Projects Info | 14-20 April 2008



Hydel push

The power deficit factor is most likely to affect the growth momentum of the country. India registered a growth rate of 9.6 per cent in 2006-07 and the growth for the fiscal ending 31st March 2008 is likely to be below 9 per cent. The scarcity of power is proving to be an obstacle in the growth story so far. Various options are being explored to overcome this power deficit situation. Power sector is charged up with the launch of Ultra mega power projects and number of Hydro projects. Renewable energy sources like solar, wind and biomass based power projects are coming to the fore to solve the demand and supply of the power. The formula devised to meet the ever growing demand for electricity is to meet the base load demand through Thermal and Nuclear power along with Run of the river Hydel stations, while peak hour demand is provided by hydel schemes with storage / pondage and pumped storage schemes.

India's power generation scenario:
The installed capacity as on 31st March 2008 was 1,43,061 MW comprising of Hydro (35908.8 MW), Thermal (91,907 MW), Nuclear (4120 MW), Renewable energy sources (11,125.2 MW. The annual growth rate in generation during 2006-07 was registered at 7.3 per cent and in 2007-08 (upto November 2007) was 6.9 per cent. This was 3.1 per cent at the end of the 9th plan and in the initial years of 10th plan. The Plant Load Factor has shown improvement over the years. The PLF upto November 2007 was recorded as 76.7%.

Challenges before the economy
The immediate challenge faced by the policy makers on the power front is to meet the peak hour demand, which is crucial to drive the growth engines of the economy. As per the April 2008 report of the Central Electricity Authority, so far the peak hour demand is manageable. The peak hour demand for March 2008 was 1,08,002 MW and the supply was 89,676 MW resulting into a peak hour deficit of around 18,326 MW, which amount to 17.0 per cent deficit. A country like India cannot afford to have a demand-supply mismatch of this magnitude.

Peak demand power scenario in WB
The states are reeling under pressure to solve the peak demand of electricity and are trying out various options to tie up with the situation. Recently, WBSEDCL commissioned the Purulia Pumped Storage Power Project (PPSP) as a step forward in the direction to meet the peak hour demand. As per CEA report, the current peak hour demand for March 2008 in the state of West Bengal was 5,379 MW and supply was 4,754 MW. Despite the commissioning of the PPSP, the overall peak hour power deficit was 625 MW which amounted to 11.6 per cent deficit.

Purulia Pumped Storage Project
The Purulia Pumped Storage Project of West Bengal State Electricity Distribution Company Ltd (WBSEDCL) envisaged 4 units of 224 MW each. This project can generate 900 MW power instantly by discharging stored water from Upper dam to Lower Dam through reversible pump-turbine and generator motor. The project located in Ajodhya Hills in Bagmundi village of Purulia district was commissioned in February 2008 and was dedicated to the nation by the Buddhadeb Bhattercharjee, Chief Minister of West Bengal on 6th April 2008. The project cost of Rs 2,953 crore is funded as a loan assistance from the Japan Bank for International Cooperation. The entire Power house was constructed under the hills, by gauging out the rocky hills of Purulia , with access through a kilometer long tunnel. HCC- L&T JV carried out a major portion of the project under contract from M/s TAISEI, one of the Japanese Contractors. HVAC System for
the entire project was carried out by Aircon Group under sub-contract from HCC- L&T JV.

Preliminary facts
The journey of Purulia Pumped Storage Hydel Scheme started in 1979 when Survey & Investigation Wing of erstwhile WBSEB, conducted a reconnaissance survey based on assessment report of Central Electricity Authority (CEA). This was followed by preliminary study by M/s DCPL and M/s Hazra Engineering, USA in 1980. The state irrigation and waterways directorate started hydrological observation work in 1982. The detailed investigation was taken up under loan assistance of 629 Million Yen from Overseas Economic Co-operation Fund, Japan and through Electric Power Development Corporation, Japan as foreign consultant along with Central Electricity Authority, Central Water Commission and Water and Power Consultancy Services (WAPCOS) as local consultant. The detailed project report was submitted to CEA by WBSEB in 1992. The techno economic clearance was accorded by CEA in July 1992. In February 1994, clearance from the Ministry of Forest and Environment received.

The Purulia Pumped Storage project is located on Kistobajar nalla, a tributary of Shaba nalla which drains into Suvarnarekha river under district Purulia, West Bengal. The total land acquired for the project is 445 ha and out of this the forest area covers 399 ha. The project was planned in such a manner that not even a single family was evicted from their land or house.

How the pumped storage scheme works?
The scheme utilizes 600 cumec of discharge from the upper reservoir of effective storage capacity of 13 Mcum with an effective head of 177 M for generation of 900 MW (4 x 225 MW) of electric power. The tail water discharges into the tail water reservoir of effective capacity of 13 Mcum. All the components of this project, except the two dam and reservoirs and switchyard are underground. In a conventional hydel scheme, water flow of a river is either stored in a barrage / dam or directly utilised at a head to generate electricity. In a pump storage scheme, storage from upper reservoir is released to the lower one for a shorter period to generate large quantity of electric power. Pumping from the lower reservoir to the upper one is done during off peak period when the cost of power is cheap. This is done to replenish the water in the upper reservoir and make it available to take the peak load.

Project Economics
Pumping requires more power than the power that the same quantity of water can generate. The logic behind using this kind of scheme is to make use of the difference between power pricing during peak and off peak hours. Generally, the peak hour power price is higher than the off peak hour pricing. The pumped water is used to produce power in the peak especially in the evening when it is costly. This helps to meet the extra power demand in the evening, stabilize power distribution system for smooth running of the industrial units and lastly improves the poor thermal hydel mix ratio of the region to a great extent.

Environmental impact
The impact of the construction of the PPS project on the environment is quite low. There is hardly any impact on flora and fauna.

Pumped storage power generation potential

94,000 MW pumped storage power generation potential is estimated by CEA and has idenfied 56 sites all over India.

9,085 MW is the pumped storage power generation potential for the eastern region.

Project benefits

Peak demand can be met instantly

Plant load factor of thermal power stations can be improved

Results in grid frequency stabilization of the region

Utilises surplus grid power to pump water from lower reservoir to upper one at lean hours

Credits: Sandeep Ravidutt Sharma, Foundation of Infrastructure Research Studies Training (FIRST)


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