Alcohol School: Innovations in ethanol

By Lisa Gibson | September 12, 2019

Delivering the last presentation of the day for The Alcohol School Sept. 12, Scott Kohl, chief technology officer for Franzenburg, discussed several innovations in ethanol production. Yield, amylase formulations, fiber separation, coproduct fractionation, accelerated fermentation, genetically modified (GM) yeast and water conservation techniques made his list of innovations.

The Alcohol School, a Lallemand Biofuels & Distilled Spirits event, is being held this week in Montreal.

Echoing previous presenter Vijay Singh, professor of Agricultural and Biological Engineering at the University of Illinois Urbana-Champaign, Kohl said current dried distillers grains with solubles is not the best feed for most animals. Protein is too high for beef cattle, fat content is too high for dairy cattle, fiber content is too high for poultry, and oil content in hog diets produces softer bacon fat.

“The industry is showing that’s going to be the next big wave of process changes,” Kohl said.

He listed current systems for coproduct diversification, including dry fractionation, dry grind separation and wet milling.

Addressing increased ethanol yield, Kohl listed methods that can boost a base yield of 2.67 gallons of ethanol per bushel of corn to 3 gallons. They include: high-gravity fermentation, non-GM yeast improvements, enzyme improvements, bacterial control, low pH alpha amylase, wet slurry conditioning, protease-assisted fermentation, GM low-glycerol yeast, and fermentation osmotic control.

And new alpha amylases have better properties, he said. They’re better able to handle recalcitrant starches, and lower pH enzymes can minimize or eliminate ammonia addition to slurry. Advanced amylase formulations can also lower sulfuric acid addition, he said.

Moving on to accelerated fermentation, Kohl said the process starts with a very high yeast dose. It reduces fermentation time by five to 10 hours, reduces glucoamylase demand by 15 to 25 percent, reduces yeast propagation cost and increases yield, he said.

Yeast are being engineered to produce that glucoamylase, one of the new GM trait advancements he listed, along with glycerol reduction. “You’ve already heard about these quite a bit, but they’re amazing,” he told his audience.

Finally, areas of improvement in water conservation include a low-pressure steam generator that uses evaporator condensate. It significantly reduces new water demand for the boiler, he said. Another option is a chiller and recycle loop for the carbon dioxide scrubber. It reduces scrubber water demand by 20 to 80 percent.