Report 2 (of 5): Only Connect, Micro Hydro - Peru

Introduction

The rural population in Peru is eight million and it is spread over an area of more than 1.2 million square kilometres. The majority of Peru’s rural population live in the remote Andean highland’s region. Communities and settlements are very small and in remote locations. The towns and cities in Peru have electricity, but the communities living in the ‘cut-off’ areas in the mountains have few facilities and little access to them. The cost of expanding the grid of electricity into the widely dispersed population of the mountains is very high and, therefore, unlikely to happen even in the long term. Before other services to meet basic needs can be introduced, it is fundamental that there is power available to these communities. This, together with the problems of expense and difficult access to the communities has meant that government programmes to develop education, sanitation, transport and health services usually only get through to larger and more accessible settlements.

Energy Needs in Peru

In 1996, only 4% of rural population had access to electricity.

• For light in the home, kerosene and candles are widely used, and for some slightly better off families, batteries are used.

• For cooking, residues from processed crops and wood from the few trees in the area are used. Wood collection is time consuming and the task is often done by women.

• For processing grains, there are a few water mills in the region, for turning grain into flour. These do not generate much power and are not fast enough to meet today’s demands. Poor farming families spend a lot of time milling by hand, using animal power, or travelling to other settlements that have a motor powered mill, for which there is an expensive charge.

Micro-hydro as an Energy Option

Peru is rich in many energy resources, such as water, petrol, coal and natural gas, all of which are yet to be fully exploited. The potential power to be gained from the country’s water resources is estimated at 75,000 Megawatts which would be enough to meet the energy needs of 20 million people in a western country where consumption is much higher per person. Micro-hydro is a sustainable method of harnessing energy from running water and can be used to generate electricity or drive machinery.

The difference between micro-hydro and larger hydro schemes is the amount of electricity they can produce and the amount of interference with the natural environment needed to produce this energy.

Unlike large scale hydro-electric schemes, micro-hydro schemes are "run-of-river" and rarely require the use of a dam for water storage or manmade lakes to hold the massive volumes of water the larger hydro schemes need in order to operate. Micro-hydro schemes do not interfere with river flow and are not harmful to the environment because they avoid the negative environmental and social impacts associated with projects of large scale hydros. With micro-hydro, a maximum capacity for the system would be up to three hundred kilowatts which would be a "stand alone" system, that is, not connected to the national grid.

Peru has used micro hydro systems since the beginning of the century, mostly for use in mining or on large farms. The technology is becoming more accessible to poorer communities because there are small workshops which make micro-hydro turbines and once installed they can be run by communities. Micro-hydro is a viable energy option technically, economically and socially.

Operating a Micro-Hydro System

A micro-hydro scheme starts operating at the intake weir, where water is diverted from the river. The function of the intake weir is to maintain the water level so that a continuous flow of water is achieved. The intake is usually protected by a trash rack of metal bars, which filters out debris. The water then passes through the settling tank or forebay which slows the water down, so that any suspended particles can settle at the bottom.

In a medium or high head installation water is conducted to the forebay by either a channel or a small canal. In a low head installation, water enters the turbine almost directly from the intake weir. From the forebay tank, water reaches the turbine from a pressure pipe or penstock. PVC piping can be used for this component as it is strong and smooth which reduces the friction. It is also relatively cheap and easy to transport and install.

The water then meets the turbine, which is located in the power house. The amount of power the turbine is able to produce depends on the distance of the fall, the speed of the flow, and the number of litres per second flowing through the system.

Turbines

Turbines come under three broad groups related to head levels - high, medium and low - and then generally into two categories, impulse and reaction turbines.

For medium to high head applications an impulse turbine is usually used. The pressurised water is converted into a high speed jet by passing through a nozzle. The jet of water strikes the specially shaped buckets or blades of the turbine rotor which then rotates.

A reaction turbine works in a very different way in that it runs filled with water. The flow of water through the turbine creates different levels of pressure across the blades which causes them to rotate.

The turbine will sometimes need to be shut down for maintenance so all installations should have a sluice gate or valve at the top of the penstock to close off the water supply. When it is closed, the water is diverted back to the river down a spillway.

©Micro-hydro Power - A Guide for Development Workers

P.Fraenkel, O.Paish, V.Bokalders, A.Harvey, A.Brown, R.Edwards

Battery Power from Micro-Hydro

Part of the versatility of micro hydro power is that the delivery of energy from the system can be adapted to suit the needs of a community and modified to get beyond any physical constraints. An IT micro-hydro project in Huacataz, Peru found that the community demand for electricity was for domestic use (lighting & television) and for powering the grain mill. The conventional method of delivering energy is through a centralized scheme that distributes electricity to domestic connections. This was not viable as the population in this community was too widely dispersed. The solution was to introduce a scheme where the grain mill was positioned centrally and served a secondary function as a battery charger. The small charge for the service of milling and battery charging meant that the scheme also raised funds for further community development and covered the running costs of the scheme.

Considerations in Installing Micro-Hydro

Pre-feasibility studies need to be done in the area where the installation of a micro-hydro scheme is being considered to determine several points:

• A suitable geographic location for a micro-hydro scheme is in an area where there are steep rivers that flow all year round. Areas that give the highest head options should be considered first as they will usually cost less per installed kilowatt. To determine the power potential of the water flowing in a river or stream, it is necessary to determine both the flow rate of the water and the head through which the water can be made to fall. The flow rate is the quantity of water flowing past a point in a given time. Knowing the flow rate will help to determine the appropriate type and size of a turbine.

• The demand for electricity needs to be determined. This will help to decide what size system will be needed; whether or not electricity demands will fluctuate seasonally or remain constant; and whether the demand is domestic or industrial, or a combination of both.

Cost

Costs currently run at between US$1,200 and US$1,500 for each kilowatt of installed power. In other words, a scheme capable of producing 10 kilowatts of power would cost between US$12,000 and US$15,000. The initial investment is high but running costs after installing the micro-hydro are low because the water is free. A micro hydro unit should last for twenty years providing that regular maintenance checks and servicing are carried out. Schemes that only provide power for driving equipment are cheaper to install.

Glossary

Head This refers to the actual height that the water falls through.

Power Power is the energy converted per second, that is to say, the rate of work being done. Energy is the total work done in a certain time.

For further information, please contact:

Further reading available from ITDG Development Bookshop

Micro-Hydro Design Manual: A guide to small-scale water power schemes
Adam Harvey and Andy Brown
This book has grown from Intermediate Technology's field experiences with micro-hydro installations and covers operation and maintenance, commissioning, electrical power, induction generators, electronic controllers, management, and energy surveys.
£35.00 1993 288pp pb (ITP) ISBN 1853391034

Micro-hydropower Source Book
Allen R. Inversin
A practical guide to design and implementation in developing countries.
£25.00 1986 285pp pb (NRECA) ISBN 0946688486

Power for Living: Rural Energy in Peru
£1.95 (ITDG)

TVE/ITDG gratefully acknowledge support for the HANDS ON programmes from the UK's Department for International Development (DFID), the European Commission (EC), the UN Foundation and UNDP/The Equator Initiative in collaboration with the Government of Canada, IDRC, IUCN, BrasilConnects and the Nature Conservancy.