Environmental Engineering Reference
In-Depth Information
60 m 3
4.5 km
DH 130 m
200 m 3
6 km. gravity
60 m 3
100 m 3
0.75 km
DH 25 m
3 km
gravity
FIGURE 10.7 Layout of water supply for three villages, Naima, Morocco. DH = dynamic head.
10.6.2 L ARGE S YSTEMS
Large systems have been considered for pumping water for irrigation and villages. These can be
classified into wind-assist and remote, stand-alone systems. Wind-assist water pumping is where
the wind turbine and another power source work in parallel to provide power on demand. Wind
assist is essentially a fuel-saving mode of operation, since it does not require any changes in irri-
gation application. Wind assist can be further divided into indirect and direct connection. The
advantages of the indirect connect are that the wind turbine does not need to be located at the well,
and electricity can be returned to the grid when the wind turbine is producing more power than is
needed by the load. A direct mechanical connection to the gear head has also been tested where
the conventional power source is electric or diesel [40, 41]. The disadvantages of the mechanical
connection are that the wind turbine has to be near the well, and the wind turbine can only be used
when water is needed.
The wind-electric water pumping system is a major change from the farm windmill in two
aspects: efficiency and volume of water. The annual efficiency is double that of the farm windmill,
and because wind turbines are available in larger sizes (1-10 kW and 50 kW permanent magnet
alternators), wind-electric systems can pump enough water for irrigation and villages. The wind-
electric system consists of a wind turbine generator connected directly to a standard three-phase
induction motor driving a centrifugal or submersible turbine pump. There is a good match between
the wind turbine output and the centrifugal pump, because both have power proportional to rpm
cubed. Another advantage of the wind-electric system is that the wind turbine can be located some
distance from the well or pump.
An example is the two wind-electric systems (10 kW) that were installed in Naima, Morocco, in
1989 for supplying water for villages and animals [42]. The spring water is some distance from the
villages. The first wind turbine pumps water from the collection tank to a large storage tank on top
of the hill (Figure 10.7). There is gravity flow to two other storage tanks, and a second wind turbine
to pump water to another village. The wind-electric systems replaced diesel pumping systems,
which were inoperable. In 1997, an additional two 1.5 kW wind-electric water pumping systems
were installed.
10.7 WIND INDUSTRY
After the oil crisis in 1973, the first step was the development of small wind turbines (defined as
<100 kW). Most companies in the United States began by importing wind turbines, finding aban-
doned units to refurbish for personal use or to sell, and then designing and building systems similar
to the wind chargers of the 1930s and 1940s (direct current, 0.1-4 kW, up to 5 m diameter). A num-
ber of home builders turned to the Savonius type because of its simplicity and ease of construction.
Search WWH ::




Custom Search