Ocean Energy: Tides, Waves and Thermal Power

Ocean energy, encompassing thermal gradients, tides, and waves, is a vast renewable resource with significant potential for coastal regions. Despite its promise, India has yet to fully realize its commercial capacity, though it holds an estimated potential of 54 GW. This emerging sector presents both opportunities and challenges for companies, given its undeveloped market structure.

An Overview of India’s Oceanic Energy Potential

Ocean Energy: Challenges, Opportunities, and Research Centers

Types of Ocean Energy:

• Thermal Energy: Generated from the sun’s heat.
• Mechanical Energy: Produced from tides and waves.

Challenges and Opportunities in Ocean Energy

• Challenges: Uncertain market entry for newcomers due to the undeveloped structure.
• Opportunities: Potential to create and seize opportunities in a less mature industry.

Ocean Energy Research Centers

• Susi Global Research Centre, Udupi: Focuses on tidal and wave energy, gravitational force electricity generation, and enhancing power output of hydel projects.

Department of Ocean Engineering, IIT Chennai

• Established in 1982.

• Objectives: Develop R&D infrastructure in Ocean Engineering.
  • Provide graduate and doctoral level education.
  • Train industry professionals and collaborate on problem-solving

Tidal Energy

Tide Generation: Caused by the gravitational pull of the sun and moon, and the Earth’s rotation.

• Local effects like shelving, funneling, reflection, and resonance increase tidal range.
  • Energy Extraction: Uses turbines in a barrage to generate electricity from tidal water.
• Requires tidal differences greater than 4 meters and favorable topographical conditions.
  • India’s Potential: Recognized potential due to India’s coastal geography.
  • Key Locations: Attractive locations include the Gulf of Cambay, Gulf of Kachchh, and the Ganges Delta in the Sundarbans.
• Tidal Barrage: Converts tidal energy into electricity using a dam across a river estuary.
• Water flows through tunnels in the barrage, turning turbines to generate power.
• Potential Capacity: Estimated economic potential: 8000-9000 MW.
  • Gulf of Cambay: ~7000 MW.
  • Gulf of Kachchh: ~1200 MW.
  • Sundarbans: <100 MW.
• Proposed Projects
• Kachchh Tidal Power Project (Gujrat)
• Durgaduani Creek Project (West Bengal)

Challenges in Tidal Energy

• Challenges of Tidal Barriers
  • Intermittent Supply: Provides power for only around 10 hours per day.
  • Expensive to build barrages and power plants.
  • Limited Locations: Requires specific geographical conditions, limiting suitable sites.
• Environmental Impact:
  • Alters ecosystems: reduced flushing, erosion, and vegetation changes.
  • May change tidal levels, affecting navigation and recreation.
  • Fish and Wildlife Concerns: Turbines can kill fish like salmon.
    • Fish ladders are not always effective.
    • Affects fish migration and wildlife habitats.
    • May destroy local wildlife habitats.
• Construction Limitations: Only feasible on ocean coastlines, not useful for inland communities.
• Efficiency: Current designs produce limited electricity.
  • Power generation is often mismatched with demand.
• Impact on Local Life: This may affect shoreline flooding and local marine life.

Wave Energy

Energy Generation: Captures energy from surface waves or pressure fluctuations below the surface.

• Converts wave motion into mechanical energy, then into electricity.
• Waves are created by wind blowing on the water surface.

• Technology:
  • Float or Buoy Systems: Series of buoys rise and fall with waves, generating electricity sent ashore via underwater cables.
  • Oscillating Water Column Devices: In-and-out wave motion forces air to turn a turbine.
• Wave Energy Potential in India:
  • Potential along 6000 km of coast: ~40,000 MW.
  • Wave energy potential: 5-15 MW per meter of coastline.
  • Realistic potential is likely less due to economic and practical constraints.
• Wave Energy Projects in India:
  • Key Locations: Thiruruvananthpuram, Vizhinjam Fisheries Harbor: 150 kW prototype plant.

Challenges in Wave Energy

Variable energy supply dependent on wave conditions.

• High cost: 15-17 cents/kWh globally.
• Requires consistently strong waves.
• Some designs are noisy.
• Must withstand rough weather.
• Visual and navigational impacts.

Ocean Thermal Energy (OTEC)

Energy Generation: Converts solar energy trapped by the ocean into usable energy.

• Uses the temperature difference between warm surface water and cold deep water.
• Potential in India:
  • Estimated Potential: 180,000 MW.
• Current OTEC Projects in India:
  • Sagar Shakthi: 1 MW prototype, near Tiruchendur coast (Tamil Nadu)
• Challenges Associated in OTEC
  • Higher cost compared to fossil fuel-generated electricity.
  • Requires a consistent temperature difference of 20°C (36°F).
  • Needs deep ocean depths close to shore.
  • Potential damage to reefs and marine ecosystems from construction.

Conclusion

Ocean energy offers a promising avenue for sustainable power generation, with various methods like tidal, wave, and thermal energy. 

• Despite challenges such as intermittent supply and high costs, ongoing research and projects like those at Susi Global Research Centre and IIT Chennai aim to overcome these barriers and harness the vast energy potential of the ocean.

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