Anaerobic digestion and production of biogas, at a scale not previously seen in the United States, is the recommendation of the St. Paul Port Authority (SPPA) to fuel Rock-Tenn in the years ahead. The recommendation, presented to the Rock-Tenn Community Advisory Panel (RCAP) at its August 4 meeting, came after more than a year of often-contentious study and debate.
Anaerobic digestion would start with agricultural or food processing byproducts as fuel and bacteria as the agent to turn that fuel into methane (also called bio-gas.) Anaerobic digestion for production of industrial quantities of biogas is a relatively new technology. Pete Klein, who presented the SPPA recommendations at the meeting, identified animal manure, rendering plant wastes, and ethanol stillage as raw materials that have been identified for generation of biogas for this project.
The SPPA recommended three possibilities, but emphasized its strong support for anaerobic digestion, their top-rated option. The other two options were a new gas-turbine co-generation facility (still powered by biogas) and gasification of renewable biomass energy crops.
Savings of 10-20% over the cost of natural gas were predicted, based on carbon offsets and federal financing guarantees and/or other public subsidies for energy efficiency and environmental impact. No new systems would need to be constructed at the Rock-Tenn plant for this alternative.
Klein pointed out that conservation and energy efficiency measures taken by Rock-Tenn have decreased peak energy demand by 23% over the past year, and that conservation efforts are on-going. In addition, investigation of ways to recover waste heat from the manufacturing process continue.
The general sense of the assembly, however, was overwhelmingly positive. RCAP member Ellen Watters observed, “For the last couple of meetings, it’s been like arranging a marriage, but the bride wasn’t here. Now, with six parties, it’s more like a menáge a trois, but everybody’s here.”
Rock-Tenn is “pretty excited about this anaerobic digestion possibility,” said Bob Carpenter, assistant general manager of the plant, while acknowledging that “when you talk about a ten year commitment, we want to look at the details.” He also said that conservation measures at the Rock-Tenn plant will continue. “We spent $800,000 this year,” Carpenter said, “and earmarked $2 million next year for energy improvement.”
Union member Steve Galewski praised the work done to get to this point. “Environmentally, you couldn’t ask for a better deal, and you’re saving a lot of jobs,” he said.
“Let it be known now that NAB agrees with the Allan Schultz (of the RCAP committee) that Peter Klein has done a terrific job of pursuing this off-site anaerobic digestion option,” said Nancy Hone, speaking for Neighbors Against the Burner, who have been steadfast in their opposition to any option involving incineration at the plant. “NAB and the citizens of the state of Minnesota want to know what we can do to bring this home.” Hone asked for an assurance that refuse-derived fuel is definitively “off the table.” She didn’t get it, as both Klein and Carpenter said they could not make that statement.
“There’s an awful lot of work to be done,” Pete Klein of SPPA warned. He said that with six parties involved, as well as financing from the Department of Energy, the project is not simple.
Many questions remain. While Klein indicated that the biogas plant (or plants) will be privately owned and operated, the owner-operator was not identified. The location—or locations—of the proposed biogas plants was not disclosed.
RCAP will study the draft energy facility study during the next two weeks, and may make its final recommendation at its August 18 meeting. District councils will also have an opportunity to weigh in, and public hearings will be scheduled in coming months.
Mary Turck is the editor of the TC Daily Planet, and has written extensively on Rock-Tenn fuel issues. She lives in St. Paul near the Rock-Tenn plant.