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