Dairy farm hot-water power use cut by two-thirds

Mahana Blue cuts North Otago dairy farm hot-water power use by two-thirds

A Kiwi engineer’s idea has been turned into a device that takes the heat from cows’ milk and uses it to heat water, reducing hot-water costs by around two-thirds in a typical milking shed.

“Dairy farmers have to use energy to cool milk as it is produced, as well as energy to heat water needed to clean up after each milking,” says , Meridian’s Rural and Business Segment Manager.

“Mahana Blue is a brilliant device that uses waste energy from the milk to heat water, significantly reducing the power needed to heat water in a typical milking shed.”

The device has been installed on a Kurow (North Otago) dairy farm owned by Meridian Energy as part of a trial to improve the energy efficiency of the operation.

“The milking shed at this farm had two hot-water heaters drawing 12kW of power. With the Mahana Blue device installed this has dropped to 3kW and reduced the cost of heating the water to around one-third of what it was previously,” says .

Mahana Blue is described as a hot-water inverter. The idea came from a Kiwi engineer, who took it to refrigeration company Danfoss NZ.

Danfoss, which is the fourth-largest refrigeration manufacturer in the world, then built the Mahana Blue inverter. It is now being installed on New Zealand farms. Danfoss has both New Zealand and international patents for Mahana Blue to enable the product to be launched on the international market following success here in New Zealand.

Mahana Blue can be retrofitted onto existing standard milk refrigeration units and uses the energy the cooling milk releases to heat water to 85C from the incoming cold water source, including ground water, supply temperatures.

Currently, in an effort to save electricity costs many dairy farmers use cheaper night rates to heat the water needed for cleaning milking equipment and the milking shed. This means, however, that they may only have enough hot water for one clean-up and need to use cold water for the second clean-up. Such savings are very small in comparison to the utilisation of a Mahana Blue system during standard day rate periods

“The Mahana Blue device means that famers have hot water whenever they milk and the more milk produced the more hot water they have. In the Kurow milk-shed this has helped improve animal hygiene and milk quality,” says .

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