Newsletter and Technical Publications
of Alternative Technologies for Freshwater Augumentation
America and The Caribbean>
PART B. TECHNOLOGY PROFILES
1.10 Pumps Powered by Non-Conventional Energy Sources
Pumping facilities are required wherever water is stored at or below
ground level. Conventionally powered pumps, such as diesel and electric
pumps, require readily available sources of fossil fuels or electricity.
In countries where access to conventional energy is limited by cost or
sources of supply, pumps powered by non-conventional energy systems may
provide an alternative.
Several types of pumps powered by non-conventional energy have potential
utility in Latin American countries. Different types of pumps have been
tested with mechanisms fabricated from local materials, using limited
fabrication skills and available energy sources. They include the
The hydraulic pump or water wheel is driven by the energy of the moving
water in a river. The circular movement of the wheel is transmitted via a
1 in. diameter shaft, fitted with an offset arm, to the piston of a small
pump. In Peru, typical pumps of this kind have capacities of 0.2 to 6.0
The hydraulic ram is a simple pump, in universal use, driven by the
energy produced by differences in hydrostatic pressure, which activates a
valve and raises the water. A ram can pump approximately one tenth of the
received water volume to a height ten times greater than the intake.
The rope pump consists of a loop of nylon rope with rubber gaskets
attached to it. The gaskets slip through the interior of a PVC pipe 1 in.
in diameter. The rope pump is operated manually by rotating a wheel, which
pulls the rope through the pipe. The effort necessary to turn the handle
depends on the length of the pipe and the depth of the water. The length
of a pipe 1 in. in diameter can range from 1 m to 12 m. A schematic of a
rope pump manufactured in Bolivia is shown in Figure 14.
There are many different variants of the hand pump, with different
designs that can be locally built or purchased ready-made. Hand pump
systems can be installed below or above ground. Field experiments have
been conducted in Bolivia using the INTI direct-action hand pump, the
Bolivian equivalent of the Tara pump developed for use in Bangladesh. This
pump, as used in Bolivia, has a lifting capacity of up to 15 m, and a
ratio of 0.7:1 between the diameters of the interior pipe, which functions
as a piston, and the exterior pipe, which conveys the water to the
required height, as shown in Figure 15.
The windmill pump is operated by making use of wind energy. The energy
generated by the wind moves a rotor which translates to the vertical
movement of a piston in the pump. Water is then drawn up through the
internal pipe, reaching heights of up to 7 m, depending on the tower size.
Windmill-powered pumps can lift water to a height of 20 m. The pump
capacity is a function of wind speed and the suction elevation. At wind
speeds of 4 m/s, pump capacities range between 0.5 and 1.5 l/s over
suction heights of 20 m and 5 m, respectively. For the same suction
heights but twice the wind speed, the capacities range between 3.2 and 4.0
Figure 14: Schematic of a Rope Pump.
Freddy Camacho Villegas, Institute of Hydraulics and Hydrology, University
of San Andrés (UMSA), La Paz, Bolivia.
Figure 15: Schematic of a Direct-Action Hand Pump.
Source: Freddy Camacho Villegas, Institute of Hydraulics
and Hydrology, University of San Andrés (UMSA), La Paz, Bolivia.
In spite of the abundance of solar radiation in Honduras, photovoltaic
solar energy has not been used as much as expected. A technical assistance
program to develop water sources for human consumption on Roatán
Island off the Honduran coast used solar panels and a photovoltaic-powered
pump system to raise the water to a 13 000 gal, reserve water storage
tank. The pumping system consisted of a submersible electric pump directly
connected to a photovoltaic cell system and operated continuously whenever
there was enough sunshine.
Extent of Use
Demand for hand pumps in individual countries in Latin America and the
Caribbean is potentially on the order of ten of thousands. However, the
relatively small, localized markets where this technology is most in
demand may not attract the large manufacturers. Thus, there are excellent
opportunities for small- and medium-sized firms providing pump sales and
servicing. The types of pumps used vary with the applications desired,
although their use is widespread.
