This Is Cornwall has an article on yet another plan for a tidal power project on the Severn Estuary - North Devon 'perfect site' for £240m tidal barrage power station.

The barrage would be 1,200 metres (three-quarters of a mile) long and would run between Northam Burrows and Braunton Burrows. A road bridge would run along the top of the barrage, which Mr Apps claims would halve the travelling distance between Bideford and Braunton as well as alleviate congestion.

The project would cost between £200 and £240 million and would be a public-private partnership. Mr Apps said the project would largely be supported through European funding as well as from private investment.

The barrage would consist of eight or nine variable pitch turbines which would produce between 88 and 100 MW. In total the scheme could power up to 72,000 homes – more than twice the number that Fullabrook Wind Farm powers.

Hope springs eternal in the UK where groups are trying to revive the Severn tidal power project - Severn Tidal Power Subsidy Below Offshore Wind. The article says the subsidies required to be similar for those for a new nuclear power plant - but for a 30 year time frame, even though the tidal power plant would work for well over a century (and wouldn't have unquantifiable decommissioning costs).

The Severn Barrage project probably will require subsidies at about the same level as nuclear power stations and less than what’s offered for offshore wind plants, the developer of the British tidal energy project said.

“We expect that the price we will be able to negotiate will fall below offshore wind, and we hope close to or perhaps at the price nuclear power is currently negotiating,” Gregory Shenkman, chairman of Hafren Power Ltd., said at a hearing in the House of Commons in London today. That would make the project economically viable, he said.

The comments are aimed at answering the criticism that the technology that’s not working at a commercial scale anywhere in Britain would cost too much. Estimates for what the dam-like structure spanning the river at the southern end of Wales ran up to 25 billion pounds ($39 billion).

The Hafren plans, put to Prime Minister David Cameron in July, involve an 11-mile (18 kilometer) barrage from Cardiff in South Wales to Weston-super-Mare in Somerset. Its 1,026 turbines would generate power on tides as the sea rises and falls. The project may create about 20,000 construction jobs and 30,000 manufacturing and service jobs.

The barrage could fulfil 16 percent of that target and be capable of generating as much as 5 percent of the U.K.’s power, the government estimates. The project would need 30 years of support through subsidies. Thereafter, it would run for at least 90 years without support, generating electricity that’s 75 percent cheaper than all other forms of generation, Shenkman said. Across its 120 year life span, the project could produce power at about 48 pounds-a-megawatt-hour, less than the 88 pounds nuclear power costs, he said.

The Independent reports that the on-again, off-again Severn tidal power project is under consideration again in the UK as the government searches for infrastructure projects to restart the economy - No 10 asks ministers: Can we now support £30bn Severn barrage?.

David Cameron has ordered ministers to consider backing a £30bn project to harness the tidal power of the Severn estuary, as the Government scrambles to find big infrastructure projects that could help kick-start growth. ...

With the potential to create 20,000 jobs, it is exactly the sort of big-ticket construction project that the coalition needs to find as George Osborne faces a growing clamour to change economic course.

Mr Davey is to consider the details of the Severn barrage plan. However, The Independent on Sunday has learnt that the Liberal Democrats, uneasy about the lack of growth, are to call on the Chancellor to authorise additional public borrowing to fund a wide range of green-energy schemes. Mr Davey's aide, Duncan Hames, has drawn up a policy to this effect.

The idea of a Severn barrage was rejected by the coalition in 2010, which argued there was "no strategic case at this time for public funding of a scheme to generate energy in the Severn estuary".

But Mr Cameron has been persuaded that the long-debated idea of a barrage is worth reconsidering, because the consortium Corlan Hafren says no state funding is required. Instead, investors from Kuwait, Qatar and a number of sovereign wealth funds have expressed support for the idea. ...

Securing government support is crucial, because time would need to be found for legislation to pass through Parliament. Peter Hain, the former Labour cabinet minister, quit his frontbench role earlier this year to champion the project. He has offered to pilot a bill through the Commons, which Mr Cameron has agreed to study.

"Tidal power is the only lunar energy source," Mr Hain said in a letter to Mr Cameron. "Tides can be forecast for years in advance, and therefore tidal power is highly predictable and consistent."

Stretching up to 18 kilometres from Brean on the north Somerset coast to Lavernock Point in South Wales, the scheme, Corlan Hafren claims, could provide 5 per cent of the UK's energy needs, saving one million tonnes of carbon every year. ...

The project is thought to include 1,000 turbines. The Severn estuary has a tidal range of 14 metres, which engineers have contemplated harnessing since the middle of the 19th century.

