Environmental groups and businesses against plans to build a Severn barrage are coming together to develop ideas for renewable energy on the estuary, the BBC reported.
The Royal Society for the Protection of Birds said it wanted to work with industry to get “the best solution” for sustainable energy from the Severn.
The charity said it was “sceptical” about a scheme to build a £30bn barrage from the Vale of Glamorgan to Somerset.
A conference to discuss harnessing the tidal power takes place on 18 April.
The event has been organised by the Royal Society for the Protection of Birds (RSPB), Bristol Port and Regen SW, an independent sustainable energy organisation.
Hafren Power, the company that wants to build the 18 km (11 mile) barrage was told on Thursday by energy minister Greg Barker that it must provide more information before the government could support it.
The minister also dismissed claims that a law to secure the barrage could be passed before the next general election.
A spokesman for Hafren Power said the company was “disappointed” but would “keep working with the government to supply answers and secure support to proceed”.