Newsletter and Technical Publications
<Sourcebook of Alternative Technologies for
in Small Island Developing States>
PART C - CASE STUDIES
5.3 Solar-powered Pumping in the Federated States of Micronesia
The State of Chuuk, Federated States of Micronesia, consists of 11 high
volcanic islands and approximately 290 low lying coral islands, with a
land surface area of 127 km2 (see Figure 40). About 40 of these islands
are inhabited. The average annual temperature is a fairly constant 27°C.
Annual rainfall averages 3 500 to 4 000 mm, with a minimum monthly
rainfall of 150 mm and a maximum monthly rainfall of about 400 mm. A
community water supply system on Unanu Island, Chuuk, was completed in
1987. It consists of four separate wells, each equipped with its own solar
pumping system. A community water supply system on the neighbouring island
of Onou was completed in 1994. The Onou Island system consisted of a
single well and tank.
Figure 40. The State of Chuuk, Federal States of
On Unanu Island, the wells consist of a series of interlocking,
ferrocement cylinders used to line the well, with the number of cylinders
being determined by the depth of the well. A concrete slab was poured
around the well at the ground surface and the well was covered by a
concrete cover. The ferrocement cylinders were made by plastering mortar
over an inner tin form. Upper and lower forms of 19 mm plywood held the
inner form in place and controlled the thickness of the mortar. The lower
plywood form controlled the shape of the female end of the cylinder. The
mortar was held in place and reinforced by 13 mm security screen. After
the mortar had cured, the upper and lower plywood forms were removed,
permitting the tin inner form to fall away from the cylinder. The
ferrocement cover was made using a modified version of the bottom plywood
Five 40-watt solar modules were mounted directly above the well to power
the pump. A positive displacement (rotary vane) type of pump (Dankoff
Solar Products) was used. The pump was mounted in the well (above the
water table) and the well covered with the ferrocement cover. Water from
the wells was pumped to two 19 m3 ferrocement storage tanks.
The tanks were constructed using pieces of flat tin tied to a framework of
reinforcing rods that had been perforated with a large number of holes.
Mortar was then plastered over the flat tin, generally in two coats on the
outside and two on the inside. Vertical reinforcing rods extending from
the sides of the tank were bent to reinforce the bottom and top of the
tank. In addition, circular rings of reinforcing rods were added to the
top and bottom. Step by step instructions for a 5 m3 tank
using this design can be found in Winter (1988a). The covers of these
tanks were made of reinforced concrete. A temporary form was made by tying
pieces of flat tin to the underside of the cover-reinforcing rods. The tin
was then propped up with pieces of local timber to temporarily support the
weight of the concrete while it cured. A manhole was cast in place in the
cover. The covers were usually conical in shape, making an angle of around
10 degrees to the horizontal.
From the tanks water flowed via gravity to water-use areas at each home.
The Onou Island system consisted of a single well and tank, equipped
with a centrifugal pump (A. Y. McDonald Co.) which was expected to have a
longer life than the rotary vane pumps used on Unanu. The pumping rate was
higher and the tank was larger (around 30 m3) than on Unanu.
Larger diameter pipes were used and the tank was elevated slightly. These
measures solved the low pressure problem in the distribution system. A
faucet especially designed for developing countries initially appeared to
solve the breakage problem, although some of the new taps may have failed
due to corrosion since they were designed for use in arid areas (rather
than in marine environments or where the water being pumped is slightly
brackish). Power was supplied to this system from a solar array placed
adjacent to an existing array used to power a solar freezer facility. This
particular location was guaranteed to be shade-free for the foreseeable
Effectiveness of the Technology
On Unanu, the primary technical problem experienced in this project was
low pressure at the water-use areas. This was because of the
small-diameter pipes used in the distribution system and insufficient
elevation of the storage tanks. In addition, the faucets used in the
water-use areas failed prematurely, apparently because children opened
coconuts by banging them on the taps. At present, this system is almost
non-functional. While the Onou system was designed to minimise these
problems, a few homeowners were reported to be leaving their faucets open
all the time to ensure that they obtain the maximum amount of water
possible. As a result, the storage tank is not kept full and homes further
along on the distribution system do not receive any water.
When the four pumping systems were installed, the community willingly
cut down coconut trees in the area to ensure that the needed sunlight
would strike the solar panels. People also agreed to keep breadfruit trees
in the vicinity of the wells trimmed. One family that owned a small
breadfruit tree adjacent to one of the wells agreed to cut it down
immediately after it produced fruit that growing season. Unfortunately,
this promise was not kept and the tree continued to grow. A few years
later, the family requested compensation from the island government for
removal of their tree. Following this, at least two other people requested
compensation for the removal of branches from their trees. As no
compensation was paid and the trees continued to grow, the system became
less and less effective as the arrays increasingly became shaded.
When the project was implemented, there were no wells in the vicinity of
the single village on the island. This technology made a freshwater source
The Unanu project suffered from lacklustre community involvement. There
was no local leadership of the project, and the traditional leaders on the
island could not resolve the issue of the shaded array. The project never
progressed to the point where it became part of the way of life on the
island. Although the system was a gift, funded through a grant from the US
Department of Energy, the community members, including women and children,
willingly donated one month of their labour to the project. However, local
municipal funds were never committed for the maintenance of the system. As
a consequence, the community did not perceive that they were contributing
any of their own resources to the project, and the project languished.
(Labour is still regarded as free on the more traditional islands.) On
Onou, the total cost of the project, including engineering assistance with
the installation, etc., was almost exactly $50 000, which, as on Onanu,
was provided by external funding sources. While this system has been
maintained, reports of its misuse by the traditional leadership of the
community likewise suggest that the lack of investment on the part of the
local community has resulted in a lack of commitment to the equitable
operation of the system. In both cases, there was no charge incurred for
using water supplied from the solar pump systems.
In future, it would seem advisable that an initial commitment by the
beneficiary community be made, perhaps in the form of a connection fee per
household, as well as a longer-term commitment, perhaps in the form of a
user fee. This approach would not preclude the possibility of a project
being subsidized. Unfortunately, the income level of some families is so
low that it would not be possible for them to underwrite the cost of their
share of a project such as this.
Dr Stephen J. Winter, Appropriate Technology Enterprises, Inc.
Bibliography Dilaha, T.A. and W.J. Zolan 1987. An Investigation of the
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Tropical Islands - A High School Teaching Supplement. Water and Energy
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(includes a companion slide presentation).
Winter, S.J. and L.D. McLeary 1985. A Ram Pump Demonstration. Water and
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