IOWA CITY (AP) — After more than a decade of success with burning oat hulls as a source of renewable energy, the University of Iowa is now turning to a new biomass source: wood chips.
The emphasis on biomass stems from the university’s ambitious goal, set by U of I President Sally Mason in 2010, of using 40 percent renewable energy by 2020. University officials have said the most effective and realistic way to reach the goal is by reducing its use of coal in favor of biomass. A February report found the university could meet the goal if it cut its 2010 coal usage by 60 percent.
The U of I currently has a stash of 3,000 tons of wood chips it plans to burn at its power plant to help provide power, steam and chilled water on campus.
The university got the wood chips through a deal with Johnson County’s Conservation Board, which needed to clear a section of dead and dying conifer trees from a park for a prairie restoration project, said Ferman Milster, principal engineer for renewables in U of I’s Office of Sustainability.
“It gave us a source of fuel at a reasonable cost,” Milster said.
Milster predicts the current wood chip supply will last through spring, at which point the university hopefully will have a new source of wood chips.
Because wood chips are heavier and larger than oat hulls, they need to be mixed with coal before being burned. Workers will ramp up the proportion of wood chips that are burned over the next few months and hopefully will have reached a comfortable blend by wintertime, said Ben Fish, assistant director of utilities and energy management.
As promising as burning wood chips and oat hulls looks, the university still has a long way to go before meeting its 2020 goal, which will require the energy equivalent of 100,000 tons of biomass per year. By comparison, the 3,000 tons of wood chips from Kent Park represents only 3 percent of that goal, Milster said.
The university is experimenting with other forms of biomass, too. In June, it planted 16 acres of a perennial grass called miscanthus x giganteus. When the grass matures, in about three years, the U of I will try burning it for fuel, said Ben Anderson, power plant maintenance and engineering manager. The heat content of miscanthus is similar to oat hulls, he said.
The university plans to plant another small plot of miscanthus in 2014, and then plant 1,000 more acres in 2015, Milster said. It also is seeking potential growers to contract with, he said.
About 15 companies and individuals have presented the university with other potential biomass sources, Fish said. They’ve considered using corn stover from farms, tree waste from landfills and wood products from a furniture manufacturer.
“The problem is we’ve got so many options, we really need to try to focus on one or two and see how well we can do those,” Fish said.
The reason so much emphasis is placed on biomass is because it replaces the university’s use of coal, which, in 2010, made up 50 percent of its total energy use, Milster said. Using wind or solar energy would replace the university’s use of purchased electricity, but in 2010, that was only 24 percent of the portfolio.
Behind all the biomass work the university is doing, the end goal is sustainability, Milster said. Iowa doesn’t have any coal mines, gas wells or oil wells, so all of its energy is imported from outside of the state, he said.
“This project has a tremendous opportunity to return those monies that we spend on coal and natural gas to the local, rural economy or other businesses,” he said. “That’s key.”