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Threat To Super High Head Langtang Projects By A.B. THAPA
The hydropower generation potential of the
Langtang river has been significantly enhanced by a relatively large storage reservoir
located in the upper reachesof the waterway. It can help to provide a round-the-year
uniform flow of about 15 cumecs in the middle and lower reaches. A total head of about
3,500 meters could be utilized for power generation by four hydropower stations to be
built in a cascade. Out of them, three power stations would be operating at an
exceptionally high head of about 1,000 meters or more. It also provides an opportunity to
make full use of the existing structures like the storage dam, tunnels, power houses of
the Kulekhani No-1 and No-2 hydropower plants suffering from acute shortage of water for
additional power generation. The development of the Langtang river would
allow us to generate electricity at perhaps the lowest rate in our region and also provide
drinking water to Kathmandu valley for free. Unfortunately, this valuable resource would
be lost if we do not intervene in time to save it. Excessive Trust In Private
Developers In the past decade, our power development
plans have been thrown into complete disarray by foreign developers who were virtually
given a free hand. The task of the regulatory body is nothing more than a formality. The
60 MW Khimti hydropower plant, the first project in the private sector, has opened a
Pandora's box. The project has had disastrous consequences for the Nepal Electricity
Authority (NEA). The seasonal energy procured from Khimti is completely wasted, although
the NEA is made to pay about US$ 9 million per annum. Many other developers were quick to
follow and some are already building hydropower plants. A few recently got permission to
carry out detailed study, but they are not yet ready to start construction. The Mini
Langtang Project appears to be one such project. We would have to sacrifice the super high
head Langtang Projects if it is decided to implement the Mini Langtang, because they
are virtually mutually exclusive. The Mini Langtang Project operates at a head of about
200 meters is in the lowermost reaches of the Langtang river. The water supply to the Mini
Langtang would have to be completely cut off to divert the Langtang river into the
Melamchi. So all the arrangements made with the private developer must be annulled before
it is too late to save the super high head Langtang Projects from having to wage legal
battles later on against the private developers. An attempt is made here to explain how
the Langtang river could be diverted into the Melamchi for power generation and urban
water supply in a most cost-effective way. The Langtang Power Projects The Langtang projects operating at a head
of about 1,000 meters and more could produce electricity at a very low cost. Moreover,
water in abundant quantity could be supplied to the Kathmandu Valley for free. The concept
of the Langtang project solely for power generation was developed under the United Nations
Development Program-supported Gandak Basin Master Plan study. This concept required some
revision to include a new component to supply drinking water to Kathmandu valley. It
necessitated the dropping of the regulated Langtang water at the end into the Melamchi
river instead of the Bhotekosi (Trisuli). According to the Gandak Basin Master Plan,
a 120-meter-high dam has been proposed on the Langtang Khola near Jaithang. The volume of
the reservoir would be about 180 million cubic meters. Based on the revised concept, the
water in the reservoir at a full supply level of 3,995 meters would be first tapped by the
Langtang-1 power station operating at a gross head of 950 meters. The installed capacity
of the Langtang-1 power station, located near Ghore Tabela about 15 km downstream from the
storage reservoir, would be about 70 MW. Water from the Langtang-1 power station
would be directly drawn into the Langtang-2 station. For augmenting the flow, the water
from the catchment downstream of the storage dam would also be drawn into the headrace
tunnel of the Langtang-2 station. The installed capacity of the Langtang-2 station
operating at a head of about 1300 meters would be about 150 MW. Why Langtang Power Would Be Cheap Of all the site characteristics, head is
the most important. Design guidelines approved by the American Society of Civil Engineers
in 1989 have given some simple reasoning that would help to explain why the super high
head Langtang power stations operating at many times greater head by comparison with other
hydropowers could be built at very low cost. "Very simply, if one doubles the head
the quantity of water needed to produce a certain amount of energy is halved, Thus, for
like site energy development the penstock area and reservoir volume are halved and further
large cost reductions occur for powerhouse and machinery costs. This fundamental
consideration is at the root of the large cost reductions that occur at higher
