Biomass Magazine webinar highlights biomass power on campuses
During Biomass Magazine’s third installment in its free webinar series, four presenters described how their respective colleges and universities successfully implemented a biomass solution into their campus energy portfolio and its resulting benefits, as well as challenges faced and future endeavors.
Ferman Milster of the University of Iowa discussed UI’s renewable and carbon reduction goals, which includes 40 percent renewable energy consumption by 2020. UI currently spends about $25 million on energy per year, consuming a just over 4 million Btu, according to Milster. Replacing 60 percent of current coal use—or 1.6 million Btu—would enable UI to reach its renewable goals, he says.
“A major thrust we’re using to promote this project is that this is local energy, as Iowa has no coal miles, oil wells, or natural gas, so it all comes from out of state,” he says, adding that even though Iowa has 23 percent wind energy production, RECs (renewable energy credits) are sold out of state.
UI’s main campus has two solid fuel boilers, a circulating fluidized bed boiler and a stoker boiler. Milster said it took about two years to figure out how to reconfigure the fuel handling system to allow oat hulls to be cofired with coal, as UI has a partnership with Quaker Oats in Cedar Rapids, Iowa. “Initially we just tried blending the oat hulls and coal together but that obviously didn’t work because of the radically different fuel properties,” he said. “It became apparent, very quickly, that we’d need a new fuel system.”
For cofiring activities in the stoker unit, the challenge has been finding a biomass source that wouldn’t cause slagging. “Right now we’re working on wood chips, but we have cofired a wide variety of materials,” Milster said.
That’s led to an expansive biomass fuel project that’s focused on growing energy crops—including miscanthus, energy trees and switchgrass—for use at UI. “Biomass has low energy density, so we’ve restricted our fuel procurement radius to fifty miles around Iowa City,” Milster said,
Work ahead will involve combustion trials with these different types of biomass, according to Milster. “We need to figure out to optimize energy crop harvest, transport and storage…nobody else is doing it in our area, so we’re kind of out here doing this on our own.”
Following Milster, the University of Minnesota-Morris’s Sustainability Director, Troy Goodnough, discussed UMM’s renewable and carbon reduction initiatives, lessons learned and impacts from biomass plant and renewable energy work.
UMM has a goal of carbon neutrality by 2015, which was largely prompted largely by students. “We also want to make more energy than we consume, and in many ways we’ve achieved that goal already,” Goodnough said.
Goodnough said when the journey to biomass began in 2001, the volatile price of natural gas was having a big impact on the university’s budget. “We needed to do something different…but it was risky moving forward with the biomass gasifier.”
An EERC research study that was performed to determine how much biomass was available within Stevens County found there was about 700,000 tons of ag residue within 100 miles of the college. Ultimately, corn cobs were chosen as fuel. Within that 100-mile radius, there are about 130,000 acres of harvested corn, which yields about half of a ton of corn cobs per acre, according to Goodnough. “At absolute max we’d need about 18,000 acres to supply biomass of full capacity, and that represents 14 percent of the acreage in Stevens County. We expect our biomass usage to grow between now and 2015 towards our target throughput goal, between 6,000-9,000 tons per year."
The total project cost $8.9 million, but only about $6.1 million after grant funding was taken into account. UMM broke ground in July 2007, and plant dedication was in September 2008.
The biomass system provides UMM with three options—steam production, chilled water and electricity—and includes a 600-ton absorption chiller and a 300-kilowatt back-pressure steam turbine that generates 15,000 pounds of steam per hour at 300 psig. “The reason we went to gasification is because working with ag residues is challenging, and we want to keep the temperature in our bed as low as possible. By not going to combustion, we can keep the bed temperature low and all of those ag minerals stay in the ash and don’t volatilize.”
On lessons learned, Goodnough said corn stover is an extremely difficult fuel, partly because it has a fair amount of HCL when it burns, it binds around equipment and poses some density challenges. “In many ways, a corn cob is a nice little energy packet we can use.”
He added that a scrubbing system that can accommodate large amounts of particulate matter is needed, and it’s important to realize all impacts of [Minnesota’s] cold temperatures.
Following Goodnough, Jack Byrne, director of sustainability integration at Middlebury College, described the college’s carbon reduction goal, which initially was 8 percent below 1990 levels, and how students performed analyses to determine what the best strategies might be to meet that goal.
A $12 million bond was approved to build a biomass gasification cogeneration facility, which was deemed as the best option. It was added onto the existing central heating power facility that hosts four oil boilers, which are used during peak demand.
“In 2009, the plant came on line, so we took about a year and a half to complete construction and commission,” Byrne said, adding that Middlebury faced of the same questions and issues that UMM did.
Though it is currently using wood chips, the college soon began looking at the idea of growing its own fuel. In 2011, Middlebury harvested about 10 acres of willows that it had planted and did four days’ worth of test burns, according to Byrne. “We developed a lot of good questions as to how to burn willows, and we decided it wasn’t long enough to know whether it was a feasible fuel source. Our next step will be to do a much longer, 20-day burn.”
Byrne said the payback on the project was expected to be 12 years, but it has dropped by about four years due to much higher than expected oil price increases. “Also, the price of wood has risen more slowly than we projected,” he said. Middlebury saves about $1.5 million to $2 million per year using biomass fuel, which amounts to about 20,000 tons per year and displaces about 1 million gallons of fuel oil.
On challenges, Byrne said there was a pretty steep learning curve, as there are a lot more moving parts to a biomass plant—conveyors, augers, the gasifier itself and ash management—and it took about a year and a half to understand the system and tweak it so it runs well. “It’s more complex than oil, and requires more attention,” he said.
The final webinar speaker was Kevin Craig of the Dalhousie Agricultural Campus in Truro, Nova Scotia.
The biomass facility there is a heating plant only, but a proposal to expand it is being considered, Craig said. He explained the K&W system was installed in 1998 and funded by the provincial government in order to demonstrate its viability to other industries in the process.
Because the system is older, plant personnel have to manually rake the furnace several times a day to stir up the fire, get rid of ash and clinkers, Craig said. “When we switched [systems], oil prices dropped quite dramatically, so oil pricing made the savings and viability of this type of system not so great. One year our saving was $24, as oil was 18 cents per liter.”
It didn’t take long, however, for oil prices in increase, and at the same time, wood prices didn’t climb so drastically. “Oil prices went up 14 percent for us, wood went up 1 percent,” Craig said.
The wood system as a prototype wasn’t large enough to heat the entire campus, so it has to be supplemented with some oil burning. “Savings during the last two years just shy of $1 million; that’s a direct comparison verses No. 2 fuel oil,” Craig said. It’s less of a savings compared to natural gas, but that isn’t readily available here [the savings are] pretty good, especially compared to the size of our campus, which has 1,000 students.”