SERIOUS investment should be lavished on an immature-yet-popular tidal "reef" that could generate huge amounts of energy from the Severn estuary, a committee of MPs and councillors has claimed.

Over the past 12 months, an inquiry has been carried out over 12 months by politicians into what is the most suitable option for what could be the world's biggest green energy project.

Boasting one of the world's biggest tidal ranges, the Severn estuary has enough power locked within its tides to generate 5 per cent of the UK's energy needs.

The investigation dismissed the massive 10-mile barrage from Cardiff to Weston-super-Mare, the most well-known idea but criticised for being unsightly and damaging to wildlife.

It said the scheme would "do serious damage to the estuary by wiping out around 80 per cent of the inter-tidal habitat." But it backed the smaller so-called Shoots barrage scheme, upstream of the Cardiff-Weston proposal.

It claimed the larger barrage option is less cost-effective than the shorter barrage and "would cause serious economic damage to the port of Bristol".

The commission, which included Liberal Democrat MPs, Welsh Assembly members and councillors in the West of England and Wales, was jointly chaired by Northavon, Gloucestershire, MP Steve Webb and Welsh Assembly member Mike German.

Mr Webb said: "With the threat of climate change getting steadily greater, there is now real urgency we get on with harnessing this source of renewable energy in an environmentally responsible way.

"We therefore reject the large Cardiff-Weston barrage which could take decades to come on stream and could do untold damage to the environment and to the local economy through its impact on the port of Bristol.

"We believe that a smaller barrage offers the best mix of power output with reduced environmental impact and also offers the chance for a major upgrade to public transport through Wales and the West of England."

The inquiry has held evidence sessions at Cardiff, Bristol and Portishead and has studied the documents which have been prepared by the Government as part of its own appraisal of options for Severn tidal power.

One of its other key recommendations was to seriously invest in innovative technology such as the tidal "reef".

The "reef" is the brainchild of Cornishman Rupert Armstrong-Evans.

It has the capacity to generate as much renewable power as any other scheme, and is the only Severn energy proposition to have secured the full backing of the environmental lobby, and has been given the thumbs-up by engineering experts Atkins.

The Wildlife Trust has recently joined the Royal Society for the Protection of Birds in backing the "reef".

The Cornishman's idea is popular because his design started by considering the "crown jewels", factors most likely to prevent a tidal scheme going go-ahead.

Most acutely, this includes the possible loss of thousands of hectares of natural habitat, the impact on fish and the costly time delays to ships travelling into Bristol port.

In January, Energy Secretary Ed Miliband announced a shortlist of five advanced schemes which had met the Government's criteria for Severn, including the controversial barrage from Cardiff to Weston-super-Mare.

£500,000 of public money has been ring-fenced for two other unproven schemes – the "reef" as well as a tidal "fence".

Public consultation ends on Thursday.