Update on Ethanol and Soy Processing in Iowa (a project of the Iowa Grain Quality Initiative

Connie Hardy, Program Specialist, Value Added Agriculture Program


Local processing of corn and soybeans in Iowa continues to expand production of food, feed, and fuel products creating opportunities for farmers to sell crops locally to processing plants as well as to grain handling facilities. In 2007, Iowa farmers produced 2.37 billion bushels of corn and 439 million bushels of soybeans. With the rapid expansion in biofuels production, Iowa has become the national leader in both ethanol and biodiesel production.  These two industries alone offer markets for 43% of Iowa’s corn production and the oil from 42% of Iowa’s soybeans at current operating capacities. Biodiesel production differs from ethanol production in that biodiesel uses one of two primary soybean crush products (oil) rather than whole grain.

Project Objectives:

1.      Maintain an objective data set to define the scope and variation involved in the current industry activities surrounding grain origination methods, impact on grain storage and co-product handling/marketing.

2.      Update data to track changes in corn processing capacities and estimate corn production and storage needs.

3.      Estimate soy processing capacity in Iowa and estimate the potential supply of vegetable oil that could be used for biodiesel production if


Update on Ethanol Processing

In 2007, four additional dry grind plants began operations to total 25 dry grind ethanol plants and 4 wet mill operations that were currently producing fuel ethanol.  There are 15 dry grind plants under construction expected to open in 2008-2009.  In addition, six ethanol plants are located just across Iowa borders and expect to access 50 percent of their inbound corn from Iowa farms.  Table 1 shows the total ethanol production capacity of these plants and estimates total corn usage and distillers grains production when plants are operating at capacity.  Estimated corn usage is based on 2.8 gallons of ethanol per bushel of corn.


Table 1.  Iowa ethanol production and corn usage  (April 1, 2008)

Summary Statistics


Ethanol Produced

Corn used
Million bu

DDGS produced
Million tons

Current dry grind plants










Wet mills





Nearby Iowa draw




















Executive Summary of Soy Processing Study

Iowa’s soybean processing industry has grown steadily in its ability to process commodity and specialty soybeans.  This report summarizes Iowa’s present capacity for soybean processing and describes soybean quality issues related to processing.  Data was gathered through interviews, written surveys, and industry reports.

Thirteen solvent extraction (crush) plants offer processing capacity for 98.5% of the soybeans grown in Iowa.  These plants are generally bulk processors of commodity soybeans, but some have developed processing schedules that can accommodate occasional processing runs of specialty soybeans for which the meal or oil carries a unique trait.  Also, some crush plants offer price premiums to the farmer based on protein and oil content or for farmers who grow particular varieties of soybeans. 

Table 2.  Summary of Iowa soybean processing capacity



(MM bushels)

Annual Oil
(MM gallons)

Max Annual
(MM gallons)

Crush plants





Expeller plants





Milling and Soyfoods










Processing plants other than solvent extraction plants have come into being more recently, within the last 20 years.  Iowa’s 11 extrusion-expelling plants separate soybeans into meal and oil using pressure and heat. Extrusion-expeller (EE) processors usually operate on a smaller scale than crush plants, and the process does not involve a chemical solvent or other additive, so it is acceptable for organic products.  Because the process involves more heat than crush plants and is slightly less efficient in removing oil from meal, the proteins in the meal may be less digestible for some species and the meal contains more oil.  Smaller operations, such as EE plants, can more easily process small runs of specialty soybeans.  EE meal is sometimes further processed into meat substitutes for to include in human foods.

The remaining soy processing plants in Iowa process whole food-grade soybeans into meal, flour, flakes, and soybean snacks.  A wide variety of soy-based food ingredients are made by these companies, usually requiring preselected varieties (identity-preserved) of soybeans in lots that have been cleaned and sorted before processing.  The products are used by the baking industry, makers of infant formulas, snack foods, cereals, and energy bars, and by the processors of soymilk and tofu.  A few plants also make finished retail food products, such as soynut snacks and cookies.

Concerns voiced by soybean processors include accessing adequate supplies of soybeans for processing, increasing prices for soybeans and vegetable oils, and the role of speculators driving input prices yet higher.  Organic and specialty soybean processors also stated that germplasm for non-GMO soybeans is diminishing, and maintaining or increasing acreage for these specialties is challenging, especially in this time of rising prices for commodity soybeans.  Organic processors who are pushed to supply their current US markets see imports from China intruding on these markets.

