Wood working

–by Liz Morrison

Southeastern Minnesota could use its abundant wood supply to generate biomass power.

That’s one of the messages from a recent meeting of the Minnesota Renewable Energy Roundtable, held July 17 in Rochester. First convened in 2006 by AURI, the Roundtable brings people and ideas together to spur renewable energy development. “Every organization represented at the Roundtable brings varying perspectives and understanding of renewable energy,” says Nan Larson, AURI’s director of innovative networks. In addition, the Roundtable connects entrepreneurs with resources and scientific expertise, helping to speed up commercialization of new products and ideas, she says.

“This event put woody biomass on the table as a legitimate source of renewable energy for Rochester and southeast Minnesota,” says Angela Gupta, a University of Minnesota Extension forester in Rochester.

The Rochester area produces about 1.6 million green tons of hardwood and softwood per year, but consumes only about 500,000 tons, according to a 2014 survey by the Minnesota Department of Natural Resources.

Rochester recently launched a 20-year, $6 billion economic development effort that aims to make the city a global health care hub. Destination Medical Center (DMC) plans to expand Rochester’s famed Mayo Clinic facilities and transform the city’s downtown core.

The ambitious public-private partnership offers an opportunity to rethink Rochester’s energy goals, Gupta says. In public meetings about DMC goals, community members expressed “a clear priority to have a sustainable city,” she says.

Other local communities are already operating wood power plants that simultaneously generate electricity and thermal energy from a single fuel source — a system known as combined heat and power, or CHP. Modern CHP plants are more efficient than either electric or thermal power plants, offering about 80% efficiency, says David Ripplinger, bioenergy specialist at North Dakota State University Extension. More efficient energy production means lower operating costs and fewer greenhouse gas emissions, he says.

St. Paul’s District Energy, for example, heats and cools the downtown with a 25-megawatt CHP plant fueled by urban wood waste. Using wood waste as biofuel keeps the material out of landfills, furnishes an economical way to dispose of damaged and diseased trees and tree trimmings, and offers stable fuel costs, says Ken Smith, CEO, District Energy St. Paul.

On the small end of the scale, Gunderson Health Systems in LaCrosse, Wisconsin, operates a 800 horsepower wood CHP plant, which powers the 325-bed medical center. In 2014, the power plant used 16,300 tons of wood, saving $260,000 over the cost of natural gas, says Alan Eber, manager of engineering and energy management at Gunderson Health Systems.

The Renewable Energy Roundtable explored key wood biomass power issues, including:

• Federal and state biomass power policies and incentives
• Biomass CHP plant economics
• Wood supplies and supply chain issues in southeastern Minnesota
• Risk assessment tools for screening potential wood power plant sites

To learn more and view presentations from the event at https://auri.org/help/innovation-networks/minnesota-renewable-energy-roundtable/july-17-2015-event/