Tidal Energy Potential Estimation and Impacts on Hydrodynamics around Tidal Power Systems along the Indian Coast

Abstract

Tidal energy is the energy derived using the tides. Most of the tidal energy feasibility studies are conducted for barrage method of tidal energy extraction. In Indian scenario, the observed conditions and the methods proposed are mostly for the barrage method mainly in the states of Gujarat in the west and West Bengal in the east where the tidal range is maximum. Assessment of energy extraction from barrage method has not been carried out in the southern parts of India due to low to medium tidal range. The first objective mainly focuses on tidal energy resource availability and the energy that can be harnessed from tides along the coast of India. Two methods are considered viz. tidal barrage and tidal stream energy. Out of 471 tidal inlets identified in 9 maritime states along the Indian coast, 130 inlets are shortlisted considering a threshold of 2.53 Mm3 tidal prism and potential energy was estimated. Total potential energy estimate considering 130 inlets is 2254.906 MW. Further 107 inlets are shortlisted considering both tidal prism greater than 2.53Mm3 and inlet throat width greater than 63m and the corresponding potential energy is estimated as 2127.281 MW. The Kinetic energy estimated was 11.68kW, 5.60kW and 25.64kW at Chapora, Mandovi and Zuari respectively. The second objective intends to study the impact of tidal energy of local hydrodynamics.The turbines are placed at the locations where highest tidal currents were observed as presented in objective 1. Five cases were considered where the simulations were carried for different locations of the tidal turbine. Total energy generated by 0.5m diameter turbine was estimated to be 118kW. Whereas the 1m diameter turbine increased the energy to 409.35kN. The total energy estimates for the turbines in parallel and turbines in tandem considering 0.4 m/s threshold for current speeds was approximated to 417.5kW and 409.35kW respectively. The morphodynamics were simulated and the sea bed morphology of Zuari creek was studied. The results of the coupled model proved that the location chosen for tidal energy extraction does not exhibit sediment transport and longer durations of simulations are required. In the third objective, tidal lagoons are established and the morphodynamics due the energy extraction are studied. A tidal lagoon can be constructed either on an existing natural rock/headland or completely by artificial means. It can either be constructed nearshore adjacent to the coast of in the tidal reservoir where conditions are feasible. Locations for the construction of tidal lagoons are identified along in Maharashtra (Jaigad 1 and Jaigad 2). The potential energy that can be extracted from the established tidal pools is estimated to be 3.69MW and 1.3MW respectively. Results of morphodynamic study for 20 days are analyzed. The bed level changes observed at Jaigad 1 and Jaigad 2 prove less sensitive to hydrodynamics. Bed level changes observed are of the order 0.04m (in 20 days) due to the construction of tidal barrage.