The factors to be considered while selecting a site for a steam power plant for economical and efficient generation are: 1. Nearness to the Load Centre 2. Supply of Water 3. Availability of Coal 4. Land Requirement 5. Type of Land 6. Transportation Facilities 7. Labour Supplies 8. Ash Disposal 9. Distance from Populated Area.
Factor # 1. Nearness to the Load Centre:
The power plant should be as near as possible to the centre of the load so that the transmission cost and losses are minimum. This factor is most important when dc supply system is adopted. However, in case of ac supply system when transformation of energy from lower voltage to higher voltage and vice versa is possible, power plant can be erected at places other than that of centre of load provided other conditions are favourable.
Factor # 2. Supply of Water:
Large quantity of water is required in a steam power plant.
It is required:
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(i) To raise the steam in boilers.
(ii) For cooling purposes such as in condensers.
(iii) As a carrying medium such as disposal of ash and
(iv) For drinking purposes.
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In steam power plants approximately 1.26 × 106 kcals of heat per MW per hour has to be disposed of in the condenser. In case of direct circulation from the source of water 120 m3 of water is required per MW per hour for this purpose. In case cooling towers are used about 2.4 m3 of water per MW per hour will be required in addition as make-up water.
With pond cooling slightly large quantity of water is required to meet evaporation and drift losses etc. but cooling effect is better. The efficiency of direct cooled plant is about 0.5% higher than that of the plant cooled by cooling towers. This means a saving of about Rs 7.5 lacs per year in fuel cost for a 2,000 MW station. Hence it is clear that the plant should be located near a river, sea or a lake.
Factor # 3. Availability of Coal:
A huge amount of coal is required for raising the steam (20,000 tonnes per day for a 2,000 MW station). Since the Government policy is to use only low grade coal with 30 to 40% ash content for power generation purposes, the steam power plant should be located near the coal mines to avoid the transport of coal and ash.
Factor # 4. Land Requirement:
The land is required not only for setting up the plant but for other purposes also such as staff colony, coal storage, ash disposal etc. For a 2,000 MW plant, the land requirement may be of the order of 200-250 acres. As the cost of the land adds up to the final cost of the plant, it should be available at a reasonable price. Land should be also available for future extension.
Factor # 5. Type of Land:
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Land should be of good bearing capacity since it is to withstand not only the dead load of the plant but also the forces transmitted to the foundations due to the operation of the plant and this total load may amount to about 7 kg per sq. cm. Moreover the land should be reasonably level and not low lying.
Factor # 6. Transportation Facilities:
The facilities must be available for transportation of heavy equipment and fuels e.g., near railway station.
Factor # 7. Labour Supplies:
Skilled and unskilled labourers should be available at reasonable rates near the site of the plant.
Factor # 8. Ash Disposal:
Ash is the main waste product of the steam power plant and with low grade coal, it may be 3.5 tonnes per day, hence some suitable means for disposal of ash should be thought of. It may be purchased by building contractors, or it can be used for brick making near the plant site. If the site is near the coal mine, it can be dumped into the disused mines. In case of site located near a river, sea or lake, ash can be dumped into it. If the waste land is available near the site, then an area of 40 hectares excavated to a depth of 6.5 metres will be required per year for a 2,000 MW plant.
Factor # 9. Distance from Populated Area:
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Since most of the modern generating stations employ pulverised fuel- residues and fumes from them are quite unhealthy, therefore the site for the power station should be away from the populated area.
All the factors are given above, but the first one help us to select the site for the thermal power station away from the towns. Nowadays more importance is given to the facilities for generation than those of distribution and site for steam power station nearby river side, where ample water is available, and no pollution of atmosphere occurs and fuel can be transported easily, is an ideal choice.
Studies have revealed that it is more economical to locate the steam power plant at or near pit head rather than at load centre. For loads exceeding 200 MW at 220 kV and 375 MW at 400 kV, transmission of electrical energy is more economical in comparison to transport of coal for distances of the order of 100 to 700 km and even more.