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Water-pumping windmills, aerogenerators (small wind electric generators), and wind–solar hybrid systems have been found to be useful for meeting water-pumping and small-power requirements in a decentralized mode in rural and remote windy areas of the country


A. Water-pumping windmill

A water-pumping windmill pumps water from wells, ponds, and bore wells for drinking, minor irrigation, salt farming, fish farming, etc. Available windmills are of two types, namely direct drive and gear type.

The most commonly used windmill has a horizontal axis rotor of 3–5.5 m diameter, with 12–24 blades mounted on the top of a 10–20 m high mild steel tower. The rotor is coupled with a reciprocating pump of 50–150 mm diameter through a connecting rod. Such windmills start lifting water when wind speed approaches 8–10 kilometres (km) per hour. Normally, a windmill is capable of pumping water in the range of 1000 to 8000 litres per hour, depending on the wind speed, the depth of water table, and the type of windmill.

Windmills are capable of pumping water from depths of 60 m. Water-pumping windmills have an advantage in that no fuel is required for their operation, and thus they can be installed in remote windy areas where other conventional means of water pumping are not feasible.

However, water-pumping windmills have limitations too. They can be operated satisfactorily only in medium wind regimes (12–18 km per hour). Further, special care is needed at the time of site selection as the sites should be free from obstacles such as buildings and trees in the surrounding areas. The cost of the system being high, many individual users do not find them affordable.

B. Aerogenerator


An aerogenerator is a small wind electric generator having a capacity of up to 30 kW. Aerogenerators are installed either in stand-alone mode or along with solar photovoltaic (SPV) systems to form a wind–solar hybrid system for decentralized power generation. An aerogenerator is suitable for power generation in unelectrified areas having adequate wind speeds. It consists of a rotor of 1–10 m diameter having 2–3 blades, permanent magnet generator, control devices, yaw mechanism, tower, storage battery, etc. The aerogenerator rotor starts moving at a wind speed of 9–12 km per hour. However, it produces optimum power at the rated wind speed of 40–45 km per hour. The limitation of not being able to provide power as and when it is required is overcome by storing it in a battery bank.



C. Wind–solar hybrid systems

When an aerogenerator and an SPV system are interfaced, the power generation from these is mutually supplemented, and the resultant hybrid system offers a reliable and cost-effective electric supply in a decentralized mode. The wind–solar hybrid system mainly consists of one or two aerogenerators along with SPV panels of suitable capacity, connected with charge controller, inverter, battery bank, etc. to supply AC power. The major advantage of the system is that it meets the basic power requirements of non-electrified remote areas, where grid power has not yet reached. The power generated from both wind and solar components is stored in a battery bank for use whenever required.