Comparison of Water and Energy Management Strategies on Two Wisconsin Dairy Farms

Abstract

Lactating cows drink between 11.0 and 17.5 gallons of water per cow per day. Confined animal feeding operations (CAFOs) are increasingly applying for large capacity well permits in order to accommodate CAFO livestock drinking needs. It is not uncommon to see over forty horsepower of well-pumping power used to supply water to CAFO-sized farms. Besides cow drinking, other major uses of water on dairy farms include pre-cooling milk and washing milk pipelines. Variable frequency drives (VFD) have been employed on CAFO well pumps in order to eliminate the need for large pressure tanks and to save pumping energy by only running well pumps at the needed pumping speed. This paper quantifies the volume of water (gallons) and the power (kilowatts) and energy (kilowatt-hours) used on two different CAFO dairy farms in Wisconsin. A comparison is made between a 2100-head dairy farm with a variable frequency drive-operated well pump and a 1750-head dairy farm with a single-speed well pump. Areas evaluated include overall power and energy consumption related to farm water use. Power monitoring data shows the CAFO dairy using a variable speed drive saves 22 kilowatts of well pumping power, typically running at 40% to 60% of overall horsepower, when compared to the CAFO dairy using single-speed well pumping.