People in our country  would  not have had to go through the present sufferings  from  the horrifying  load-shedding situation had our planners and policy-makers  cared  to pay due attention to techno-economic aspects  in course of planning  hydropower projects in recent years.   It is still possible to improve substantially the present electric power shortage situation within  relatively a  very short period perhaps at less than half the investment earmarked  by the government for the  generation  of electric energy  in  near future if  our  power development plans  are  adequately rationalized  based on  sound  engineering practices.


Understanding of Energy Economics

Our electricity planners do not appear to take cognizance of the fact  that  the electricity  price   (as well as generation cost)  varies not only with the seasons but it also widely varies  even  within a very short period of just one day.  The cost  of  generation of  electricity for the supply of peaking demand in the evening  hours can  be usually about three times  more expensive than that of  the off-peak  hours.  For  example,  the 10,800 MW Karnali Chisapani hydropower would be generating annually 20,800 GWhr  firm peaking energy  whereas  the   much smaller 2,500 MW capacity   alternative Karnali Chisapani hydropower could also have generated  annually the same amount of 20,800 GWhr firm energy at almost one third the investment of the former if the latter  was  to be dedicated to  meet  the demand for the base load instead of peaking.   The wide difference in value of energies used for peaking and base load is  the prime  cause  that serves as the basis for the feasibility of pump storage projects, which are built at enormous investment to  obtain one unit electricity for peaking purpose by  spending  two units of electricity generated during the off-peak hours.


Worsening Power Shortage Crisis

At present our country is reeling from  acute   shortage of electric power. Most of our industries are  on the verge of collapse. People are facing great hardship due to  long hours  of  load -shedding.  We are now pushed to an extreme desperate situation. It  has even started to cross the mind of  some of our decision makers that the introduction of diesel power plants on a gigantic scale is the only solution to end the  present power shortage crisis.  Our planners must bear in mind that diesel power stations might be feasible to supply power to meet the  requirements  for extremely short duration peaking demand  but under no circumstances it would be feasible to meet the demand for base load at a time when the price of petroleum  products are skyrocketing.


Nature of Load-shedding

At present during  the wet season months  quite limited areas are affected by load-shedding lasting  only for a very short period in the evening. Even such limited disruption in supply of power might have been  to a  certain  extent the result of transmission lines congestion  coupled  with the NEA’s power purchase agreements biased in the IPP’s favour.  One of the executives of the NEA Keshav Upadhyay  has painfully written in  the NEA  Bulletin dated Falgun 2067 touching on the subject of power tariff    “…energy rate of the NEA plants would have further lowered but for stiff conditions in power purchase agreements like  take or pay  which forces the system operator to shut down NEA owned run-off-river plants…”.  


It is predicted that during the coming dry months the load-shedding is going  to  exceed  16 hours a day from the present 11 hours.  Even now,  the midnight hours when the electricity demand is the lowest are not excluded from load-shedding. It is  quite obvious  that the NEA is now facing acute shortage of base load energy  which could have been  produced at exceptionally low cost within a very short period. Seasonal  energy produced on a massive scale during few monsoon months  could not  be substitute for the firm energy  needed to meet the  ever increasing  unfulfilled  demand for base load during the dry seasons.


Seasonal Energy is Worthless

In the context of Nepal the seasonal energy is now worth nothing.  At present there is not any demand for seasonal energy inside Nepal. The export  of such short duration seasonal energy might not be feasible because  its value  could be only equivalent to saving in costs of the  fuels in Indian thermal plants as a result of substitution to electricity imported from Nepal. According to the World Bank financed Karnali Project report  the value of such exported seasonal energy  could be  equal to only 10% of the value of the firm energy. Contrary to very low valuation of the seasonal energy,  the cost of the transmission  specially provided  to export seasonal energy could be as high as  20% of the value of the firm energy.


Storage Projects Not Suited

Large storage projects like the Budhi-Gandaki project and West  Seti project would not be suited to resolve quickly the present power shortage crisis because it would  take quite a long time to make arrangement to recover irrigation benefits accruing  to downstream region.  The irrigation  benefits are found to be far exceeding the power benefit.  For example, according to the detailed feasibility report of the Kankai Storage Dam Project carried out by the German Government in 1978 the annual irrigation benefit was found to be US Dollars 31.4 million whereas the power benefit was only US Dollars 7.2 million.


Gross Misuse of Existing Hydropower Projects

All the NEA owned hydropower projects,  like the Kali-Gandaki, both Trisuli, both Marshyangdi, both Kulekhani and others are  capable  to run at full capacity even during the dry season periods.  They  have  been built at enormous cost to supply electricity to meet the demand for peaking. Obviously,  the generation cost of such peaking energy is always very high. Unfortunately at present the full capacity  of these hydropower projects built  to generate high  valued  peaking  energy has  not been fully utilized during the critically important dry season periods.  They are now  operated to  produce   a  very large  proportion  of cheap energy to meet  the demand for base load.   Thus,  the  reservoirs, high barrages, turbines, generators, transmission lines and civil structures provided  to generate and transmit peaking energy have not been utilized to the full extent. It is one of the reasons why the generation cost of the NEA produced electricity  is high. 


