Pico-Hydro – Viet Nam

November 2004

Indigenous communities in rural Viet Nam, such as the Muong, often lack any form of power generation. This provides them with little opportunity to undertake practical and income-generating activities after nightfall. Recently, however, the Muong have adopted a form of hydropower, known as pico-hydro – the smallest scale of hydropower system. The kinetic power of moving water is transformed into electrical power by a turbine and generator. This gives the community valuable light in the evening and the ability to explore new technological avenues.

Access to Services

Around the world, 900 million people live in absolute poverty in rural areas, depending on the consumption and sale of natural products for much of their livelihoods. The Viet Nam Living Standard Survey, conducted in 1992-3, revealed that half the country’s population lived in poverty, rising to 90 per cent in rural areas. Many rural communities lack access to basic technologies that have been available for centuries. These technologies have been unable to meet the needs of the rural poor due to a combination of social, political, technological, institutional, cultural and economic factors. Yet, since the introduction of the doi moi (renovation) policy in 1986, the Vietnamese government’s long-term economic objective has been to industrialise and modernise, so as to move Viet Nam from an agriculturally-based economy towards a newly industrialised economy. While aiming for high annual GDP growth rates, the government has attempted to strike a balance between economic and social development, with special attention to hunger eradication and poverty reduction.

However, this is not an easy task, and a number of problems have resulted from the reform process. Particularly prevalent is the growing disparity between rural and urban areas, with the prosperity and growth of urban areas not reproduced in the agriculturally dependent rural areas. To address this problem, the United Nations launched an assistance strategy which focused on four main areas:

  • Governance – promoting socio-economic management.
  • Environment – re-afforestation; biodiversity management; renewable energy.
  • Basic human needs – clean water and sanitation; access to energy sources.
  • Rural development – area development; people’s participation.
Households in Viet Nam with access to electricity in 1994 %
Total 62
Urban 92
Rural 54

Despite this commitment to rural development, the gap between urban and rural areas continues to increase. It is not only a gap in wealth that is of concern; access to basic services is also a major issue for rural communities. As the table indicates, only just over half the rural areas in Viet Nam have access to electricity. The trend to privatise basic services has also increased costs for many poor people, and small-scale providers tend to be under-resourced and expensive. The impact on the lives of women and children in particular – on their time, energy and health – is huge. To help resolve this situation, small-scale hydropower schemes have been established in Viet Nam, using low head pico-turbines. These are either manufactured in Viet Nam or imported from China. Locally manufactured units have the advantage of being easier to repair, and a more competitive in price, once the shipping costs and import taxes associated with the Chinese units have been taken into account. Indigenous communities such as the Muong, are able to tap into the benefits of pico-hydro.

The Muong

The Muong are one of the largest ethnic minorities in the Indochina region, as well as the second largest ethnic group in Viet Nam. They inhabit the mountainous slopes of north central Viet Nam, from the lower reaches of the Da River to the upper reaches of the Ma River. The Muong speak a Mon-Khmer language that is closely related to Vietnamese. While the forefathers of the Viet peoples migrated down to the plains and became influenced by the Chinese, the Muong’s ancestors stayed in the mountains, preserving their culture. The Vietnamese government has initiated policies to assimilate the Muong into the mainstream structure of the nation.

Muong villages generally consist of 10 to 50 households living in houses that are raised about 2 metres off the ground on wooden stilts. They are usually situated on plateaus, or near water at higher altitudes (over 750 metres). Most of the Muong do not live near any major lines of communication.

The Appeal of Pico-Hydro

Pico-hydro is hydropower with a maximum electrical output of 5 kilowatts (kW), sufficient to power light bulbs, radios, televisions, refrigerators and food processors. Hydropower systems of this size benefit over the larger systems in terms of cost and simplicity of design. Recent innovations in pico-hydro technology have made it an economic and versatile source of power even in some of the world’s most resource-poor and inaccessible places. Standard AC electricity can be produced and distributed throughout a village to power electrical appliances, or it can charge large batteries for households.

The market for pico-hydro systems has now become substantial among small communities, who are attracted to pico-hydro for the following reasons:

  • © Zul/ITDG
    © Zul/ITDG

    Small communities are often without electricity even in countries with extensive grid electrification. Despite high demand for electrification, grid connection for small communities remains unattractive to commercial providers due to their relatively low power consumption.

  • Only small water flows are required for pico-hydro systems, meaning that many suitable sites are likely to exist. A small stream or spring often provides enough water.
  • Pico-hydro equipment is small and compact. The component parts can be easily transported into remote and inaccessible regions.
  • Local manufacture is possible, and the design principles and fabrication processes can be easily learned. This can keep some equipment costs in proportion to local wages.
  • The number of houses connected to each scheme is small, usually under 100 households. This eases maintenance and reduces capital requirements.
  • Well-designed pico-hydro systems have a lower cost per kW than solar or wind power.

How it Works

green-current-picohydro2The water source is usually a stream or an irrigation canal, which must be reliable and not required for another use. Springs are excellent sources as they can often be depended on, even in dry weather. The water is fed into the ‘forebay tank’ (A), which can be enlarged to form a small reservoir for use during dry periods. The water flows from the forebay tank down a pipe known as the ‘penstock’ (B). At the end of the penstock, the water is fed through a flow-shaping nozzle (C), which creates a high-pressure jet. The greater the drop from the forebay tank to the nozzle (A to C), the lower the volume of water required to produce sufficient power. Local topology, environment, materials and budget dictate the ability to affect this. The hydropower (short for hydraulic power) in the jet is transmitted to a turbine (D), which changes it into mechanical power. This occurs when the blades in the turbine are struck by the water and caused to rotate. The generator (E) converts rotating power into electrical power, thereby transforming flowing water into electricity.

