Tidal Power

Sustainable Technology

Can Tidal Power be a big success?
Previously I chose to write about La Rance tidal plant for my sustainable technology issue. La Rance Tidal Barrage is the only one large scale commercial tidal power station in the world . Currently La Rance Tidal Plant is still the only main mass energy producing plant, although there are future plans to create more, they take many years to implement and build. There are also two other barrages - one being the 20MW Annapolis station in Nova Scotia, and the other a small 0.5MW plant in Russia. As you can tell the 240MW barrage in France grants it being superior to its brothers.
Tidal Power is a form of hydropower that exploits the movement of water caused by tidal currents or the rise and fall in sea levels due to the tides. Although not yet widely used, tidal power has potential for future electricity generation and is more predictable than wind energy and solar power.

Describe the primary sustainable technology objective or issue.
If there is one thing we can safely predict and be sure of on this planet, it is the coming and going of the tide. This gives this form of renewable energy, tidal power, a distinct advantage over other sources that are not as predictable and reliable, such as wind or solar. According to the Department of Trade and Industry, almost 10% of the United Kingdom’s electricity needs could be met by tidal power.

Analyze the possible technical alternatives and consequences regarding that objective or issue.
The following diagram is a simplified version of a tidal barrage:

As well as tidal power there is also another similar form, called Wave Power.

Waves are not as consistent as the tide and therefore there is a definite problem with matching supply and demand. This is one of the main reasons that Wave power has so far been restricted to small scale schemes. Waves are a very powerful source of energy. The problem is that it's not easy to harness this energy and convert it into electricity in large amounts. Thus, wave power stations are rare.

How does it work?
At a wave power station, the waves arriving cause the water in the chamber to rise and fall, which means that air is forced in and out of the hole in the top of the chamber.
Of course there are many disadvantages to using wave energy. It highly depends on the waves - sometimes you'll get loads of energy, sometimes nothing. It would also require a huge amount of planning time and to make sure that the station would be strong enough to withstand very rough weather.

There can be environmental impacts resulting from wave powered devices. But, like other renewables, these impacts must be compared to the effects of fossil or nuclear generation.

Devices that are on-shore can have environmental benefits, such as helping to reduce the erosion of the landscape. Any devices off shore can have an effect on the aquatic life in that area but this again is very site specific and hard to predict. But anchoring systems can become almost like artificial reefs, creating a place for new colonisation.

Discuss the potential political and financial effects of the project.

The construction of a barrage requires a very long project. The barrage will have environmental and ecological impacts not only during construction but will change the area affected forever. Just what these impacts will be is very hard to measure as they are site specific, and each barrage is different.

The required start of the construction of a barrage has been the main stumbling block to its deployment. It is not an attractive proposition to an investor due to long payback periods. This problem could be solved by government funding or large organisations getting involved with tidal power. In terms of long term costs, once the construction of the barrage is complete, there are very small maintenance and running costs and the turbines only need replacing once around every 30 years. The life of the plant is indefinite and for its entire life it will receive free fuel from the tide.
The economics of a tidal barrage are very complicated. The optimum design would be the one that produced the most power but also had the smallest barrage possible.
Discuss the potential effects that this project may have for sustainable development from a national or global perspective.
Perhaps the largest disadvantages of tidal barrages are the environmental and ecological affects on the local area. This is very difficult to predict, each site is different and there are not many projects that are available for comparison. The change in water level and possible flooding would affect the vegetation around the coast, having an impact on the shoreline
The quality of the water in the estuary would also be affected, the sediment levels would change, affecting the turbidity of the water and therefore affecting the animals that live in it and depend upon it such as fish and birds.

Fish would undoubtedly be affected unless provision was made for them to pass through the barrage without being killed by turbines. All these changes would affect the types of birds that are in the area, as they will migrate to other areas with more favourable conditions for them.
These effects are not all bad, and may allow different species of plant and creature to flourish in an area where they are not normally found. But these issues are very delicate.
Tidal energy has potential to become a viable option for large scale. Tidal Streams are the most attractive method, having reduced environmental and ecological impacts and being cheaper and quicker installed. The proposed Stingray project is important to demonstrate the potential for the tidal energy industry in Scotland.
Another proposed barrage is across the Servern estuary, In my opinion and the public’s, tidal power technology has moved on from typical tidal barrage concepts in terms of moving technology offshore.

There is a fine line between creating sustainable energy sources and sustaining the local environment. What is the point in creating technologies that help to sustain the national/global energy demand and help to decrease emissions, but also cause serious, sustainable detriment to the local environment? This is a big factor with the development of tidal barrages. As well as long term advantages to the world, there is also disadvantages.

I for one would not rule out the construction of a Severn Barrage, as I think this could be the most efficient way of capturing tidal energy, generating a commercially viable amount of cheap electricity. However it is important to realise that the main environmental concern is that the rise in water levels upstream of the Barrage would destroy estuarine habitats.
The Government needs to continue its funding of renewable development, and ensure that funds are directed towards the technologies which show the most potential.
In recent years this has been wind power, but tidal power is knocking on the door new technology.

As an island nation, we've always relied on the ocean around us for food, travel, trade and protection. Now it's providing us with clean energy too. The waves crashing onto our western shores carry the power of the Atlantic behind them.

http://www.esru.strath.ac.uk/