improving life through science and technology. irrigated corn to ethanol net energy balance emily...
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Improving Life through Science and Technology.
Irrigated Corn to Ethanol Net Energy BalanceEmily Seawright, Ronald D. Lacewell, Naveen Adusumilli, Ed Rister, and Robert Taylor
Southwest Renewable Energy ConferenceSeptember 15, 2010
Biofuels
• Congressional Mandates
• Corn Ethanol
• Cellulosic Biofuels– High energy sorghum– Algae– Switchgrass
Myths
• Dedicated bioenergy crops will not affect conventional food crops– marginal lands only
• Food prices will not be impacted– Limitless high quality land– Small quantity of ethanol
Characteristics
• 18-22 inches of rainfall
• Corn, cotton, sorghum, soybeans, wheat
• Ogallala Aquifer– Depth varies– 81% of water within
400 feet of surface
http://www.hpwd.com/the_ogallala.asp
Objective
• Net energy balance of irrigated corn on the High Plains of Texas
Assumptions• Yield of 200 bushels/acre• Pumping depths of 250, 350, 450 feet• PSI of 25 and 45• Co-product credit of 15,400 BTUs• High Plains Crop budgets
– Center pivot—natural gas, strip till/natural gas, electricity
– Furrow—natural gas
Data
• Input quantities from crop budgets and literature
• Natural gas and electricity quantities calculated using Lacewell and Collins (1986)
– Natural gas
– Electricity
1,000 ft3 = (2.31*PSI)+Lift)]*[0.11427/(PE*DE)]*(0.002544/EE)
kWh = (2.37*PSI)+Lift] * [0.101141/PE)]
Lacewell, Ronald D., and Glenn S. Collins. 1986. “Energy Inputs on Western Groundwater Irrigated Areas.” In Energy and Water Management in Western Irrigated Agriculture, edited by Norman K. Whittlesey, 155-76. Boulder: Westview Press.
Calculating Net BTUs
BTUs from Ethanol
Co-product Credit
ProductionConversion
Net BTUs per Acre
Inputs for Production
Irrigation
Production
Two column with textResults of Energy Use per Acre for Each Enterprise
Budget at 350 Lift for 25 and 45 PSI in the High Plains of Texas
Energy Use – 25 PSI
Sprinkler-NG
Strip Till-NG
Furrow-NG
Sprinkler-Electricity
BTUs from Ethanol 44,688,000 44,688,000 42,560,000 38,304,000
Production 26,084,552 25,998,267 25,827,497 12,798,963
Conversion 34,632,024 34,632,024 32,982,880 29,684,592
Co-product Credit 15,400 15,400 15,400 15,400
Net BTUs (6,973,376) (6,887,091) (7,626,377) 3,582,045
Energy Use – 45 PSI
Production 28,191,344 28,105,059 --- 13,353,034
Net BTUs (9,080,168) (8,993,883) --- 3,027,974
Energy Use per Acre
Net Energy Balance—350 Lift and 25 PSI
Net Energy Balance—350 Lift and 45 PSI
Net Energy Balance by Pumping Depth
Net Energy Balance by Pumping Depth
Limitations
• BTU estimates taken from literature—many sources varied
Not ConsideredValue of mobile fuel for cars, trucks, and airplanes
Conclusions and Implications
• Electricity is more expensive…..
Thus, more natural gas is used on High Plains
• Ethanol from irrigated corn in High Plains has negative energy balance
Questions?
http://www.climateark.org/shared/alerts/send.aspx?id=corn_ethanol2
Shutterstock. February 19, 2009. http://www.faqs.org/photo-dict/phrase/1115/corn.html