Biorefinery Beckons: Plant will produce ethanol from corn stover

Jan. 3, 2013
Iowa facility will be one of the first and largest commercial biorefineries in the world.

After almost a decade of research, development and trials, advanced biofuels are moving toward commercialization. Five established companies intend to build large-scale biorefineries in the U.S. over the next 12 to 18 months. When operational, these facilities will generate nearly 110 million gallons of advanced biofuels annually.

Figure 1. Unit at Vonore, Tenn., can produce 250,000 gallons/year of ethanol from agricultural residues.

DuPont is in the process of constructing one of these biorefineries — a facility in Nevada, Iowa, that the company broke ground on in November 2012. The plant will be one of the first and largest commercial biorefineries in the world making fuel from cellulose. The facility will take 18 months to complete and will produce 30 million gallons a year of cellulosic ethanol via conversion of corn stover from local farms. Specifically, to supply the corn stover for the plant, DuPont will contract with more than 500 local farmers to gather, store and deliver more than 375,000 dry tons of stover per year to the Nevada facility. The stover will be collected from an approximate 30-mile radius around the new facility and harvested off of 190,000 acres.

How did we get to this point and what will it take to be successful? DuPont has invested millions of dollars in advanced biofuels research and development over many years. In 2011, we purchased Danisco and its Genencor unit and added their expertise into a new unit: DuPont Industrial Biosciences. This integration allows us to optimize DuPont's bioscience technology and commercialization capabilities with Genencor's biofuel enzyme technology.

Genencor has made great progress in developing enzymes to convert a range of renewable nonfood feedstocks such as corn stover, switch grass and wheat straw, as well as municipal waste, to cellulosic ethanol. Its third-generation enzyme technology, released in 2011, converts glucan (C6) and xylan (C5) sugars with a greater ethanol yield per unit of feedstock. DuPont has been trialing these enzymes at its cellulosic ethanol demonstration plant in Vonore, Tenn. (Figure 1). The ethanol produced there powers vehicles at the University of Tennessee.

With the major technical challenges of enzyme optimization and cellulosic conversion overcome, our attention has focused on developing a sustainable feedstock supply chain for the planned Iowa plant and a model for the industry in years to come. Working in collaboration with Iowa State University and DuPont's Pioneer division, we created the Corn Stover Harvest and Collection Project in 2010. Our first year, we worked with just six area farms totaling slightly more than 2,500 acres. Our harvest test program evaluated equipment options and configurations for corn stover harvest, collection, transportation and storage.

The following year, we increased the pilot program to 50 corn growers and 7,500 acres. We conducted critical research and development to advance equipment productivity, improve feedstock quality and evaluate cost-effective approaches for minimizing feedstock losses during storage. A significant learning from our overall project in 2011 was that most participating corn growers see agronomic value in having a portion of the stover removed from their fields. In addition, the majority reported agronomic advantages were the greatest overall value they derived from stover harvest.

In 2012, the project expanded to more than 100 corn growers and harvested corn stover from approximately 25,000 acres. This represents approximately one-seventh of our first biorefinery's annual feedstock requirement. The focus in 2012 was on conducting a commercially representative harvest operation and proving the business model for corn stover supply. These pilots demonstrate the viability of a custom third-party harvest model — one of several corn-stover-harvest options DuPont is developing to support commercialization of cellulosic ethanol production.

We specifically selected Nevada, Iowa, for the facility because Lincolnway Energy operates a corn-grain ethanol processing plant there. We will be able to achieve synergies in both energy and logistical management from this co-location with Lincolnway. Our ultimate goal is to partner with other companies and license these technologies to biofuel producers in the U.S. and other parts of the world.

Under the Renewable Fuel Standard (RFS), Congress has enacted targets for increasing the use of advanced biofuels as transportation fuels. This RFS calls for the U.S. to produce 36 billion gallons/year of advanced biofuels by 2022. Beyond cellulosic ethanol, DuPont is working to commercialize biobutanol via a joint venture with BP called Butamax Advanced Biofuels. It was formed in 2009 specifically to develop biobutanol technology. Biobutanol will provide improved options for expanding energy supplies and accelerate the move to renewable transportation fuels.

Today, we are on the verge of commercializing these biofuels. The next challenge will be to gain even larger scale and improved economics to ensure advanced biofuels achieve their full potential for greater energy security, economic development and environmental benefits.

JAN KONINCKX is global business director, biorefineries, for DuPont Industrial Biosciences, Wilmington, Del. E-mail him at [email protected].

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