By Brad Heins, WCROC Dairy Scientist, Kirsten Sharpe, U of MN Graduate Student, Animal Science, and Michael Reese, Renewable Energy Director
Consumer interest and concern is growing in regards to sustainability of livestock production systems. Demand for reduced carbon emissions within agricultural systems has been growing along with increasing demand for food. Baseline fossil fuel consumption within agricultural systems, including dairy production, is scarce. Therefore, there is a need to discern where and how fossil energy is being used within dairy production systems. Determining baseline energy use is the first step in investigating the demand for a reduced carbon footprint within dairy production systems. The objectives of this study were to measure total electricity use and determine specific areas of high-energy consumption in commercial dairy barns and milking centers located in the Upper Midwest of the United States.
Four commercial dairy barns representative of typical Midwest dairy farms and located in west central Minnesota were evaluated in the study. The dairy farms were: 1) a 9,500 cow cross-ventilated barn with a rotary milking parlor (Farm A), 2) a 300 cow naturally-ventilated barn with stirring fans for air movement and 6 automatic milking systems (Farm B), 3) a 200 cow naturally-ventilated barn with stirring fans for air movement and a parabone milking parlor (Farm C), and 4) a 400 cow naturally-ventilated barn with stirring fans for air movement and a parallel milking parlor (Farm D).
Electricity use was monitored from July 2018 to December 2018. Two-hundred ninety-two (292) electric loads across the four farms were monitored on the farm side of the electric utility meter to evaluate areas of highest energy usage. Some of the monitored electric loads included freestall barn fans, water heaters, compressors, chillers, manure pumps, and pressure washers.
Based on preliminary results, fans were the largest electrical load across all four dairy farms. Fan usage during the summer ranged from 36 to 59% of the total electricity measured. Regular maintenance, proper control settings, design, sizing, location, selecting energy efficient fans and motors, and other factors all could influence the efficiency of these ventilation/cooling systems. Farms B, C, and D had greater electricity usage across all months for milk cooling (compressors and chillers) than Farm A. This is likely due to the fact that Farm A does not utilize bulk tanks to store milk, but instead, milk is directly loaded onto bulk milk trucks. Lighting use ranged from 7 to 21% of the total electricity use measured across the four farms, which suggests there is potential to reduce energy usage by upgrading to more efficient lighting systems such as LEDs. For heating, energy usage includes water heating, heating units in the milking parlor and work rooms, and generator engine block heaters. Average monthly energy use for heating ranged from 5% of electricity used on Farm A to 32% of electricity used on Farm C.
The results of this study provide recent energy usage for farm energy benchmarks, agricultural energy policy, economic evaluations, and further research into dairy farm energy studies. The data will also be useful to producers who are searching for areas for reduced energy usage in their own production systems. Improving the efficiency of electrical components in dairy operations could provide opportunities to improve the carbon footprint of dairy production systems.