Ten sites on the seabed off the north coast of Scotland have been leased out to power companies in an effort to generate wave and tidal energy.

In the first project of its kind in the world, areas in the Pentland Firth and around Orkney have been leased to seven companies by the Crown Estate.

Environment Correspondent David Shukman went to Leith to take a look inside one of Pelamis Wave Power's giant wave machines to find out how it harnesses the power of the sea to generate electricity.