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From Farm to Biorefinery: Ethanol Production Efficiency Improves

August 18, 2011


In the second part of RFA's series on the improving efficiencies of corn ethanol production, the focus will be specifically on input use—both on the farm and at the biorefinery. Last week we noted the dramatic increase in grain productivity. Significant growth in corn yield per acre has allowed farmers to double annual production since 1980 on roughly the same amount of land. It is often assumed that this incredible growth in corn yields is the result of increased use of fertilizer. But data from USDA clearly show this is not the case. In fact, the data show that 2010 application rates of the three common macronutrient fertilizers (nitrogen, potassium, and phosphate) were the same--or below—the application rates seen in the early 1980s. Thus, nitrogen application per bushel of corn produced is down more than 30% since the early 1980s, while potassium and phosphate usage per bushel are down some 40%.   Similar improvements have been seen in the use of other important resources needed for corn production. According to a landmark study by the Keystone Alliance (a group including both farm groups and environmental organizations, such as Environmental Defense Fund and The Nature Conservancy) the amount of water, energy, and land required to produce a bushel of corn were substantially reduced between 1987 and 2007. The same kind of dramatic gains are being made at the ethanol biorefinery. Before getting into the nitty-gritty details, here are a few facts to keep in mind.  Roughly 90% of the nation's ethanol is produced using the dry mill process, with the remainder using what is known as a wet mill process.  Also, slightly more than 90% of the energy needed to run the nation's 200+ ethanol biorefineries comes from natural gas—a plentiful domestic resource.  Finally, some 22% of these facilities are using Combined Heat and Power (CHP) technologies. The average dry mill ethanol plant in 2008 used 28% less thermal energy per gallon than it did just seven years earlier in 2001. According to a recent study published in Biotechnology Letters by a researcher at the University of Illinois-Chicago, the average dry mill today uses less than 26,000 BTUs of thermal energy to produce a gallon of ethanol. That compares to the 77,000 BTUs of energy contained in the gallon. The same is true for both electricity demand and water consumption.  Electricity demand fell 32% from 2001 to 2008 and water use fell by 47%. All the while, ethanol producers are increasing the amount of ethanol they can produce from the same bushel of corn.  Ethanol yields per bushel are up 5% since 2001.  Additionally, ethanol producers are providing ever-increasing amounts of distillers grains, the livestock feed co-product of ethanol production.  In 2011, the industry is expected to produce nearly 40 million metric tons of distillers grains for use in dairy, beef, swine and poultry diets in the U.S. and around the world. As the data clearly demonstrate, America's ethanol producers are mirroring the efficiency gains of the American farmers upon whom they rely for feedstock.  As existing processes evolve and new production technologies emerge, ethanol production in the U.S. will not only increase in volume, but also in efficiency. Without a doubt, today's ethanol industry is high-tech and increasingly energy efficient. While new sources of crude oil require more energy for extraction and refining and are increasingly carbon intensive, ethanol's energy and environmental track record continues to shine. In the next installment, we will look at the performance of ethanol production system as a whole and how it compares to petroleum production and use.