Southland Dairy Shed Trial Tests Energy Efficiency

Media Release

20 March 2007

Southland Dairy Shed Trial Puts Energy Efficiency to the Test

Most New Zealand dairy sheds could reduce electricity costs by $3000 to $5000 per year with limited capital expenditure and a payback period of less than five years, according to a trial of efficiency measures.

The two-season study by the New Zealand Centre for Advanced Engineering, commissioned by Venture Southland, is examining energy efficiency measures ranging from small changes in shed practices to significant investment in commercially-available technology. Funded by Dairy Insight and the Sustainable Farming Fund, the project initially looked at equipment and practices on 15 Southland farms and installed monitoring equipment at two of these. Following this work, which was carried out in the 2005/06 dairy season, trials have been set up at five farms and are being monitored through the 2006/07 season.

CAENZ project manager Warren Gregory says the project aimed to put the most promising equipment to the test, to verify manufacturer’s claims and provide an independent assessment of the various options.

Most large dairy farms in Southland spend between $12,000 and $16,000 per year on electricity. Around 60-70 percent of energy is consumed by water heaters, the milk chiller and the vacuum pump, with the balance needed for other pumps and lighting.

The study found that a number of significant savings could be made with a payback period of five years or less, particularly in the area of water heating.

“One of the most promising is the use of a Mahana Blue heat pump for recovering heat from the milk vat chiller and using it to heat water to 85 degrees Celsius. For a large farm the estimated savings of around $2200 per year will pay back the cost of the unit within four years. If you add to this a variable speed drive for the vacuum pump then the combined energy savings, from only two modifications, is going to be around 30 per cent,” Mr Gregory said.

The study found little scope for alternative energy sources or on-site generation under the current electricity pricing regime. Solar panels, biogas and wind turbines were unlikely to be economic in the near future.

Mr Gregory says there appeared to be limited adoption of energy-saving equipment and processes to date. “This probably reflects the fact that energy costs by world standards are not high, and energy is still only a small item among total dairy farm operating expenses. But as energy prices rise, efficiency will inevitably become a great priority. This study will provide an independent baseline that farmers can refer to when they come to make those decisions.”

The trial is also monitoring the impact of energy saving initiatives on water usage and effluent disposal, to provide an overview of secondary benefits.

Robin McNeill, Enterprise Project Manager for Venture Southland, said the results provided farmers with an independent assessment of energy saving systems for the first time.

“By providing this information, farmers and farm management companies can now make their own assessments and determine an energy efficiency strategy which is suited to their own situation,” he said.

“The suppliers and manufacturers of this equipment will be able to use the results to assess their products’ performance and work on further improvements.

“In addition, we also have a much clearer idea of how on-farm energy efficiency can contribute to more efficient use of the electricity distribution network.”

Results of the study will be made available to universities and other training providers through Dexcel and the Agriculture ITO. A summary of each trial is available at www.cowshed.org.nz. A final project report will be presented to Venture Southland in July 2007.

ENDS

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