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.

Water Well

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.

2. How much water do I need to pump?

For years, Aermotor Windmill's "Average Water Needs" chart has been a simple, yet invaluable, tool to help determine average water needs.

3. What are the pumping capacities of Aermotor Windmills?

Pumps and cylinders used with the various sizes of mills should be capable of giving a clear stroke equal in inches to the diameter of the windwheel in feet: i.e., 8 inches for 8 foot, 10 inches for 10 foot, etc.

*Pumping capacities of Aermotor Windmills shown in the table below are approximate, based on the mill set on the long stroke, operating in a 15 to 20 mile-an-hour wind. The short stroke increases elevation by one-third and reduces pumping capacities by one-fourth.