Proposals for a giant water wheel stretching across the River Mersey are due to be revealed.

The river is one of the best sites for renewable energy created by tides, in the UK, a new study claims.

The report claims the Mersey's unusual shape and wide range of tides can be used to produce environmentally- friendly power.

If the plans get the go-ahead, the wheel turbine could produce enough electricity for half a million homes.

The study was sponsored by Peel Holdings, who operate the Mersey Docks and Harbour Company, and the North West Development Agency.

Professor Peter Guthrie, Professor of Engineering for Sustainable Development at Cambridge University, was part of the research team.