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Wave and Tidal Energy:
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Hari Srinivas |
| One-Pager Series C-071 |
The ocean holds immense energy potential, and wave and tidal energy have emerged as promising renewable energy sources. Unlike solar and wind energy, which depend on weather variability, wave and tidal energy rely on predictable oceanic movements, making them reliable and consistent. These energy sources harness the kinetic and gravitational forces of water bodies to generate electricity, reducing dependence on fossil fuels while contributing to a more sustainable energy mix.
Wave and Tidal Energy Systems
There are two primary ways to extract energy from the ocean:
Wave Energy
Wave energy is generated by the movement of ocean waves caused by wind blowing across the water surface. This energy can be harnessed using specialized technologies, including:
- Oscillating Water Columns (OWC): These systems use the movement of waves to compress air in a chamber, driving a turbine to generate electricity.
- Point Absorbers: Floating devices that move up and down with wave motion, converting mechanical energy into electrical power.
- Attenuators: Long, floating structures aligned parallel to wave direction that flex with the movement of waves, producing electricity through hydraulic systems.
- Overtopping Devices: Structures that capture waves in a reservoir, using the collected water to drive hydro turbines.
Tidal energy is generated by the gravitational pull of the moon and the sun, which causes periodic rises and falls in sea levels. The two main types of tidal energy technologies are:
- Tidal Barrages: Large dam-like structures built across estuaries that use sluice gates to control water flow. As tides move in and out, the water turns turbines, generating electricity.
- Tidal Stream Generators: These devices function like underwater wind turbines, capturing kinetic energy from fast-moving tidal currents.
Key Terms and Definitions
- Wave Energy - Energy harnessed from ocean surface waves, driven by wind and atmospheric pressure differences.
- Tidal Energy - Energy generated from the predictable rise and fall of ocean tides due to gravitational interactions between the Earth, moon, and sun.
- Oscillating Water Column (OWC) - A wave energy technology that converts wave-induced air pressure into electricity using turbines.
- Tidal Barrage - A dam-like structure that captures tidal energy by controlling water flow through turbines.
- Tidal Stream Generator - An underwater turbine that captures energy from fast-moving tidal currents, similar to wind turbines.
Advantages of Wave and Tidal Energy
Predictable and reliable - Unlike solar and wind, ocean-based energy sources follow consistent and natural cycles, providing stable electricity generation. Wave and tidal energy sources asssit in meeting Zero Carbon emissions goals. They also produce no direct greenhouse gas emissions, helping combat climate change.
Wave and tidal energy sources are considered to have "High Energy Density" that is, water is much denser than air, allowing water energy technologies to generate more power with smaller installations compared to wind or solar. They also have a longer lifespan. For example, tidal power plants, such as those using barrages, can last for decades with minimal maintenance.
There is also the potential for coastal energy independence. Countries with extensive coastlines can reduce dependence on imported fossil fuels by investing in marine renewable energy.
Challenges of Wave and Tidal Energy
- High Initial Costs: The infrastructure for wave and tidal energy requires significant investment in technology, installation, and maintenance.
- Environmental Impact: Tidal barrages and underwater turbines can alter marine ecosystems, affecting fish migration and sediment movement.
- Limited Suitable Locations: Not all coastal regions have the required wave activity or tidal range to generate significant power.
- Technology Development: Wave and tidal energy technologies are still in their early stages compared to more mature renewable sources like solar and wind.
- Grid Connection Challenges: Offshore energy systems require extensive underwater cabling and grid infrastructure to transport electricity to land.
Future of Wave and Tidal Energy
Despite the challenges, advancements in marine renewable technologies are making wave and tidal energy more viable. Innovations such as floating tidal turbines, modular wave energy converters, and low-impact designs are helping to reduce costs and environmental concerns. Countries like the UK, Canada, and Norway are investing heavily in wave and tidal projects, setting the stage for wider global adoption.
As research and infrastructure development continue, ocean energy could play a key role in the transition to a sustainable and resilient global energy system.
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Contact: Hari Srinivas - hsrinivas@gdrc.org