Making electricity from the movement of the tides is a fairly new undertaking. The first modern tidal wave / tidal energy plant was brought online in 1966 in France. This is an extremely expensive way of harnessing energy, so isn’t very popular, yet. It’s a form of hydro-power generation and plants are currently found mostly in Europe and Asia. While there are a few plants in Canada, there are currently none in the US of this writing (early 2014), although a tidal energy plant is scheduled to be built in New York in 2015.
If you want to know the specifics of how it works, check out these links for the details.
From The History Channel