Horrific Plan

The generation cost of the peaking energy,  as  explained above,  is about two to three  times more expensive than that of the energy supplied to meet the demand for  base load.   A  fifty percent proportion of the base load and the peak load capacities of the power stations operating in a power grid  is normally considered to be optimum mix. It implies in our case that the overall firm generating capacity of our power grid should have already grown very high on top of the existing 450 MW firm capacity ( 400 MW peaking capacity  and  50 MW base load capacity)  in order to effectively use the additional peaking capacity of the NEA proposed 456 MW Upper Tama-Kosi project.   Thus, it would be too uneconomic under present circumstances  to implement  a hydropower project suitable to produce excessively large peaking power such as the 456 MW Upper Tama-Kosi project.


We are at present grossly underutilizing the capacity of the existing hydropower plants  and at the same time we are  preparing to implement  at huge cost  excessively  large  new hydropower projects  that are not  feasible  to meet  the required type of demand  for electricity supply in immediate  future.  As a result, the generation cost of the electricity would   be sharply increased  in future,  and it would also take a very long time to implement  the project  earmarked  to  provide quick relief from the worsening power shortage crisis.


Mini Upper Tama-Kosi Project

For quick relief from  the present power shortage crisis   relatively  a much  smaller  alternative of the NEA proposed 456 MW Upper Tama-Kosi Project would be best suited for implementation in near future. The proposed alternative to NEA’s 456 MW project  would involve  far   less risk of damages to structures at the time of glacier lakes outburst floods (GLOF). Similarly, the possibility of substantial drop in generation of electricity  resulting  from  the seepage  of water through the highly porous floor of the reservoir particularly in dry seasons ,  when the demand for electricity is the highest, would be almost totally avoided.


Considering  the nature of the present demand for electricity in our country and also the vulnerability of main project structures,  the installed capacity of the Upper Tama-Kosi Project must be limited to just over 100 MW. Even after such drastic reduction in installed capacity  the total generation of electric energy during the dry season period would still be equal or even exceeding the generation by the NEA proposed 456 MW project  despite the fact that the cost of such mini- project would be only about one third.  As the demand for peaking energy grows in future  the installed capacity could be raised with ease by providing additional structures if it     is  found  after some years of operation  that the GLOF and the geology of reservoir site  would not pose serious threat to the safety of the project.


Danger of  GLOF

There are several rapidly growing glacier lakes near the project site in Tibet.  The great  risk of glacier lakes outburst floods (GLOF) to high gated barrage  and other structures of the NEA proposed Upper Tama-Kosi project  should not be underestimated. We already have a bitter experience of the 1984 Digcho GLOF  when the Namche hydropower built on the upper reach of the Dudh-Kosi river was completely washed away.


The reconstruction cost could be too much if the barrage and intake structure of the NEA proposed Upper Tama-Kosi project would be seriously damaged by big GLOF. Power supply would be suspended for a very long time which would have terrible consequences for the economy of entire country.


The Mini Upper Tama-Kosi project would be  having only ungated   weir across the river.  The GLOF would cause only limited damage to the weir.  The damage could be repaired within a short period  at a relatively  small cost.


Seepage through Reservoir floor

It is reported that the flat reach of the  Tama-Kosi  river serving as the floor of the reservoir of the NEA proposed  hydropower  project  is made of 300 meters high fill materials over the original  river bed.  The fill materials had accumulated after the landside dammed the river.
There is a great possibility of excessively large seepage  of water from the reservoir.  As a result of such seepage, there can be significant reduction in electricity  generation in dry season. 


The mini Upper Tama-kosi project would not require the provision of a reservoir.  The question of energy losses resulting from the seepage  through the floor of the reservoir does not arise.


In Conclusion


Nepal does not need  to go  for  large storage projects to generate   enough  firm energy needed to meet  our demand for base load  for coming many years.  There are  many  suitable  identified run-of- river type projects in the mid hill regions.


The Mini Upper Tama-Kosi  hydropower would  be  relatively a very small project which could  be  implemented   within a   short period  to provide quick relief from the present severe  load-shedding. The generated electricity would be very cheap and thus it might not be necessary to raise significantly the electricity tariff within the coming few years.


There would not be much hitches in implementing initially the proposed  mini project as first stage of the large 456 MW Upper Tama-Kosi project.


Dr. Thapa is a water resources expert and former member secretary of Water and Energy Commission.