Riding the wind

WIND power has been used for centuries
to lift water in farms, especially in countries like Australia and the us. Some
problems inherent in the existing windpump designs - high initial cost, difficulty in local manufacturing, and the
need for regular maintenance - have
rendered this age-old technology nonviable in developing countries. Sandy
Polak and Paul Dawson, at the uK-based
Neale Consulting Engineers Ltd, have
developed a modern windpump design,
tailored to the needs of developing
countries (Appropriate Technology,
Vol 21, No 4, March, 1995).

Designers of this machine - called
the Poldaw windpump - set certain
design criteria stemming from their
experience for developing it for individual farmers and small communities at
an affordable price. While giving top
priority to robustness and reliability of
the machinery, they wanted to make it
maintenance free. The aim was to have a
windpump with a minimum 20-year
lifespan for all its structural components. The design, it was felt, should use
readily available low-cost material and
should require the minimum of labour
and equipment to manufacture.

The installation was aimed to be
simple, quick and safe. Since carrying
out assembly involved risk, requiring to
be perched on top of a tower, the hazard
could be avoided by assembling the
entire machine with the tower lying on
the ground and then winching the
whole assembly upright. As the target
was a small, affordable windpump, the
minimum size criteria meant that a
rotor diameter of at least 3 metre had to
be maintained.

Keeping these criteria in view, the
designers built a modified version of the
windpump using low-cost, reliable
components. The total weight of the
machine, including a 6-metre high
tower, is 400 kg. Built in steel, the pump
uses standard ballbearings which
require minimum maintenance. With
its size changeable according to the size
of the well, the machine works in winds
with a speed as low as 6 miles per hour
and has an automatic storm protection
mechanism.

Construction and testing of the first
machine was successfully carried out
during late 1994. Currently, the design
for a larger machine with a rotor diameter of 5 metres and twice the water out-
put is underway. A demonstration
machine is operational at the Centre for
Alternative Technology, Macynlleth,
Wales (UK).