Tidal and current energy

The book chapter deals with both tidal rise and fall energy and hydrokinetic energy from tides, ocean currents and rivers. (River energy is included because the proposed technologies share some characteristics with those proposed for tidal currents.) Out of the many devices proposed, some have been built, but most of these have disappeared as a result of either lack of financial support, poor design or poor management. The aim of this chapter is not to catalogue every device past or present, but rather to summarize the main types of technology and the most interesting and promising.