Development of an analytical model for real-time assessment of tidal barrage power generation

Abstract

The world is focusing on renewable energy especiallyonsolar, wind and tidal energy. However, research on tidal power, more specifically, tidal barrage power, has not yet received dueattention.Current approaches and practices for the assessment of tidal barrage power generation do not consider the continuous changes in the head differences between the sea and basin. Rather a static overall estimate using an arbitrary reduction in efficiency and head difference is used. Several equations or formulas based on this assumption are used to assess tidal power. Most of them use a static head rather dynamic head.This study considers the real-time changes in water levels inside and outside the basin to compute the actual power generation potential based on dynamic water head, with the specific objectives of developing an analytical model to assess real-time power and energy, and assessing an optimum basin configuration that generates the maximum tidal power. This study also assesses the tidal barrage power potential in the coastal area of Bangladesh. A hypothetical model for continuous generation is used as a base case to compute thedynamic head for a tidal barrage. This base model did not consider minimum head for turbine operation to avoid cavitation or provision of gates to increase the efficiency of operation and used a simplified sinusoidal tidal water level variation. However, in reality the observed tide is a superimposition of a series of tidal constituents having different tidal amplitudes, speeds and phase angles. Also, water level at the basin side at any particular time depends on the area of the basin, volume of the basin, basin configuration, water level of the basin, water passing through turbines, etc. In this study, a generalized polynomial equation is developed to calculate water surface area in terms of water level. The real-time analyticalmodel developed in this study, referred to as the‘RTA Model’, introduces a set of parameters that more closely represents the actual and real-time water level variations in the basin and the sea. A set of equations represents the discharge through the turbine and gate and computes power generation during different tidal phases. The analytical model has the flexibility to change the turbine capacity (size and number) and gate capacity (size and number).This model is implemented in Excel to test different realistic situations or scenarios of the base case, such as flood-ebb generation and ebb generation. In these cases, the thresholds for power generation and gate operation are considered.