The future for tidal power projects in the UK wasn't looking so good last week when the government announced the severn barrage project would not go ahead (but that they would support 8 new nuclear power plants - on existing sites, with no public subsidy involved, which will probably make getting them actually built rather tricky).

The BBC reports that things have turned around this week though, with a 400 MW tidal power project getting the go ahead for Pentland Firth in Scotland - Pentland Firth tidal project set for development.

A huge tidal project is set to be developed in the Pentland Firth after the rights to the site were awarded to a consortium by the Crown Estate.

It has described the Inner Sound, which lies between the Caithness coast and island of Stroma, as one of the Firth's "most energetic" tidal areas.

The scheme could involve up to 400 submerged turbines, generating enough energy to power 400,000 homes.

A 25-year operational lease for the site was awarded to MeyGen. It is a joint venture between tidal technology provider Atlantis Resources Corporation, International Power and investment bank Morgan Stanley.

The award of the lease comes after two years of feasibility work in the waters of the Pentland Firth.

Subject to planning consent, the consortium plans to install hundreds of turbines in the Inner Sound area. Construction is expected to take place on a phased basis until 2020.

The project will be one of the biggest in the world, with the potential to generate up to 400MW of power.

The scheme is part of efforts to develop the Pentland Firth and waters surrounding the Orkney Islands in the largest planned wave and tidal generating programme in the world.

Earlier this year, areas in the Pentland Firth and around Orkney were leased to seven companies, which aim to generate enough electricity to supply 750,000 homes by 2020 from a range of wave and tidal devices.

The FT has an article on the slow progress towards deciding what type of tidal power scheme will be built on the severn estuary - Severn tidal power schemes: Prepare for a dust-up

Among the UK government’s raft of carbon reduction plans announced today, it confirmed it will be making a decision on a Severn River estuary tidal power scheme next year.

It will not be easy to get there, however. Few oppose harnessing the Severn’s massive power. The idea has been around for decades - in fact more than a century, according to some reports - because of its high tidal range of up to 11.3m. Located in Britain’s south-west, it is also handily close to people and industry, meaning transmission costs would not be a big hurdle.

The UK government undertook a feasibility study into power schemes using the Severn last year, and decided to provide further funding to five of 10 proposed projects. This decision, however, prompted outrage. Opponents to big barrages have several criticisms: damage to bird habitats, impact on shipping, and unnecessary expense are the main objections.

Cambridge physics professor David Mackay, who examined the UK’s available renewable resources in his book ‘Without Hot Air’, likes tidal power but points out that the while a Severn barrage could theoretically provide current Severn barrage proposals only use energy from the tide moving in one direction, halving its potential.

But a coalition of green groups criticised the choice, saying the government favoured big expensive projects over lower-impact proposals such as lagoons. The government response was that these were the only ones that were realistic, and it had put a smaller amount of money towards ‘embryonic’ approaches such as low-barrage heads, tidal fences and lagoons, which it says have yet to be proven.

The big bad of the schemes, from the critics’ point of view, is the Cardiff-Weston plan which is estimated to cost about £20bn - but would produce an impressive 5 per cent of the UK’s power needs. Of the four other schemes, which range from £2.3bn to £4bn, one would provide 1 per cent and the others, about half of that amount.

The FT has a post on the ongoing bickering about the Severn tidal power scheme and which is the best option - Greens get angry about Severn tidal power scheme.

Plans for a tidal power scheme in the Severn estuary came under attack yesterday from green groups claiming the shortlist of projects drawn up by the government was “seriously flawed”.

Green groups have been concerned about the proposed tidal power scheme for some time, since it returned to vogue. A tidal power scheme taking advantage of the Severn’s extraordinary tidal range - one of the biggest in the world - has been mooted since at least the 1920s. As the government has sought to find ways to fulfil its target of generating 35-40 per cent of the UK’s electricity from renewable sources by 2020, the idea has come back into favour.

Earlier this year, the government published a shortlist of five projects and started a consultation process to assess their impacts and feasibility. The first consultation, on a hydroelectric barrage, closed two weeks ago.

Atkins, the engineering company, was commissioned by the Royal Society for the Protection of Birds to draw up a review of the shortlist of projects, which both found lacking.

Tidal energy from the Severn could satisfy as much as 5 per cent of the UK’s electricity needs. But, depending on how it is implemented, such a scheme could also cause severe damage to wildlife in the area, including birds, shorelife, and fish, and to plants that thrive in the delicate ecosystem.

The Atkins review found that the shortlist was based on out-of-date calculations, some from a study carried out 30 years ago, and criteria that the consultants said was skewed against more innovative and potentially more environmentally friendly projects.

