Issuu on Google+

Csaba Zagoni REBE CAT 0941436 - Module 3. Assessment (2009)

Pico-hydro hardware solutions in rural Nepal Csaba Zagoni Centre for Alternative Technology REBE 24 December 2009

1. Introduction In the present context, 42 GW of Nepal’s hydropower potential is known to be economically viable out of the 83 GW theoretical potential (Ghimire, 2008), however, in 2008 the total installed capacity was only 611 MW of which 148 MW came from the private sector (Shestra, 2008). Depending on scale, the technology can cause serious negative environmental effects, and have GHG emissions comparable to a fossil-fuel plant (Giles, 2006). Nevertheless, carefully designed small-scale hydropower plants have little negative environmental impact, therefore they have the potential of delivering clean energy to the communities of the ecologically sensitive Himalaya region (Rijal, 2000.) According to the assessment carried out by the World Bank (2006), in areas where gridextensions are unlikely in the near future, off-grid pico-hydro schemes with output of less than 5kW (Pokharel, 2006), have the prospects to be 3-5 times more cost-effective than other electricity generation technologies including solar PV, wind, and diesel-generators (fig. 1, p. 1). (World Bank, 2006.) This paper aims to identify the power-demand of rural communities in highland Nepal and discuss the potential of pico-hydro schemes in meeting this demand. Four different locally manufactured, standardized pico-hydro packages are compared, the upgrading of traditional water mills is studied and financial issues are considered.

Figure 1. Predicted cost for off-grid electricity (Source: Williams et al., 2009)

2. Power demand of rural communities page 1 of 8


Csaba Zagoni REBE CAT 0941436 - Module 3. Assessment (2009)

Domestic lighting is the first and basic power demand of rural communities. In high-elevation areas of Nepal, lighting at night is produced by burning pine resin, which creates an unhealthy, smoky indoor environment and contributes to deforestation (Zahnd et al., 2007). By electrifying domestic lighting, a pico-hydro power plant can reduce fossil-fuel usage, and thus cut down CO2 emissions, lower the number of house-fires, improve indoor air-quality and extend working/ studying hours per day (Williams, 2007). Combining current WLED technology with pico-hydro power generation is a cost-effective and highly-efficient solution for meeting domestic lighting needs. Two 1W WLED light per household provides better quality lighting than currently used traditional methods (Bhusal et al., 2007), which means that a generator can supply 500 households per kW. By providing energy for lighting only, the load-factor of a hydropower plant rarely exceeds 10% (Paish, 2002) and it used to be general practice to utilize an air-heater as a ballast load. To reduce the amount of energy wasted, newer plants are designed to heat water in an insulated tank to promote both maintaining personal hygiene and supply warm/hot water for cooking purposes thus lowering firewood consumption (Zahnd et al. 2007). For a project to become economically viable, it is necessary that the plant has a high loadfactor, and if possible, part of the power generated is used directly for income generating activities (Paish, 2002). In rural areas grain grinding, rice hulling, oil expelling and saw milling are the basic power-intensive tasks of agricultural and industrial production, therefore the most cost-effective use of hydropower is driving mechanical machinery in addition to meeting the community’s electricity needs (UNDP, 2009). Different choices of end-uses benefit those members of the communities as well, who cannot be connected to the electricity supply because of financial reasons or location (Khennas et al., 2000).

3. Standardized pico-hydro packages As small scale hydropower is a well-established, mature technology, the main challenge of the design process of a rural site in a developing country is to realize a project that is addressing the needs of the community, that is affordable to build and operate, has minimal environmental impact and that is able to co-operate with local communities in successfully managing the scheme in the long-run. (Mahat, 2004.) Although each and every site is unique, in order to maintain a low-cost approach, using locally manufactured standardized equipment has great potential, with great care to be taken not to compromise technical quality. (Williams et al., 2009.) High-head, low-flow schemes are the most common among recently installed pico-hydro projects (PEEDA, 2009). The Peltric Set is a Nepalese-made standardized pico-hydro package consisting of a small vertical shaft pelton turbine coupled with an induction generator. This simple, robust, lightweight and low-cost package has proved to be reliable and it is being manufactured at a rate of 100 per annum. (CRT/N, 2005.) The design of the Pico Power Pack (fig. 2, p. 3) is based on the successful Peltric Set with a different horizontal arrangement to increase ease of inspection and maintenance. The typical required flow is between 3 to 15 l/s and the range of head is 25-100 m. In addition to the mains AC output, it includes a free shaft which can be used to drive mechanical loads. (Maher, 1999.) Many communities don’t have suitable sites for peltric-type high-head turbines, however they might have low-head, high-flow rivers or irrigation channels nearby (PEEDA, 2009). At the present, low-head pico-hydro schemes are uncommon in Nepal, however, recent research has been focusing on the development of affordable packages for these sites (Williams et al., 2009). Nepal Hydro Electric (NHE) has recently developed a pico-hydro package based on a 73% efficient volute cased propeller turbine which requires a head of 3.3 m (PEEDA, 2009).

