Why aren't we using the tides to generate renewable energy?

As the global community intensifies its search for sustainable energy solutions, tidal energy stands out as a promising, yet underutilised, renewable resource. While harnessing tides' power could significantly contribute to the world's energy needs, various factors have limited its widespread adoption. This article explores the benefits and challenges of tidal energy, successful examples around the world, and the future prospects of this renewable energy source.

Benefits of tidal energy

There are many reasons why we might want to harness the power of the tides to meet our growing energy needs, let's explore the main ones.

Predictability

Unlike wind and solar energy, tidal energy is highly predictable. Tides follow a consistent and reliable cycle, driven by the gravitational pull of the moon and sun. This predictability allows for more accurate planning and integration into the energy grid, reducing the need for backup power sources. We can also generate during the flat points at tide change, which leads me to storability.

Storability

The predictability of tidal energy also makes it easier to store. Advanced energy storage solutions can be synchronized with tidal cycles to ensure a steady electricity supply, even when tides are not at their peak.

Energy potential

Tidal energy has the potential to generate substantial amounts of electricity. According to the World Energy Council, the global potential for tidal power is estimated to be around 1,200 terawatt-hours (TWh) per year, enough to meet the annual electricity consumption of approximately 100 million homes.

Benefits of tidal energy over wind generation

While both tidal and wind energy are renewable, tidal energy offers distinct advantages. Tides are more predictable than wind, which is highly variable and dependent on weather conditions. This reliability can lead to a more stable energy supply and potentially lower operational costs over time.

Where are there tidal power stations?

While tidal power stations are few and far between, especially compared to wind or solar farms, several countries have already demonstrated the viability of tidal energy through successful projects

La Rance Tidal Power Plant, France

Operational since 1966, this plant is one of the oldest and most successful tidal power stations in the world. It has a capacity of 240 megawatts (MW) and produces about 500 gigawatt-hours (GWh) of electricity annually, enough to power around 130,000 homes.

Sihwa Lake Tidal Power Station, South Korea

This is currently the largest tidal power installation in the world, with an installed capacity of 254 MW. It generates approximately 552 GWh of electricity per year, providing a significant portion of the energy needs for the surrounding area.

MeyGen Tidal Energy Project, Scotland

Located in the Pentland Firth, this project aims to install up to 398 MW of tidal stream turbines. The first phase, which has a capacity of 6 MW, is already operational and contributing to the grid.

What are the challenges of Tidal Energy generation?

Despite its advantages, tidal energy faces several challenges that have hindered its widespread adoption.

The initial high costs of developing tidal energy infrastructure are significantly higher than those for wind or solar power. This includes the costs of underwater construction, specialized materials, and maintenance in harsh marine environments.

Furthermore, tidal power plants can disrupt local ecosystems. The construction and operation of tidal barrages or turbines can affect marine life, including fish and other aquatic species, by altering their habitats and migration patterns.

As well as ecological impacts, tidal energy projects can also impact coastal and estuarine environments. Changes in tidal flows can lead to sedimentation issues, erosion, and changes in water quality, which can affect both marine and terrestrial ecosystems.

Finally, the technology for harnessing tidal energy is still in its developmental stages compared to wind and solar energy and presents significant technological challenges. This includes the need for robust and efficient turbines that can withstand the harsh conditions of the ocean.

What's the future of Tidal Energy Production?

Despite these challenges, several new tidal energy projects are under construction or in the planning stages, indicating a growing interest in this renewable resource:

• Swansea Bay Tidal Lagoon, Wales, UK: This ambitious project aims to generate around 320 MW of electricity, enough to power 155,000 homes. It will use a combination of tidal range and tidal stream technologies to harness the energy of the tides.
• Raz Blanchard Tidal Farm, France: Set to become one of the largest tidal energy projects in Europe, this farm will have an installed capacity of up to 100 MW. It will be located in one of the strongest tidal currents in Europe, off the coast of Normandy.
• Fundy Ocean Research Center for Energy (FORCE), Canada: Located in the Bay of Fundy, which has the highest tidal range in the world, FORCE is a leading research centre for tidal energy. It aims to test and deploy various tidal energy technologies with a potential capacity of up to 64 MW.

Conclusion

Tidal energy offers a reliable and significant source of renewable energy, with benefits such as predictability, storability, and substantial energy potential, especially considering the scheme for the Bay of Fundy, which has the highest tidal range in the world and the scheme for Swansea Bay, positioned in the second highest tidal range in the world.

However, the high costs, ecological and environmental impacts, and technological challenges have limited its widespread use. With ongoing advancements and new projects underway, the future of tidal energy looks promising, but its full potential will depend on overcoming these hurdles. As technology improves and costs decrease, tidal energy could play a crucial role in the global transition to sustainable energy.