Initial 'Greening' Agriculture Energy Project Completed
Michael Reese, Eric Buchanan, Brad Heins, Joel Tallaksen, Kirsten Sharpe, and Lee Johnston (West Central Research and Outreach Center), Larry Jacobson (Dept of Bioproducts and Biosystems Engineering), Prodromos Daoutidis (Dept of Chemical Engineering and Material Science), and Laura Kalambokidis (Dept of Applied Economics)
A four year study to better understand the types and amounts of energies consumed in dairy and crop production was recently completed by researchers at the West Central Research and Outreach Center (WCROC) and in partnership with several key collaborators within the broader University of Minnesota. With this information, effective and optimized energy strategies were developed to reduce fossil energy consumption and the carbon footprint of these production systems.
Producing more food for the world’s growing population while having less impact is a grand challenge! Some of the potential impact of growing food is related to the manner in which energy is consumed in production agriculture. Large amounts and diverse forms of energy are used in the production of grain, meat, milk, and other agricultural products. Fossil-derived energy is the primary feedstock for electricity, propane, natural gas, diesel fuel, and gasoline used on farms. In addition, critical crop inputs such as nitrogen fertilizer are derived primarily from natural gas. Retailers and food processors are actively engaged in lowering the carbon footprint of their products as a response to outside concerns by consumer and environmental groups. The greatest progress in lowering the carbon footprint of agricultural products needs to occur on farms. The 'Greening' Agriculture Energy project began to address this emerging issue through the audit of energy consumed in crop and dairy production, the development of energy-optimized systems, and the evaluation of life cycle impacts, economics, and policy.
The initial IREE research project was developed into a series of five task which included:
Task 1. Conduct baseline energy audits and then develop and energy-optimized systems in conventional grazing dairy and organic grazing dairy as well as conventional and organic crop and pasture production
Task 2. Perform life cycle assessments in the conventional and organic dairy while comparing audited un-optimized with optimized energy systems.
Task 3. Evaluate the financial and economic feasibility of the energy-optimized dairy production system.
Task 4. Develop and evaluate policy options to encourage agricultural producers to adopt energy-optimized production systems.
Task 5. Deliver the knowledge and information gained to agricultural producers, energy professionals, and other stakeholders.
The first objective was to understand how much energy is used to harvest milk in a typical Minnesota dairy parlor, and where that energy is used, in the hope that a more energy efficient and cost effective system could be developed and implemented. During three years of data monitoring from late 2013 through 2016, the WCROC dairy produced about 340,000 gallons of milk per year milking an average of 207 cows per day. Collecting and cooling the milk, as well as cleaning the parlor and milking equipment, consumed an average of about 1.4 gallons of water and 2.8 megajoules of energy per gallon of milk. About 60% of the total energy consumed at the WCROC dairy parlor is used to heat the parlor and the water used to clean the parlor and milking equipment. About 15% of the total energy is used to collect and cool the milk. Results suggest these activities are the best places to improve energy efficiency and lower the fossil fuel demands of the milking parlor. New energy systems designed to harvest as much heat as possible from fresh milk and employ it to heat the large amount of hot water used daily in the parlor should reduce the overall energy footprint of milk.
The second objective was to determine the life cycle energy and greenhouse gas (GHG) impacts of feed and dairy production. The fossil energy and GHG impacts of crop production at WCROC were analyzed. Life cycle assessment (LCA) methodology was used to analyze a number of common agricultural crops grown using conventional or organic production systems. Inputs analyzed included tillage operations, pesticides, synthetic fertilizers, manures, and postharvest transport/processing. Preliminary fossil energy use and greenhouse gas emission impacts were analyzed for more than 10 crops. Nitrogen fertilizers were an important component of both systems and had significant impacts on systems. Use of diesel fuel for tractors was another important consideration. For organic systems, analysis of individual crops is complicated by the synergistic benefits of all the crops in the rotation. Therefore, organic and conventional crops were not directly compared. Future work will more accurately examine organic cropping as a system.
Dairy LCA efforts focused on the fossil energy and greenhouse gas emission impacts of the organic and conventional dairy production systems at the WCROC. The work was a cradle-to-gate look at production of milk from the growth of replacement animals to the storage of cold milk in a bulk tank. All inputs and outputs of animals at different stages were inventoried. Activities were grouped into two major areas, animal husbandry and milking operations. Animal husbandry data mainly focused on feed production, which relied heavily on findings from the cropping LCA work. The energy auditing work done in for this project was used to analyze the types and amounts of energy required to harvest milk. In terms of GHG emissions, enteric emissions were the largest single source. This was followed by manure nitrous oxide and methane emissions. In terms of fossil energy, the majority of fossil fuels used in the system were for the production of crops (feed). An analysis of the energy saving equipment added as part of this study found that it had a limited impact on the overall greenhouse gas emissions due to the large value attributed to feed production. These systems did reduce the milking operations fossil energy by up to 93%. However, fossil energy reductions in the cropping system inputs are needed to greatly reduce the overall fossil energy inputs in the dairy system.
Finally, the economics of adding energy efficient upgrades and renewable energy generation to Minnesota dairies were modeled. In general, energy efficiency upgrades had the lowest simple payback and return on investment. Renewable energy generation such as wind or solar can be economically viable for dairy producers if they are able to take full advantage of incentives created through state and federal policy. Policy and regulatory reform may be necessary to see widespread adoption.
Initial funding for this project was provided by the Initiative for Renewable Energy and the Environment (IREE). The IREE funding was then leveraged to develop significant funding to continue and expand the effort to ‘Green” energy consumed in production agriculture. The initial IREE project funding was directly and indirectly leveraged to develop an estimated $7.2 million with another $1.1 million of projects currently seeking final approval from the Minnesota legislature. These leveraged projects include audit and energy-optimization of swine production systems, further development of dairy renewable electric systems, expanded life cycle assessments, continued research into the production of renewable nitrogen fertilizer, and use of renewable anhydrous ammonia as a fuel for tractors and generators. The ultimate goal is to provide ag producers with research-based information they can effectively use to optimize energy systems on their farms. View more information and results of this project.
The researchers are grateful for the financial support provided by Institute on the Environment (formerly IREE), Rapid Agricultural Response Fund, Xcel Energy ratepayers through the Xcel Renewable Development Fund, and the Environment and Natural Resources Trust Fund via the Legislative Citizens’ Commission on Minnesota Resources (LCCMR).
Energy Guidebook for Dairies: optimizing energy systems for Midwest dairy production
Energy Decision Tool for Dairies (macro-enabled excel file)