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Blue Economy – Ocean Energy

By Capt. Vikrant Nagarkar

Capt. Vikrant Nagarkar highlights the importance of renewable wave & tidal energy, especially for a developing country like India.

Concerns about carbon dioxide emissions and global warming, and the security and long-term availability of fossil fuel supplies has led to greatly renewed interest in all forms of renewable energy. The time may have come to consider ocean renewable energy as well.

To start with, one must understand that ocean energy refers to all forms of renewable energy derived from the sea. There are two main types of ocean technology: Thermal Energy, derived from the Sun, and Mechanical Energy, generated by wave & tide. All forms of energy from the ocean are still at an early stage of commercialisation. While ocean power is not yet widely deployed globally, it is a growing market with research underway in several countries, including Australia, Canada, USA, the UK and India.

“While ocean power is not yet widely deployed globally, it is a growing market with research underway in several countries, including Australia, Canada, USA, the UK and India.”

Energy is inherent in the movement of ocean waves, in the difference in temperature between warm surface waters and cooler deep waters, in the disparity in salinity between fresh water and salt, and in marine currents and tides. The International Energy Agency estimates that wave power could potentially produce 8,000 to 80,000 TWh yearly; ocean thermal energy could produce 10,000 TWh; osmotic power (from salinity differences) could produce 2,000 TWh; and tides and marine currents could produce 1,100 TWh. Ocean thermal energy, osmotic energy, marine currents and some types of wave energy could produce base load power, electricity that is consistent and reliable.

“Ocean thermal energy, osmotic energy, marine currents and some types of wave energy could produce base load power, electricity that is consistent and reliable.”

The areas with the most wave energy potential are the Pacific Northwest and Alaska in the United States, and the U.K. and Scotland. The Indian government has identified potential locations for wave power development along the west coast of India in Maharashtra, Goa, Karnataka and Kerala. Kanyakumari, located at the southern tip of the Indian peninsula, has the highest power owing to the effects of refraction and strong winds. A 1 MW wave-to-energy plant, the country’s first floating device, is to be implemented by the Agency for New and Renewable Energy Research and Technology (ANERT) to tap the power of waves off the Vizhinjam coast. The project at Vizhinjam is a pilot project initiated by the IIT Chennai undertaking of the National Institute of Ocean Technology (NIOT).

“A 1 MW wave-to-energy plant, the country’s first floating device, is to be implemented by the Agency for New and Renewable Energy Research and Technology (ANERT) to tap the power of waves off the Vizhinjam coast.”

It is interesting to note that the tidally driven waves running along the coasts of China, Korea and parts of Europe hold the most promise for dynamic tidal power while tropical oceans along the equator are the best places to exploit ocean thermal energy.

Wave energy is generated when converters capture the energy contained in ocean waves and use it to generate electricity. Converters include oscillating water columns that trap air pockets to drive a turbine; oscillating body converters that use wave motion; and overtopping converters that make use of height differences. The following figures depict different types of converters:

Tidal Energy is a renewable energy source, resulting from gravitational fields of both the sun and the moon, combining with Earth’s rotation around its axis, to cause, high and low tides.

The difference in potential energy between high & low tide is the source of power generation from tidal energy; produced either by tidal-range technologies using a barrage (a dam or other barrier) to harvest power between high and low tide; tidal-current or tidal-stream technologies; or hybrid applications. The following figure depicts a tidal current turbine.

Figure-2 A tall turbine (much like a wind turbine) anchored to a base, is placed on the sea floor. The tidal currents move the rotors, generating electricity. When the tide goes out, the rotors reverse direction and continue to generate electricity, which is sent to the grid on shore via a cable.

The potential sites for tidal energy projects in India are the Gulf of Kutch (estimated potential of 1200 MW), Gulf of Cambay (7000 MW) and the Durgaduani Creek in the Sundarbans Delta (100 MW).

“A developing Country like India needs to work aggressively at generating this type of energy to achieve its climate change goals.”

A developing Country like India needs to work aggressively at generating this type of energy to achieve its climate change goals. The renewable green energy is predictable, effective at low-speed and has a long life span. At the same time, one must not forget the cost effectiveness. At present the process has not been developed fully and the cost is high; since converters need to be installed near sea areas, installation and maintenance cost will be high. India needs to follow the example of South Korea, which is the world’s leading tidal energy generating country, followed by the UK & other countries in Europe.

One of the most important factors for any country is its own security. If India can install dummy turbines in and around India’s coast, it can gather intelligence input about the underwater activity of neighbouring nations. This will ensure that the nation’s security is not compromised.

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About The Author

Capt. Vikrant Nagarkar

Capt. Vikrant Nagarkar completed his B.Sc (Phy) from Pune University and in 1992 achieved Certificate Proficiency (Govt of India) for the post of Radio Officer on ships. Subsequently, he started his career in Merchant Navy as a Radio Officer. After completing the required sea time, he successfully finished several examinations for different categories of the Certificate of Competency from Fleetwood Nautical College, Blackpool, UK. In 2009, he accomplished the position of Captain and sailed until 2019 when he took voluntary retirement from the Merchant Navy. Since then, Capt. Nagarkar has been working as a Sr. Assistant faculty in Tolani Maritime Institute, Talegaon.