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Smart water management
VER since the first settlement,
water and obtaining it has been
a subject of great debate in
Even today, for many landholders
and rural communities, the windmill
is still the lifeline for households and
livestock alike. But it is now being
suggested that the rapid growth of
the solar energy industry in recent
years is threatening the iconic role of
the windmill in the Australian rural
Or is it?
Windmills for pumping water have
been used around the world, particu-
larly in Europe, for centuries.
The modern-day windmill is a low-
cost, low-maintenance item with no
gears and with its bearings being
greased for life, so in this age of
sophisticated electronics, the ques-
tion must be asked "why use elec-
tronics when a piece of string will
Windmills can be bought with or
without furling, a mechanism that
allows the windwheel to be turned
away from the wind to reduce the
water supply when less water is
It can also be bought with hinged
legs for easy and safer servicing with-
out the need for tower climbing.
When it comes to windmills vs
solar and which is best, there is no
In trying to reach a conclusion, a
lot will depend on location and local
The right answer may have nothing
to do with how each system works,
but more to do with the cost of main-
Generally, it appears solar is
becoming more dominant in the
'windmills vs solar' debate, and par-
ticularly so with smaller systems.
Two factors seem to have influ-
enced this -- firstly, 1.8 metre and
2.4m windwheels can now be
replaced with cheaper solar systems,
and secondly, the buying decision is
often made based on what the cus-
tomer wants rather than what is best
in the long-term.
With bigger solar systems, howev-
er, the cost can be prohibitive.
A windmill will do much more
work for the dollars invested than a
The crossover point is a 3m wind-
wheel -- it is in this area that the crit-
ical issue of cost of maintenance
comes into play.
The popular perception among
many landholders is that solar is
maintenance-free, and that it costs a
fortune to maintain a windmill.
The unfortunate fact is that when it
comes to pumping water, there will
always be maintenance costs.
Many landholders undertake much
of the maintenance work on wind-
mills themselves, but an experienced
contractor and qualified technician is
generally required to do this work
with a solar system, and the cost of
this needs to be recognised.
Depending on location, this cost
can be extreme.
Potential buyers wanting to make
the right decision should always ask
themselves what the cost of annual
maintenance is likely to be.
Wind, solar both free
Make the right choice for water management
AT the heart of all water management strategies is the
pumping of the available water for use, and choosing the
right pump for the job is critical.
With the vast expansion of irrigated agriculture, intensive
livestock and improved home and living conditions water has
suddenly become one of every landholder's most valuable
assets. The old windmill and the muddy dam are not ade-
quate to fill the water needs on most properties.
The new heart of most farm water systems today is the
Landholders buying a new pump are confronted with a
vast array of options for managing their water systems,
whether they be for irrigation, watering livestock or firefight-
Generally speaking there are two broad groups of pump
types: the positive displacement type and the rotary dynamic
type, and within these two categories there are many differ-
A positive displacement pump must put out as much water
as it takes in - the flow cannot be restricted by valves etc.
With these types the quantity of water pumped is directly
proportional to pump speed and their efficiency is generally
rated around the 50 per cent mark, regardless of the flow
The positive displacement pumps are still most useful for
low volume -- high head operations -- 20 litres a minute at
Much more common today are pumps which work by spin-
ning the water at high speed to create the pressure.
These are known as rotary dynamic or pressure raising
pumps, and include spur gear units as well as axial flow or
impeller types and the universal centrifugal pump.
For general work today, it is the centrifugal that comes to
With centrifugal pumps, mechanical energy from the
impeller propels the water at increasing speed as it rotates.
This system has several advantages over standard positive
displacement type pumps.
• Output can be controlled by an outlet valve without
causing any damage.
• It becomes more efficient (up to 90pc) as the flow rate is
• It has fewer moving parts to service - maintenance costs
are about a third compared with positive displacement
• It is much more adaptable to electric drive - centrifugal
pumps are designed for peak efficiency at standard electric
motor speeds of 2880 and 1440 rpm.
For high pressure low volume applications such as moving
water from bores for stock and household use, multiple stage
centrifugal pumps are available.
Electric motors are especially suited to pumping - they are
usually more efficient and economical to run than engines -
and they can have the advantage of automatic on/off opera-
tion. If power is available at the pump site, electrically pow-
ered units are hard to beat.
Hard to beat - free
power from the wind.
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