Comparison on energy efficiency, carbon emissions, and cost implications of cross-flow, mixed-flow, and double-flow grain dryers in evaluating process sustainability

Addressing the need to optimize energy efficiency and reduce greenhouse gas emissions in high-temperature grain drying operations is crucial for the sustainability of the agricultural sector. This study investigated energy efficiency, carbon emissions, and cost implications of high-temperature grain drying systems commonly used on farms. Three dryer types were assessed over a three-year period with mixed-flow, cross-flow, and double-flow drying mechanisms. Data on grain moisture, temperature, ambient conditions, fuel consumption, and electrical usage were collected from five farms in Alberta, Canada. Results showed that energy efficiency ranged from 18-91%, with the double-flow dryer demonstrating the highest efficiency and the lowest energy consumption of 3.1-5.4 GigaJoule/tonne of moisture removed. Carbon emissions varied inversely with initial grain moisture, decreasing by 10.2% per percentage point increase in grain moisture content. Emissions per tonne of moisture removed increased with higher moisture removal rates. Cost analysis revealed that the carbon levy imposed on natural gas for drying surpassed the actual fuel costs by 25.4-71.3%, with projections indicating a 92-168% increase in carbon levy by 2030. In terms of cost per tonne of moisture removed, the double-flow dryer exhibited the lowest costs, ranging from CAD $63.5 to $91/tonne of moisture removed. However, mixed-flow dryers showed the highest costs, with values reaching up to CAD $162.3/t. These findings could provide valuable insights for farmers to enhance the sustainability and economic viability of grain drying operations.