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Harnessing tidal energy for power generation
This article is about the feasibility of making a tidal generator by using low tide and high tide available at the coastal areas of Pakistan. But, first, let’s understand the principle of working of the tidal-wave power generator.
Three chambers of an enclosure (as demonstrated in Fig 1) generate power in sequence (see Fig 2). The sequence can be optimized to meet the needs of the operator. For instance, if the need is for maximum output, all three enclosures generate only during the extreme high tide periods and the extreme low tide periods. If the operator needs a continuous output, then the chambers generate sequentially, reducing the over-all output, but providing continuous power. The continuous power option is important to the operator.
Other forms of alternative energy have been plagued by the inability to generate on demand. Base-load capacity is generating equipment that is available at all times. Peak-load capacity is generating equipment that is available either quickly or at predictable times that conform to the demand.
Nuclear power plants cannot be shut down quickly and are operated 24 hours per day and, therefore, nuclear is a base-load type of power.
Fossil fuels plants are somewhat easier to shut down but typically they vent the steam to the atmosphere when demand for electricity declines at night.
Hydroelectric power is the sole power source that can be shut down quickly and restarted quickly, without major losses in efficiency.
Tidal Electric’s (TE’s) tidal power generator is essentially hydroelectricity (with some enhanced features) and therefore it can be supplied in a manner that conforms to the demand, either as base-load or as peak-load power. This is an unprecedented level of flexibility in capacity. Even conventional hydroelectricity is subject to seasonal variations in power output due to seasonal differences in rainfall.
Conventional hydroelectricity is directly related to rainfall run-off and snowmelt. But TE’s tidal generator allows the operator to shape the output curve to the demand curve and to either enhance existing generation or to stand alone as a sole power source.
We should try to find the sites available at the coastal areas of Pakistan for the erection of a prototype tidal generator. For this purpose the survey of the coastal areas of the Pakistan should be done which would let us know the potential sites available for the tidal wave. Moreover, data throughout the year would be collected regarding the rise and fall in tide and a database would be established. In the meanwhile material like books, journals etc. would be searched for the proposed design based on the data base already made. Progress/work already done in the field in Pakistan and abroad.
Seventy-five per cent of the Earth’s surface consists of water. It is because of this abundance of water that gives our planet the look of a lovely blue-green globe and its multitude of biodiversity. Water fulfils our every day needs in many ways. Into the 21st century, when public attention is focused on the environment — and our society is increasing at an ever accelerating pace, the energy crisis continues to burden us. Questions as to what to do about increasing energy demands and future requirements haunt our thoughts. The possibilities of utilizing the power of the oceans by pollution-free tidal power generation appear to be most attractive. Tidal power has been used to limited extent over several centuries but only recently has any significant effort been put forth to realizing its vast potential.
Tidal power has, on a small scale, been used throughout the history of mankind. It was not until the twentieth century that large-scale tidal projects were considered. Today, sites suitable for the utilization of tidal power exist in many countries around the world — most significant among them are France, United Kingdom, Russia, Canada, and the United States. In Pakistan, no scientific work of any significance has come to light.
There are a number of sites around the world that have the right combination of coast geometry and significantly large tidal range to make them potential sites for tidal power plants. It is at these spots that extraction of large quantities of tidal energy is possible.
The following figure indicates the potential sites for a traditional barrage system. It also indicates the estimated potential generating capacity of each site for a reasonable capital outlay and shows the mean tidal range in metres.
There are six tidal power stations in operation at present, most producing less than one megawatt of electricity. The largest tidal power station, built in 1965, is on the La Rance River estuary in France and has 24 ten-megawatt turbines with reversible blades.
Tidal power plants currently in planning include a 40-megawatt plant in Nova Scotia and a 400-kilowatt plant in Russia.
In Australia, several studies have been made of the potential for tidal power stations in the Kimberley region on the northwest coast of Western Australia. The tidal range throughout that area is suitable, between nine and twelve meters, however environmental concerns such as possible silting up of the bays needs to be considered.
It is possible to harness energy from the tides but technology is not yet commercially available, making this energy source not cost competitive. It is necessary when selecting a site to assess economic feasibility. On an average, the estimated cost to construct and run a tidal power facility with an average annual output of 3423GWh would total about $1.2billion, not including operational costs and maintenance (this cost exceeds that of coal and oil power plants). The benefits derived from inclusion of a tidal power plant are due to the cost of the fuels saved.
In terms of economy, some primary benefits of using tidal power are that it can replace fossil fuels and nuclear generated energy; it can reduce oil needs by one-half; it can save three million barrels of oil, 330,000 tons of coal, or 90.8 tons of uranium.
Tidal wave power generation has several advantages over conventional resources. Some of the primary advantages are: it is a renewable resource of energy; it is pollution-free; it can produceenergy 24x7x365. Interstingly, the peak output coincides with peak energy demand. Moreover, water is a free resource. Above all, it is highly efficient (coal/oil efficiency = 30 per cent, tidal power efficiency = 80 per cent).
In a society with increasing energy demands and decreasing supplies, we must look to the future and develop our best potential renewable resource. Tidal power fits the bill, a natural source of energy with many benefits. The planet’s tidal capability greatly exceeds that of the world’s entire coal and oil supply. It is an ideal source of energy with great potential. When developed, tidal power could be a primary provider for our future energy requirements.
Some of the potential sites of the world surveyed are given below:
1. Siberia
2. Inchon, Korea
3. Hangchow, China
4. Hall’s Point, Australia
5. New Zealand
6. Anchorage, Alaska
7. Panama
8. Chile
9. Punta Loyola, Argentina
10. Brazil
11. Bay of Fundy
12. Frobisher Bay, Canada
13. England
14. Antwerp, Belgium
15. LeHavre, France
16. Guinea
17. Gujarat, India
18. Burma
19. Semzha River, Russia
20. Colorado River, Mexico
21. Madagascar
A survey for the coastal areas of Pakistan is badly needed to point out the potential sites for the tidal wave energy generation.
The writer
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