Energy is beside water probably the most crucial thing people need for living and developing. Without it social development couldn’t raise as fast as seen in the past at high industrialized countries.

 

Theories like this are well known but the reality is very often different. The following article should give a small glimpse about the energy situation in Nepal also known as the roof of the world.

Within the past three years the author visited Nepal several times as member of the Austrian partner team performing an international academic exchange project supported by the Austrian development agency under the APPEAR track. Teaching, supervising and research issues played an integrative part at this project to understand the past and present energy situation – demand and supply – in this country and to develop new theses as a basis for policy makers.

Country information
Nepal, known as the roof of the world, is geographically surrounded by India from east, west and south and China in the north as seen at Figure 1. The total area of the country is 147.181 km² with a population of 26.5 million (as per 2011 national census). The country consists of three ecological zones along north to south called Mountain, Hill and Terai respectively. This classification is also valid for socio-economic, cultural and ethnic divisions of the country.

Economical and energetic background
Looking at the country development one significant parameter is the Gross Domestic Product (GDP) and its development. Analyzing the definition of GDP we realize that it bases strongly on the population and its growth rate, economic productivity and of course on energy availability as all national produced goods and services are counted. Figure 2 shows the past growth rate from 1986 till today and different scenarios for the future up to 2030.

In the past we saw a non tendentious trend which complicates the prognoses for the future. Therefore four anticipated growth scenarios have been considered by Bhattarai [2] to capture the future energy demand. The selected different growth scenarios for this purpose are business as usual (3,9% GDP growth), low (4,4%), medium (5,6%) and high economic growth (6,5%) respectively. Official sources sometimes publish even higher economic growth rates but questionable is the energy supply side for such a country development. Breaking down the energy demand into several categories of consumption we can notify that the biggest demand is still the residential sector with a share of approximately 90% of the total energy needed. This means that most of the energy is needed for heating, cocking and nowadays electricity production with gen-sets because of the power cuts up to 16 hours a day in the dry season. Transport and industrial sectors don’t play even today these roles as maybe expected (see Figure 3). The finished study based on [2] showed a remarkable situation for the country and its future development respectively industrialization.

Looking at figure 3 it gets clear that the residential sector with underlying energy consumption for cocking and heating is the biggest and most important one. Remarkable is also the share of 85% usage of solid biomass for daily life purposes. Another notable value is the 9% share of petroleum products because there are no national resources for this energy source and they have to be imported via India. By today the other sources play a lower important role. When importing fossil fuels from outside of Nepal the external trade balance as an economical parameter has to be considered in the same way like the GDP before. And here we can notice a significant change due to the people’s change in lifestyle. Since 2011 the value of imported petroleum products climbed above 100% of the total export’s earnings which means a deficit at the trade balance (see Figure 4). This gap is closed nowadays by remittances from the emigrated young Nepali abroad.

As this situation is not really sustainable for the country logical questions about energy transition and change appeared. To answer questions like this a present energy source analysis has to be done. Nepal has on the one hand no crude oil reserves but on the other hand a unique topology with high mountains and therefore enough water for a substantial hydro potential. The biggest problem up to now are accurate data sets to estimate the hydro potential and the possibility of hydropower development to fulfil the energy transition from petroleum products towards electricity produced by hydropower plants. This gap has been closed by Bajracharya [4] who performed the latest hydro potential study.

Hydro potential
Nepal is topographically divided into three major river basins which are the Koshi, Narayani and Karnali basin. The rest of the landscape contributes maybe 10% of the catchment area. Therefore the study was performed by taking these three major river basins into account. Basically we have to estimate the head drop H and river discharge Q to get the hydro potential of a given area or river section. Head drop can be calculated manually from the topographic map or automatically along the river system from Digital Elevation Model (DEM) using GIS software. Regarding the river discharge several data sets have to be taken in account and combined to fulfil the task which is in fact more difficult than the head drop estimation. Within the study the Soil and Water Assessment Tool (SWAT) hydrological model has been used by considering data from the (i) Digital Elevation Model (DEM), (ii) stream network, (iii)

land use map, (iv) soil map and (v) weather data (precipitation, temperature, solar radiation, wind velocity, relative humidity). With this methodology following Run-Off-River (ROR) potential at annual mean flow and 30% flow exceedance for the river basins have been found.

