Dairy Energy Use from an LCA Perspective

August 19, 2015

By Joel Tallaksen, Renewable Energy Scientist

WCROC DairyOver the last two years, the dairy program at the West Central Research and Outreach Center (WCROC) in Morris has collected data about how energy is used in the Center’s dairy operations.   This included all the electricity, natural gas, and petroleum products used directly in animal care, along with the indirect energy used to grow feed for the dairy.  As the research goes forward, we are beginning to add new energy saving equipment, renewable energy production, and practices to help lower the energy requirements for our dairy operations.  One of the goals in collecting this data was to perform a life cycle assessment (LCA) study on our dairy products.  The main questions we are seeking to answer:

  • How do changes in milking system equipment and animal care impact the carbon and fossil energy footprint of the WCROC dairy operation?
  • What are the differences in carbon and energy footprints between the WCROC organic and convention dairy production systems?
  • What further improvements in the dairy system could reduce environmental impacts?

Using the first two years of data, a preliminary LCA model has been developed for the organic dairy system.  In terms of fossil energy use in the organic system, milk harvesting operations used more than herd feeding/maintenance (Figure 1), 5400 and 3330 BTU per gallon of milk respectively. We have already identified equipment that is more efficient that what we are currently using.  This suggests that fossil energy use per gallon of milk could be greatly reduced by replacing older equipment with new, more efficient technology or substituting renewable sources of energy into the milk harvesting process (Figure 2).  In fact, a new scroll compressor installed to replace an older failed piston compressor reduced fossil energy use per kg of milk by roughly 3%.  These savings have a fairly quick payback and could help a farmer’s bottom-line.

Another important consideration is carbon dioxide emissions, otherwise referred to as greenhouse gas or carbon footprint.  Carbon footprint is likely to play and increasing role in agricultural policy, but is already impacting marketing of some agricultural products.  In examining the WCROC dairy carbon footprint (Figure 3), it was found that emissions related to animal husbandry were higher than for milk harvesting operations, 8.91 and 0.58 lbs CO2 per gallon respectively.  Reducing GHG emission is more difficult as manure management and enteric (digestive) gases are a major component of GHGs.  We are planning to examine more areas that might reduce the carbon footprint as we continue our study.

More information is available at the WCROC renewable energy home page.

LCA Graph, dairy parlor

Funding for this work has come from a number of sources, including: the Legislative and Citizens Committee on Minnesota Resources, Rapid Ag Response Fund (Univ. of Mn), and IREE (Univ. of Mn).