The use of hydraulic pumps in Honduras is limited to the southern,
northwestern, and northern sections of the country, where rivers of
sufficient size are located. In contrast, they are widely used in Peru.
Hydraulic ram pumps, operating in lower volume river flows, have been
adapted for use in numerous areas of Honduras, including the central zone
and the eastern, western, and northwestern sections. This technology is
functional for use in rural development, primarily for domestic use,
livestock watering, and crop irrigation.
Rope pumps, because of their simplicity of design and ease of
construction, are used in many countries. They are usually built locally
by the individual operators. These pumps are used extensively in Honduras,
Peru, Haiti, and Bolivia.
Windmill-driven pumps are used relatively rarely. Although very
functional, they are mainly used for domestic water supply and cattle
watering on a small scale. This technology has been used in Peru and the
central region of Panama. Windmill pumps of similar design have been used
in Honduras and in Centro Las Gavistas, Colombia. In Peru,
windmill-powered pumps have 12 arms, 5 m in diameter, which can reach 30
rpm at a height of 6 m above the ground. The pump mechanism consists of a
reciprocating piston 6 in. in diameter, a cylinder, a casing, and a
Photovoltaic technology can provide electric power to drive water pumps
in areas with abundant insolation. However, its high cost and
sophisticated technical requirements limit its use. Most individuals,
communities and institutions would find this technology too expensive at
its present level of development. Roatán Island, Honduras, in the
Caribbean Sea, is not fully served by conventional sources of electricity
and for this reason is one of the few places in Honduras where solar pump
technology is utilized; four systems provide service to four communities.
Photovoltaic-powered pumps have also been tested in Haiti.
Operation and Maintenance
Operation of most of these non-conventional systems is
relatively simple, although most require additional labor. Some of the
pumps, like the hand and rope pumps, require constant attention to keep
them operating efficiently. Most of the pumps require the use of
anti-corrosive paints to protect the exposed metal parts, and frequent
oiling (twice a month) of the parts of the pump where friction between
different parts can be expected. However, it is important to avoid the use
of heavy-metal-based (e.g., lead paints) and to avoid contaminating the
insides of the pumps with hydrocarbon residues, especially if the water is
to be used for human consumption. Such contamination can lead to chronic
public health problems. In general the following factors should be
considered in thedesign of a hand pump system:
- Non-wearing parts of the pump must be durable and reliable enough to
last at least ten years.
- The wearing parts should be readily accessible, require no special
skills to service, be inexpensive to replace, and be of consistent high
quality to ensure interchangeability.
- A below-ground system should be as light as possible so that it can
be extracted when necessary, even from deep wells, without the need for
specialized lifting equipment.
- The impact of corrosion should be minimized by using materials which
are inherently corrosion-resistant.
- Pumps should be able to be easily maintained by caretakers drawn from
the community who have minimal skills, using a few simple tools and with
modest training; this generally means that the pumps should be
manufactured, or be capable of being manufactured, in the country of
use, primarily to ensure the availability of spare parts.
- Pumps and spare parts should be cost-effective.
- Boreholes must be designed and constructed in a manner appropriate to
the capabilities of the pump to be used and suitable for use under local
- Pumps should be acceptable to the users; i.e., used consistently,
viewed positively with few complaints, and not liable to be vandalized.
These features are applicable to the design of all pumping systems.
The need for maintenance varies with the type of pump, from pumps
requiring minimal maintenance to pumps requiring almost constant upkeep.
The hydraulic pump, which is impelled by the river stream, requires very
little maintenance. On the other hand, maintenance is probably the single
most important element in hand pump operation. To address this issue, the
concept of village-level operation and maintenance (VLOM) was developed to
provide local villagers with the option of maintaining the pumps at the
community level. The principles of VLOM are embodied in the design
criteria set out above. In meeting these criteria, the manufacturing
processes and raw materials required for pump maintenance should be
already available in the country of use or should be capable of developing
as self-supporting, commercial enterprises there.
