Ethanol Featured Articles
Reducing Global Warming Impact of Ethanol Production
The global warming impact of the production of ethanol at the Illinois River Energy Center is significantly less than the average ethanol production plant in the US, writes Chris Harris, Senior Editor for TheBioenergySite.
According to a report from the University of Illinois, the amount of global warming produced by production at the Illinois River Energy Center is anything between 21 per cent and 32 per cent less than the general outputs for ethanol production.
The study, "The Global Warming and Land Use Impact of Corn Ethanol Produced at the Illinois River Energy Center" by Steffan Mueller at the University of Illinois Energy Resources Center, together with Ken Copenhaver from the Institute for Technology Development and Michelle Wander from the University of Illinois at Urbana-Champaign looked at 29 corn growers supplying the Illinois River Energy Center with corn and it examined their growing and agricultural practices.
The study used the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) Model to examine the global warming impact of the plant and the growers during the year from March 2007 to February 2008.
During this time at total of a total of 272 growers delivered directly to the Illinois River Energy Center, accounting for about 75 per cent of the Illinois River Energy Center's total corn feedstock of 20,450,000 bushels. The remainder is sourced from grain elevators.
The 29 growers examined in the study accounted for about 12 per cent of the Center's feedstock - a total of 2,528,850 bushels of corn which represents 6.9 million gallons of ethanol production. The 29 growers, used in the survey delivered varying amounts of corn to the energy plant - varying between 8,000 bushels and 355,000 bushels.
The survey also took into account the different areas the growers and corn came from.
The 29 showed that their yield of corn over the last three years has gradually increased from 167.4 bushels per acre in 2005 to 196.1 bushels per acre last year. The rise in yields was reflected not just across the whole of the studied group but individually as well.
The survey also looked at the methods of tillage used - conventional, no tillage, minimal tillage or strip tillage - the number of tractor trip made across the field and how and how far the corn was transported to the Illinois River Energy Center and the fuel consumption. The average distance for each trip was 29.5 miles.
The study also asked about the fertiliser programme on each farm how much nitrogen fertiliser was used as well as potash and phosphorus.
The type of corn and the pesticide programmes used were also logged with the vast majority - 89 per cent using genetically modified corn.
How the corn was dried was also examined, with 26 out of the 29 indicating that they used some form of propane or natural gas drying system. The electricity used during the drying process was also assessed as well as the amount of fuel used in the growing process - whether it is in tractor trips, fuel used by contractors or in hauling the corn to the ethanol plant. Finally, on the farm, the study looked at the energy used in irrigating the crops.
At the ethanol plant the study looked at the production process at the Illinois River Energy Center.
The ethanol plant started operation in December 2006 and uses a natural gas fired boiler for steam generation and natural gas fired rotary drum dryers.
The majority of whole stillage at the ethanol plant is converted and sold as Dried Distillers Grains with Solubles, a small fraction of Wet Distillers Grains is also sold and all of the DDGS is sold to Asia. The DDGS is sold through backhaul arrangements, meaning that if the containers were not loaded with DDGS they would probably return. All the corn is shipped to the ethanol plant by truck and the majority of ethanol is shipped to the terminal by truck, with a smaller amount by rail.
The survey used three sets of data to set the parameters for the Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) Model and the results show that the Illinois River Energy Center produces corn ethanol with a substantially lower global warming impact than the current standard value for corn ethanol in the US - 54.8g CO2e/MJ compared to 69.1g CO2e/MJ.
The report says that this reduction is primarily due to higher corn yields, reduced on-farm energy consumption, and reduced energy consumption at the biorefinery. Compared to gasoline, the GWI of IRE corn ethanol is 40% lower (54.8 g CO2e/MJ vs. 92.1 g CO2e/MJ for gasoline).
There was also reduced agricultural energy consumption in IRE's corn draw area (5.5 gal/acre vs. >10 gal/acre), lower custom work and input hauling energy consumption, and lower ethanol plant energy consumption (29,404 Btu/gal vs. 35,889 Btu/gal, LHV inclusive of electricity).
"IRE is currently exploring advanced technologies that may further reduce the GWI of its ethanol product including corn fractionation and a digester to offset natural gas consumption with biogas," says the report.
"The results also indicate that if advanced agricultural management practices such as no-till and winter crops were promoted, the GWI of IRE corn ethanol could drop to as low as 41.4 g CO2e/MJ or a 55 per cent reduction from gasoline.
"Finally, the study finds a much lower on-farm energy consumption of 7,855 Btu per bushel for IRE supplied corn than the current GREET default value of 22,500 Btu per bushel (representing US national average). The large difference should prompt a reassessment of GREET's agricultural energy default value."
Further Reading
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- | You can view the full report by clicking here. |
November 2008