page 2 of 8


Csaba Zagoni REBE CAT 0941436 - Module 3. Assessment (2009)

Figure 2. The Pico Power Pack generates AC electricity and allows mechanical equipment to be driven. (Source: Maher, 1999)

Kathmandu Metal Industry has developed a pico-sized crossflow turbine package of 100W 5kW power named the KMI Crossric, with the operating ranges of 5 - 20 m head and 5 - 50 l/s flow (PEEDA, 2009). All of the modern pico-hydro packages are connected to an electronic load controller (ELC), which regulates the voltage and the frequency of the electricity supplied. Any extra power generated on top of the actual demand is directed to a correctly-sized ballast load, in most cases to a water heater (Smith et al., 2000). The ELC makes it possible to use mechanical power and generate electricity at the same time. If the mechanical load takes all the available power at the shaft, the generator runs slower than it is necessary for excitation. As the mechanical load is reduced, the shaft spins faster and when the minimal speed for excitation is exceeded, the generator starts producing electric power and any excess power is routed to the ballast load. In this state, the generator acts as an electrical brake, preventing overspeeding by self-regulation. This is highly beneficial in the case when the mechanical load is inconsistent such as milling and sawing as it improves performance and life span. (Maher, 1999.)

4. Improved Water Mills

Figure 3. Comparison of a Traditional Water Mill and an Improved Water Mill (Source: CRT/N, 2009)

There are more than 25000 indigenous watermills (“gharats”) in Nepal, harnessing the energy of mountain streams for grinding grains (Shrestha, 2007). These “gharats” are made of local materials with low capital cost, they have very low running costs and are easy to maintain. They are usually located close to the village, on the bank of a perennial stream, with a diversion channel providing 3-6 m head. They consist of a wooden chute, wooden vertical-axis runner, page 3 of 8


Csaba Zagoni REBE CAT 0941436 - Module 3. Assessment (2009)

wooden shaft and two grinding stones. The typical mechanical power produced is 0.5-1.5 kW with an efficiency of 15-25% and they grind 5-10 kg of grain per hour. (Sharma et al., 2008.) In cases, where adequate flow and head of water is available to produce a minimum of 5 kW power at the shaft, the traditional “gharat” can be modified to provide mechanical power at an improved efficiency and generate electricity. Figure 3. (p. 3) shows the comparison of a traditional water mill and an improved water mill. The main improvements are replacement of the wooden runner with a metal runner with buckets (or a one-piece casting steel cross-flow turbine), and using a long steel shaft with ball bearings. This allows for driving the generator as well as other mechanical equipment for different end-uses. The wooden chute is replaced with HDPE pipe and a spear valve is fitted. (Sharma et al., 2008.) The benefits of improved efficiency (typically 30-40%) results in higher grinding output (20-30 kg/h) and operation at lower flow rates thus extending the milling season into the drier seasons (Shrestha, 2007).

5. Comparison The following discussion is based on data gathered from the following sources: Shakya (2007), AEPC (2009), CRT/N (2005), Maher (1999), PEEDA (2009), Sharma et al. (2008) and Zahnd et al. (2009).

Figure 4. Different options to meet rural energy needs (Costs in Nepalese Rupees). (Source: Shakya, 2007)

Figure 4. (p. 4) shows different options to meet rural energy needs. Subsidies are calculated on a per household basis, although the total subsidy cannot exceed the amount set by the ‘subsidy per kW’ value (AEPC, 2009). In cases when the extension of the national grid is unlikely during the payback period of the renewable energy project, these schemes can prove to be a cost-effective way of improving the lives of rural communities. Solar PV systems can provide electricity for single households, but although it has the highest rate of subsidy among RE technologies it is usually unfeasible on community level due to its high capital cost. The cost/kW value of a new micro-hydro plant and a new pico-hydro plant after deducting the maximum available subsidy is 115000 NPR/kW, while it is 110000 NPR/kW in case of an improved water mill. The main difference is that on top of electricity generation, in the case of a new hydro plant, this cost covers only an option to couple mechanical machinery to the shaft, whereas in case of an IWM, the cost includes an improved working mill plus the option of different mechanical enduses.

page 4 of 8


Csaba Zagoni REBE CAT 0941436 - Module 3. Assessment (2009) Figure 5. Comparison of pico-hydro packages and the Improved Water Mill. (Sources: (1) CRT/N, 2005. (2) Maher, 1999. (3) PEEDA, 2009. (4) Sharma et al., 2008)

