Wind for electricity generation
In areas where households are widely dispersed, or where grid costs are very high, battery
charging is an option. In rural areas, a few tens of watts of power are usually sufficient as a
source of lighting and of power for a radio or television. The preferable option for such turbines
is the use of family units (one unit per family), but in some cases battery charging stations
may also used, although this is not common. The use of rechargeable batteries reduces the
inconvenience of intermittent supply due to fluctuating wind speeds.
12- and 24-volt direct current wind generators are suitable for battery charging applications,
and are commercially available. Smaller turbines (50 -150 Watts) are available for individual
household connection. Practical Action has developed low-cost small scale wind turbines for
Wind generator system
A typical small wind generator has a rotor
directly coupled to the generator, producing
AC (alternating current) electricity at 120 /
240 volts. This is then rectified to 12 / 24
volts of DC (direct current) for domestic use
or battery charging.
1 turbine & tower
2 charge controller
4 fuse boxes
5 dump load resister
7 Inverter (optional, for AC appliances)
8 electrical socket
When devising any renewable energy system,
the energy demand should be carefully
considered. Small-scale wind turbines are
suitable for low-energy light bulbs, radios,
mobile phone charging and occasional
television use, whilst highly demanding
appliances such as electric heaters, toasters
and irons are not suitable, as their energy
consumption is too great.
Figure 3 : The components of a small wind energy
Illustration: Soluciones Prácticas.
Local production of existing designs is
simpler than developing a new machines, but the design will have to suit the local
manufacturing capabilities and availability of materials which means that turbines in
developing countries may need to be different to mass produced products.
The production of small- and medium-sized machines locally is generally much cheaper than
imported machines. It also enables manufacturers to make minor modifications during the
production process, allowing them to suit systems to their desired end-uses and to the
conditions under which they are expected to operate.
Whilst most components can be made by small engineering workshops, some parts - such as
magnets or electrical equipment - may have to be imported.
Towers can be made of welded steel, preferably galvanised, which can be manufactured in a
local engineering works. The foundations can be cast from reinforced concrete on site.
The specifications for one of Practical Action’s small-scale wind turbines are shown below.