heads." A joint team of German, Japanese and US
consultants has made an interesting reference to a Canadian high head project vis-a-vis
the Upper Arun project to be operated at moderately high head. "It is worth
mentioning that the search of the worldwide inventory of the existing hydropower
installations identified only one plant with a combined head and flow magnitudes greater
than that of the Upper Arun - Kemano in British Columbia, Canada". At present the
electricity generated by the 896 MW Kemano Project with a 16.3 km long headrace tunnel
operating at 800 m head provides power for Alcan's aluminum smelters at Kitimat at a cost
below US cents 3 per KWh. Escape From Ruinous Financial
Burden People at decision-making levels, including
politicians, businessmen and all those who like to identify themselves to be knowledgeable
in the field of water resources, never tire of praising how the Melamchi water supply
project is a blessing to Kathmandu. Inhabitants of the valley, however, are unaware that
they would have to pay a monthly water bill of about Rs. 4,000 at present price levels
after the Melamchi project becomes operational - unless the government decides to open its
coffers in the form of subsidy. The Melamchi planners have completely overlooked the
paying capacity of the vast majority of Kathmandu residents who are surviving on very
small income. There is an urgent need to review the Melamchi project to spare
Kathmanduites ruinous financial burden. Fortunately, the Langtang projects can help to
avert this situation. Power To Subsidize Water Supply The way the Melamchi project has been drawn
up clearly shows that the planners were unfamiliar with the water resources potential of
the river. A Melamchi project conceived primarily as a power project linked with the
existing Kulekhani hydropower plants acutely suffering from water shortages and also with
the Langtang projects could provide Kathmandu water almost for free. A Melamchi project
exclusively for water supply is obviously very expensive. The project involves the
construction of a 28-km delivery tunnel. Besides, the tunnel size adopted is based on
construction requirement that is very big for a scant dry season flow of only about 1.5
cumec. The proposed tunnel could be used as a transit route for surplus Melamchi and
Langtang waters into the Kulekhani storage reservoir that is suffering from acute water
shortage. After the Langtang diversion, the Melamchi
tunnel could be expected to run in full capacity of about 15 cumecs throughout the year.
It would permit a 35 MW Melamchi tunnel hydropower operating at a head of about 300 meters
to generate annually about 300 GWh of energy, which is 50 percent greater the generation
of the Kulekhani No-1 and No-2 stations put together. Water Supply To Kulekhani Electricity generation from the Kulekhani
projects could be increased by five times if the combined flow of the Melamchi and the
Langtang, after setting aside adequate quantity of water for Kathmandu valley, is
delivered into the reservoir . It would be necessary to increase the capacity of the
Kulekhani power stations. An additional 300 MW power station would be needed to utilize
the 1,000 meters head between the Kulekhani storage reservoir and the tailrace of the
Kulekhani-2 near Bhainse. New Ideas Are Explored There is no denying the fact that countries
all over world are currently engaged in fierce fights not in the battlefield but in the
economic front and are trying their utmost to find new ways to gain ground against
competitors. For this purpose even developing countries like ours are providing all-out
support to encourage and promote new research in very complicated areas of science and
technology to apply the findings A Role For ICIMOD The possibility of developing the Langtang
project for generation of exceptionally cheap electricity on a scale sufficient to meet
our country's requirement for quite some time and also to supply drinking water to
Kathmandu valley for free should not remain a mystery to institutions like the National
Planning Commission, Federation of Nepalese Chambers of Commerce and Industry or the
International Center for Integrated Mountain Development (ICIMOD). Institutions like
ICIMOD are expected to act as think-tanks to reach out to member governments to sort out
exceptionally vital problems threatening the whole region, such as the Kosi flood problem.
It could also help to develop awareness of the vast potential of the Langtang river
towards boosting socio-economic development the nation. The total firm power generation of the
proposed four power stations could be about 2,500 GWh and their total capacity 550 MW. The
projects could be developed in several stages. All are very high head power stations. At
such, the unit construction cost could be only about US $ 1,000 per KW capacity if the
high dam cost is not considered. The generation cost of electricity could be slightly over
US cents 2 per KWh. Thapa is a water resources expert. |
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editor: spotligh@mos.com.np |
