Case Study 2: Windsor NSW, Turf Farm 2

  Soft Hose Boom, with 660’ ft of 3” layflat hose

May 2014, Tallemenco was also contracted by NSW Dept Primary Industries to conduct a detailed pumping energy efficiency audit on a second turf farm in the Hawkesbury District.

However, this farm was known to be in a run-down state, with energy savings likely to be identified.

A 158’ long Soft Hose Boom irrigated turf on the farm. A direct driven 50HP direct drive electric pump took 190 gpm from the Hawkesbury River and delivered it to the Boom approx 4300’ away via 8”/6” PVC pipe.

      Measuring residual pressure on the Boom.

The audit measured pump efficiency plus friction losses across each major pipe and irrigation equipment sector. The system had 81 AF /yr usage, approx $10,700/yr electricity cost at ave 30c/kWh and pumped head was 180 ft.

The soft hose boom above was the emitter in this audit. Water was supplied with 660’ of 3” lay flat hose. Friction across the layflat hose was measured at 40psi. A 3 ½” hose would have had only 15 psi loss.

The resulting energy savings from using the larger hose would have paid for the larger diameter hose in 2 years.

Findings

This table summarises the findings in terms of $$/AF attributed to deficiencies in the irrigation system.

It was found that the layflat hose supplying the boom irrigator was undersized and incurring a 92’ (40 psi) head loss, 59’ (25.6 psi) over and above expected losses.

In addition to the large layflat hose friction losses, there was excessive residual pressure on the Boom, and the pump was considerably down in performance and running well off BEP, resulting in a combined operating cost of $132/AF.

Assuming the layflat hose hydraulics is restored with a larger hose, and the pump was replaced with the correct size and BEP, the system would then run at $4,330pa and $53.4/AF, a saving of $6,370.

That’s a full 60% annual energy saving.

In this case, the replacement of the layflat hose firstly would yield 33% energy saving (based on reducing pumped head from 180’ to 120’).

The pump would then need to be replaced with a lower head pump with correct BEP (or fitted with a VFD) to potentiate those savings, resulting in a further 26% saving.

33% + 26% = ≈ 60% identified achievable saving.

Had a pump test only be carried out here, a further 33% energy savings ($3,500pa) would have been overlooked from upgrading the layflat hose from 3” to 3 ½”.

In this case, since the pump was operating to the left of BEP, the existing pump could have been fitted with a VFD to potentiate the energy savings from upgrading the layflat from 3” to 3 ½”.

Estimated remedial costs were $5,000 for hose upsize plus $5,000 for VFD, resulting in a ROI of 1.7 yrs.

Quantifying pumping energy efficiency in an irrigation system has long been understood to be made with a simple pump test. Ignored was the significant additional potential energy savings available in irrigation system pipelines due to poor hydraulics.

The WATER PUMPING INSTITUTE’s aim is to educate water engineers in the art and science of identifying hydraulic in-efficiencies in irrigation (and other water) systems. This is achieved through its training course “Pumping System Master Class (US)” with “Fit for Purpose” software which comes with the training course.

These case studies have been compiled as living proof of the feasibility and practicality of identifying (or incorporating into new systems) up to 50% hydraulic savings from pumping system energy audits. These case studies demonstrate the importance and savings advantages of quantifying hydraulic efficiencies when conducting pumping energy audits.