Figure 5 shows that the first impression of a hugh hydro potential was correct and confirms an old hydro potential study from the 1960s. Much more interesting is the fact that up till know only approximately 700MW have been harvested. Thus shows the really hugh hydro potential in Nepal. Correlating with the shown energy demand above it gets clear that a transition from expensive petroleum products to clean and cheap electricity out of hydropower could be done easily. This would mean that instead of using expensive LPG for cocking a change to electric stoves feed with cheap electricity from hydropower could solve the present energy situation. Additionally it would help to have smokeless food preparation with less impact to the women at home which reduces health complaints as well.

Both studies [2] and [4] performed under the APPEAR project of the institute have shown the need for transition of the energy supply side if the country development and industrialization should step forward. The government has already noticed this situation and negotiates power purchase contracts with private investors. Beside this some power stations are developed by the Nepal Electricity Authority (NEA) itself. One major problem up to day is the existing electrical grid. This lacks in construction and is the bottleneck in developing more hydropower plants than up till now.

The following part of this article should show a brief impression about hydropower plant development in Nepal and its difficulties. Even if this country seems to be an Eldorado for private investment and installation of new hydropower plants, the landscape, affordable manpower and legislation have to be considered.

Hydropower Plant site visits
In the past three years the author undertakes several trips to Nepal. Mostly occupied with teaching purposes it was still enough time to visit various Hydropower Plants to get an impression about the difficulties but also possibilities of installment at this nice country. Small as well as Large Hydropower Stations and also at different development stages have been visited. Table 1 should give an overview about the visited sites and development stages.

Site name	Type	Capacity	Development stage
Upper Tamakoshi	Run-Off River	456 MW	Under construction
Kaligandaki	Run-Off River	144 MW	In Operation
Middle Marsyangdi	Run-Off River	70 MW	In Operation
Kulekhani I and II	Storage-Type	60 MW + 32 MW	In progress
Trishuli	Run-Off River	60 MW	In Operation
Maikhola	Run-Off River	22 MW	Under construction
Kulekhani III	Storage-Type	14 MW	Under construction
Andhikhola	Run-Off River	9.4MW	Upgrading from 5.1 to 9.4 MW

Table 1. Visited Hydropower Plants during project visits

Out of table 1 some hydropower plants will be discussed to give an idea about the construction of a hydropower plant at such rural areas.

a)     Hydropower Plant UPPER TAMAKOSHI
The construction site for the Hydropower Plant Upper Tamakoshi is located northeast of Kathmandu close to the Chinese border near the village Charikot (see Figure 1). It is the biggest Hydropower station under construction in Nepal today. Key figures of this project are listed at table 2. After its completion it will be used as a daily peaking Run-of-River hydropower station with an installed capacity of 456 MW and a planned annual energy output of 2.281 GWh.

Project Type	Daily Peaking Run-of-River
Catchment Area	1745 km²
Installed Capacity	456 MW
Annual Energy	2.281 GWh
Design Discharge	66 m3/s
Gross Head	822 m
Headrace Tunnel	7.86 km
Penstock	724 m
Power House	Underground, 6 Units
Tailrace Tunnel	2.98 km
Transmission Line	220 kV double circuit, 47 km long
Project Cost	US$ 441 Mill. (Excl. IDC)
Construction Period	5.5 years

Table 2. Key figures of the Hydropower Plant “Upper Tamakoshi”

The beginning of the project can be found in the mid of the 1980s of the last century. In 1985 the project identification took place with a planned installed capacity of 113 MW. A first pre-feasibility study was done from the Austrian geologist Dr. Christian Uhlir in 1999. His main idea was to use the natural dam at the Tamakoshi River for the use of the power plant. The natural dam, which was built by landslides in former ages, is shown in Figure 6. Dr. Uhlir planned an installed capacity of 120 MW. Nevertheless, his idea was not realized. After some years, more feasibility studies were done from the NEA and Norconsult AS from the years 2001 to 2005. Finally the detailed engineering design was done by a joint venture of Norconsult AS and Lahmeyer International from 2007 to 2008. The financial arrangement for this project was finalized 2011.   

Before starting with the construction site some 68 km of road access to this rural area has to build. Only the construction of this site supporting road lasted about 5 years from 2006 till 2011. Within this time the financial arrangement was done. Figure 7 gives an impression about the problematic of road construction at this country.

