuable inter-tidal areas of the Estuary. Indeed, lagoons may offer potentially significant wildlife habitat. Yet, lagoons would generate twice as much power per square mile impounded than the Barrage and could extract about 25 - 40% more energy from two thirds of the impounded area.

Considering the wider environmental and economic issues, the sourcing of large volumes of aggregates for the lagoons would be critical because this could result in substantial adverse impacts. Yet, every tonne of aggregate used in lagoon construction would enable the generation of about three times more electricity than a tonne of coal burnt in a power station, and there would be no greenhouse gas or acid gas emissions.

Lagoons would not impede shipping but the Barrage could provide a novel transport link.

Both technologies would generate significant quantities of low-carbon electricity close tolarge populations. However, the Unit generation cost, output timings, storage capability and smaller capital costs of lagoons are likely to be far more attractive to private investors and consumers.

FOE January 2004