2018-19 Rapid Ag: Development of Low-Carbon Footprint Energy Systems for Swine Production Facilities

May 31, 2017

Principal Leader

Lee Johnston


West Central Research and Outreach Center at Morris

Funding Awarded

  • 2018 Fiscal Year: $108,170 
  • 2019 Fiscal Year: $65,254

The Problem

Timely research is required as food processors and retailers are increasingly stating their new mission to reduce the carbon footprint of food products. For example, Smithfield Foods, the world’s largest pork producer, recently announced its “commitment to reduce greenhouse gas emissions in its supply chain 25% by 2025.”(Schmitt, 2016)1 To achieve these significant reductions in greenhouse gas emissions, a paradigm shift is necessary in the methods used to produce feedstuffs and in the design of how energy is produced and consumed on hog farms. If greenhouse gas emission targets such as those proposed by Smithfield Foods are to be realized, swine producers need innovative, proven designs for a wide range of electrical and thermal energy applications.


In 2012, the West Central Research and Outreach Center (WCROC) established a goal to reduce fossil energy consumption and the carbon footprint of production agriculture. Several researchers across the University are leading or collaborating on projects to meet this goal. The WCROC provides an excellent location for this work with the combination of renewable energy, crop, dairy, and swine research programs co-located at the Center. These applied research programs provide the production facilities necessary to:

  1. Establish baseline energy consumption using conventional energy systems at WCROC and on-farms
  2. Design and evaluate improved energy systems and processes
  3. Conduct life cycle assessment to quantify progress made towards reducing carbon footprints
  4. Demonstrate to producers the technology and how it may be applied on farms

Through energy auditing and life cycle assessment of crop (feed) and swine production systems, our research team has determined that the feed pigs eat is the largest contributor to the carbon footprint of pork production. Our project team currently has several projects underway focused on reducing the carbon footprint of feed consumed by pigs. In commercial pork production, feed is often purchased so the carbon footprint contribution of feed is often out of the direct control of swine producers.

Even though a smaller contributor than feed, significant progress can be made by improving the manner in which energy is generated and consumed on pig farms. Cost-effective, on-site generation of clean energy has become more viable in the last decade and costs for renewable energy systems continue to decrease. Solar photovoltaic systems have decreased significantly in price over the past decade and, with new incentives, may be a viable option for on-site energy generation at hog farms. Research at the WCROC indicates that it is possible to generate all the annual electrical energy required for a finishing barn by installing solar PV on the entire southern half of the barn roof. Moreover, research results from on-farm energy audits conducted at six Minnesota commercial swine facilities over an 18-month period have shown that energy consumed for piglet heat lamps is one of the largest energy loads within the pork production system. Heat lamps for piglets are responsible for 44 to 46% of the total electric consumption and 29 to 34% of the total direct fossil energy consumption when thermal heat (propane) is also considered.

As part of a current sponsored project at WCROC, our research team is installing a system for cooling post-farrowing sows using chilled water circulated under pads placed in the floor of farrowing stalls. The sows will be cooled by transferring their body heat to the cool water circulating in the pads. Additionally, sows will be supplied with cooled drinking water through standard nipple waterers. Chilled drinking water provided to sows has been shown to improve feed intake and performance (Jeon et al, 2006, 2014).3,4 This cooling system will be powered by a 20 kW solar PV system mounted on the roof of the farrowing building. Our team was awarded a grant through the MN Environment and Natural Resource Trust Fund (ENRTF) to design and study these two innovative methods for cooling sows. We anticipate 

the cooling systems will lower ventilation rates and thus emissions of odor and greenhouse gases, and reduce water usage. These outcomes will lower the carbon footprint of Minnesota-produced pork. Considering the important research findings that piglet heat lamps consume significant quantities of fossil energy, we now propose to address this issue by transferring heat removed from sows to piglets via a heat exchanger and a heat pump. The heat collected from the sows via cooling pads will warm water that will go through the heat pump and then be circulated through the pads that piglets lie on in the creep area of the farrowing stall to provide warmth. With warm creep pads for piglets to lie on, we expect heat lamp use to be reduced drastically or maybe even eliminated. Creep pads designed for circulating warm water are currently available commercially. Our coordinated approach to managing heat (cooling sows and warming piglets) will efficiently keep sows and piglets in their distinctly different thermal comfort zone, improve animal welfare, enhance sow and piglet performance, and better utilize the power generated by on-site solar PV systems. In the long-term, we believe this approach will add to the incremental improvement in reducing the carbon footprint of pork. This proposal to the RARF is timely in that we can save money by installing and evaluating the sow cooling and piglet warming systems concurrently. Research will be conducted in the WCROC farrowing facility. A second focus of this proposed study is the comparison of the warm water piglet pads with electric piglet heating pads. We are anticipating questions from swine producers such as “how do warm water piglet pads compare to electric heating pads? Which type of piglet heating pad is more cost effective?” The research team will evaluate the heating performance of both pads, pig performance and behavior, energy consumption, and capital costs associated with both systems. We will address the questions of which system is more easily operated and maintained, which is more energy efficient, and which is more cost effective especially considering the use of on-site solar electricity to power the systems. Evaluation of warm water and electric heating pads allows us to use electricity generated by the on-site PV system during seasons that do not require cooling of lactating sows.


Johnston and his team plan to lower the carbon-footprint of pork production by developing and evaluating innovative methods of using on-site renewable energy generation to heat piglets. This project builds upon several years of research and sponsored projects with the overall goal of reducing fossil energy consumption in production agriculture and the carbon footprint of agricultural products. Specific project objectives include:

  1. Design, install, and test pads for warming piglets using heat collected from their heat-stressed mothers.
  2. Determine if the pads improve both piglet and sow comfort using video-recordings of piglet and sow behaviors
  3. Perform life cycle analysis of the novel system versus the conventional heating system
  4. Compare warm water pads with electric pads for heating piglets.


  1. Schmitt, J., 2016. Trimming the Pork: IonE research guides first major meat industry GHG reductions. Http://environment.umn.edu/discovery/trimming-pork-ione-research-guides-first-major-meat-industry-ghg-reductions/
  2. Johnston, L., 2016. Reducing fossil fuel use in swine - one piece at a time. Presentation. National Pork Board Swine Educators Conference. St. Louis, MO. September 27, 2016
  3. Jeon, J.H., Yeon, S.C., Choi, Y.H., Chang, H.H., 2006. Effects of chilled drinking water on the performance of lactating sows and their litters during high ambient temperatures under farm conditions. Livest. Prod. Sci. 105:86-93
  4. Jeon, J.H. and Kim, D. H., 2014. Methods to Supply Chilled Drinking Water for Lactating Sows During High Ambient Temperature. Italian Journal of Animal Science, 13:4, 341, DOI:10.4081/ijas.2014.3431