International Biomass Conference & Expo: Using waste streams

By Lisa Gibson
Posted May 5, 2010, at 3:45 p.m. CST

The two challenges to effective and widespread use of waste streams from the livestock and biofuels industries are controlling air-deposited nutrients and greenhouse gas emissions, according to David Bracht, attorney with Husch Blackwell Sanders LLP and speaker at the International Biomass Conference & Expo.

Livestock operations are growing in size and that means growing waste streams, while biofuels operations are facing increased regulations and an emphasis on carbon footprint reduction, he said. Both problems can be addressed by biomass energy technologies. "Use nature as a solution," Bracht said.

Most existing animal waste stream systems use anaerobic digestion, as it is the easiest, he said, but there's room for improvement. "The next generation of these systems will go beyond just methane," he said, adding that advanced systems can increase energy capture up to three times the Btu value. "You really have to have an end user in mind," he cautioned prospective developers, emphasizing that the user needs to be close to the operation.

AD systems can process many different kinds of waste streams. "Anything that biodegrades is a candidate for anaerobic digestion," said Norma McDonald, North America sales manager for Organic Waste Systems Inc. She discussed components of different types of manure compatible with the company's systems, drawing on her family's farming experience. Crop residuals can also be digested, but wood cannot. "I want to clear one thing up right now," she said. "Anaerobic digestion does not compete with other uses of woody biomass."

Off-farm residuals such as syrup stillage, glycerine and yard waste are digestible, as well, and McDonald discussed dry anaerobic digestion, along with wet. The resulting biogas is more eco-friendly than landfill gas, she said, and allows self-sufficiency for livestock and poultry farmers, who made up about one-third of her audience.

Professor Eugene Allevato of Woodbury University in Burbank, Calif., along with his students and colleagues, are studying the anaerobic digestion of horse manure, as the area surrounding the college is comprised heavily of equine operations. One horse produces seven to nine tons of manure per year, according to a student-produced DVD Allevato showed. Experiments that mixed food samples with the manure produced more biogas, according to the video.

The problem of methane emissions from animals such as cattle and horses can be attributed to their confinement to relatively small areas, Allevato said. Many in the biomass industry seem more interested in large projects, but there is a business niche in small AD operations, he added.

Besides AD, gasification is also a solution for waste stream management, as discussed by panelist Goutam Shahani, vice president of sales and marketing for Heat Transfer International (HTI). Biomass use will grow in the next 10 years, he said, and the company is prepared to advance with that growth. "We at HTI are very excited about this opportunity and we definitely want to be a part of this future," he said.

HTI has developed a Starved Air Low Temperature (SALT) gasification system that uses partial oxidation and is clean and controlled, he said, emphasizing the difference between gasification and the historically dirty combustion process. The company has one current project using SALT that processes 67 tons of litter per day and can provide 500 kilowatts of electricity to the grid, he said. The company focuses primarily on cost reduction. "I think that's number one," he said. "In today's economic environment, a project has to be economic or people will not invest in it." The gasification system does not need water, another significant benefit, and is flexible in feedstock compatibility as well as energy production, as it can generate heat, steam and electricity, Shahani said.