Strangford Lough, near Belfast runs cold, swift and deep, and is one of the fastest tidal areas in the world. Under the surface lies a submerged turbine that looks like a cross between an airplane propeller and an underwater windmill, converting the energy of tidal flows into electricity.

Green, clean and unlikely to harm marine life, the 300-tonne turbine is generating enough electricity to power 1,000 houses. Oliver Steeds travels to Northern Ireland's coast to find out about the potential of tidal power.