ARS | Publication request: Cotton gin electrical energy use trends and 2009 audit results

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 31, 2012
Publication Date: May 23, 2012
Citation: Funk, P.A., Hardin IV, R.G. 2012. Cotton gin electrical energy use trends and 2009 audit results. Applied Engineering in Agriculture. 28(4):503-510.

Interpretive Summary: Energy costs are of concern to the US cotton ginning industry (as they were during the transition to automation in the late 1950’s and during the energy crisis in the late 1970’s). This paper summarizes the past half century of published work related to electrical energy use in cotton gins. It also reports original research conducted by the USDA-ARS cotton ginning laboratories measuring electrical power and energy at each motor (typically over 90) for post-harvest processing of cotton at twenty locations selected for their diversity, including capacity (17 to 72 bales h-1), throughput (5,000 to 70,000 480 pound bales) and geography (CA, NM, TX, MS, MO, AR). There has been a slight decrease in the energy used by cotton gins, partly because of more efficient motors and operations and partly because of reductions in air handling. These improvements came despite the increased energy demanded by more stringent air quality regulations. There is no silver bullet - reducing energy requirements in an already efficient industry will come from keeping processing plants operating at maximum capacity, reducing down-time,modest improvements to hardware and control systems and eliminating the few pneumatic conveying systems that may be replaced with alternate materials handling technology.

Technical Abstract: Cotton gin energy costs have risen more than other operating costs. Energy audits were conducted in twenty US cotton gins representing a range of capacities in six states. The average participating saw gin used 39.5 kWh to process a bale. The average roller gin used 62.6 kWh. Gins have become larger, from a connected power of 570 W (764 hp) in 1962 to over 2237 W (3,000 hp) today. Energy costs are a larger proportion, 20% of the total cost of ginning, compared to 6 to 10% of the total in the 1970’s, even though energy consumed per bale processed is less, approximately 73% of the electricity consumed in 1982. Connected power and energy consumption were allocated to five categories: seed cotton cleaning, ginning, lint cleaning, bale packaging and materials handling. Materials handling accounted for the largest portion, over half of the electricity consumed by a gin, as it has since the 1960’s. Since the 1980’s the power and energy allocated to ginning has decreased slightly, and that allocated to lint cleaning has decreased significantly. Best practices still include: operating at full capacity; avoiding down time; reducing fan load; minimizing materials handling burden and improving electric motor efficiency.