Tài liệu Tiếng anh. Tidal power plants in the world and Vietnam

Tidal power plants in the world and Vietnam

1. What is Tidal power?

Tidal power, or tidal energy, is a technology harnessed by converting energy from tides into useful forms of power, mainly electricity, using various methods. It is considered a form of hydropower that holds the potential for a more sustainable future.

1. Principle and Source of Energy

Tidal energy is drawn from the Earth's oceanic tides. Tidal forces result from periodic variations in the gravitational attraction exerted by celestial bodies, primarily the Moon and the Sun. These forces create corresponding motions or currents in the world's oceans, leading to periodic changes in sea levels.

Tidal power is unique as it is the only technology that draws on energy inherent in the orbital characteristics of the Earth–Moon system, and, to a lesser extent, the Earth–Sun system. These changes in tides are highly regular and predictable due to the consistent pattern of the Earth's rotation and the Moon's orbit around the Earth. Because tides are ultimately due to gravitational interaction with the Moon and Sun and the Earth's rotation, tidal power is practically inexhaustible and is thus classified as a renewable energy resource.

1. Methods of Harnessing Tidal Power

There are three main established methods to harness the energy created by tides and currents:

1. Tidal Turbines (Tidal Stream Generator): These devices use the kinetic energy of moving water to power turbines, operating similarly to how wind turbines use wind. They are located below the water’s surface, where the water current pushes the blades, which are connected to a generator that creates electricity. The largest marine current power plant to date is the MeyGen project in northern Scotland, with its first four underwater rotors beginning operation in April 2018.
2. Tidal Barrages: These are low-walled dams, typically installed at tidal inlets or estuaries. These systems utilize the potential energy derived from the difference in height (hydraulic head) between high and low tides. The barrage holds a large basin of potential energy as the tide rises; as the tide recedes, the water is released through large turbines connected to generators to produce electrical power. The Rance Tidal Power Station in France (240 MW) and the Sihwa Lake facility in South Korea (254 MW) are examples of dam-construction type tidal power plants. The Sihwa Lake power station is currently the largest in the world.
3. Tidal Fences: This method is a hybrid of tidal barrages and tidal turbines. Vertical tidal fence turnstiles are installed together in a 'fence-like' structure. The energy from tidal currents pushes these turnstile blades, which are connected to a generator to create electricity.

Other concepts include Tidal Lagoons, which involve constructing artificial circular retaining walls with embedded turbines to capture potential energy, and Dynamic Tidal Power (DTP), a theoretical technology proposing very long dams (30–50 km) built out from the coasts to exploit tidal phase differences and water-level differentials.

1. Advantages of Tidal Energy (Pros)

Tidal energy is a beneficial option for a number of reasons:

• Renewable Source: The energy source does not deplete as it is used.
• Predictable Energy Generation: Production is highly predictable because it relies on consistent tidal currents that follow a forecastable pattern. This contrasts with solar power, which is less predictable due to weather patterns and sunlight exposure.
• Zero Carbon Emissions: Tidal power plants are a clean energy source and do not emit any harmful gases, aiding in the reduction of greenhouse gas emissions. The global warming potential (carbon footprint) of tidal generation ranges between 15 and 37 gCO2-eq/kWhe.
• High Generation Capacity and Reliability: The density of water allows turbines to be powered even when water moves at slow speeds. Tidal energy has high reliability and excellent energy density.

