Tidal Energy Ryan Saad Sufie Energy Resources Assignment

Tidal Energy Ryan, Saad, Sufie Energy Resources Assignment SPH 3 U

What is Tidal Energy? • A type of hydropower that is used to generate electricity by converting the energy of tides into usable energy.

Tidal Stream Generators (TSGs) • Tidal Stream Generators make use of the kinetic energy of moving currents to turn turbines and power generators. • The amount of power generated by TSGs is dependent on the strength of the water current.

TSGs - Advantages • Constant streams of water currents allow a constant generation of electricity. • Highly efficient; TSGs convert about 80% of the kinetic energy of the water into electricity.

TSGs - Disadvantages • Difficult to install and maintain the underwater turbines. • Changes in tidal movement reduces efficiency. • Devices sometimes break down because of excessively strong water currents and sea water corrosion. • Floor mounting may disrupt habitats of sea life.

Types of TSGs • Horizontal Axis Turbines • Vertical Axis Turbines • Reciprocating Devices • Venturi Effect Tidal Stream Devices

Tidal Barrages • Dams that use the raising and receding tides and the potential energy involved. • When the tides rise, water flows from the sea into the basin of water that the dam is holding back. • When the tides recede, the water is released through gates of turbines, which power generators.

Tidal Barrages - Advantages • The tides are predictable because of the relation to the moon, thus making it a reliable source of renewable energy. • Barrages are not dependent on random weather patterns, unlike wind or solar energy. • It is a cheap energy source once the initial cost is paid off.

Tidal Barrages - Disadvantages • Fish and other marine life can be hurt or even killed by colliding into or going through the turbines; their movements or migrations could also be affected. • Limited suitable locations, needs good sized tides and large areas for the dam and the water retainment

Types of Tidal Barrages • Ebb Generation • Flood Generation • Two-Way Generation • Double Basin Tidal Generation

Dynamic Tidal Power (DTP) • An untried, proposed technology which involves building long wall-like dams straight out from the coasts of specific areas. • As waves hit the dams, strong coastal-parallel currents are created and can be captured and transformed into electricity through generators.

DTP - Advantages • A single dam can produce 8 to 15 gigawatts (8 to 15 billion watts) in an hour. • Very stable compared to other methods. • High availability, only requires a wide coast. • Potential for combined functions, such as with coastal protection.

DTP - Disadvantages • Unsure if the technology involved will be efficient or even successful, since it is not currently in use. • Can only be tested on a large scale, which could be expensive. • There is potential to negatively affect the environment and the ecosystem.

Tidal Lagoons • Tidal Lagoons are a newer design concept, involves building circular wall-dams that retain water, capture potential energy of the tides, and transform it into electricity using turbines and generators. • Similar to Tidal Barrages, but artificial location and no pre-existing ecosystem.

Tidal Lagoons - Advantages • Tidal Lagoons are reliable because of constant electricity generation and predictability. • Easy to combine with special pumps that use renewable energy to raise water levels, increasing energy production. • Dam could support potential local sports, such as walking, cycling and swimming.

Tidal Lagoons - Disadvantages • Higher cost due to large size and amount of resources needed. • Do not capture as much as water as the other methods, individually they create less energy. • Energy generation is significantly lower than other technology, such as wind- or tidal streamgenerated.

Application of Methods • Tidal Barrage; Rance Tidal Power Station in France, opened 1966 (World first and largest tidal power station until the one in Korea is installed). • Stream Generator; Seagen in Strangford Lough in the U. K. • Tidal Lagoon; Swansea Bay Project construction is scheduled for completion in U. K. by 2017

Tidal Energy Vs. Wind Energy • Tidal energy costs more to operate and construct the machines than wind energy. • Wind energy is unpredictable due to unstable weather conditions; tidal energy is completely predictable. • Water turbines produce much more electricity than wind turbines; Water turbines produce an average of 1, 824, 000 k. Wh per day, wind turbines produce an average of 14400 k. Wh per day. • Wind turbines create noise for people living nearby, and may harm birds and other wildlife.

Tidal Energy Vs. Solar Energy ● Initial cost of solar energy panels are cheaper than tidal energy devices. ● Weather patterns directly affect the efficiency of solar energy since solar panels depend solely on sunlight. Tidal energy produces more electricity, constantly. ● Solar panels require space on land to be built: the amount of space depends on the amount of panels. ● Solar energy produces pollution, Nitrogen trifluoride and sulfur hexafluoride… these greenhouse gases have an impact on global warming; tidal energy is pollution free.

Monetary Cost of Building a Tidal Project • Construction cost • There is a high capital cost for a tidal project, with a 5 to 7 year construction. Meanwhile, the high cost of engineering design, using large manpower. • The cost of one tidal turbine that converts 65 kw of power costs $4, 000. However, at the same time, it introduces job opportunities to complete construction which is good for the economy. • Maintenance A minimum lifespan of 120 years is estimated by engineers.

Environmental Impacts • A mortality of rate of fishes passing through a tidal barrage is 20% -80%. • Holding back the tide allows silt to build up in the river bed, reducing the water flow for years! • Disrupted fish migrate; may reduce the fish population in the oceans. • The noise pollution produced by the turbines.

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