Although estimates of global tidal energy-generating potential vary, tides have a total energy of 3,000 gigawatts. However, the analysis of how much of that energy is available for power generation by tidal barrages ranges from 120 to 400 GW, depending on location and conversion potential. The wind and the sun are less predictable than the tides. Tidal power is a renewable energy source. Tidal Power turns approximately 80% of kinetic energy into electricity, whereas coal and oil only convert 30% of the energy stored within. This article will explain to you about the Tidal energy which will be helpful in preparing the Environment syllabus for the UPSC Civil Service exam.

What exactly is Tidal Energy?

• Tidal energy is generated by the gravitational interaction between the Earth, the sun, and the moon, which causes the natural rise and fall of tides.
• The tides can be used to generate electricity by creating a reservoir or basin behind a barrage and then passing tidal waters through turbines in the barrage.
• The intensity of the water from the rise and fall of tides is a form of kinetic energy, and tidal energy is created using the movement of tides and oceans.
• The energy of tidal flows is converted into power by a tidal generator.
• It is a type of gravitational hydropower that generates electricity by using the movement of water to push a turbine.
• Greater tidal variation and higher tidal current velocities can significantly boost a site's tidal electricity generation potential.

How is power generated from Tidal Energy?

• By constructing floodgate dams across sea/ocean inlets, oceanic tides are used to generate electricity.
• Water flows into the inlet during high tide and is trapped when the gate is closed.
• The water retained by the floodgate flows back to the sea via a pipe.
• This water then passes through a power-generating turbine after the tide falls outside the floodgate.

Methods of Harnessing Tidal Energy

Tidal Stream Generator

• Tidal stream generators use the kinetic energy of moving water to power turbines, similar to how wind turbines use wind energy to power turbines.
• Some tidal generators can be integrated within existing bridge structures or are completely submerged, eliminating issues about aesthetics and visual impact.
• High velocities can be created at specific locations by land constrictions such as straits or inlets, which can be captured using turbines.
• Horizontal, vertical, open, or ducted turbines are all options.

Tidal Barrage

• Tidal barrages take advantage of the difference in height (or hydraulic head) between high and low tides to generate potential energy.
• The potential energy from a tide is grabbed by strategically placing specialized dams when using tidal barrages to generate power.
• The temporary boost in tidal power is diverted into a vast basin behind the dam, which holds a large quantity of potential energy when the sea level rises and the tide begins to come in.
• As the tide recedes, this energy is transferred to mechanical energy as the water is discharged through enormous turbines, which generate electrical power via generators.
• Barrages are basically dams that span the entire length of a tidal estuary.

Tidal Lagoon

• Constructing circular retaining walls fitted with turbines that can capture the potential energy of tides is a new tidal energy design option.
• The reservoirs constructed are comparable to tidal barrages, except that the area is artificial and there is no pre-existing ecosystem.
• The lagoons can also be set up in a double (or triple) configuration, either without pumping or with pumping that flattens the power production.
• Excess to grid demand renewable energy, such as wind turbines or solar photovoltaic arrays, could be used to generate pumping power.
• Rather than being restricted, excess renewable energy might be utilized and stored for later use.

Tidal Energy Potential in India

• The moon's gravitational force causes the tidal cycle to occur every 12 hours.
• "Potential energy" is the difference in water height between low and high tide.
• The height of high tide must be at least five meters (16 feet) higher than low tide to capture enough power from the tidal energy potential.
• There are only about 20 places on the planet where the tides are this high, and India is one of them.
• The Gulf of Cambay and the Gulf of Kutch on the west coast of Gujarat have maximum tidal ranges of 11m and 8m, respectively, with average tidal ranges of 6.77m and 5.23m.

Governments Initiative

• In 2011, the Gujarat government signed an agreement with GPCL, Atlantis Resource Corporation (UK), and PMES, Singapore to build a 250 MW tidal power project in the Gulf of Kutch.
• The first phase of a 50 MW tidal power project at Mandavi in the Kutch district has begun.
• In 2008, the Ministry of New and Renewable Energy (MNRE) approved a demonstration project to build a 3.75 MW tidal power plant at Durgaduani Creek in the Sunderbans, West Bengal, but it never saw the light of day.

Challenges

• It has been nearly 40 years since India began efforts to assess and harness tidal power, but the country has yet to make any significant progress in this area, despite rapid progress in other renewable energy sources.
• A parliamentary panel has now requested that the Indian government reassess the potential of tidal power in India, investigate the practically exploitable potential, conduct additional research in the field, and develop a tidal power pilot project.
• In 2007 and 2011, India began construction on two tidal power projects in West Bengal and Gujarat, with installed capacities of 3.75 and 50 megawatts, respectively.
• However, both of these projects were suspended due to exorbitant costs.
• The project cost for the 3.75 MW Durgaduani tidal power project in West Bengal was Rs. 2.38 billion (Rs. 238 crore).
• The estimated cost of the 50 MW tidal power project in Gujarat's Gulf of Kutch was Rs. 7.5 billion (Rs. 750 crores) per megawatt of power.
• Exorbitant costs and environmental risks are two major reasons why tidal power projects have yet to be developed in India.
• Because of various obstacles, tidal power is not actively pursued on a global scale as well.

