Miriam O'reilly explores the viability of the Severn barrage project, potentially the biggest, most expensive and most controversial source of sustainable energy in the UK.
It could supply five per cent of our energy needs, but building it has a ten million-ton carbon footprint and a price tag of 15 billion pounds.
It could supply clean, renewable energy for the next 100 years, but its construction would wipe out fragile and unique wildlife habitats and unpick European conservation legislation.
Miriam speaks to politicians, environmentalists and engineers to gauge the current mood and the future prospects of the project.
Miriam O'reilly explores the viability of the controversial sustainable energy project.