New milk chilling technology could save millions
Dairy farm energy costs could be reduced by up to $42 million a year if farmers installed efficient milk chillers, which also reduce hot water costs, and insulated their vats.
Nationwide, dairy farmers spend $250m a year on power, of which 17 per cent is used for refrigeration ($42.5m) and 24 per cent for hot water ($60m).
A typical South Island farm of 900 cows chews through 440 kWh hours per day to bring its milk down to a safe temperature, the equivalent of cooling down a 24-storey building.
The average dairy farm spends more than $20,000 a year on electricity, EECA projects and relations manager, Kirk Archibald, said.
New chillers using heat recovery could reduce national dairy hot water costs by $30m, and smart chilling could save $8.5m. Milk vat insulation could reduce costs by a further $4m.
By mid-2016, farmers will have to upgrade or replace their chillers in order to comply with new requirements to have milk chilled to 6 degrees Celsius within two hours of milking.
Archibald estimates about 40 per cent of farmers need to improve their chillers to meet the standards.
A half a dozen companies have developed chillers, but one - the Vari-cool chiller developed by Hamilton company Coolsense - has been co-funded by the Energy Efficiency and Conservation Authority because of its innovative features.
Not only does it reduce electricity costs by chilling milk more efficiently, it also produces hot water as a by-product.
Coolsense designer Allan Steele said it was simpler to replace chillers than to upgrade existing ones.
The price for one of the new Vari-cool chillers at the top end is $80,000 for a 2000-cow farm, or $35,000 for 400 cows.
Steele said milk chilling was a complex business. All milk was chilled with bore water first, which brought the temperature down from 36 degrees to 20.
"There's a whole raft of things that come into play - bore water temperatures, the amount of power available on the farm, how much hot water they use, do they have enough water to chill the milk before the chilling system takes over," Steele said.
In South Island regions the natural water temperature was quite low, but in some North Island areas such as Waikato, Bay of Plenty and Northland, faultlines lifted the bore water temperatures to as high as 26 degrees.
"The whole of the Tatua dairy factory area has either got poor quality water, because it's full of iron and manganese so you can't use it because it ruins your heat exchangers, or it's very warm.
"The South Island is a heck of a lot colder but they've got problems because their herds are so huge," Steele said.
The Vari-cool chiller was the first machine of its kind that could speed up to rapidly chill milk, then throttle itself back to keep the milk at a constant temperature.
Steele said the chiller would advantage Fonterra because its 17,000 tanker fleet could visit farms much earlier in the morning.
"People who snap chill milk can have it picked up five minutes after finishing milking, so a tanker can pick it up at 7am rather than 9am. The same mileage is being covered, but there's less capital expense for Fonterra," Steele said.
Rylib Dairies near Hinds in Canterbury milks 820 cows twice daily and has been operating the new plant since February.
Assistant farm manager, Scott Armstrong, said the farm was saving a third on its chilling costs.
"We're also saving on the cost of hot water. The heat recovery gives us 1500 litres of hot water a day to wash our equipment."
In August and September the farm saved $2055 and 8821 kilowatts of power, a reduction of 28 per cent in kilowatt units per kilogram of milk solids on the previous year.