Controversial plans for a tidal barrage in the Severn Estuary capable of generating up to five per cent of the UK electricity moved a step closer to reality today with the publication of 10 project proposals.

The 10 options vary by size, proposed location and preferred technology. They include plans for a giant barrage running from Minehead to Aberthaw near the mouth of the estuary, several smaller barrages upstream, a "tidal fence" that combines tidal turbines with open sections, a series of tidal lagoons, a " tidal reef" based on floating turbines, and a Severn Lake Scheme that would feature a 1km-wide barrage that would also support wave farms and marinas.

The 10 separate proposals will be assessed as part of the government's on-going feasibility study ahead of a shortlist being drawn up later in the year.

Hinting at the government's support for the idea, business secretary John Hutton praised the new proposals. "Harnessing the power of the Severn Estuary could be an engineering project of breathtaking scale," he said. "Such a project could play an important role in our ambition to dramatically increase the amount of energy from renewable sources."

Welsh Assembly Government environment, sustainability and housing minister, Jane Davidson added that the range of proposals showed that contrary to media reports, a number of different approaches were being considered that will have differing effects. "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," she said.

Environmentalists remain divided on the proposals. The government's independent Sustainable Development Commission signalled its support for the plans earlier this year, claiming in a report that as long as precautions were taken to limit, the impact on local wildlife then the benefits of the scheme would outweigh the costs.

However, a coalition of conservation groups including the RSPB, the National Trust and WWF recently outlined their opposition to the proposed £15bn project, issuing a report claiming that the costs had been underestimated and that it would prove "exorbitantly expensive".