Like other hydroelectricity (electricity made using water), tidal power produces no pollution and is a renewable energy source, because tides are caused by events that happen in the solar system and so will not run out. Tidal power has great potential for future power and electricity generation because of the very large amount of energy contained in these rotational systems. Tidal power is reliably predictable (unlike wind power and solar power). In Europe, tide mills have been used for nearly 1,000 years, mainly for grinding grains. Modern tide mills provide tidal stream power.