BASOCHHU HYDROPOWER PLANT
| The Basochhu/Rurichu Rivers were identified in the mid 1970’s by hydropower engineers as a potential source of energy production in the medium size range. Concrete plans, however had not been developed until 1989, when the Austrian Government took interest in the project and financed the pre-feasibility study. In the same year a team of engineers visited the site and commenced the preparation of the pre-feasibility study which showed promising results. In 1993 and 1994, a team of Austrian Engineers carried out the preliminary design of the project. On 14th April 1995, the Financing Agreement was signed between the Royal Government of Bhutan and the Government of Austria. In 1996, an offer for the engineering and consultancy services for the Upper Stage was finalized while at the same time the Project |
Management Unit (PMU) was established within the then Department of Power, Thimphu for the coordination and general administration of the project. The Technical Implementation Agreement (TIA) was signed between a Consortium of Austrian Consultants and the PMU on 20th September 1996.
The project taps the water from the Basochu stream, which has a catchments area of 162 km2, above the Basochu waterfall through a 2.6 km long headrace tunnel and a 1.4 km long penstock. The two generating units have a total capacity of 24 MW and a mean annual energy generation of 105 million units.
The Lower Stage project taps 8 m3/s water from the tailrace of Upper Stage and 2 m3/s from the Rurichu stream, which has a catchments area of 64 km2. It has a 2.53 km long penstock. The two generating units have a total capacity of 40 MW and a mean annual energy generation of about 185 million units.
| The Austrian Government committed Austrian Shilling (ATS) 350 million for undertaking the project. Out of this total amount, ATS 180 million was grant while ATS 170 million was provided as interest free loan. As this initial commitment of loan and grant were not sufficient to meet the project cost, the additional requirement of Nu. 396 million was met from an equal cost sharing arrangements between the two governments. The total cost of the Upper Stage was 1,446 million Ngultrums. Austrian Government Grant was 37.3%. Austrian Government Loan is 49.0%. The RGoB Contribution was 13.7%. A Loan Subsidiary Agreement was signed between the Ministry of Finance |
and the then Basochhu Hydro Power Corporation Limited (BHPCL) on 14 October 2004 to transfer the loan availed by MOF for the construction of Basochhu Upper Stage Project to BHPCL. The total loan amount availed was Euro 17,150,788.86 (Euro seventeen million one hundred fifty thousand seven hundred eighty eight and eighty six cents) which is equivalent to Nu 708,000,000 (Ngultrum seven hundred eight million). As per the agreement BHP is required to pay to MOF at a consolidated rate interest fixed at 6% per annum on the loan amount and outstanding from time to time. BHP shall repay the principal amount of the loan in 20 years in equal annual instalment of Nu. 35,400,000. The first repayment started from 15 December 2006. The loan is dominated in Ngultrum and any foreign exchange fluctuation risk of the original loan between the Borrower and Lender shall be borne by MoF, RGOB. The total cost of the Upper Stage is shown below :
Sources / Type | Austrian Government (≈ Nu.) Millions | RGOB Contribution (Nu.) Millions | |
Grant | 540 | - | |
Loan | 708 | 192 | Interest free loan |
Total | 1,248 | 192 | 1,440 |
Financing of the Lower Stage (40MW)
The Subsidiary Loan Agreement was signed between Ministry of Finance (MOF), RGOB and the then BHPCL to transfer the loan availed for the construction of Lower Stage from Republic of Austria on 1 August 2006. The total loan amount of Euro 31,245,437.25 (Euro thirty one million, two hundred and forty five thousand four hundred thirty seven and thirty five cents which is equivalent to Nu. 1,648,872,940.86 (Ngultrum one billion six hundred and forty eight million eight hundred seventy two thousand nine hundred forty and eighty six chetrums). BHP shall pay to MOF, RGOB an interest at the rate of 6% per annum on the loan amount on the fifteenth day of each quarter. The first interest payment started from 15 September 2006. BHP shall pay to MOF, RGOB the principal loan amount in thirty equal consecutive semi annual repayments. The first repayment is due on 15 June 2010 for a period of 15 years. Similarly, MOF shall bear any foreign exchange fluctuation risk of the original loan between the Borrower and Lender shall be borne by MoF, RGOB. The total cost of the project is summarized below :
Sources / Type | Austrian Government (≈ Nu.) Millions | RGOB Contribution (Nu.) Millions | |
Loan | 1,648.87 | 137 | |
TA (Grant) | 46 | - | 2.786% |
Total | 1,684 | 137 | 1,821 |
Salient Features of Basochhu Hydropower Plant
Upper Stage
River | : BasochhuConcrete gravity, 19.5mlong & 9m |
Diversion weir | : High |
Desilting basins | : Chamber 3 (57x4.1x5 m) |
Headrace tunnel | : 2.6 km (2.5 m diameter) |
Surge shaft | : 23.6 m high (4 m diameter) |
Penstock length | : 1.368 km |
Gross head | : 356 m |
Design discharge | : 8 m3/sec |
Installed capacity | : 24 MW |
No. of Units | : 2 |
Turbine Type | : Pelton |
Mean annual energy | : 105 GWh (MU) |
Powerhouse elevation | : 1433.4 m.a.s.l |
Lower Stage
Rivers | : Basochhu + Rurichhu |
Gross/Net head Design | : 483/459 m |
Discharge | : 10 m3/s |
Pond | : 84,000 m3 (total storage capacity) |
Penstock length | : 2.53 km (1.6m diameter) |
Length of penstock tunnel | : 421 m |
Length of Rurichu tunnel | : 870 m |
Installed capacity | : 40 MW |
No. of Units | : 2 |
Turbine Type | : Pelton |
Mean annual energy | : 186 GWh (MU) |
Powerhouse elevation | : l950 m.a.s |
SCHEME
Rivers | : Basochhu + Rurichhu |
Installed capacity | : 64 MW |
Mean annual energy | : 291 MU |
Operational and Financial Performance
The Upper Stage Units of BHP were commissioned in 2002 and the Lower Stage Units in 2005. After the commissioning of the project, BHP sold energy separately to BPC and CHP at the rates prescribed by the Royal Government of Bhutan but after July 2005, CHP became as the Bulk Purchaser/Seller of electrical energy to the Western Region of Bhutan.
All the energy generated by BHP is sold within Bhutan. CHP has been the bulk buyer of BHP power since July 1, 2005.
Tariff (Nu. per kWh) | 2002-July 1, 2005 | July 1, 2005 -2008 |
Domestic | | |
Sale to CHP | 1.5 | 1.20 |
Sale to BPC | 0.5 | 0 |
Manpower
The power plants being highly automated require skills at different levels for its regular operation. The fact that a team of more than a dozen highly specialised experts commissioned the plants would mean that BHP would need such highly specialised and experienced experts at all times with a good inventory of spares to keep the plants running. Automation required that a complex system be managed. Simply locating some faults in the system is a big challenge. Repair/ replacement of faulty components are another one. The same maintenance crew is now engaged in the maintenance of two power stations. With the transfer of the 220 kV switchyard from BPC to BHP, there is another challenge of operating and maintaining a high voltage substation also.
BHP Organogram