1. Disadvantages and Challenges (Cons)

Despite its potential, tidal power deployment is challenged by several factors:

• Expensive Source of Energy: Constructing a tidal power plant involves a high upfront cost. The levelized cost of energy (LCOE) for commercial-scale tidal power is high, falling between $130 and $280 per megawatt-hour (MWh), significantly higher than utility-scale solar energy (about $24 to $96 per MWh).
• Limited Installation Sites: Tidal power stations must meet specific geographical requirements, limiting potential stations to coastal areas. Sites need a significant difference in height between high and low tides to sufficiently move the turbine blades.
• Intermittent Energy Source: Tidal power is dependent on the natural rise and fall of tides, making it an intermittent source. Since electricity production occurs around peak tide times, tidal power plants might not always align with peak energy demand (usually morning and evening).
• Environmental Impact:
  • Tidal Turbines: High-speed water increases the risk of wildlife collisions (blade strike) for fish and other marine organisms. They also generate low-level noise beneath the water surface, which can negatively impact marine mammals, such as seals.
  • Tidal Barrages: Installing a barrage can change the shoreline, affect large ecosystems that rely on tidal flats, disrupt sediment processes, and inhibit the movement of migrating fish.
• Corrosion and Fouling: Saltwater causes corrosion in metal parts, making maintenance difficult due to the depth and size of the generators. Furthermore, high tidal currents and biological productivity can lead to fouling (growth of marine organisms) on the structure.

1. Famous Tidal Power Plants in the World:
   • 1. La Rance Tidal Power Plant – France
     2. Sihwa Lake Tidal Power Station – South Korea
     3. MeyGen Tidal Stream Project – Scotland (UK)
     4. Annapolis Royal Tidal Power Plant – Canada
     5. Jiangxia Tidal Power Station – China
     6. Kislaya Guba Tidal Power Station – Russia
     7. Swansea Bay Tidal Lagoon (Proposed) – Wales (UK)
2. Tidal Energy in Vietnam:

1. Status (Current state)

• Vietnam does not yet have any commercial tidal power plants in operation (i.e., no large scale “tidal barrage” or “tidal stream” facility) reported.
• Marine-renewable-energy research (including tidal) is still at an early stage in Vietnam. According to an article:
• A survey of tidal energy potential in coastal Vietnam found that along the Hải Phòng – Quảng Ninh coastal area and southeast region the potential is measurable but not yet exploited. Hải Phòng (north-east Vietnam) the potential installed capacity could be up to ~550 MW, accounting for about 96% of Vietnam’s tidal technical potential (according to the source) — though this is an estimate, not existing capacity.

2. Potential (What the studies show)

• A 2022 paper “Tidal energy potential in coastal Vietnam” reports that for the Hai Phong-Quang Ninh area and southeastern region, the prospective output is ~ 41.6 GWh per km² per year.
• Another recent study “Estimation of tidal energy potential in the Vietnam East Sea” (2024) presents semi-empirical modelling of tidal potential in sea area off Vietnam.
• A marine-energy overview states: “Vietnam has potential for current and tidal energy … small, enclosed bays such as certain coastal areas of Quảng Ninh and Hải Phòng, with tidal ranges of 3-4 m, could still be considered for small- to medium-scale projects.”
• From the same source: Although the tidal ranges are not as large as global “hotspots” (like Canada or UK), there are local zones with favourable conditions (tidal amplitude 3–4 m) for development.

3. Key Strengths & Opportunities

• Strategic location: A coastline >3,000 km and numerous bays/estuaries provide various potential sites.

4. Challenges & Constraints

• Magnitude of tidal range: Many of the world’s most productive tidal power plants are in locations with large tidal ranges or strong currents — Vietnam’s typical tidal ranges (3-4 m in some good zones) are moderate, thus yield per site may be lower.
• Technology & cost: Tidal-power technology (especially barrage/lagoon or tidal-stream turbines) remains relatively more expensive and less mature than many wind/solar technologies.
• Data and research gaps: Very few full-scale feasibility studies, limited data on long-term tidal/current fields, sediment & ecosystem impacts.
• Infrastructure & regulatory: Offshore/sea-based installations face higher logistical, environmental, regulatory complexity (marine permits, ecological impacts, grid connection).
• Scale & economic viability: Given moderate potential at site level, achieving cost-competitive large scale may be challenging unless site selection is optimal and technology costs reduced.