Toolkit For Ethanol's Next Stage

There are multiple options in the ethanol producer’s toolkit in the ongoing quest to improve efficiency and yield. They can be as basic as staying on top of maintenance and improving the reliability of the dozens of systems in the plant to reduce downtime. Some require systematic approaches to evaluating process parameters to identify the sweet spot. Other efforts may mean investing in new machinery or system upgrades, or choosing from an array of new products, with the accompanying challenge of validating their efficacy. Where have producers focused their attention in recent years and what lies ahead?

“From the moment you start up a plant and start producing ethanol, there’s always a search for, how can I produce more ethanol with less inputs?” said Lars Dunn, director of technical service for DuPont Industrial Biosciences and the 2014 recipient of the Award of Excellence at the International Fuel Ethanol Workshop & Expo.

Hands down, the most important investment of the past five years has been corn oil extraction, estimated to be installed at 90-plus percent of ethanol plants. However, there’s a new round of mechanical improvements underway, Dunn pointed out. The new equipment is designed “to get more of the starch, more of the fermentable sugars out of the matrix of the grain and into solution where it can be converted to ethanol,” he said. “Things like selective milling, cavitation, ultrasound—some kind of mechanical treatment to get more starch out of the grain.” 

At the same time, enzyme companies, like DuPont, Novozymes and others, have developed new enzymes that achieve “the same things as the mechanical means, but without the capital investment,” he said. On top of that, genetic engineers have developed a corn variety that produces its own alpha amylase and yeast that produces its own glucoamylase.

Two ethanol producers, Keith Kor, general manager at Pinal Energy LLC, and Neal Jakel, former general manager at Illinois River Energy LLC, recently acquired by CHS Inc., echoed Dunn in naming the main technologies being adopted across the industry but gave equal emphasis to incremental improvements. 

Jakel said the team at IRE has 30 to 40 projects on the books, looking for incremental gains. “You need a plan, both long term and short term,” he stressed. In times of poor margins, such as in 2012, those plans may focus on low-cost, high-return projects, while periods of healthy margins open the door for larger investments. “You have to be ready for that,” he advised, adding that improvements need to be ongoing, if nothing else, to survive the next downturn, and provide returns to investors in spite of the margin environment. One area to focus on, he said, is to improve reliability and reduce downtime. “We used to have seven-day shutdowns, two or three times a year, and now it’s five days maybe twice a year,” which, he pointed out, results in a substantial increase in gallons of ethanol produced.

At Pinal Energy, Kor said they reduced downtime significantly through modifications in distillation. The team installed new trays in the beer column and rerouted feeds to run thin stillage through all three evaporators, modifications that reduced fouling and thus downtime.

The big gain at Pinal Energy in Arizona came from a systematic evaluation of process variables, Kor said. The team tested a number of changes. “What happens if we change the pH, increase or decrease enzymes, or change when we pitch the yeast? What happens if we raise the temperature 5 degrees?” Using Six-Sigma methodology, the Pinal team found the sweet spot, which improved ethanol yield from 2.68 to 2.76 gallons per bushel of corn, according to Kor.

Finding the sweet spot has been the goal for Nicholas Giffen, senior scientist, data analyst with Novozymes North America. Speaking at the FEW, he described his work in helping to develop the company’s Golden Batch software. The system uses statistical analyses of operational data to identify correlations among various process parameters to find those giving the best yield: the golden batch. Giffen showed an example from a 110 MMgy plant, and how a statistical method called recursive partitioning found a correlation between slurry solids, cell counts and temperature. Analyzing multiple fermentations, a certain combination of the three parameters resulted in ethanol yields of 1.2 percent above the average and increased the frequency of golden batches from 15 percent overall to 35.5 percent.

Once the statistical analysis identified the three key parameters, a root cause analysis determined the solids were being impacted by an enzyme issue at low solids. A cell count issue was caused by inconsistent propagation times and fermentations that were too fast at high cell counts. And, an analysis of prop temperature found lower temperatures increased viability. Using those insights, the set points for solids and prop temperature were adjusted and plant operators were trained to send the prop at the correct time to ensure proper cell counts. The Golden Batch analysis was then used to validate the implemented changes. In the applications to date, Giffen reported, each ethanol plant has proved to be unique, with different sets of three to five key variables rising to the top in the Golden Batch analysis.

