Himachal Pradesh is endowed with about 21000 MW of exploitable hydro potential, excluding about 750 MW in small /mini/micro hydro electrical potential, in its five river basins. Being environment friendly source of energy, Govt of India /Govt of Himachal Pradesh has encouraged participation of private sector in a big way, with renewed set of incentives for its exploitation.
Govt. of Himachal Pradesh has entrusted the task of implementation of self identified Sorang Barakhamba SHP Small Hydroelectric Project to M/S Jaya Enterprises in the private sector on Build, Own, and Operate and Maintain (BOOM) basis. After detailed studies it was found that scheme with the enhanced capacity of 25 MW is a optimal one and gives maximum cost – benefit ratio.
PROJECT
Proposed Sorang Barakhamba Small hydroelectric project (3 x 8.33 MW) is a run – of – the river type development on Sorang khad, a tributary of Satluj river in District Kinnaur Himachal Pradesh. The scheme envisages diversion of Sorang khad inflows by constructing a diversion weir at El 2200 m. The diverted inflows will be carried through conveyance box type channel to a surface desilting tank, which will be designed to exclude all silt particles down to 0.20 mm size. The silt free water will be carried through head race tunnel up to an underground surge shaft. The inflows will be lead to surface power house through a surface penstock to feed three no’s Francis type turbine driven generating units of 8.33 MW capacity each.
The proposed Sorang Barakhamba Small Hydro Electric Project is an upstream development of the project being developed by M/S Himachal Sorang Power Private Ltd. There is no other project upstream of this scheme awarded so far. Therefore, the scheme does not interfere with any other schemes of HIMURJA/HPSEB.
Himachal Pradesh is located in the Western portion of the Great Himalayan Mountain range of Northern India., bounded by the state of J&K to the North, Tibet to the East and plains of North India to the South and West. National Highway NH – 22 connects Kinnaur district from Shimla (State Capital). Chaura village is at the boundary of district Kinnaur and district Shimla and is gateway to the district Kinnaur. The diversion site is upstream of village Sorang and Barakhamba and proposed power house site is on the left bank of Sorang khad downstream of village Sorang. The location plan of the project is shown in drawing SB – 01.
Climate / Precipitation
The climate of this basin is harsh and cold during winter and is pleasant during summer season. The catchment receives rainfall from south West monsoon and snowfall in winter due to Westerly disturbances. Normal annual rainfall/snowfall in the region is 900 mm. The temperature falls to -5 degrees C during winter and rises to 30 degrees C during the summer.
Water availability
In flows of Sorang khad have been gauged for limited period but the data of inflows of Bhaba khad, an adjoining tributary of Satluj river, are available foe a long duration. Flows of the Bhaba khad have been to assess the water availability of Sorang Barakhamba SHP at Diversion site.
Power generation
The power generation during 75% dependable year has been worked out 118.04 MU. After allowing 1.0 % power to be consumed in auxiliaries & transformation losses, 2% power as transmission losses, and 15% free power to state government as royalty i.e. 12% royalty & 3% as additional free power upto thirteenth year after I.A irrespective of any extension granted the net saleable energy available is estimated at 97.32 MU.
Project structures
The civil engineering structures proposed for this project are discussed as follows:-
Diversion weir
For diversion of Sorang khad inflows, raised crested type weir is proposed at E1± 2200 m. The length of the diversion weir is 20 m to draw a discharge of 19.5 cumecs including discharge required for flushing. Shingle flushing system will be provided at collection chamber to flush the shingle back into khad through Shingle flushing tunnel.
Desilting Arrangement.
A surface desilting tank is proposed downstream of diversion weir. The desilting tank will be designed to exclude all silt particles down to 0.20 mm size. The under ground desilting tank will comprise one chamber of size 60 m x 16.00 m x 5.11 m with central silt gutter type silt flushing system.
Water conductor system
For carrying the inflows from desilting tank to forebay. 2.5 m D- Shaped head race tunnel is proposed. The length of power tunnel shall be± 1400 m. The power tunnel will carry design discharge of 13.04 cumecs at 2.62 m/sec velocity with a bed slope of 1:72 in pressure flow condition.
Surge Tank
At the end of power tunnel, an underground surge tank will be provided to cater for the sudden acceptance/rejection of load. The size of the surge tank has been proposed as 7 meter diameter and 35 m height.
Penstock
The water from surge tank will be led to power house through a surface penstock of ± 2100 mm dia. The penstock pipe will be fabricated from high tension steel plates with welded joints. Suitable saddle supports and anchor blocks shall be provided to support the penstock pipe. The penstock pipe will carry the design discharge of 13.04 cumecs at 3.7 m/sec velocity. Suitable inlet valve will be provided to regulate the flow to power house. The length of main penstock will be ± 380 m, which will trifurcate near power house into three branch penstocks of 1300 mm diameter to feed three turbines.
Power house
A surface power house is proposed on left bank of Sorang khad with normal tail water level at E1 + 1960 m. The power house will house three nos, horizontal axis francis turbines driven generating units of 8.333 MW each. The outflow from turbine shall be led through a tail race channel of size 3.00 m x 2.5 m to Sorang. A switchyard is proposed near the power house.
The power generated from this project will be fed into HPSEB Sub Station at Kotla near Jeori.
COST ESTIMATE
The estimated cost of this project at March – 2010 price level has tentatively been worked out at Rs 16472 lac comprising Rs 10527 lac for civil works, Rs. 5120 lac for generating plant and equipment and Rs. 825 lac for transmission line and associated transmission network. The total cost of project including IDC, FC and LADC has been worked out at Rs. 19902 lac. A provision of Rs 247 lac has been made for local area development works.
FINANCIAL ASPECTS
The financial forecast of project has been worked out considering cost of project and energy available for sale. Annual working expenses has been worked out @ 17.17% of project cost comprising to 11.5% interest, 3.17% depreciation, 1.5% O & M, 1% general reserve /other miscellaneous expenses. The levelised tariff has accordingly been worked out at Rs. 3.00 per kwh for operating period of 30 years. A debt service ratio of 1.3 and IRR has been worked as 7.6% considering a sale rate of Rs 3.35 per unit for saleable energy and CDM benefits likely to be earned by this project. Thus this project is very attractive and economically better than other sources of energy in the area.