Atkins found the shortlisting process “seriously underestimated” the amount of electricity that could be produced by more innovative and potentially less environmentally harmful projects, and underestimated the cost of some of the bigger schemes on the shortlist, such as a barrage from Cardiff to Weston.

Martin Harper, head of sustainable development at the RSPB, said: “The government doesn’t need to rush to judgement on this. If they do, there is a serious risk they will pick the wrong project. As this review shows, that could mean unnecessary damage to the environment, an oversized bill for the taxpayer and all for less electricity than is possible.”

The Department of Energy and Climate Change said all of the technically feasible schemes had been included on the shortlist, which it said had been reviewed by a panel of independent experts.

Any less developed technologies, such as tidal reefs and fences of the sort favoured by green groups, had not been ruled out, the government said, as £500,000 was to be devoted to studying them. However, they could not be shortlisted as they might be decades away from commercial deployment.

In a rebuke to the RSPB, the Department added: “It’s not possible to rule out the options on the proposed Severn tidal shortlist, and simultaneously call for serious and urgent action on climate change.”

The Guardian has a report on some new tidal power technology from a company in Wales inspired by ship propellers and wind turbines - Tidal power gets a boost from propeller and wind turbine techonology.

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.

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.

Finding a way to harness the power of the Severn's tides is important as it would represent a big step towards Britain's target of generating 35% of all electricity from renewable sources by 2020.

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.

Ministers have already called the scheme "visionary" and a "trailblazer for clean, green energy".

But 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.

But 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.

Discussions over plans for a tidal power project in the Severn estuary are continuing, with environmental groups pushing for a tidal reef instead of a barrage. The BBC reports - Severn reef plan is 'more green'.

Conservationists claim building a reef across the Severn Estuary would be cheaper, less damaging and generate more power than a proposed barrage. A study for the RSPB found a reef would hold back about 2m (6ft 6in) of water and not alter tidal patterns as much.

A feasibility study for the Welsh Assembly Government and the UK government on harnessing the estuary's tidal power started in January. A consultation on which projects to shortlist is expected to begin in 2009.

Supporters of a proposal for a 10 mile (16km) barrage between Cardiff and Weston-super-Mare argue it could generate some 17,000 gigawatt hours (gwh) of electricity each year, the equivalent of almost 5% of the UK's needs. The River Severn's tidal power can be seen by surfers taking on the Severn bore

The RSPB asked engineers Atkins to examine the feasibility of a "greener" alternative to a barrage. The research concluded a 12 mile (19 km) reef would cost about £2bn less and produce 20,000 gwh.

This proposal would see a reef built across the Severn between Aberthaw in the Vale of Glamorgan and Minehead in Somerset, making it the most westerly option. Like the Cardiff-Weston barrage, it would generate electricity as water flowed through turbines but it would not hold back the full height of the tide.

The study found that a reef could generate electricity for longer periods than the barrage, and therefore be more be able to meet power needs at peak demand times

WalsOnline reports that the list of options under consideration for the Severn Estuary tidal power project has been released - Revealed – the rival proposals for generating green energy from the Severn Estuary.

THE 10 potential schemes for generating green energy from the Severn Estuary were yesterday unveiled by the Government. More than 150 years after a Gloucestershire gentleman first painted his dream of a barrage across the estuary, the publication of a list of 10 options signalled a significant step towards making something similar a reality. ...

Announcing the list in a joint press statement with Wales’ Environment Minister Jane Davidson, the UK’s Business Minister John Hutton hailed the potential of the rival options to deliver a project of breathtaking scale.

He said: “Harnessing the power of the Severn Estuary could be an engineering project of breathtaking scale and we will look at the full range of technologies and locations. Such a project could play an important role in our ambition to dramatically increase the amount of energy from renewable sources. The tidal range on the Severn is the second largest in the world and has the potential to provide around 5% of the UK’s current electricity demand.” ...

Friends of the Earth campaigner Neil Crumpton said: “There are some exciting tidal projects on the table which could produce as much as 10% of the UK’s renewable energy 2020 target in a more cost effective way than the Severn Barrage and without damaging the environment or threatening access to the port at Bristol.

“The Government is currently trying to wriggle out of EU targets for green energy. If ministers focused their efforts on developing Britain’s vast renewable energy reserves – including the Severn Estuary – instead, they could build a thriving renewable industry. This would help avoid disastrous climate change and generate billions of pounds, hundreds of thousands of jobs and a clean and a secure energy supply for the UK.” ...

Liberal Democrat MP for Cardiff Central Jenny Willott said: “I am glad that the Government is publicly acknowledging the full range of tidal power options that could be used in the Severn Estuary.

