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Goodman Fielder:  Energy Management 

Energy NZ has been a provider of energy management services to Goodman Fielder over the past decade.

In this role it became aware of the company’s keen interest in the use of oven waste heat to meet the requirement of proofer ovens for heat and humidity. This would result in a boilerless bakery and the corresponding notable reduction in energy, maintenance, compliance and water treatment costs.

As this concept had already been unsuccessfully trialled at an Australian bakery, Energy NZ’s initial challenge was to convince Goodman Fielder of the project’s viability.

“We succeeded in doing so by expertly detailing why the Australian project had failed versus the positive signs that underpinned the Hawke’s Bay project - all backed by robust and rational engineering data,” exclaims Energy NZ director Andy Logue. “A single supplier with a performance guarantee also played a critical role in convincing Goodman Fielder executives that the project was feasible.

“Once the project received the green light the second challenge was getting the system commissioned – which took much longer than initially anticipated – and operational.”

Logue elaborates that the project, which at the outset appeared relatively easy and straightforward, soon proved otherwise. “This was because a large number of variables were at play across a number of systems and changes on one system invariably had knock-on effects on other systems.”

Goodman Fielder persevered and on April 5, 2016, Quality Bakers Hawkes Bay became the first boilerless industrial bakery in Australasia.

Soon thereafter it faced its biggest challenge in the form of winter, without incident.

The project alone resulted in a 20% reduction in the site’s overall energy consumption in conjunction with maintenance, compliance and water treatment savings.

OceanaGold; Macraes Goldmine: Energy Management

Energy NZ has undertake two compressed air audits of OceanGold's Macraes gold mine, with the first saving it 57% in compressed air energy in 2016 and the second consolidating air compressor operations and estimating a total saving of 75% or $220,000 per annum if recommendations are heeded.

Energy NZ’s first in-depth compressed air audit of New Zealand’s largest gold mine in Central Otago in 2010 showed the possibility of significant compressed air energy savings via compressed air leaks, alternative tank aeration, improved multi-compressor control and improved air quality.

The audit was carried out by Energy NZ’s accredited compressed air auditors and certified ultrasonic leak detection engineers.

OceanaGold followed Energy NZ’s audit recommendations and proceeded to execute systematic improvements to the mine’s compressed air system over the next six years, including installing blowers to offset compressed air use, improving air quality, repairing compressed air leaks and switching off compressors.

As a result of the success of this endeavour OceanaGold contracted Energy NZ to revisit its compressed air system at a later date.

The objectives of the second audit's assessment included quantifying the savings made after the first audit, recalculating the remaining compressed air efficiency and identifying opportunities for increased efficiency.

The assessment revealed that the site’s compressed air energy use had been reduced by a staggering 57%, exceeding Energy NZ’s initial estimation and resulting in a cost reduction of approximately $180,000 per annum. Significant reductions in maintenance costs were also achieved.

Currently OceanaGold is implementing NZ Energy's remaining compressed air recommendations, which it conservatively estimates could result in a total energy saving of 75% ($220,000 per annum).

Once complete, the site will operate on a single 55 kW variable-speed drive compressor as opposed to three air compressors totalling 410 kW in capacity.

BoxKraft: Power Factor & Tariff

Rodger Eaton of BoxKraft, an Auckland based packaging company, had recently acquired a new business and moved into a new site. After a few months at full production, managers were surprised at how much the energy bill had increased.

Andy Logue of Energy NZ - specialists in Energy Management services - was called in to analyse the problem. “We found a power-quality issue that was leading to significant network penalty charges but could be fixed with a system called power factor correction. The initial $21,000 investment would pay for itself in less than 18 months” says Andy.

Whilst investigating the issue, Energy NZ consultant Ross Grant, discovered BoxKraft could save another $5,000 a year by switching to a different network tariff which was better suited to their energy-use profile.

Combining both power factor correction and a change to their network tariff meant BoxKraft would wipe out a quarter of their annual energy bill on an on-going basis. “That was the cherry on the top”, says Andy. Results like this aren’t unusual. “If your business has an energy bill of more than $10,000 a month and you don’t know where it’s going, contact an Energy Management specialist,” he says.

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