Tidal Power: How It Works [Barrage]

Barrage Tidal Lagoon

Barrage Tidal Power
Barrage Tidal is a capital intensive method for generating tidal power. A barrage is similar to a hydroelectric dam, but differs in a few key ways. The barrage is essentially a large concrete structure that spans an estuary basin, bay or river with gates (sluices) that enable waves to move in and out of the dammed area. At high tide, the sluices are closed. Once the tide shifts directions and ebbs, the sluices are opened allowing the higher water levels in the basin to flow through the barrage and pass the hydroelectric turbine on its way out to sea. Once emptied, the basin is refilled when the tide flows back to shore.

Energy calculation
E = 1/2 x A x ? x g x h^2
where:
   h is the vertical tidal range,
   A is the horizontal area of the barrage basin,
   ? is the density of water = 1025 kg per cubic meter and
   g is the acceleration due to the Earth's gravity = 9.81 meters per second squared.

Barrage Tidal Power does not appear to be a viable method for energy production for a number of reasons. The most important appear to be the very high capital cost, low return on investment due to the short daily electricity production period, and negative effects to the surrounding habitats. As a result, the focus of much of the remaining sections on Tidal Power will focus on Tidal Stream Generators.

(Video describes how a Barrage works and problems associated with such projects)