In Figure 8 the layout of the Upper Tamakoshi hydropower project is depicted. Starting from the dam, a headrace tunnel with a length of 7.86 km connects the reservoir with the penstock (which is built as a vertical shaft), the surge shaft and the powerhouse, where 6 units of Pelton turbines are located in an underground cavern.

Figure 9 gives an impression of constructing the headrace tunnel without tunnel boring machine (TBM) just made by drilling and blasting and Figure 10 shows the drilling of the vertical shaft for the penstock afterwards.

Upper Tamakoshi is one of the biggest hydropower plants up till now and will supply enough electricity to the electrical grid to reduce power cuts to zero within June and September. This time period of the year is also known as the rainy season which means a lot of heavy rainfalls due to the monsoon and therefore high sediment loads at the river. How these sediments affect the turbine runners will be shown at the next hydropower station.

b)     Hydropower Plant MIDDLE MARSYANGDI
The Run-of-River hydropower plant Middle Marsyangdi has an installed capacity of 70 MW. Two units of Francis turbines were put into operation in 2008. Additional key figures of the project are listed in Table 3.

Project Type	Daily Peaking Run-of-River
Installed Capacity	70 MW
Annual Energy	398 GWh
Design Discharge	80 m3/s
Gross Head	120 m
Headrace Tunnel	5.14 km
Penstock	470 m
Power House	Underground, 2 Units
Transmission Line	220 kV double circuit
Project Cost	US$ 173 Mill. (Excl. IDC)
Construction Period	6 years

Table 3. Key figures of the Hydropower Plant “Middle Marsyangdi”

During the wet season in Nepal (approx. from June to August) problems occur due to heavy sediment erosion. In Figure 11 a Francis runner of Middle Marsyangdi is depicted. The runner was used during two monsoon seasons. The sediments from the Himalayan region caused serious damages on the inlet of the turbine. This fact is a challenging future task for the hydropower station Middle Marsyangdi and as well as for other hydropower plants in Nepal which are in a Himalayan catchment area.

c)     Hydropower Plant ANDHIKHOLA
An interesting upgrading project in Nepal is done at the Andhikhola hydropower station. The plant was built in 1991 with an installed capacity of 5.1 MW. With the upgrading, the capacity will be increased up to 9.4 MW. The key figures of this project are listed in Tab. 4.

Project Type	Run-of-River
Installed Capacity	9.4 MW
Annual Energy	68.38 GWh
Design Discharge	2.7 m3/s
Gross Head	248.8 m
Power House, Turbine Unit	3 Units

Table 4. Key figures of the Hydropower Plant “Andhikhola”

At the Andhikhola project water from the Andhikhola River is channeled into the Kaliganddaki River as shown in Figure 13. In the middle of the headrace and tailrace tunnel, the power house with 3 Pelton units is located. Because of the fact that the mountains in this region consists of soft rock (see Figure 14) the dropshaft has to be built vertically with a length of 234 m.

In this shaft, the two penstocks are located, an old existing one and a new one which was built to increase the capacity of the power plant. It´s a very unique fact, that this tunnel represents the only access tunnel to the powerhouse. All material, electromechanical equipment and as well workers has to be moved through this vertical tunnel by a crane platform (see Figure 14, right).

For the upgrading process from 5.1 to 9.4 MW, modifications at the dam structure, settlement basin, powerhouse cavern and headrace tunnel have to be done for example. The actual status (May 2014) of the construction progress of the dam structure and powerhouse is shown in Figure 15. For upgrading the electromechanical equipment, the cavern was enlarged. All the excavated material was removed through the 1087 m long tailrace tunnel. This tailrace tunnel was widened during the upgrading process. Due to the weak rock conditions, the walls began to deform at some positions in the tunnel (see Figure 14). A lot of effort to support these weak points by using steel profiles has to be done.

Conclusion
Performing this international university linking project we learned a lot of hydropower development in foreign countries. Nepal has a hugh hydropower potential and the need to explore it. Welfare and healthcare could be increased if a transition from expensive petroleum products towards sustainable hydropower will be performed. The potential is there, it is just to raise it. The author would like to thank all project members for their contribution throughout the entire project and wishes Nepal a successful energy transition towards a better future for the country.

The presented article gives a small glimpse of the experienced visits. Experience and information exchange are appreciated.

 

by Ass.Prof. Dipl.-Ing. Dr.techn. Eduard DOUJAK / Institute für Energy Systems andThermodynamics / Vienna University of Technology