The key concern relates to the loss of inter-tidal feeding areas for water birds.

BBC: The ebb and flow of tidal power

The changes, the company has said, mean its plans are more fish-friendly and will reduce the amount of inter-tidal mud flats that will be lost to feeding birds.

BBC: Severn Barrage: Time to 'grasp opportunity', says Hain

The changes, the company has said, mean its plans are more fish-friendly and will also reduce the amount of inter-tidal mudflats that will be lost to feeding birds.

BBC: Severn Barrage: Ed Davey says ?30bn plan could progress

Sinovel Wind Group Co ( SHA: 601558), another leading Chinese manufacturer in large-scale onshore, offshore and inter-tidal wind turbines, reported a net loss of 280.3 million yuan during the same period.

FORBES: First Solar, Now China Wind Power In Washington's Crosshairs

Although a scheme such as the Russell lagoons would cover about 60% of area affected by the Cardiff-Weston proposal, the environmental group argued that it would leave much of the inter-tidal mudflats and salt marshes unaffected.

BBC: The ebb and flow of tidal power

The changes, the company says, mean its plans are more fish-friendly and will also reduce the amount of inter-tidal mud flats that will be lost to feeding birds, while still generating 5% of the UK's energy needs or enough to power 3.4 million homes.

BBC: Severn Barrage artist's impression