Tidal power harnesses the energy from tidal movements and has several advantages as an energy resource. The tides are driven by the gravitational pull of the Moon and Sun and provide a reliable source of power for around 10 hours each day when the tides are moving in or out. Tidal power stations could be built in estuaries where large tidal ranges occur, such as the Severn estuary in the UK. Once constructed, tidal power stations have low operating costs since they do not require fuel and have minimal environmental impacts compared to other sources like fossil fuels. However, tidal power is only viable in select locations with suitable tidal characteristics and may impact local wildlife habitats.