The ongoing feasibility study, commissioned by Secretary of State for Energy John Hutton, will now look in further detail at the 10 schemes. A short list will be published later this year highlighting which preferred proposals could be taken forward for more extensive research. Announcing the proposals to stakeholders, John Hutton 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."

Welsh Assembly Government Environment, Sustainability and Housing Minister, Jane Davidson said:

"The aim of the joint feasibility study is to look at all the potential options for generating renewable and sustainable energy from the huge tidal range of the Severn estuary.

"It is important to stress that while there is much talk of a 'barrage' this feasibility study is looking at a range of other options.

"The potential here is great and the Severn Estuary is a resource that could help us make a significant contribution to the proposed UK renewables target of 15% by 2020."

The ten options under consideration are::

1. Outer Barrage from Minehead to Aberthaw: this would be the largest barrage and would make maximum use of the Severn Estuary tidal resource

2. Middle Barrage from Brean Down to Lavernock Point: most well-studied option, known as the Cardiff-Weston barrage

3. Middle Barrage from Hinkley to Lavernock Point: as option 2 but lands at Hinkley

4. Inner Barrage (Shoots Barrage): also known as English Stones scheme and studied in detail by the Sustainable Development Commission

5. Beachley Barrage: barrage further upstream, smaller generating capacity than Shoots.

6. Tidal Fence proposal: a barrier constructed over part of the Cardiff to Weston line, with open sections, incorporating tidal stream turbines to capture energy from the ebb and flood tides.

7. Lagoon enclosure on the Welsh grounds (Fleming lagoon): one of the previously studied Russell lagoons from 1980s

8. Tidal lagoon concept: a proposal for a number of tidal lagoons

9. Tidal reef proposal: a concept that would include floating turbines and caissons

10. Severn Lake Scheme: a 1 km wide barrage in the same location as the Cardiff-Weston scheme designed to allow the construction of a number of additional features, including a wave farm on the seaward side and four marinas

The proposals gathered will now be assessed and used to develop the draft Strategic Environmental Assessment (SEA) scoping report. This report will look in to what issues need to be covered to carry out the SEA.

The ongoing feasibility study (which is being managed by consultant Parsons Brinckerhoff) will run for two years and will be a two stage process with a decision point at the end of each. The first stage work, likely to run until late 2008, will focus on high level issues and short-listing potential tidal power project options. It will reach a first view on whether there are any fundamental issues that mean the project cannot proceed. At this point there will be a decision to either stop the study, or to continue with evidence gathering and assessments. A map outlining the locations of the various projects can be viewed on the BERR website.

The study has six key work areas:

• Environmental - impacts on biodiversity and wildlife; flood management; geomorphology; water quality; landscape; compensatory habitat
• Engineering and Technical - options appraisal; costs; design and construction; grid linkage
• Economic - financing; ownership; energy market impacts
• Regional - impacts on business; regional social and economic impacts
• Planning and consents - regulatory compliance
• Stakeholder engagement and communication