Everything I need to know about generating power from tides

Tidal Energy

While technology has done a lot to improve lifestyles, the numerous inventions and man-made machines require energy to run on and depend on some form of fuel. The high demand for fuel has caused the most-widely used fossil fuels to become dearer and the challenge for today’s scientists is how to generate energy.

Again, technology comes to the rescue with tidal power. Scientists and environmentalists have developed ways to harness the tremendous power of violent ocean tides.

Trends

Jung Seung Woo, Seung Woo Jung, Kim Min Jung, and Kim Hyun Jun from Korea have developed a prototype of a wave and solar energy generator that works day and night. While during the day, the devices that float on the ocean surface trap solar and tidal energy, during the night, it works as a tidal power generator. The device uses some of the power generated to glow at night acting as beacons to guide ships safely away from them. The electricity which is generated is sent ashore via underwater cables.

France has also been actively exploring ways of tapping tidal power with its ambitious €40m (£35m) Paimpol-Bréhat project. The project will see the world’s largest tidal array that consists of four 16-metre turbines, being installed out at sea. Initially, one of the turbines will be tested in 35 meters of water off the Bréhat Island. The other three turbines will be installed in 2012. 2 MWs of power generated by this array will be sufficient to power 4,000 French households.

The Benefits

While the world explores several sources of clean energy, tidal power has several advantages over other forms of green and alternative energy.

a. Unlike solar and wind power that largely depend on weather conditions, tidal movements are very predictable and reliable.
b. The density of water being much higher than air it means that a turbine used to harness tidal power can be significantly smaller than a wind turbine that generates the amount of electrical output.
c. Tidal turbines work noiselessly. Although industrial wind turbines are relatively silent, utility-sized wind turbines are known to generate low-frequency noise that people living in the vicinity complain about.
d. Since these turbines do not use oils or grease for lubrication, they pose no threat to the environment.

The Lowdown

a. Environmental hazard

Setting up large structures on the seabed causes considerable damage to the ecosystem. Also, placing these objects in the water reduces the amount of water that moves between a basin where the power is generated and the sea, leading to higher chances of pollution. This reduced exchange of water would also reduce the salinity of water in the basin, significantly affecting life on the seabed.

b. Fish and marine life
As marine life forms and fish pass through these barrages, even the most innovatively designed barrages are responsible for about 15 per cent of the mortality per pass through. Hence, in the long run, marine life can be severely impacted.

c. Irregular power supply
Power can be generated only when there is tidal movement in or out of the basin. Although tides are predictable, they are not constant. Hence, power can be generated only during particular times of the day.

d. High start-up cost
The cost of setting up a tidal array is astronomically high. This may discourage investors from putting their money in tidal power generation.

e. Damage
Erratic weather conditions and frequent hurricanes raise the fear of damage to the expensive equipment installed on the floor of the ocean. Although this was a major concern during the recent Hurricane Irene, Ocean Power Technologies’ PowerBuoy deployed off the coast of New Jersey withstood the severe conditions experienced during the hurricane. Surprisingly, after facing the onslaught for two days, the PowerBuoy emerged undamaged and fully operational. It even maintained a regular supply of electricity during the hurricane. Although this is a testament to the high levels of engineering skills, it highlights the need for the best engineering and materials that should be used in making turbines. This further raises the cost of manufacturing tidal turbines.

The Impact
Every country is looking for ways and means of responding to the high demand for energy. And, with the focus on the need for green and renewable energy, governments are leaving no stone unturned, even if it lies on the bottom of the ocean. Tidal power looks more prospective, with wind and solar energy being very seasonal and time bound. The popular saying, ‘time and tide waits for none’ makes tidal energy the much-preferred source of energy in the future.