Figure 5. (p. 4) compares different pico-hydro packages and the IMW. In case of a high-head site, the Peltric Set and the Pico Power Pack are the two options, the former being more widespread, while the latter has the possibility of different mechanical end-uses. When a low-head high-flow watersource is available, there are multiple options to be considered based on the needs of the community and the location of the appropriate site of the proposed plant and/or existing water mills. If a traditional water mill exists 3 miles away from the community, and an irrigation channel is running much closer, it might be a better option to install a new KMI Crosstric close to the centre of the community. On one hand, this would save on transmission losses and allow for future upgrades of the plant for other mechanical end-uses without the drawback of difficult material transportation. On the other hand, capital costs would be higher, and the water mill would continue to operate with a low efficiency. In case a traditional water mill exists near the centre of the community, improvement and electrification of the mill would result in lower capital costs and the mill operating at a higher efficiency as opposed to setting up a new hydro plant.

Figure 6. Economic features of water mill improvements for different end-uses in Nepalese Rupees. (Source: CRT/N, 2009)

Figure 6. (p. 5) shows the economic features of different mill improvements for different enduses. The difference between the annual net income of a grinding and hulling IWM with and without electrification is really small compared to the great differences in net investment. This explains that the payback period for an IWM with electrification is roughly twice as long as for one with mechanical end-uses only. The government subsidy seems to be trying to address this issue, however the high capital cost makes this option quite unattractive for communities or local businesses. Alternative financing solutions need to be sought for, to promote and make rural electrification economically more attractive, as it has invaluable benefits in sustainable rural development (Zahnd et al., 2009).

page 5 of 8


Csaba Zagoni REBE CAT 0941436 - Module 3. Assessment (2009)

6. Conclusion Nepal has a massive untapped potential of hydro-power generation. In rural mountaneous areas where grid extension is unlikely in the near future, pico-hydro projects have the potential to meet then energy-need of small communities in a cost-effective way. Domestic indoor lighting is the basic power demand of communities without electricity. Picohydro schemes have the potential to provide clean indoor lighting, thus creating a healthier living environment, preventing house fires and increasing working/studying hours per day. The environmental benefits are lowered CO2 emissions by reducing fossil fuel usage and decreased rate of deforestation. Aiming for sustainable development, part of the power generated can be used directly for income generating activities through mechanical end-uses such as grain grinding, oil expelling and saw milling. To reduce costs and make schemes financially viable, locally manufactured standardized equipment packages can be used, or traditional water mills can be upgraded. When deciding between a new-built plant or an upgrade of an existing water mill, site specific choices have to consider local demand of electrical/mechanical power, distance of plant from community centre and economic issues. Government subsidies exist to make pico-hydro schemes more economically attractive, although alternative financing solutions need to be found to further support rural electrification as a means of sustainable development.

5.2. Limitations of the essay • pricing and technical specification of pico-hydro packages are difficult or impossible to obtain online • many manufacturer websites are offline, out-of-date or they lack important data • it is hard to compare pico-hydro package costs only (purchase, transport and installation) as most data found are of entire projects • the four pico-hydro packages discussed are only the main options of the many available different alternatives • the wide range of the power produced by existing water mills makes the comparison with new-built pico-hydro plants difficult

5.3. Implications for existing orthodoxy • hydro-power in general has a bad reputation for its environmental impacts • rural electrification is not an end but a means of sustainable development • government subsidies try to address the problem of high initial investment of pico-hydro projects, however in many cases they are still not financially attractive • changes in cultural patterns are generally slower than advancement of technology • improvements of existing water mills might cause social friction as some natives might want to stick to their traditions

5.4. Future research • obtaining detailed technical specification and pricing by contacting individual manufacturers • comparison of transportation costs considering hardware weight and size • comparison of skills needed for operation and maintenance of pico-hydro packages and level of training required • gathering feedback from locals to further improve the IWM concept • identifying further demand of already electrified communities to develop advanced electric load management for pico-hydro solutions (supply of schools, social buildings, uninterrupted supply of medical institutions)

page 6 of 8


Csaba Zagoni REBE CAT 0941436 - Module 3. Assessment (2009)

