Energy Monitoring in Gins - 2013 Update

Authors: Hardin Iv, Robert; Funk, Paul

Submitted to: National Cotton Council Beltwide Cotton Conference
Publication Type: Proceedings
Publication Acceptance Date: 2/22/2014
Publication Date: 3/6/2014
Citation: Hardin Iv, R.G., Funk, P.A. 2014. Energy Monitoring in Gins - 2013 Update. National Cotton Council Beltwide Cotton Conference. January 6-8, 2014. New Orleans, LA. 576-583.

Interpretive Summary: In a recent ginning cost survey, the average electricity and fuel cost per bale was $5.18. Energy costs were the second largest source of variable costs for cotton gins, accounting for a quarter of variable costs. Recent research has shown that average gin electricity use has decreased from near 50 kWh/bale to 40 kWh/bale. Fuel use has also decreased over time as control systems and burner designs have improved. These previous studies of gin energy use 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. Electricity use was monitored at two gins from 2010-2013. 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. Fuel consumption was estimated beginning in 2011 by measuring temperatures and air flow rates. The gins used 32.0 and 26.2 kWh/bale in 2012, similar to their electricity use in 2010 and 2011, but less than the average electricity use, 41 kWh/bale, reported in a recent survey. The gins used 1.57 and 4.04 L LPG/bale (0.41 and 1.07 gal/bale) in 2012. One gin used more fuel per bale in 2012, while the other gin required less, probably due to differences in weather. Processing rate was the primary factor affecting electricity use per bale and also significantly affected fuel use, with less energy required at higher processing rates. Seed cotton moisture and ambient temperature also affected fuel use. Different varieties of cotton ginned at significantly different rates; consequently, the energy used per bale was also different. Electricity used by different gin stand components indicated that further research needs to be conducted to improve gin stand controls to maximize processing rate while maintaining fiber quality. Variety effects were consistent from 2011 to 2012. Managers should operate gins at full capacity as frequently as possible and avoid idling equipment for long periods. Seed cotton needs to be properly stored so that cotton enters the gin at a desirable moisture content, thus reducing fuel use and maximizing processing rate.

Technical Abstract: Energy, comprised of electricity and fuel, is the second largest source of variable costs for cotton gins, after labor. Few studies of gin energy use have been conducted recently and none have monitored energy use continuously throughout the ginning season. More detailed information is needed to identify management strategies and design systems that can reduce energy use. Electricity use was monitored continuously throughout the 2010-2012 ginning seasons at two gins, and fuel use was also calculated from air flow and temperature measurements during the 2011 and 2012 ginning seasons. Electricity use averaged 32.0 kWh bale-1 and 26.2 kWh bale-1 in 2012, similar to results from 2010 and 2011. LPG use was 1.57 L bale-1 (0.41 gal bale-1) and 4.04 L bale-1 (1.07 gal bale-1). Greater variation was observed in fuel use, both within a ginning season and between years. Cultivar had a significant effect on processing rate, electricity use, and agitator tube motor current. Further research is needed to identify the optimum process rate for different cultivars and develop improved gin stand control systems. Higher processing rates reduced electricity and fuel use per bale for all years at both gins. To reduce energy costs, gins should be operated at maximum capacity as often as possible and equipment should not be left idling during significant downtime.