Energy efficiency - podcast transcription

Energy efficiency

Greg: Welcome to Dairy News. I’m Greg Mills and today I have with me Tony Dowman. Energy costs. Everyone sees their electricity bill rising from time to time, so is there something we can do about these energy costs on a dairy farm?

Tony: If we look at the energy specifically in the dairy shed, a large amount of that energy is consumed in cooling the milk and in heating the water which seems a bit weird when we’re busy taking heat out of milk to put into the atmosphere and then we’re using electricity to put heat into cold water.

So those are the two large areas of electricity consumption in the dairy. Other areas of course are the vacuum pumps and other pumps which are producing pressurised water or vacuum for the plant and there’s some ways that we can actually incorporate a bit newer technology to overcome the energy consumption in these parts of the dairy.

Hot water for argument’s sake, there are heat reclaiming units that you can buy. Unfortunately not very cost effective to transfer the heat out of the milk directly into your water to save on heating costs. There are new technology in the form of heat pumps which can actually extract heat either from the ground or from the air and put it into your water. They have their limitations. They can only get to about 60 degrees Celsius. They struggle in winter time to find enough heat to actually put enough heat into your water.

Solar’s been around for a long time. Again, they have limitations on the volume that they can produce at the right temperature, because most dairy farms require some water at least between 80 and 90 degrees Celsius and either heat pumps or solar hot water units can produce water at that temperature.

Other energy savers can be variable speed pumps on your vacuum pump or your milk pump and they basically speed up and slow down depending on what the demand is for pumping milk or for supplying vacuum which saves a few dollars in your electricity bill. But again, you have to pay for variable speed motors.

Greg: Tony what about utilising off peak electricity? That’s available but may not fit in with your times of milking. So is there some way we can take advantage of off peak rates?

Tony: Yes you can. We can actually generate all our cold for want of a better term, using off peak power at night time. So we can actually cool a large quantity of water or glycog or a smaller quantity of ice such as that used in ice banks using cheap electricity at night time. Then use this stored cold to remove the heat from the milk during milking periods.

Again, you’ve got to pay for that sort of technology and that capacity that you need to store that amount of cold. So, it is done. It’s been done for a long time, thermal storage, nothing new there but it is definitely another option.

Greg: Is there some sort of volume of production that you need to be having to consider some of these options?

Tony: No it’s not. Basically the bigger the farm, the bigger the thermal storage that’s required. You need about two and a half to three times as much water to go through a plate cooler as you’ve got milk. What you’ve got to do is then say well if I’m producing 3,000 litres of milk a day, I need up to about 9,000 litres of chilled water a day to cool the milk down.

So you do the calculations, work out what it’s going to cost to build that thermal storage system and then say "Is that cheaper than just paying commercial rates for electricity 24 hours a day?"
 
Greg: How cold do I have to get that water to make that system work?

Tony: Your milk has to be stored below four degrees Celsius. What most heat exchange units try to take milk down to about one degree Celsius which means your bulk milk storage fat doesn’t do any cooling. It just maintains the temperature and is basically a huge insulation bat and there’s very little refrigeration going on by the vat itself. All the cooling is done on the heat exchanges.

Greg: Tony, is there a way of getting cheaper electricity if you can’t implement any of these other situations because of cost reasons?

Tony: The electricity supply industry has been deregulated for a number of years now and it’s only a phone call to see whether somebody else can supply you with cheaper electricity. The other option you’ve got is in the form of collective bargaining. If a number of farmers can get together and say "This is the amount of electricity we want to buy at a better price," maybe there’s some savings to be made by a bulk deal.

Greg: Thank you Tony.

Tony: No worries.

Disclaimer

Users rely on the information in this podcast at their own risk. The Department of Industry and Investment and the State of NSW do not warrant nor represent that the information is complete, current, reliable nor error free, and they disclaim all liability concerning the podcast to the extent permitted by law. Details about disclaimers, privacy and copyright are available on our website at www.dpi.nsw.gov.au/legal or by calling 02 6391 3552.

Return to the dairy podcast page