A windmill is one of the most energy
efficient and ingenious ways ever
devised to pump water from the ground. A
windmill harnesses the free and
renewable power of the wind and uses
that energy to lift underground water to
the surface for agricultural and other
uses.
Because windmills are so efficient
and durable, the basic design hasn't
changed in almost 120 years. The secret
lies in the way a windmill harnesses the
wind's energy to power a n ingenious
water pump located deep underground.
Windmill
The power of the wind is captured and
harnessed in two steps. Each step is
easy to identify by simply observing a
windmill in action.
First, notice how the fan turns. A
windmill captures the energy of the wind
with the large, circular fan, or
"wheel", located at the top of the
tower. When the wind blows, the fan
rotates. This turning (rotary) motion is
so commonplace that it's easily taken
for granted. But don't. This is where
the free energy of the wind is captured.
Second, look just below the turning
wheel and notice a long rod moving up
and down. This "sucker rod", is powered
by the windmill's motor. This motor is a
unique set of mechanical gears that
converts the rotary motion of the wheel
into a reciprocating (up and down)
motion that powers the cylinder pump
located deep underground.
Groundwater
Water trapped in an underground,
water-bearing formation is called an
aquifer. The top of an aquifer is called
the "water table". The depth of this
water table is important because it
determines how deep a water well must be
drilled. It also determines the size of
the windmill required to pump water to
the surface.
A water well is a small-diameter hole
drilled into the earth's crust that
fills up with water. As the well is
drilled, it passes through various
underground layers of sand and gravel,
and extends into an aquifer, or
underground water-bearing formation.
Once the well is drilled to the
proper depth, the well wall is
reinforced and perforated to allow water
from the surrounding aquifer to seep
into the well. Gravity causes the water
to rise to the level of the underground
water table.
A sealed "drop pipe" is then inserted
into the well until its lower end is
fully immersed in the well water.
Cylinder Pump
The cylinder pump operates in a very
ingenious way. It doesn't use
high-powered suction. Instead, it builds
a "column of water" from the aquifer to
the surface within the drop pipe... from
the bottom upward.
The cylinder pump accomplishes this
feat by creating a one-way flow of water
within the drop pipe and constantly
ratcheting water upward.
Two specialized pump valves work
together to draw well water into the
bottom of the drop pipe and then ratchet
the water column upward. By repeatedly
adding water to the bottom of the water
column, the drop pipe fills and water
pours out the top into a storage tank.
