Coskata Unveils Semi-Commercial Feedstock-Flexible Ethanol Facility; Springboard for Full-Scale Commercial Rollout

15 October 2009

Coskata’s semi-commercial facility in Madison, Pa. Click to enlarge.

Coskata Inc., a syngas to ethanol company, officially launched its semi-commercial “Flexethanol” facility located in Madison, PA. The site represents the successful scale-up of the company’s feedstock-flexible bio-thermochemical technology, and will serve as a springboard for the construction of Coskata commercial facilities and licensing of the technology to other producers.

The Coskata process can produce more than 100 gallons of ethanol per ton of dry, ash-free biomass material at a cost competitive with expected gasoline prices—around $1.00 per gallon, according to Wes Bolsen, the company’s Chief Marketing Officer & VP, Government Affairs. Actual production cost will vary, either below or above $1.00 per gallon, based on the cost of feedstock and the cost of power for the specific plant, he noted.

A 1,500-gallon bioreactor at the Madison facility. Click to enlarge.

By comparison, the theoretical yield of ethanol from a dry ton of corn is 124.4 gallons, according to the DOE, and 113 gallons from corn stover. Depending on feedstock and process, the DOE says, actual yield can be anywhere from 60% to 90% of theoretical. Achieving high yield may be costly, DOE notes, so lower yield processes could in some cases be more cost-effective.

Depending on the feedstock and with the cogeneration of bioelectricity or steam export, the Coskata process can result in up to a 96% reduction of CO₂ in the production of the fuel and is up to 7.7 times more energy positive compared to conventional gasoline, according to an evaluation by Dr. Michael Wang at Argonne National Laboratory. (Earlier post.)

The process also uses less than half the water per gallon than required for the production of gasoline from conventional crude, and about one-third to one-quarter of the water per gallon required for the production of gasoline from oil sands oil, Bolsen said.

A study earlier this year by researchers at Argonne National Laboratory examining consumptive water use in fuel production (earlier post) found that:

• 3.4 to 6.6 gallons of water are required to produce one gallon of gasoline from domestic crude.

• 2.8 to 5.8 gallons of water are required to produce one gallon of gasoline from Saudi Arabian Conventional Oil.

• 2.6 to 6.2 gallons of water are required to produce one gallon of gasoline from oil sands oil (varying with method of bitumen production).

• On average, approximately 3.0 gallons of water are required to produce one gallon of corn ethanol. (Production only, not factoring in irrigation, which can boost consumption per gallon to more than 300 gallons of water per gallon ethanol, depending upon the region.)

• Cellulosic ethanol produced via a biochemical process (such as dilute acid pretreatment followed by enzymatic hydrolysis) consumes 9.8 gallon of water; with increased ethanol yield, it is estimated that water consumption can be reduced to 5.9 gallons.

• Fast pyrolysis of forest wood residue consumes 2.3 gallon of water to produce 1 gallon of biofuel (containing 50% bio-based diesel and 50% bio-gasoline).

• Optimized thermochemical production of cellulosic ethanol requires 1.9 gallons of water per gallon of ethanol.

From a lifecycle perspective, cellulosic biofuels consume a minimal amount of water relative to most sources of corn ethanol. Cellulosic ethanol produced from switchgrass via a BC process consumes nearly as much water (9.8 gallon) as ethanol produced from corn grown in Region 5 (10.0 gallon). However, cellulosic ethanol produced from switchgrass via a TC gasification requires 80% less water.

—Wu et al. (2009)

The process. The Coskata process takes a thermo-biochemical pathway via a three-stage process. It first gasifies the feedstock to syngas (CO and H₂), then uses proprietary microorganisms—licensed from Oklahoma State University and the University of Oklahoma—to convert simultaneously both CO and H₂ into ethanol. Coskata’s biological fermentation technology is ethanol-specific and enzyme independent, contributing to high energy conversion rates and ethanol yields.

As syngas fermentation leads to lower ethanol concentrations than corn fermentations, the energy and cost to separate the ethanol from water is proportionally higher, Coskata notes. To reduce this differential, Coskata has exclusively licensed membrane separation technology to reduce the energy requirement of the third step, the separation and recovery of the ethanol.

Additionally, the process requires no additional chemicals or pre-treatments, serving to streamline operational costs.

The Madison facility. The Madison facility is a demonstration of “minimum scale engineering”—the smallest size that will still allow the company to scale directly to 50 million and 100 million gallon Coskata facilities. Some of the ethanol that is being produced at the facility has been delivered to the General Motors Milford Proving Grounds for early testing, as well as to another major strategic partner. GM announced its strategic partnership, including an investment, with Coskata at the North American International Auto Show in Detroit in January 2008. (Earlier post.)

The Madison facility is designed to serve both as commercial-scale proof of the technology as well as a source for learnings to further optimize the technology. The facility has been running for several weeks, prior to its official launch today. The Madison facility has three separate bio-reactors, two gasifiers and two separation systems—a traditional separation system and Coskata’s membrane system.

Scale-up allowed us to figure out that the bugs were better than we thought. Scale up lots of times makes things better—there is more residence time to convert the gas into ethanol. The tallest reactor in the system is 65-feet tall. We couldn’t have that in our pilot facility [in Warrenville, Il.]. This is the first time the bugs have been able to see the full scale. We have been surprised and taken some things out of the design.

We’ve also seen the robustness of the organisms. When you don’t feed them for a couple of hours [based on a process outage] they go to sleep and come back and start producing ethanol again right away. You never really know until you get out there.

—Wes Bolsen

Unlike other technologies and facilities that may rely on one primary source of feedstock, Coskata’s flex ethanol facility will be producing ethanol from numerous feedstocks, including wood biomass, agricultural waste, sustainable energy crops, and construction waste. This flexible approach at the Madison facility is enabled by Westinghouse Plasma Corporation (WPC), a wholly owned subsidiary of Alter NRG, and their plasma gasification technology.

The Madison facility will use Southern Pine as a feedstock through most of 2009, in order to supply design details for Project Flagship, Coskata’s first commercial-scale facility. Coskata, which to date has funded its development itself, through its investors, has submitted a grant proposal to the US Department of Energy under the Integrated Biorefineries FOA for additional funding to support testing additional high-impact feedstocks in 2010 that would result in 4-6 additional commercial-scale facilities:

• Agricultural residues (bagasse, corn stover and rice straw);

• New energy crops such as fast-growing trees (Eucalyptus) and grass (Miscanthus and Switchgrass); and

• Sorted waste (construction and demolition).

The feedstock flexible nature of the Coskata approach also allows for geographic flexibility, meaning facilities can be built anywhere a feedstock can be sourced or delivered.

Commercial-scale plans. Coskata is developing its own commercial-scale facilities, with the initial plant to be located in the Southeast of the US in the “wood basket”, Bolsen said. Coskata has finalized the design and is in the final phases of pulling together project financing. At the same time, he noted, interest in licensing is increasing.

Although Coskata is gasifier-agnostic, it has designed in a plasma gasifier to its first commercial facility, Bolsen said, but is open to using multiple different gasifiers in the future as well.

We’re probably going to have to license more than we thought at first...9-10 for every one we build. There is pent-up demand for cellulosic biofuels, given the RFS (Renewable Fuels Standard).

—Wes Bolsen

Resources

• M. Wu, M. Mintz, M. Wang, and S. Arora (2009) Consumptive Water Use in the Production of Ethanol and Petroleum Gasoline (ANL/ESD/09-1)