Open access peer-reviewed chapter

# Production and Use of Evolving Corn-Based Fuel Ethanol Coproducts in the U.S.

By Kurt A. Rosentrater

Submitted: May 30th 2014Reviewed: November 18th 2014Published: September 30th 2015

DOI: 10.5772/59951

## 1. Introduction

We face many challenges in our society, due especially to growing population pressures and increased economic mobility. These can result in increased demands for food, clothing, housing, and consumer goods. Additionally, there has been a growing need for energy during the last several decades, which historically has been met primarily by use of fossil fuels. In the U.S., transportation fuels generally account for about 1/3 of all energy consumed. Of this, about 90% comes from fossil sources. Between 1/2 and 2/3 of the total U.S. demand for petroleum has been met by imports during the last 30 years [1]. Many argue that this scenario is not sustainable in the long run, and other energy alternatives are needed. During 2005-2010, the U.S. experienced some of the highest growth rates ever seen in the domestic biofuels industry.

## 5. Coproduct Evolution

Even though the corn ethanol industry is maturing, there continue to be efforts to develop new, valued-added materials from the corn kernels as well as from the coproduct materials. When these research efforts are commercialised, they will result in more products from the corn kernel itself (an approach known as upstream fractionation) and the distillers grains (known as downstream fractionation). These types of fractionation approaches can result in the separation of components of high, medium, and low value (Figure 9). For example, several mechanical and chemical approaches have been developed to remove protein, fibre, or oil components from the endosperm (which contains the starch). This type of separation will allow a highly-concentrated starch substrate to be introduced to the fermentation process, and will allow the other corn kernel components to be used for human food or other high-value applications. [31] provided an extensive discussion regarding various pre-fermentation fractionation approaches. On the other hand, post-fermentation fractionation techniques have also been examined. For example, [32] used a combination of air classification and sieving to separate fibre particles from DDGS. All of these approaches, if implemented commercially, will alter the chemical composition and digestibility of the resulting DDGS.

Many plants have recently begun adding capabilities to concentrate nutrient streams such as oil, protein, and fibre into specific fractions, which can then be used for targeted markets and specific uses. For example, one company in Iowa is now separating fibre from the DDGS and using it as a feedstock for cellulosic ethanol production. Additionally, many companies have begun removing oil from the whole stillage and/or CDS streams (Figure 10). This oil, which is officially known as Distillers Oil, Feed Grade (Figure 11), can readily be converted into biodiesel or animal feed ingredients, but they cannot be used for food grade corn oil, because they are too degraded. In fact, more than 85% of U.S. ethanol plants are now removing oil, because the economics are so favourable. Of note, in 2010 almost no ethanol plants were extracting oil...the rapid increase has solely been due to added value streams for the ethanol plants. On the horizon is concentrated corn proteins, which can be used for high-value animal feeds (such as aquaculture or pet foods), or other feed applications which require high protein levels (such as monogastrics or younger animals).

As these process modifications are developed, tested, and implemented at commercial facilities, improvements in coproducts will be realized and increasingly used in the marketplace. These new products will require extensive investigation in order to determine how to optimally use them and to quantify their values in the marketplace.

## 6. Conclusions

The fuel ethanol industry in the U.S. has grown exponentially during the last decade in response to government mandates and due to increased demand for alternative fuels. This has become especially pronounced as the price of gasoline has drastically fluctuated, and consumers have realized that fuel prices are problematic. Additionally, energy has become an issue of national security. Corn-based ethanol is not the entire solution to transportation fuel needs. But it is clearly a key component to addressing energy needs. Corn ethanol is seen by many as a transition to other bio-based fuels in the long run; but this industrial sector will continue to play a key role in the bioeconomy, as it is a proven approach to large-scale industrial bioprocessing. And as the industry grows, coproducts will become increasingly important for economic and environmental sustainability. One way to improve sustainability is to diversify coproducts as well as integrate systems (Figure 12, for example), where materials and energy cycle and recycle. For example, upstream outputs become downstream inputs for various components of a biorefinery factory, animal operation, energy production (i.e., heat, electricity, steam, etc.), feedstock operation, and other systems. A closed loop system would be the ultimate scenario. By integrating these various components, and developing a diversified portfolio (beyond just ethanol and distillers grains) the biorefinery will not only produce fuel, but also fertilizer, feed, food, industrial products, energy, and more importantly, can be self-sustaining.

## List of Abbreviations

CDS: Condensed distillers solubles

DDG: Distillers dried grains

DDGS: Distillers dried grains with solubles

DWG: Distillers wet grains

DWGS: Distillers wet grains with solubles

RFS: Renewable Fuel Standard

SBM: Soybean meal

## How to cite and reference

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Kurt A. Rosentrater (September 30th 2015). Production and Use of Evolving Corn-Based Fuel Ethanol Coproducts in the U.S., Biofuels - Status and Perspective, Krzysztof Biernat, IntechOpen, DOI: 10.5772/59951. Available from:

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