The four photovoltaic-powered pumping systems in operation on Roatán
Island were installed in 1986. Their operation and maintenance are
performed by the residents of the communities using the pumps. It is
usually a very simple task, consisting of cleaning of the solar panels,
protecting the wells from contamination, and occasionally replacing the
submersible electric pumps when they fail. These submersible pumps are the
component of the system which fails most frequently. During a ten-year
period, two pumps have been damaged in each community, requiring an
average of a new pump every five years. The rest of the photovoltaic
system has only suffered from some corrosion due to the saline environment
on the island. In addition, some of the photovoltaic panels have lost some
of their efficiency, apparently as a result of construction defects. It is
significant to note that, even though two of the communities now have
access to electricity service, they continue to power their water supply
system with the solar panels.
Level of Involvement
Few governments have participated in the application of non-conventional
energy sources to the pumping of water. Most pumping systems using such
sources have been developed by local communities in cooperation with NGOs
and financed by external agencies, such as USAID. Likewise, whenever
system operators have needed technical and financial assistance (for
example, to replace a pump), NGOs generally have provided the necessary
technical assistance, and financial support has been forthcoming from
organizations such as the U.S. Peace Corps and Volunteers in Technical
Assistance (VITA), and, in Honduras, the Sandia National Laboratory of the
The hydraulic ram pump locally manufactured in Honduras costs
approximately $200 in local retail establishments, excluding installation
costs. The estimated costs of variously sized hydraulic ram pumps in Peru
are shown in Table 5. Hydraulic ram pump design criteria should include
the volume of water available, lifting height, water gradient, and pumping
TABLE 5. Estimated Cost ($) of Hydraulic Ram Pumps.
Source: Catholic University of Peru.
The rope pump has an average cost of less than $250, excluding
installation and well digging. Materials are very simple and may be
The windmill-driven pump is estimated to cost between $800 and $1 000,
excluding installation and well excavation, and is available only from
specialized suppliers. The manufacturing costs of three different models
used in Peru were estimated at $2 700, $3 500, and $6 000 for windmill
pumps with a rotor diameter of 3.5 m, 5 m and 10 m, respectively.
Installation and maintenance costs were estimated at 15% of the
Economics is the principal constraint on the use of the photovoltaic
energy technology. Use of this technology usually requires a large initial
investment. The difficulties of communication and transportation in rural
areas, combined with the relatively few specialized suppliers, increases
the initial cost of photovoltaic-powered systems significantly, although
recent technological advances are reducing it.
Effectiveness of the Technology
The hydraulic pump can lift water to a maximum height of 25 m. These
pumps perform favorably in comparison with other, similar technologies. At
river velocities of 2.0 m/sec and discharges of 0.40 m3/sec, a
hydraulic pump can yield enough water to irrigate an area of approximately
1 800 m2 of crops. Alternatively, the pump can supply 72
dwellings and a population of 500 persons or a cattle shed of 140 cows,
with water for domestic or stock-watering use.
The yield of the rope pump depends on the physical condition of the
user. Pumping rates are related to the rate at which the driving wheel is
turned, and the suction height. The following yields, in an average work
cycle for wells of varying depths, have been reported from Honduras: 11
gal/min at 80 rpm from 2.5 m depth; 7 gal/min at 60 rpm from 7.0 m depth;
and 6 gal/min at 50 rpm from 12.0 m depth.
The efficiency of the windmill-powered pumps varies directly in
proportion to the speed of the wind. At wind speeds ranging from 5 to 18
km/hr, the daily yield varies from 3 to 12 m3/day,
respectively, assuming an average of 6 working hours/day.
This technology is suitable for use in regions where fuel or electricity
is unavailable. For this reason, these alternatively powered pumps are
well suited for use in the rural areas of most Latin American and
In general, the advantages common to these types of pumping systems are
that they do not use combustible fuels, have a low cost to manufacture and
are inexpensive to purchase, and incur minimal maintenance requirements.
