Ten different energy schemes are on the drawing board as the British government weighs up its options for harnessing the tidal power of the Severn Estuary in an innovative scheme to develop wave power as a viable alternative energy source.

The potential projects, which could provide clean, green energy from the tide, will be looked at during the two-year feasibility study being carried out by Bristol-based company Parsons Brinckerhoff. A shortlist of preferred options to be taken forward for more extensive research is due to be announced in December, when the feasibility study ends.

Among the schemes under consideration is the well-documented 10-mile barrage from Brean Down, near Weston-super-Mare, to Lavernock Point near Cardiff. A larger barrage could also be built further down the Bristol Channel from Minehead to Aberthaw, making maximum use of the Severn Estuary tidal resource, while a barrage at Beachley would be upstream of the old Severn Bridge and generate less energy.

Three other barrages and two variations on a lagoon are also under consideration. Also on the list is a tidal fence, which is seen by some as better for wildlife and shipping than a barrage as it would have open sections. There is also a reef design of floating turbines and a ''lake'' scheme – including a wave power station facing the incoming tide.

The Environment Agency, Friends of the Earth, the Wildfowl and Wetlands Trust at Slimbridge and the South West Regional Development Agency are among the organisations which have contributed to the multi-million pound feasibility study, which aims to assess the costs, benefits and environmental impact of a tidal power scheme.

Secretary of State for Energy 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 in the proposals. The Severn's tidal range is the second largest in the world and has the potential to provide around five per cent of the UK's current electricity demand.''

The cost of the ventures ranges from £650 million to £15 billion and while the review process will take some time to conclude it seems inevitable that one of the 10 ventures being proposed will be chosen as the preferred option. The chosen scheme could help make a significant contribution to the proposed target of generating 15 per cent of the nation's power from renewable energy by 2020.

The government's sustainability watchdog the Sustainable Development Commission (SDC) last year said a tidal barrage blocking the tide's flow through the estuary, such as the original Brean Down to Lavernock scheme, could be built if it complied with environmental laws. But some groups say it would harm estuary wildlife.

The Severn Tidal Power Group, a consortium of construction giants Sir Robert McAlpine, Taylor Wimpey, Balfour Beatty and Alstom, has backed the idea of a barrage, and welcomed the proposals. Spokesman Roger Hull said, ''It's very important to look at all the options to make sure the best one doesn't get missed, and that everyone understands that they have all been looked at.''

Weston MP John Penrose said, ''Choosing the best way to harness the Severn's tidal power is an incredibly important decision that has to be taken fairly and without bias. It is Britain's biggest single potential source of renewable energy and we'll be living with the consequences for centuries.''

Northavon MP Steve Webb, whose constituency borders the upper reaches of the estuary, said: ''It's vital that the study should be genuinely open to all the alternatives, and the fact that a varied list of alternatives is being considered is a welcome development.''