5. Energy production

Mathematical modelling of the energy sent out from a tidal barrage involves several major considerations. Firstly, characteristics of suitable turbines that can also operate as low head pumps must be available. Next, the physical parameters of the scheme must be established. These include the basin data; the tide shape, tidal ranges and their frequencies at the barrage; and the efficiency of the electrical system, including the effect of auxiliary power requirements at various turbine outputs. Finally, and most importantly, a Dynamic programming technique is used to determine the locus of operating points, at the various heads, so that the optimum energy output ensues. Having established the above, the sensitivity of the energy output to a number of scheme parameters should be tested. The sensitivity to turbine and pump speed must be first to be investigated. Once the best speed is established it is, thereafter, kept constant. The trends from the sensitivity analyses lead to the specification of the major scheme parameters for energy capture. Account is also taken of the benefits which could derive from the ebb-generation plus flood pumping mode of operation, compared to ebb generation alone. While Dynamic Programming is acknowledged as the most accurate method of calculation, it is shown that comparable results can be obtained by a much simpler means.

• METHOD

• ENERGY MODELLING

• SELECTION OF BARRAGE PARAMETERS AND OPERATING MODES

• OPTIMISING FOR MAXIMUM VALUE

• THE EFFECT OF TIDAL AND ESTUARY DYNAMICS ON ENERGY OUTPUT

• SUMMARY OF FINDINGS

• OPERATING REGIME FOR A TURBINE IN A TIDAL SCHEME

• MAXIMUM TURBINE OUTPUT AT “CONSTANT” HEAD ACROSS THE BARRAGE

• REFERENCES