Tidal lagoon: Could Swansea Bay become world first?
Plans for a £1.3bn tidal lagoon in Swansea Bay have been backed by a government-commissioned review.
Charles Hendry's independent report into the technology's viability said it would make a "strong contribution" to the UK's energy supply.
He said it was cost effective and would bring "significant economic opportunity".
The UK government still needs to agree on a deal and a marine licence would also need to be approved.
BBC environment analyst Roger Harrabin reports