“All too often, ministers have talked up a Severn Barrage over other technologies, and have been in danger of presenting it as a simple matter of take it or leave it. As with nuclear power, this clearly isn’t the case.

“What we need now is absolute impartiality from the Government. The feasibility study must be allowed to carry out its detailed work without any whiff of political pressure in favour of one technology over another.”

The Severn Barrage shortlist

1. A giant barrage from Minehead, north Devon, to Aberthaw, Vale of Glamorgan - This 15-mile proposal crosses deeper areas of the Severn Estuary but potentially generates more power. Supported by flood groups in Somerset, engineer Rupert Armstrong Evans has put forward plans for 1,000 turbines generating 20 terawatt hours of electricity and with less impact on sea levels. Critics warn it would be an expensive option.

2. Middle Barrage from Brean Down to Lavernock Point, Sully, Vale of Glamorgan - Brought to the public eye by the Severn Tidal Power Group, a consortium of four of Britain’s leading builders, this is the best- known proposal and is often called the Cardiff Weston barrage. A 1989 study estimated it could generate 17 terawatt hours of electricity per year at a cost of around £15bn based on proven technology as used at La Rance, near St Malo, France, for 40 years.

3. Middle Barrage from Hinkley to Lavernock Point, Sully, Vale of Glamorgan - A similar proposal to the Brean Down proposal but with a different landing point in the West Country.

4. Inner Barrage (also known as Shoots or Hooker Barrage) - Favoured by the Friends of the Earth Cymru, this bird life-friendly proposal would be built near the second Severn crossing. A 2006 study suggested it could generate one seventh of the power of the Cardiff Weston barrage at a 10th of the cost.

5. Beachley Barrage - The first proposal for a barrage, put forward in 1849, it was painted by the surveyor, architect and engineer Thomas Fulljames of Gloucestershire.

6. Tidal Fence - Backed by a multinational group of academics, engineers and green energy groups, the proposal would generate one fifth of the power of the Cardiff Weston barrage along the same path. Backers claim the tidal stream technology provides advantages for shipping and wildlife.

7. Fleming Lagoons - Built against the banks of the Severn, the Severn Development Commission estimated a scheme based around three lagoons could generate 6.5 terawatt hours of electricity a year.

8. Tidal Lagoons - Friends of the Earth Cymru backs balanced, free-standing lagoons along with a smaller Shoots Barrage. They generate power in the same way as a barrage without obstructing the entire Estuary, minimising the impact on bird life.

9. Tidal Reef Proposal - A tidal stream energy concept including floating turbines housed in caissons and suggested as part of the outer barrage from Minehead to Aberthaw.

10. Severn Lake Scheme - Proposed by Neath entrepreneur Gareth Woodham, this mile-wide causeway along the line of the Sully Barrage would also include marinas, executive islands with a road and rail link with two lock gates, 200 hydro-electric turbines and two wave farms.

The BBC has an update on efforts to build a tidal power facility on the Severn estuary.

In January, the UK government and Welsh Assembly launched a two-year feasibility study into the possibility of harnessing tidal energy in the Severn estuary in order to generate electricity. It has the second largest tidal range in the world, which could be used to meet up to 5% of the UK's electricity needs.

Two forms of technology are being assessed by the study: tidal barrages and tidal lagoons. The concepts are not new and there have been plans to tap into the river's resource since the middle of the 19th Century.

The big tidal range also makes the area an internationally important habitat for migrating birds. Environmentalists say that a 16km (10 mile) barrage stretching from Cardiff to Weston-super-Mare would destroy vital feeding sites.

The feasibility study, which is expected to conclude early in 2010, is tasked with identifying a "single preferred tidal range project" from a number of options proposed. ...

Although there are a number of proposals for tidal barrages stretching across the Bristol Channel, the feasibility study is likely to concentrate on two options.
Graphic showing the cross-section of a tidal barrage (Image: BBC)

The first is the widely reported scheme that plans to build a 16.1km (10 mile) barrage from just south of Cardiff across to the Somerset coast, near Weston-Super-Mare. The other is the "Shoots" proposal, a much smaller project that would see a 4.1km (2.5 mile) barrage stretch across the Severn at roughly the same point at the current two road crossings.

The Sustainable Development Commission (SDC), the government's independent advisers, published a report in October 2007 that examined the potential of tidal power around the UK's coastline.

The Commission's report estimated that the large Cardiff-Weston plan would cost in the region of £15bn to construct, while the smaller Shoots scheme would require £1.5bn. If given the green light, the barrage is expected to take about 12 years to build.