Each of these pumps has a negligible environmental impact. Specific
advantages of each type are as follows:
- The technology works 24 hours a day.
- It is usable for pressurized-water irrigation systems (microjet and
Hydraulic ram pump
- The technology produces a high yield.
- It can be coupled with most water irrigation systems.
- Construction does not require skilled labor.
- The technology has a minimal potential for water contamination.
- The design is proper for the tropics.
- Windmill arms do not need protection against storms.
- The technology is easy to install.
- The pump uses a readily available energy source.
- The technology requires little maintenance.
- It is clean, thereby reducing the possibility of contamination.
- No combustible fuels are needed.
- It is easy to install in a relatively short period of time.
- The technology is simple and reliable.
- The solar panels have a long life expectancy.
- It may be incorporated into a flexible, modular system which adapts
easily to community needs.
- Hydraulic pumps and hydraulic ram pumps must be located close to
river channels, which makes them vulnerable to flood damage unless the
equipment can be removed at short notice.
- The use of hydraulic pumps and hydraulic ram pumps is limited to the
irrigation of small areas. The rope pump cannot raise water far above
the surface of the well; it is limited to wells of less than 8m in
- Windmill-powered pumps are not recommended for agricultural purposes
because water extraction is difficult at depths of greater than 20 m.
- Repairs to photovoltaic-powered pumps, particularly in rural areas,
may be dependent on imported parts; inventories of critical spares are
needed to avoid stoppages due to breakdowns and waiting times while
replacements are found.
- The initial cost of a photovoltaic system is considerable, and the
regular maintenance may be extensive and costly if storage batteries are
With the exception of the photovoltaic-powered pumps, the
alternative energy sources used to power the pumps are traditional and
well accepted by the communities. At this time, the cost of
solar-energy-powered systems limits the level of community acceptance.
Further Development of the Technology
Improvements in pump design are needed to increase the efficacy of these
technologies. For hydraulic pumps, these include the use of a double
turbine to increase the torque from the main axis so that pumps of greater
capacity can be used. The rope pump can be improved through changes in the
construction and operation of the pumps, particularly in rural areas, to
increase the discharge height of the pump. Aspects of hand pumps also need
improvement. Some common needs include:
- Development of quality standards and quality control procedures,
including simple tests, for PVC pipes manufactured in developing
- Development of design guidelines for plastic, riser main assemblies,
including suggested material and dimensional specifications.
- Research on alternative materials for use as non-sliding bearings in
- Investigation of the design and manufacture of plastic pump elements
to reduce costs and improve the reliability of pump cylinders.
- Development of practical designs for sealless pistons and solid state
- Assessment and development of additional methods for protecting
cylinders against sand contamination.
- Development of improved designs for pump rod and riser and
- Assessment of techniques for preventing corrosion, including cathodic
protection, plating techniques, and coating with plastics or rubber.
- Development of reliable, easy-to-release couplings for pump nodes.
Freddy Camacho Villegas, Instituto de Hidráulica
e Hidrología (IHH), Universidad Mayor de San Andrés (UMSA),
Calle 30 s/n, Cota Cota, Casilla Postal No. 699, La Paz, Bolivia. Tel.
(591-2)79-5724. Fax (591-2)79-2622.
María Concepción Donoso, Directora, Centro
del Agua del Trópico Húmedo para América Latina y el
Caribe (CATHALAC), Apartado Postal 873372, Panamá 7, Panamá.
Tel (507)228-7944/228-7072. Fax (507)228-3311. E-mail:
Jose Luis Monroy C., Instituto de Hidráulica e
Hidrologia (IHH), Universidad Mayor de San Andrés (UMSA), Calle 30
s/n, Cota Cota, Casilla de Correo 699, La Paz, Bolivia. Tel.
(591-2)79-5724 / 79-5725. Fax (591-2)79-2622.
Rebén Ledezma, Centro de Promoción y
Cooperación Campesina YUNTA, Calle Colombia 257, La Paz, Bolivia.
Miguel Hadzich Marín, Coordinador de
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