University Sees Biomass as Future for Energy Generation
Biomass has been in use at the University of Missouri power plant since 2005. The power plant boilers have been cofiring wood waste up to 5 percent with coal in the existing plant boilers, consuming between 5,000 and 6,000 tons of woody biomass this year.
So far, using biomass as an alternative fuel source has had a positive impact on the university campus. Overall, greenhouse gas emissions have been reduced by 7,000 tons per year and the reduction in carbon dioxide emissions is equivalent to planting 28,000 acres of trees. In addition, by sourcing locally grown biomass, the university has reduced diesel fuel consumption by almost 16,000 gallons per year that would have been used to transport coal to the power plant from neighboring Illinois.
The university recently made the decision to replace an existing boiler with a 100 percent biomass-fired boiler that will produce 150,000 pounds of steam per hour. This will increase the power plant’s steam output by 30,000 pounds per hour once the unit is replaced—enough to build capacity and meet anticipated growth. The new boiler should be in operation in 2012.
“We needed to add steam capacity at the power plant, so we began looking at our options,” says Gregg Coffin, superintendent of the University of Missouri power plant. “We could expand using coal, but that would be problematic from an environmental standpoint. Obtaining a permit would be difficult, and we anticipated push-back from the campus and local community in regard to adding another coal-fired boiler.”
The university believed it could install a biomass boiler much more cost-effectively for the life cycle, compared with natural gas. Plus the biomass would provide several benefits that a natural gas boiler would not. Biomass is 100 percent renewable and would provide an investment back into the local economy instead of purchasing coal and natural gas from other states.
“We have the potential—with this new biomass boiler—to displace about 25 percent of our coal consumption,” Coffin says. “It’s a pretty significant jump considering we’re currently at less than 5 percent.”
Creating a Sustainable Supply Chain
The biggest challenge according to Coffin will be sourcing biomass fuel for the boiler and having adequate storage and handling systems in place to serve the unit. The new boiler will require 100,000 tons of biomass annually, which is a substantial jump from the 6,000 tons currently being sourced.
Coffin sees about one-third of the woody biomass fuel coming from waste stream sources—mills, chopped pallets, development clearing, tree trimming and ice storm damage—one-third from forestry management and thinning efforts and another third coming from growing biomass instead of traditional crops.
“We are tapping into the resources here at the university,” Coffin says. “The university forestry department has been actively involved with the project, helping source woody biomass from waste trees. They’re highly interested in supporting a forestry thinning effort and establishing the criteria for that.”
According to Hank Stelzer, a state forestry extension specialist for the University of Missouri, the state forests are not in the best of health.
“Forest thinning would greatly improve the health and quality of our forests and at the same time provide a good, renewable source of fuel for the plant,” Stelzer says. “We’re developing a set of thinning and harvesting guidelines to make sure we protect the long-term integrity of the state forests, yet create a sustainable source of biomass, not just for the university but for other facilities across the state.”
Biomass—A New Value-Added Crop
The university is exploring options to grow woody biomass crops on marginal ground and in the river bottom areas across the state that were affected by flooding in 1993. The land in these areas is no longer economically viable for traditional row crops as the soil profile features a deep sand formation. While this type of soil isn’t suited for row crops, it is ideal for certain species of trees, such as willow and cottonwood.
Stelzer and other forestry faculty are in the process of establishing research plots that will test various species of trees to determine their potential as energy crops. The University of Missouri’s Center for Agroforestry began experimenting with different species of cottonwood and hybrid poplar back in the late 1990s and over the years has identified select clonal varieties that are well-suited to the soil conditions in Missouri. Today, the research is being done in collaboration with the State University of New York, University of Minnesota and Mississippi State University.
Traditionally willow and cottonwood trees have been planted in a 10-foot-by-10-foot spacing pattern and were allowed to grow for five to six years before being harvested. Stelzer says that current thinking is to plant the trees in a double-row configuration, however, where two rows will be planted close together on 2-foot-by-2-foot centers with a 5-foot space and then another double row of trees.
“Basically we will set the cuttings in year one and clip out the tops to help promote multiple sprouts,” Stelzer says. “The trees will grow for three years and reach a height of up to 20 feet with several stems (eight to 10) coming from that clump. The neat thing is, especially with willow and cottonwood trees, is the ability to harvest the trees about every three years or six times over the 20-year life of the tree. At 20 years of life the trees will be removed and the process starts all over.”
Stelzer says that producers can expect to produce 9 to 13 dry tons woody biomass per acre at the end of the three-year growing cycle, and this number will go up as the university identifies higher yielding varieties over time. At the current price the power plant is paying ($35 per ton) that would generate $315 to $473 in revenue to the farmer on just one acre. That’s enough to get a farmer’s attention considering the input and production costs are minimal.
Harvesting the woody biomass is another issue, but a team of researchers at the State University of New York have been working with New Holland, a leading agricultural equipment manufacturer, to develop specialized equipment to harvest the woody biomass. Basically, the team has created a harvesting head that is fitted onto a New Holland forage harvesting machine. As the machine moves through a field of trees, the harvesting head clips off the trees, which are then fed into the machine and a cutter drum chops the woody biomass into small pieces, similar to processing a tree in a brush chipper. The resulting processed woody biomass is placed onto trucks and transferred to a storage site.
The MU Forestry Department, in cooperation with the MU Center for Agroforestry, is developing a pilot program at the Horticultural and Agroforestry Research Center in New Franklin, Mo., that will include test plantings of various tree species to produce woody biomass. The pilot will also test harvesting options and deliver the resulting wood chips to the power plant. The purpose of the pilot project is to show farmers how they can adapt this new crop to their farms.
“Woody biomass production has the potential to be more profitable and economical than traditional row crops, especially in the Missouri river bottoms laid waste by the floods of 1993 and 1995,” Stelzer says. “It also allows farmers to regain lost production acres with fewer disturbances to the land compared with traditional agronomic production. We’re also enabling the farmer to integrate forestry practices into other areas of the farm that will not only provide another source of income, but also serve as a sediment, nutrient and pesticide trap in the root systems of these trees.”
Considering More Than Woody Biomass
Coffin and his team are also seriously exploring how to utilize corncobs in the new boiler as the university is located in the heart of Missouri corn production. Plus the new boiler technology burns at a lower combustion temperature making it more suitable to agricultural-based fuels.
“The new boiler can handle a full-size cob and the opportunities to source cobs as a fuel source are abundant in our state,” Coffin says. “The biggest challenge is collection and storage. However, companies are developing innovative collection systems that are showing promise. We just need to address how to deal with such a large volume of material.”
This project will truly be a test to see how the biomass industry can and will develop in the state.
Should the price of biomass become more expensive than natural gas, however, Coffin has the ability to switch the boiler over to gas until the price of biomass comes back in line with fossil fuels.
Either way, the university and the Columbia community will see a reduction in conventional emissions.
“I believe the campus community appreciates this opportunity to produce energy from a renewable crop and reduce greenhouse gas and carbon emissions,” Coffin says. “We’re creating something here that’s a win-win for everyone involved and from the calls we’re receiving, there’s a lot of support for the direction we’re taking.”
Greg Ehm is a features writer for Two Rivers Marketing in Des Moines, Iowa. Reach him at email@example.com