The typical dairy farm uses large amounts of energy in the milking activity. The high energy consumption is due to the frequency of milking and the energy intensive nature of collecting milk, keeping it cool, and cleaning the equipment. Renewable energy systems generally become more economically efficient as the amount of energy used increases, making dairy farms a great place to incorporate on-site generation.
The average dairy farm is energy inefficient, often using expensive fossil-fuel sources such as heating oil or propane to heat water. One of the difficulties encountered with renewable energy systems is that they produce energy intermittently while the load on a dairy farm is very consistent, since cows are typically milked twice every day (large dairies might milk continuously). An efficient energy storage technology and system could significantly improve the feasibility of renewable energy on dairy farms. A dairy farm's need for both heat and electricity provides an ideal situation to evaluate thermal storage as a renewable energy solution.
The West Central Research and Outreach Center (WCROC) dairy milks between 200 and 280 cows twice daily and is representative of a midsize Minnesota dairy farm. The WCROC dairy provides an ideal testing opportunity to evaluate and demonstrate the effect of on-site renewable energy generation and energy-efficient upgrades on fossil fuel consumption and greenhouse gas emissions. The existing dairy equipment is typical for similarly sized dairy farms.
Greening of Ag: Improving Energy Use
Based on our initial audit of the dairy parlor at the WCROC in 2013-2014 as part of our Greening of Ag Initiative, we developed a two-prong approach in order to develop a “net-zero” dairy parlor where the same amount of energy consumed is also produced on-site through wind and solar power generation.
Identify energy inefficiencies to reduce the amount of power being used by the system. For example, we installed a variable frequency drive in the milking parlor. A variable system matches the motor system to the demand in order to reduce the total electrical load as opposed to having the drive run at full speed even when the system doesn’t demand it.
Install renewable energy components to the dairy parlor:
- Heat pump – collects the heat from the milk as it’s harvested (at approximately 100 degrees F), and stores it in a 2,000 gallon thermal storage tank.
- Solar thermal collectors – collects solar energy and stores it in the thermal storage tank. The panels are located just outside of our dairy facility.
- Heat exchangers – devices that transfer heat between a warm substance and a cold substance. Used to put heat into the storage tank and remove it for pre-heating water to properly sanitize milking equipment.
Part of our initial research included completing a Life Cycle Assessment (LCA) of our dairy parlor energy use; find out more about step 2.
The installation two small-scale, 10 kW wind turbines and 54 kW of solar PV panels. At 70 feet tall, the turbines will help generate enough electricity with the ground mounted solar PV system to make the milking parlor “net-zero.” The turbines are a downwind design, and are mounted on tilt-down monopole towers allowing for easier access. Find out more about this phase of the project.
Once everything is in place, we can begin to operate our milking parlor with the goal of generating as much energy as we use. View the renewable energy generation and storage schematic diagram (PDF).
Funding for this project is provided by Legislative-Citizen Commission on Minnesota Resource (LCCMR), U of MN Agricultural Research Response Fund, and Xcel Renewable Development Fund.
- Energy Consumption in Commercial Midwest Dairy Barns (2019)
- Renewable Energy Systems for Dairy: a 2017 update
- WCROC Dairy: powered by solar and wind energy (PDF)
- WCROC Net Zero Energy Dairy Barn (PDF)
- WCROC Researchers work to make milk greener (MPR News)