Improving Life through Science and Technology. Irrigated Corn to Ethanol Net Energy Balance Emily Seawright, Ronald D. Lacewell, Naveen Adusumilli, Ed Rister, and Robert Taylor Southwest Renewable Energy Conference September 15, 2010

Biofuels Congressional Mandates Corn Ethanol CellulosicBiofuels –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 inches of rainfall Corn, cotton, sorghum, soybeans, wheat Ogallala Aquifer –Depth varies –81% of water within 400 feet of surface

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 ft 3 = (2.31*PSI)+Lift)]*[ /(PE*DE)]*( /EE) kWh = (2.37*PSI)+Lift] * [ /PE)] Lacewell, Ronald D., and Glenn S. Collins “Energy Inputs on Western Groundwater Irrigated Areas.” In Energy and Water Management in Western Irrigated Agriculture, edited by Norman K. Whittlesey, Boulder: Westview Press.

Calculating Net BTUs

Inputs for Production Irrigation

Production

Two column with text Results 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 PSISprinkler-NGStrip Till-NGFurrow-NGSprinkler- Electricity BTUs from Ethanol 44,688,000 42,560,00038,304,000 Production 26,084,55225,998,26725,827,49712,798,963 Conversion 34,632,024 32,982,88029,684,592 Co-product Credit 15,400 Net BTUs (6,973,376)(6,887,091)(7,626,377)3,582,045 Energy Use – 45 PSI Production 28,191,34428,105, ,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

Limitations BTU estimates taken from literature—many sources varied Not Considered Value 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? Shutterstock. February 19,