September 5, 2017 at 3:32 p.m.

Going green

WCROC hosts Midwest Farm Energy Conference

By by Missy Mussman- | Comments: 0 | Leave a comment

MORRIS, Minn. - Renewable energy and energy efficiency projects for dairy operations were the focus of a three-day energy conference held at the West Central Research and Outreach Center (WCROC) on June 18 near Morris, Minn.
"We have a great opportunity to study renewable energy on our dairy operation at the WCROC," Brad Heins, an assistant professor who works with the dairy herd at the WCROC, said.
The WCROC has been working diligently on their energy efficiency project by conducting baseline data for the energy consumption on the campus dairy.
"So many producers don't know how much energy they are using on their dairy operations," Heins said. "By doing the baseline data collection, you get an idea of what is going on."
The data revealed where a majority of the energy was being used throughout the operation, including lighting, ventilation, washing and water heating, feed handling, manure handling, water pumping and compressed air.
"But the greatest amount of energy used is from cooling and harvesting the milk," Heins said. "According to a study at NATC in Ithaca, N.Y., those two areas combined make up 40 percent of the electricity used on farms."
The WCROC uses approximately 100,000 kWh per year, 4,500 therms per year of natural gas for the furnace and water heater and close to 200,000 gallons of hot water per year.
"Milking is energy intensive," Eric Buchanan, a renewable energy scientist with the WCROC, said.
Since the WCROC dairy has two bulk tanks to store the organic and conventional herds' milk separately, they were able to see the difference in energy used in a scroll compressor, which is a new type of compressor, versus the reciprocating compressor - an older system.
The reciprocating compressor used 1.08 kWh per hundredweight to cool the milk and the scroll compressor only used .73 kWh per hundredweight.
"That's a 32 percent drop," Heins said. "That's a lot of money saved with that much difference. The old compressor sucks a lot of energy."
They also installed a variable frequency drive (VFD), to the vacuum pump in the parlor matching the motor speed to the actual demand.
"When we installed the VFD, we went from using around 55 kWh and dropped it down to 12 to 15 kWh," Heins said. "That was a huge drop in energy usage."
Currently, they are installing an electric heat pump, which will obtain heat from solar thermal collectors and the refrigeration heat recovery from the bulk tank and waste lagoons. They are also installing a 2,300-gallon thermal storage tank, which will use stored heat to pre-heat all water to the proper temperature.
Other items they are hoping to install within the next year are solar PV panels and a wind turbine.
"We want to make our energy loads as efficient as possible, convert all our thermal loads to electricity and add renewable energy systems and storage to meet our demand to reach net zero," Buchanan said. "For dairy producers the big thing they need to look at besides making their energy loads more efficient is to also be as practical as possible. It's not always economical to do certain projects."
The WCROC is working to conduct a Life Cycle Assessment (LCA), which is a system that calculates a single score to quantify the environmental impacts for items and the systems used to build them.
"Global warming potential and fossil energy usage are the biggest environmental impacts people look at, especially with agriculture," Joel Tallaksen, a renewable energy scientist at the WCROC, said. "The LCA can help determine if it's a sustainable practice."
Doing the LCA on dairy systems, Tallaksen examines all the inputs such as feed, fuel, electricity and water, and all the outputs such as milk, meat, manure and emissions of carbon dioxide and methane.
The LCA was completed for the organic dairy herd. Their carbon footprint value was 1.12 kgl of carbon dioxide with 63 percent of that value coming from enteric emissions and 17 percent coming from manure management. The overall fossil energy footprint was 2.35 megajoules per kg of milk with 60 percent of the energy coming from milk harvesting operations and 40 percent coming from feed production.
According to Tallaksen, the preliminary findings from the WCROC's dairy system seem reasonable given the large variability in Dairy LCA studies.
"The carbon footprint will be difficult to improve because of the amount of enteric and manure storage emissions," Tallaksen said. "But energy optimization systems will likely change the fossil energy footprint significantly."
For the WCROC, reducing the fossil energy footprint is the goal.
"We are working towards 'greening' our dairy's energy usage here," Heins said.
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