Advantages of Tidal Energy

• Due to gravitational forces, tides are predictable and consistent in their energy output.
• Tidal energy will become more affordable and efficient as technology advances.
• Due to the stability under various design conditions, it protects against coastal flooding.
• Due to the stability under various design conditions, it protects against coastal flooding.
• Storm surges and waves can be absorbed by tidal lagoons once every 500 years.
• Tidal power equipment and facilities can last much longer and be more cost-effective than other renewable technologies.

Limitations of Tidal Energy

• The construction of tidal power plants is currently costlier due to the high capital requirements.
• Blade strikes on fish attempting to enter the lagoon, acoustic output from turbines, and changes in sedimentation processes and habitat change are the main environmental concerns.
• On the other hand, all of these effects are localized and do not affect the entire estuary or bay.
• Equipment maintenance and repair can be complex.
• Demand for energy is limited. Since powerful tides only occur 10 hours per day on average, tidal energy storage capacity must be developed.
• It's difficult to provide tidal energy to coastal communities because the tides' energy is often a long way from where the electricity will be used inland.

Conclusion

Tidal stream energy has greater potential than wave or offshore wind energy; yet, only a few sites are ideal for tidal stream energy extraction. Although tidal stream energy extraction technology is still in its early stages of development, it has enormous potential to become a substantial part of the future energy mix for sites. Tidal barrages, along with other technologies, have been studied in order to better understand how to harness ocean energy. Despite the fact that tidal energy is not yet a mainstream commercial energy source, it has the potential to be used as a commercial renewable energy source.

FAQs

Question. What is tidal energy?

Question. How is tidal energy harnessed?

Question. What are the advantages of tidal energy?

Question. What are the disadvantages of tidal energy?

Question. Where is tidal energy used?

MCQs

1. What causes tidal energy?

A) Wind and water currents

B) Gravitational forces of the moon and sun

C) Earth’s rotation

D) Ocean temperature changes

2. Which technology is used to harness tidal energy?

A) Solar panels

B) Wind turbines

C) Tidal stream generators and tidal range systems

D) Geothermal plants

3. What is a major environmental concern associated with tidal energy?

A) Air pollution

B) Disruption of marine ecosystems

C) Excessive greenhouse gas emissions

D) Land degradation

4. Which of the following is an advantage of tidal energy?

A) It is not affected by seasonal variations

B) It produces large quantities of greenhouse gases

C) It requires large land areas

D) It is a highly intermittent energy source

5. Which country has the La Rance Tidal Power Station, one of the earliest operational tidal power stations?

A) United Kingdom

B) Canada

C) France

D) South Korea

GS Mains Questions and Model Answers

Q1. Discuss the potential of tidal energy as a renewable source of power.

Answer: Tidal energy is a promising renewable energy source due to its predictability, high energy density, and minimal environmental impact. Unlike solar and wind energy, tidal energy is not affected by weather fluctuations and can provide a constant source of power. The gravitational forces of the moon and sun create tidal movements, which can be harnessed using tidal stream generators and tidal range systems. While tidal energy has the potential to significantly contribute to the energy mix, challenges like high initial costs, environmental concerns, and the limited availability of suitable locations for installation remain. Despite these challenges, ongoing technological advancements and investments in infrastructure could help unlock its full potential.

Q2. Analyze the advantages and disadvantages of tidal energy in the context of global energy needs.

Answer: Tidal energy offers several advantages, such as reliability, predictability, and low environmental emissions. It can provide a constant and sustainable source of power, crucial for addressing the world’s growing energy demands. Unlike wind or solar power, tidal energy is not intermittent, as tides occur consistently. However, the disadvantages include high initial costs for construction, maintenance, and the limited number of locations where tidal energy plants can be installed. Additionally, tidal range systems can disrupt local marine ecosystems, affecting biodiversity. As the global shift towards cleaner energy sources continues, the development of cost-effective, environmentally sustainable tidal energy systems will be critical for addressing future energy needs.

Q3. Evaluate the environmental implications of using tidal energy for power generation.

Answer: Tidal energy is considered environmentally friendly compared to fossil fuels, as it produces little to no greenhouse gas emissions during operation. However, the construction and operation of tidal power plants, particularly tidal range systems, can disrupt marine ecosystems by altering natural water flow, sediment movement, and local habitats. The impact on marine life, including fish migration and ecosystem stability, needs to be carefully assessed. In addition, the construction of infrastructure, such as dams or underwater turbines, can affect the local aquatic environment. Despite these concerns, tidal energy has a much lower environmental footprint than many other energy sources, making it a viable option for future power generation with proper environmental safeguards.

Previous Year Questions on Tidal Energy

1. UPSC CSE (IAS) Prelims 2020

Question: What are the key challenges associated with tidal energy as a renewable energy source?

Answer: The key challenges of tidal energy include high initial costs for infrastructure development, limited suitable locations, environmental concerns related to the disruption of marine ecosystems, and the technological complexity involved in harnessing tidal power efficiently. While it is a predictable and reliable source of energy, these challenges must be addressed for its widespread adoption.

2. UPSC CSE (IAS) Mains 2019

Question: Evaluate the feasibility of tidal energy as a solution to global energy needs.

Answer: Tidal energy offers a promising alternative to conventional power sources, with advantages like predictability and sustainability. However, its feasibility is limited by high costs, environmental concerns, and site-specific requirements. While it may not replace other major renewable energy sources like wind or solar, it can complement the energy mix, especially in coastal regions with suitable tidal movements. With advancements in technology and infrastructure, tidal energy has the potential to become a significant part of the global energy solution.