Biofuel processing from vegetable oil

Soy biodiesel

The most rapid growth has occurred in biodiesel manufacture. Iowa currently has 14 biodiesel plants and can process 318 million gallons per year (mgy) of biodiesel fuel and 2 plants yet under construction representing an additional 35 mgy.  This amount of production would require approximately 72.6% of the oil from Iowa’s 2007 soybean crop.  Fourteen more biodiesel plants are in various stages of planning.  If all of these plants come into operation, they will add 485 mgy of biodiesel processing capacity and would, by themselves, require nearly 100% of the soybean oil in Iowa’s 2007 crop.  Many biodiesel plants are designed as “multi-feedstock” plants, meaning that they can use other vegetable oils and animal fat to make biodiesel.  Iowa’s 2007 corn crop could deliver an estimated 350 gallons of oil per acre, which translates into about 500 mgy of biodiesel.

Rapid growth in biofuels production has resulted in 13 new biodiesel plants in Iowa designed to use soybean oil as a primary feedstock.  Biodiesel is not a direct soybean use, but it uses oil extracted by a soybean processing plant. This represents 258 million gallons per year (mgy) of processing capacity. Some of these plants are capable of using other vegetable oils and animal fat as feedstocks.  Three plants are under construction that will add another 95 mgy in processing capacity.  In addition, there are 14 plants in various stages of planning that could add another 485 mgy of biodiesel processing capacity.  Iowa’s 2007 soybean crop (443 mil bu) could potentially yield 486.6 million gallons of biodiesel fuel. The plants presently operating and those that are under construction could produce 72.6% of the potential biodiesel yield from Iowa’s 2007 soybean crop.  If all of the planned plants are built, Iowa’s total biodiesel processing capacity would represent 172.2% of the biodiesel that could be made from Iowa’s 2007 soybean crop.  (Table 3.)

Table 3.  Iowa Biodiesel Processing Capacity and Soybean Oil Use

As the dry-grind ethanol industry expands and develops, more emphasis is being placed on oil extraction.   New plants are adding fractionation capability to separate corn germ and to extract the oil from either corn germ or distillers grains.  Even at plants where whole corn is used in fermentation, ethanol processors are extracting oil from the fermentation broth.  With a great percentage of Iowa corn now being processed in Iowa, it is worth considering what contribution corn oil could make toward the demand for vegetable oil in biodiesel manufacture.  The following estimates consider total oil available from Iowa’s major crops, but they do not address any quality differences that may exist between corn oil and soybean oil in terms of biodiesel processing.

Table 4.  Per acre oil yield from 2007 Iowa corn and soybean crops 

Table 4. estimates the per acre oil yield from soybeans and corn based on 2007 average crop yields in Iowa, assuming 2.0 lb/bu of corn oil and 10.9 lb/bu of soybean oil.  Table 5. estimates maximum oil yield (9626.5 million lbs) from the total Iowa corn and soybean crops and the maximum amount of biodiesel yield (987.4 mgy) from all of the corn and soybean oil in Iowa.  The 16 biodiesel plants currently operating and under construction in Iowa would produce 35.8% of this total if all were operating at full capacity, and the 14 planned plants would produce another 49.1% of the total if all were built and operating at full capacity.

Table 5.  Maximum oil and biodiesel yield from 2007 Iowa crops

Demand for corn from the ethanol industry prompted a significant shift between 2006 and 2007 in the relative number of acres that farmers decided to plant with corn versus soybeans.  However, the acreage shift did not have a significant impact on the total amount of oil that could potentially be used for biodiesel.  (Table 6.)

Table 6.  Maximum biodiesel yield from 2006 and 2007 Iowa crops


This report has been presented to the 2007 Integrated Crop Management conference participants (approximately 50 in a concurrent session), the Iowa Grain Quality Initiative Advisory Committee (20 participants), and to the Agriculture and Natural Resources Extension field specialists in the ISU College of Agriculture (approximately 60 participants).  It is also posted on the Iowa Grain Quality Initiative website www.iowagrain.org and on the Value Added Agriculture Program website www.iavaap.org.

The ethanol and soy processing surveys have served as a basis for the Grain Storage Module, a web-based decision maker created by the Iowa Grain Quality Initiative for farmers and grain handlers considering building new storage.  It has also helped the IGQI participants better communicate the implications of new local demand for corn and soybeans and how ISU Extension can assist farmers to participate in these new markets.


100 Corn and Soybean Production and Protection

180 Other ANR Programs

Page last updated: February 19, 2009
Page maintained by Linda Schultz, lschultz@iastate.edu