Hot Water, Energy and the Milking Centre
Table of Contents
Milking centres on dairy farms are some of the largest users of energy in Ontario agriculture. Most of the energy is used to heat the water for cleaning the milk contact surfaces of the milking equipment and the bulk tank.
Bulk tanks are washed usually every second day, and the milking equipment and pipelines usually twice a day. The bulk tanks and milking equipment are cleaned, typically using four cycles: rinse (usually warm water, which is half hot and half cold), wash (hot water), acid rinse (may be warm or cold water) and sanitize (cold water).
MSTOR estimates the average volume of water used per day to be 14 L (3.1 gal (imp)) per milking cow for tie stall pipeline systems and 17 L (3.7 gal (imp)) per milking cow for free stall parlours.
Approximately 360,000 cows are milked daily in Ontario1. Assuming half of the cows are milked in tie stalls and half in parlours, and using the average volumes of water as estimated above, over 5.5 million L (1.2 million gal (imp.)) of water are used daily in the milking centre (see Table 1). Of this volume, approximately 75% is used for maintaining the milking equipment and pipelines2; 12% for the bulk tank2; and the remainder (13%) for floors, water conditioners, etc. These volumes are assumed to be half hot water and half cold water. Each farm is different, so a particular dairy farm needs to measure its actual volumes to obtain more accurate figures.
This example, which uses reasonable assumptions as described above, estimates the hot water used annually in Ontario milking centres and the resulting hydro usage, assuming no heat-reclaiming equipment is used. The number of farms that use heat reclaimers is unknown.
Well water is usually around 10°C (50°F), and hot water tanks are usually set at about 77°C (170°F). Therefore, heating well water to the proper temperature requires a rise of 77°C - 10°C = 67°C (170°F - 50°F = 120°F).
To heat 1,018,350,000 L of water 67°C requires 79,601,025 kW-h (see endnote3). If electricity costs 12 cents per kW-h, the cost is approximately $9.6 million annually to heat the hot water in all the milking centres in Ontario.
There are many ways to reduce the energy required to heat water. Listed below are some ideas that producers can investigate further for their operations.
2 H. Cuthbertson et al. Milking Centre Waste Management in Ontario. CSAE Paper No. 95-513. (Mansonville, QC: CSAE/SCGR, 1995).
3 Equations used:
4 Dairy Farmers of Ontario
5 Dairy Farmers of Ontario
This Factsheet was reviewed by Jake DeBruyn, P.Eng, OMAFRA, Guelph.
This Factsheet was developed with sponsorship from Hydro One and in partnership with the Ontario Power Authority, the Ontario Federation of Agriculture, the Ministry of Energy and the Ministry of Agriculture, Food and Rural Affairs.
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