Bigger is not always better

By Country News on June 27, 2016

When it comes to equipment in robotic dairies, bigger is not always better, as FutureDairy energy audits have showed.

Gabriel Hakim, of AgVet Projects, undertook energy assessments on 10 farms with automatic milking systems (AMS).

One of his key findings was that most AMS dairies were operating with equipment that was oversized for the needs of automatic milking, resulting in unnecessary electricity consumption.

"When building an AMS it can be tempting to repurpose equipment from the existing dairy but automatic milking can place quite different demands on equipment to conventional milking,’’ Mr Hakim said.

For example the milking equipment on AMS farms that use voluntary cow movement operates at a low capacity for up to 20 hours a day, compared with conventional milking which usually occurs in two intensive milking sessions a day.

"Operating equipment that is not sized correctly runs a real risk of loss in energy efficiency and excessive energy use,’’ Mr Hakim said.

He found that many of the AMS dairies in the study had an oversized compressor. Some also had vacuum pumps that were much bigger than required and most had hot water systems suitable for a conventional dairy, which was bigger than needed for an AMS.

"Operating oversize or over-capacity equipment wastes a considerable amount of energy. For example if you are running a grossly oversized vacuum pump a significant proportion of the energy can be used just driving the pump.

"The same is likely for compressors. Studies in other industries where compressed air is used have shown that as much as 30 to 50 per cent of energy consumption was used to service leaks, artificial demand and system inefficiencies. This warrants further investigation for AMS dairies.’’

When planning an AMS, Mr Hakim recommended weighing up the savings made in capital outlay — by retaining existing equipment — against the longer-term operating costs.

FutureDairy project leader Associate Professor Kendra Kerrisk said although energy consumption was higher in AMS than conventional milking systems, energy consumption was a relatively small part of the overall economics of robotic milking.

"Higher energy costs certainly doesn’t mean that AMS is uneconomic. In fact although shed running costs are commonly reported to be higher, animal health and labour costs are significantly lower on many AMS farms, resulting in a favourable bottom line,’’ she said. 

The AMS energy study was funded through Dairy Australia’s project Smarter Energy Use on Australian Dairy Farms, funded by the Department of Industry and Science as part of the Energy Efficiency Information Grants Program. 

 Large variation

The research found significant variation between AMS farms in the amount of energy consumed and the price paid for energy, suggesting there are likely to be considerable opportunities for most AMS farms to cut energy bills and reduce greenhouse emissions.

The range in the amount of energy consumed on AMS farms was 53.72 to 132 kWh/1000litres milk.

Mr Hakim said the farm with the greatest energy use consumed two-and-a-half times as much energy per 1000litres of milk harvested as the farm with the lowest energy use, and in general  energy consumption tended to be higher in robotic than conventional dairies.

"Although our data is fairly limited so far, on average AMS dairies appear to consume about 1½ times as much energy per 1000litres milk harvested as conventional dairies,’’ Mr Hakim said.

He was cautious about making further conclusions from the AMS energy audits, given the small number of farms involved and the large variation in their energy use.

"I’m reasonably confident in our data for conventional milking systems as it is based on nearly 200 dairy farms across three states. But further investigation is needed to understand energy use on AMS farms.’’

 

Shop around

Mr Hakim also urged all dairy farmers to shop around for their energy supplier. In the AMS study he found a large variation in the tariff rate charges for peak (22.01 to 36.78 ¢/kWh) and off-peak electricity (8.86 to 19.39¢/kWh).

``Previous studies have shown a similar variation in tariffs paid by farmers with conventional milking systems. Despite energy costs being a small component of whole farm operating costs, those paying at the higher end of the range stand to save thousands of dollars a year by switching to tariffs at the lower end.’’

The AMS energy study was funded through Dairy Australia’s project Smarter Energy Use on Australian Dairy Farms, funded by the Department of Industry and Science as part of the Energy Efficiency Information Grants Program. 

By Country News on June 27, 2016

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