Why is it in the news ?

Union Ministry of State for Power and New & Renewable Energy (IC) and Skill Development & Entrepreneurship has approved a proposal to declare ocean energy as Renewable Energy.

  1. Energy produced using various forms of ocean energy such as tidal, wave, ocean thermal energy conversion etc. shall now be considered as Renewable Energy and be eligible for meeting the non-solar Renewable Purchase Obligations (RPO).
  2. RPOs make it compulsory for all large consumers of energy to ensure that a certain percentage of that energy mix is from renewable sources such as wind and solar.
  3. The compulsion is like an implicit subsidy boost to the renewable sector. It generates demand for a sector in its infancy.
  4. The Renewable Purchase Obligations (RPO) has been the major driving force in India to promote the renewable energy sector. 

Introduction to Ocean Energy 

  1. Oceans cover 70 per cent of the earth’s surface and represent an enormous amount of energy in the form of wave, tidal, marine current and thermal gradient. 
  2. A variety of different technologies are currently under development throughout the world to harness this energy in all its forms. 
  3. Deployment is currently limited, but the sector has the potential to grow, fuelling economic growth, reduction of carbon footprint and creating jobs not only along the coasts but also inland along its supply chains.
  4. Most types of technologies are currently at pre-research and development or demonstration stages or the initial stage of commercialisation. 

What is Ocean Thermal Energy Conversion (OTEC) ? 

  1. Ocean thermal energy conversion, or OTEC, uses ocean temperature differences from the surface to depths lower than 1,000 meters, to extract energy. 
  2. A temperature difference of only 20°C can yield usable energy. 
  3. OTEC has a theoretical potential of 180,000 MW in India subject to suitable technological evolution.


Ocean Energy

Ocean energy is mostly exploited by just a few technologies: Wave, Tidal, Current Energy and Ocean Thermal Energy.

Tidal Energy 

  • The tidal cycle occurs every 12 hours due to the gravitational force of the moon. The difference in water height from low tide and high tide is potential energy. 
  • Similar to traditional hydropower generated from dams, tidal water can be captured in a barrage across an estuary during high tide and forced through a hydro-turbine during low tide. 
  • The capital cost for tidal energy power plants is very high due to high civil construction and high power purchase tariff. 
  • The Gulf of Cambay and the Gulf of Kutch in Gujarat on the west coast have locations in the country where potential exists.
  • Total identified potential of Tidal Energy is about 12455 MW, with potential locations identified at Khambhat & Kutch regions, and large backwaters, where barrage technology could be used.

Wave Energy 

  1. Wave energy is generated by the movement of a device either floating on the surface of the ocean or moored to the ocean floor. 
  2. The total theoretical potential of wave energy in India along the country’s coast is estimated to be about 40,000 MW. 
  3. This energy is however less intensive than what is available in more northern and southern latitudes.

Ocean current energy

  1. The energy of ocean currents under the surface is comparable to the wind above it. Underwater turbines — large propellers tethered to the seabed — are used to derive power from this source. 

Ocean thermal energy

  1. Oceans have huge heat reservoirs. 
  2. The temperature differential between warm surface waters and cold deeper layers in intertropical regions can be used to generate steam and then power.

Osmotic energy

  1. This technique produces energy from the movement of water across a membrane between a saltwater reservoir and freshwater reservoir.