Energy Efficiency Studies Show How Greenhouses, Dairy Farms Can Increase Use of Renewable Energy Sources

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The Colorado Department of Agriculture (CDA) partnered with the Colorado Energy Office (CEO) and the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) to study ways of improving energy efficiency in agricultural settings. Led by NREL’s Joint Institute for Strategic Energy Analysis (JISEA), the two studies explore how to use anaerobic digestion and solar energy as alternatives to conventional energy production. 

“As we deal with the intensifying effects of human caused climate change, it's important we look for new ways to reduce the cost of energy in food systems, reduce emissions, increase food production in areas with little or no access to grid electricity, and increase food resilience and security,” said Liz Weber, JISEA project manager and analyst at NREL. “These two studies offer insights into how to use emerging research for power generation and energy storage on farms and in greenhouses to increase sustainability and the use of renewable energy.”

The first study looked at how greenhouses can improve energy efficiency in controlled environment agriculture (CEA), which tends to be extremely energy intensive. Right now, most of this energy demand is served by fossil fuels. Greenhouses are critical to ensuring agricultural successes in arid, arctic, and urban locations, because they allow for precise control over water and nutrient cycles, shelter crops from adverse weather conditions and pests, and maximize crop productivity. Finding ways to increase reliance on sustainable and renewable energy will ensure more stable, reliable, and resilient energy sources for greenhouses. 

“There is no one-size-fits-all solution for greenhouses, but the appropriate combination of technical and non-technical heat and power generation could improve the sustainability and resilience in the face of climate change and evolving industry,” said Gail Mosey, the lead researcher in the study from NREL.

The second study focused on how anaerobic digestion, which occurs when specific types of microorganisms break down organic matter in the absence of oxygen to produce biogas, can power agricultural operations. To produce the case study, researchers looked at how existing dairy farms can generate energy from animal waste to improve air and water quality while reducing greenhouse gas emissions. 

“Through our research, we’ve found that an anaerobic digester system at the Aurora Organic Dairy could produce enough energy to meet all the farm’s electricity demands and export up to two megawatts back to the grid, producing enough energy to heat approximately 216,000 gallons of water per day,” said Darlene Steward, the study’s lead researcher from NREL. “In addition, if dairies use their own renewable natural gas, the dairy farms could significantly reduce their CO2 emissions from fossil fuels and manure management, while completely meeting and even surpassing their needs of fueling the milk truck fleet.” 

According to the U.S. Environmental Protection Agency Inventory of U.S. Greenhouse Gas Emissions and Sinks report, methane emissions from livestock manure management accounted for an estimated  9.5% of total anthropogenic methane emissions in the United States in 2019, with beef and dairy cattle emitting more methane than any other domestic animal type. This means the agriculture sector is uniquely positioned to be a leader in reducing greenhouse gas emissions: the study modeled the anaerobic digestion system based on 10,900 milking cows, showing the Aurora Organic Dairy could create pure natural gas (methane) equivalent to 1.34 million gallons of gasoline per year. 

You can see the Anaerobic Digestion study and the Renewable Energy study on the JISEA page.

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