ARS | Publication request: Electricity use patterns in cotton gins

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 21, 2012
Publication Date: December 21, 2012
Citation: Hardin IV, R.G., Funk, P.A. 2012. Electricity use patterns in cotton gins. Applied Engineering in Agriculture. 28(6): 841-849.

Interpretive Summary: Energy costs are the second largest source of variable costs for cotton gins, with electricity accounting for 18% of variable costs. Energy use has typically not been a major consideration in gin design; consequently, a significant opportunity exists to improve gin profitability by reducing energy use. Studies of gin energy use have been conducted previously; however, this research only used data from utility bills or a single measurement during the ginning season. More comprehensive research is needed to understand causes of variation in electricity use at gins and identify specific opportunities in gins for energy conservation. In this study, electricity use was monitored throughout the entire season for several gins across the cotton belt. Motor loads were recorded for the large motors in gins: gin stands, fans, cleaning machinery, module feeders, and bale presses. Total power consumed by the gins was also monitored. The gins monitored in 2010 averaged 35.8 kWh/bale, slightly less than the average electricity use, 40-56 kWh/bale, reported in past surveys. Differences in electricity use between monitored gins were likely due to differences in layout and installed equipment. Because electricity use was continuously measured throughout the ginning season, a model of the effect of processing rate on electricity use per bale was developed. Managers should operate gins at full capacity as frequently as possible and avoid idling equipment for periods longer than several minutes. Material handling uses over one-half of the electricity in gins because pneumatic conveying is inherently energy intensive. Replacing fans used for pneumatic conveying with mechanical conveying systems can significantly reduce energy use.

Technical Abstract: Energy costs are the second largest source of variable costs for cotton gins, with electricity accounting for 18% of variable costs. Energy use has typically not been a major consideration in gin design and previous studies of energy use have utilized instantaneous readings or aggregated season-long values. In this study, electrical energy use was monitored throughout the entire season for several gins throughout the cotton belt. Motor loads were recorded for gin stands, fans, cleaning machinery, module feeders, and bale presses. Power consumption and power factor were recorded at motor control center disconnects. The gins monitored in 2010 averaged 35.8 kWh bale-1, slightly less than the annual average values reported in past surveys. Differences in electricity use between monitored gins were likely due to differences in layout and installed equipment. The primary factor affecting electricity use per bale at a specific gin was the processing rate. For maximum energy efficiency, cotton ginners should operate at full capacity as frequently as possible and avoid idling equipment for periods longer than several minutes.