Six-Sigma and Golden Batch are just two systems that can be applied to process control. Other speakers at the FEW described other approaches, including Hank Brittain from OPX Control, who spoke on scoring and improving process control systems; Srinivas Budaraju with Rockwell Automation, who discussed model predictive control; Bill Whitlock with Novozymes described InDex, an analytical method for cook process optimization, and Glen Bowen with Ashland Water Technologies spoke on performance-based monitoring in process and water treatment chemical programs.

Trialing Technologies
Conducting proper trials is a big part of evaluating new technologies, and was the focus for other speakers at the FEW. Small, incremental improvements bring potentially substantial profits, but can be hard to validate. Chris Richards with Lallemand Biofuels and Distilled Spirits, outlined the elements of a successful plant trial in the panel on approaches to evaluating new process or technology deployments. The protocol should state the trial objectives and any assumptions, he advised, and outline how the trial will be implemented—the duration, how the baseline is to be set, sampling methodology, how comparisons between the baseline and trials are to be done. The protocol should define the responsibilities of the various parties involved and include steps to reduce risk, such as running a trial in a single fermentor and waiting for results before entering the full trial or implementing changes incrementally.

Fred Clark with Arisdyne Systems described his company’s approach to conducting trials, including outfitting a mobile laboratory to bring to sites to reduce disruptions from the added test runs. Ethanol plant operations are inherently variable with multiple sources, he pointed out, such as feedstock conditions, enzyme and yeast nutrition dosing, ambient and process temperatures, pH, backset and distillation, not to mention time. Everyone struggles to show small yield lifts, he said, yet small, incremental improvements potentially translate into substantial profits.

Looking Ahead
The FEW producer panel in the opening general session posed the question of what the next stage for ethanol innovation will be. Kor and Jakel spoke on the panel, along with James Moe, president of Poet Plant Management, and Paul Koehler, vice president corporate development at Pacific Ethanol Inc. All mentioned the expectation that cellulosic ethanol technologies will be adopted. “It’s the guys with the strong balance sheets that are in the front of that,” Jakel said.

The future will be a continuous evolution, said Moe, “looking at the entire landscape of technology and identifying the opportunities. It may be hardware technology, maybe chemical or cellulosic. It might be market opportunities in our specific locations. It should be an exciting time in the industry.”

Jakel put product diversification high on his list of changes ahead. Many plants are going to build on oil extraction to tool their distillers grains for the best market near them, be it cattle for producers in Nebraska and Kansas or monogastrics for those further east in the Corn Belt. “The next thing will be precursor chemicals such as biobutanol, adipic acid and succinic acid,” he added.

For Koehler, driving down the carbon score is the focus ahead for Pacific Ethanol’s plants that serve the California market. That will include improvements to existing assets, plus bringing in new feedstocks to add to the corn now used.

Better carbon scores for product being shipped to California is big on Kor’s horizon as well. Pinal Energy will be adding biomass-fueled combined heat and power, he reported. Using wood waste from the Phoenix area just 40 miles north of the plant, Pinal Energy will get between 5 and 6 MW of electrical power plus process steam.

Looking ahead at the ethanol industry, Kor predicted just as producers widely adopted oil extraction in the past five years, the industry is going to move into fiber extraction for cellulosic ethanol in the next five. New coproducts are going to emerge, with corn oil-to-biodiesel very likely, along with zein protein extraction, which has a variety of food and industrial uses, for use in biodegegradable plastics, among others. “You’re going to see more and more ways to get the best value,” he said, “and we’re going to make plants more efficient.”

“In the 1980s,” Kor continued, “2.62 gallons per bushel and 10 percent alcohol in the ferms were good. Now it’s not. Now we see 16 and 17 percent alcohol in ferms and 2.9 to 3 is the gold standard to achieve for yield.” Energy use has been nearly halved, he added. “In the early days, energy use was around 40,000 to 44,000 Btu per gallon produced. “Nowadays, we’re at 18,000 to 26,000 Btu per gallon. Nobody thought we’d ever get there, but we did. We’ll continue to see improvement in all these areas.”

Dunn used terms of efficiency in the conversion of fermentable sugars to ethanol to quantify the industry’s improvement. “In the 1980s, we were in the low 80s in efficiency. We’ve made a big leap in the last decade, going up by 10 percent,” he said. The average in modern ethanol plants is at 92 to 93 percent efficiency, he added. “The really good ones might be up there at 95 percent. What you’re getting at is an improvement of a few percent.  With scale, for a 100 MMGy plant, 2 percent is 2 million gallons.  At $2.50-plus a gallon, that’s a substantial amount of money.”

Author: Susanne Retka Schill
Senior Editor, Ethanol Producer Magazine
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