Solar Water Pumping Module 1

Introduction | Water Pumping Systems for Remote Areas | Types of Water Pumping Systems | How Much Energy is Required to Pump Water? | The Basic Layout of a Pumping System |

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Introduction

In Australia, one of the driest countries in the world,  when the need for water is greatest, and the only consistent energy source available is the sun’s energy, a system is now widely in use which is almost a perfect solution  to this scenario. Solar water pumping systems – the hi-tech solution to an age-old problem.

  

Water Pumping Systems for Remote Areas

The availability of useable water is a critical issue in many areas of Australia, particularly in hot remote regions.

 Water in good quantities is essential for the following:

• Potable water supply ( drinking and personal use)
• Livestock watering and crop irrigation
• Orchards and vegetable farms

 Water resources are generally classified as:

• Surface - dams, soaks, rivers and streams, and
• Sub-surface – bores, wells, or other underground water

For many reasons, water is often stored in a tank or other storage device for later use. It is often essential to move water from one location to another by pumping.

Any pumping “system” comprises four basic parts:

• energy source,
• controls,
• drive stage (motor)
• and pump.

The amount of energy required to do a job of pumping is firstly an amount to overcome the force of gravity, and lift the water to a given height , then a further amount of energy to overcome the total losses in the system – more on this later.

It is therefore understandable that to pump a given amount of water to a given height above ground level, a sub surface pumping system must be larger than a surface pumping system, as the water must first be lifted to the surface before being pushed up to the final delivery point.

 

 
Types of Water Pumping Systems

Water can be moved from one location to another by using either the force of gravity, or some type of mechanical pumping system. The energy required to do this work of pumping water can come from several sources, the most popular in remote areas being renewable energy sources, such as the sun and wind, with fossil fuel engine driven pumps generally pumping for higher volumes. In some cases, human energy is used to pump water.

Again, it is important to remember that different amounts of energy are needed in pumping systems to pump a given amount of water in a given time – it all depends on the location of the water supply (or water resource), and the location of the final water delivery point, plus, as always, the losses in the system.

Here are a few different types of pumping systems:

Hand pump Very low volume with short lifting capacity	Solar water pump Uses solar energy to drive the motor and pump – usually small to medium volumes at medium lifting capacity	Wind pump or Windmill Depending on wind speed can pump high volumes at high lifts	Engine driven pumps using Petrol or diesel Capable of high volumes at high to medium lifts

 

How Much Energy is Required to Pump Water?

The amount of energy required to pump water for a particular application depends on several factors:

• The required volume per unit time
• The distance that the water must be lifted to the pump
• The distance that the water must be pushed from the pump
• The friction losses in the pipeline used
• The total losses in the pumping mechanism, and even
• The temperature of the water and other environmental or physical factors

 

In order to initially calculate this energy, there are some standard terms that are used to describe some of the above factors - more about this later.

It is however a good idea now to start thinking of the values describing these standard terms – for example:

Volumes per unit time for solar water pumps are usually measured in litres per second, whereas a large engine powered pump might be rated as cubic metres per hour.

Distances (and heights) are measured in metres and the total lifting distance (the vertical distance from the water source to where it is stored) is known as the system “head”

Sizing of pipelines attached to pumps are usually given as an inside diameter in mm, with a wall thickness rating (e.g. class 6 etc) to allow a choice of low, medium or high pressure piping to be selected, depending on the application

Friction losses are used for pumping system sizing, and are dependent on the size and type of the pipe used and the volume of water being forced through the pipe – these losses are given as equivalent head loss in metres

 
The Basic Layout of a Pumping System

Each segment of a pumping system layout has a specific terminology – the diagram below shows the basic segments.

  Indicates a possible location for the pump and/or drive motor, but not necessarily the energy source mechanism.

Possible pump locations and types will vary according to the resource, cost and personal preference. Floating pumps sit on the surface of the water, while surface pumps are installed on land and lift water from a dam, well or soak, and submersible pumps are situated under the waters surface, generally down a borehole. The actual selection of the pump depends on the intended application.

 

This is the end of Module 1.