© Zul/ITDG
© Zul/ITDG

The distribution system then connects the electricity supply from the generator to the houses. This is often the most expensive part of the pico-hydro system. An electric controller needs to be connected to the generator. This matches the electrical power that is produced to the demand for electrical current that is connected in the houses. This maintains a steady voltage. Without a load controller, the voltage changes as lights and other devices are switched on and off.

To ensure that this system is successfully set up, the following six phases should be addressed.

  1. Planning
    1. Finalise and make adjustments to the design, particularly paying attention to the locations of the powerhouse, forebay and intake.
    2. Ensure that sufficient gradient exists for water flow.
    3. Distribution system: check length and size of electricity distribution cable.
  2. Preparation
    1. Order and store all required materials.
    2. Clear a path through the vegetation for the penstock.
    3. Clear the site and construct the foundations for the powerhouse, allowing correct positioning of turbine and generator.
    4. Identify a suitable location for an earth connection near the powerhouse.
    5. Distribution system: connect distribution cables, erecting poles where necessary.
  3. Construction and assembly
    1. Lay the penstock in position.
    2. Position intake and dig a canal if necessary.
    3. Assemble turbine and generator base frame support structure.
    4. Construct the walls and roof of the powerhouse.
    5. Excavate and position the earth electrode. Attach a cable to powerhouse.
    6. Distribution system: position electric load-limiters. Connect service cables to main distribution system.
  4. Connection
    1. Connect penstock sections and support the penstock where necessary.
    2. Line the forebay or reservoir.
    3. Connect load controller and protection devices to generators.
    4. Distribution system: Connect protection devices.
  5. Testing
    1. Check penstock and filters for leaks.
    2. Test-run the turbine and generator.
    3. Check operation of controller.
    4. Distribution system: connect the distribution system to the load controller.
  6. Commissioning
    1. Cover penstock with turf or soil.
    2. Train operators and managers.
    3. Resolve any electrical problem with domestic connections.

Social Impact

‘Since we got power, life has changed. Our lives have become brighter.’
Dinh Quang Cao

The advent of reliable electricity produced by the pico-hydro system in Viet Nam has been a welcome addition, as Dinh Quang Cao describes. Those who most directly benefit from pico-hydro projects are members of the community who are active in activities and support other self-help community development projects. Since pico-hydro is small scale, the families that benefit from electrification are those nearest the powerhouse, while those living further away benefit less directly from the increased opportunities for charging batteries. An objective of pico-hydro projects is to stimulate economic activities among families, such as sewing and hand-crafts. Home-based income-generating activities become more profitable with the availability of light in the evenings.

‘With better lighting my wife can work and walk in the house easier, and my children can have better light to do their homework.’
Ban Van Giang

Other benefits of the system include:

  • More light is generated than can be obtained from kerosene lamps and the smoke emitted from these lamps is avoided.
  • Cooking becomes an easier and less stressful task with improved light and reliable power.
  • Children are able to study for longer in the evenings with less eye strain.
  • The health hazard posed by kerosene lamps is removed.
  • The use of an electric light acts as a stimulus to help keep the local social life active and the environment clean.
  • Economic benefits accrue from the decreased quantity of kerosene purchased by households. Pico-hydro power can also be used to charge batteries, thus removing the need to purchase batteries.

Community-managed electrification through pico-hydro systems also has the ability to provide indirect benefits to the community as a whole, such as stimulating village industry and development of technical skills, and the provision of lighting and refrigeration for health centres. In order to maximise benefits in the community, members need to be provided with information on options that improve individual livelihoods and community equity.

Lessons Learned

  1. Do not underestimate the complexity of the task.
    Acquiring information, tools, materials and the people to implement the project is not always easy, and if underestimated can lead to disinterest in the project by community members.
  2. Assess the technical ability of those involved.
    The ability of designers and installers should not be assumed. This can lead to mistakes and having to rebuild sections of the system.
  3. Establish clear lines of communication.
    An essential and often neglected factor. Often assumptions are not communicated and confirmed, leading to errors in construction. For example, designers may assume that those with plumbing skills know how to go about the construction. Where experience is lacking, the plumber’s assumptions may be inaccurate.
  4. Avoid having too many helpers.
    Too many cooks can spoil the broth! The views offered by a crowd of on-looking community members can result in wrong judgements and wrong solutions.

Pico-hydro, therefore, provides an excellent opportunity for rural and marginalised communities that have little or no access to electricity. Yet, if care is not taken in establishing and maintaining the system, it can become a costly venture. If the skills are not made available to maintain the turbines, they can easily break, leaving the community with the financial burden of buying a new turbine or paying for the existing one to be fixed by outsiders. A well-established and maintained system, on the other hand, can provide a reliable source of electricity for the community.

Further Information


Maher, P. and Smith, N. (2001). Pico-Hydro for Village Power: A Practical Manual for Schemes up to 5kW in Hilly Areas. Nottingham: Nottingham Trent University Micro Hydro Research Group.

Pico-Hydro. Issues 1-9. (1997-2001).

Smith, N., Harvey, A., Kapali, S. and Upadhyaya, D. (1998). Socio-economic and Technical Assessment of Existing Pico-Hydro Schemes: Report to the Department for International Development. Nottingham: Nottingham Trent University Micro Hydro Research Group.

Donor and Supporting Organisations

Department for International Development (DFID) www.dfid.gov.uk

USAID www.usaid.gov

World Bank www.worldbank.org


ITDG Technical Briefs answers.practicalaction.org

PowerPal www.powerpal.com

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