Tidal power in India yet to be harnessed

India is estimated to have a potential of about 54 gigawatts (GW) of ocean energy including about 12.4 GW of tidal power. However, even after four decades of starting efforts to harness tidal power, India is yet to make a breakthrough, as a Mongabay-India report points out.

Government reports say that the technology required to convert tidal energy into electricity is very similar to the technology used in traditional hydroelectric power plants except that water is able to flow in both directions and this must be taken into account in the development of the generators.

The technology required for tidal power is well developed, and the main barrier to increased use of the tides is that of construction costs. The future costs of other sources of electricity, and concern over their environmental impacts, will ultimately determine whether humankind extensively harnesses the gravitational power of the moon.

According to the Ministry of New and Renewable Energy (MNRE), Government of India, the estimated potential of tidal and wave power is “purely theoretical and does not necessarily constitute a practically exploitable potential”. The potential areas with low/medium tidal wave strength are in the Gulf of Khambat, Gulf of Kutch and southern regions in Gujarat, Palk Bay- Mannar Channel in Tamil Nadu, and Hoogly river, South Haldia and Sunderbans in West Bengal. Tidal energy is still in research and development phase and has not been implemented on a commercial scale in India. The earlier efforts for harnessing tidal power were not successful due to high capital costs.

India had started two tidal power projects of 3.75 megawatts and 50 megawatts installed capacity in 2007 and 2011 in West Bengal and Gujarat respectively. But both these projects were dropped because of exorbitant costs. In the case of the 3.75 MW Durgaduani tidal power project in West Bengal, the project cost was Rs 2.38 billion – which is about Rs 635 million per MW. While in the case of the 50 MW tidal power project at the Gulf of Kutch in Gujarat, the estimated cost was Rs 7.5 billion – which is about Rs 150 million for every megawatt of power.

The Mongabay-India reports points out that a parliamentary panel has now asked the Indian government to go back to the drawing board and “reassess” the potential of tidal, wave and ocean-thermal power to “explore the practically exploitable potential”. Ocean energy refers to all forms of renewable energy derived from the sea including tidal power which is harnessed by converting energy from the natural rise and fall of ocean tides and currents to electricity.

Wave energy in the form of motion of ocean waves can be extracted using energy conversion devices. In fact, it has been about 40 years since India started efforts to assess and harness tidal power but it is yet to achieve any solid breakthrough in its development even as the country made rapid strides in boosting other sources of renewable power.

The cost of power from such tidal power plants is too high, according to the MNRE, which states that the “normative cost of installation of one MW solar, wind, biomass, hydro and thermal power plant is Rs 35 million, Rs 55 million, Rs 60 million, Rs 100-150 million, and Rs 50 million respectively.

The ministry informed the panel that tidal power represents the smallest share (about 535 MW) of the global installed capacity of renewable energy. It said two tidal power projects, 240 MW La Rance station in France (installed in 1966) and the 254 MW Sihwa plant in South Korea (installed in 2011), constitute more than 90% of the total installed capacity of tidal energy.

The ministry said that, at present, tidal power technologies are not cost-competitive and the main focus is on technology development. The panel asked that the MNRE may “also evaluate global experience in this regard.”

India has a target of installed capacity of 175 GW by 2022 and 450 GW by 2030. Though tidal power is not included in the 175 GW target, the MNRE said, “all sources of renewable energy, including tidal energy, will be considered in the deployment targets for 2030.”

In August 2019, the central government had issued a notification clarifying that energy produced using various forms of ocean energy such as tidal, wave, ocean thermal energy conversion, “shall be eligible for meeting non-solar renewable purchase obligations (RPOs)”.The RPO is a mechanism under the Electricity Act 2003 by which the big consumers have to purchase a certain percentage of their total consumption of electricity from renewable energy sources.