7. References AEPC, 2009. Subsidy policy for MHP projects in Nepal. Alternative Energy Promotion Centre. Available from: http://www.aepc.gov.np (Accessed on 24th December 2009) BHUSAL, P., ZAHND, A., ELOHOLMA, M., HALONEN. L., 2007. Energy-efficient innovative lighting and energy supply solutions in developing countries. International Review of Electrical Engineering (I.R.E.E.), 2 (5), pp. 665-670. CHALISE, S.R., KANSAKAR, S.R., REES, G., CROKER, K., ZAIDMAN, M., 2003. Management of water resources and low flow estimation for the Himalayan basins of Nepal. Journal of Hydrology. 282. pp. 25-35. CRT/N, 2009. RE Practices in Nepal – Micro Hydro Technology Improved Water Mill (IWM), Nepal. Available from: http://www.crtnepal.org (Accessed on 24th December 2009) CRT/N, 2005. Manual on micro-hydro development. Available from: www.inforse.org/asia/pdf/ Nepal_Micro_Hydro_Manual.pdf (Accessed on 24th December 2009) GHIMIRE, H.K., 2008. Harnessing of Mini Scale Hydropower for Rural Electrification in Nepal. Available from: http://www.nepjol.info/index.php/HN/article/viewFile/1165/1178 (Accessed on 24th December 2009) GILES, J., 2006. Methane quashes green credentials of hydropower. Nature. 444, pp. 524–525. ICIMOD, 2009. Climate change in the Himalayas. International Centre for Integrated Mountain Development, Information sheet 03/09. Available from: http://books.icimod.org/uploads/tmp/icimodclimate_change_in_the_himalayas.pdf (Accessed on 24th December 2009) KHENNAS, S., BARNETT, A., 2000. Best practices for sustainable development of micro hydro power in developing countries. ESMAP Technical Paper 006, IBRD, World Bank. MAHAT, I., 2004. Implementation of alternative energy technologies in Nepal: towards the achievement of sustainable livelihoods. Energy for Sustainable Development. 8 (2), pp. 9-16. MAHER, P., SMITH, N., 1999. The Pico Power Pack: a new design for pico-hydro. Pico Hydro. 10. pp. 7-8. PAISH, O., 2002. Small hydro power: technology and current status. Renewable and Sustainable Energy Reviews. 6. pp. 537-556. PEEDA, 2009. Low-head pico-hydro promotion project, Nepal. Available from: http:// www.peeda.net/ (Accessed on 24th December 2009) POKHAREL, G. R., 2006. Plans and policies for RE development. Available from: http://www.sarienergy.org/PageFiles/What_We_Do/activities/Renewable_Energy_April_2008/Nepal_Pokharel.pdf (Accessed on 24th December 2009) RIJAL, K., 2000. Mini and micro hydro power development: status, issues and strategies for the Hindu Kush Himalayan Region. NESS Journal of Engineering. 9. SHAKYA, B., 2007. Improved Water Mill - Appropriate source of energy for rural people. Centre for Rural Technology Nepal. Available from: http://www.iim.uni-flensburg.de/sesam/upload/ Asiana_Alumni/21._IWM_appropriate_source_of_energy_for__rural_people-Bhupendra.pdf (Accessed on 24th December 2009) SHARMA, R. C., BISHT, Y., SHARMA, R., SINGH, D., 2008. Gharats (watermills): Indigenous device for sustainable development of renewable hydro-energy in Uttrakhand Himalayas. Renewable Energy. 33. pp. 2199-2206. page 7 of 8


Csaba Zagoni REBE CAT 0941436 - Module 3. Assessment (2009)

SHRESTHA, R. M., 2008. Hydropower development in Nepal: Issues, opportunities and challenges. 3rd NRN Regional Conference, 24-25 May 2008, Bangkok, Thailand SHRESTHA, L., 2007. Upgraded water mills improve livelihoods in the Himalayan villages of Nepal. Centre for Rural Technology Nepal. Available from: http://www.ashdenawards.org/files/ reports/CRT_Nepal_2007_Technical_report_.pdf (Accessed on 24th December 2009) SMITH, N., RANJITKAR, G., 2000. Nepal case study - part one (Installation and performance of the Pico Power Pack). Pico Hydro. 4. pp. 2-4. UNDP, 2009. Expanding energy access in developing countries: The role of mechanical power. Practical Action. ISBN 978 1 85339 704 2 WILLIAMS, A., 2007. Pico-hydro for cost-effective lighting. Boiling Point. 53. pp. 14-16. WILLIAMS, A. A., SIMPSON, R., 2009. Pico-hydro - reducing technical risks for rural electrification. Renewable Energy. 34. pp. 1986-1991. WORLD BANK, 2006. Technical and economic assessment of off-grid, mini-grid and grid electrification technologies – summary report. World Bank Energy Unit; WWF, 2005. An overview of glaciers, glacier retreat and subsequent impacts in Nepal, India and China. WWF Nepal. Available from: http://assets.panda.org/downloads/ himalayaglaciersreport2005.pdf (Accessed on 24th December 2009) ZAHND, A. AND KIMBER, H.M., 2009. Benefits from a renewable energy village electrification system. Renewable Energy. 34 (2), pp. 362–368. ZAHND, A. AND McKAY, K., 2007. Pico-hydro Power Plant for elementary lighting as Part of a Holistic Community Development Project in a remote and impoverished Himalayan Village in Nepal. RIDS - Nepal.

page 8 of 8


Pico-hydro hardware solutions in rural Nepal