The results of the government's energy review, which could have a major impact on parts of Somerset, are to be published on Tuesday.
Some fear a tidal barrage would destroy a unique habitat
The review looks at how the UK can meet its future energy needs.
Proposals include building a £10bn 10-mile (16km) barrage across the Severn Estuary between Lavernock Point, near Cardiff, to Brean Down, Somerset.
There is also speculation that a new nuclear power station may be built at Hinkley Point.
Hinkley A, the first power station at the site, closed in 2000, and Hinkley B is due to shut in 2011.
Planning permission for a third station was granted in 1990, but the government chose not to proceed.
Although, planning permission has now lapsed, many in the industry believe Hinkley remains a prime location.
Residents have been strongly opposed to a third reactor.
There has also been opposition to the Severn barrage proposals.
The river has the second highest tidal range in the world and harnessing its power could provide up to 10% of the UK's electricity needs.
But environmental and wildlife groups fear a barrage could destroy a unique habitat.
The estuary is a special area for conservation and provides food for more than 63,000 migratory and wintering water birds.
"Incentives for renewable energy are hugely welcome but they do not mean wildlife sites are now up for grabs," said Mark Robins, South West regional policy officer for the RSPB.
"Any statement of national renewables need should be accompanied by a strategic environmental assessment."
The RSPB has said it would vigorously maintain its opposition to energy generation schemes that threaten rare or high numbers of wild birds and important wildlife sites.