Biomass boiler nearing completion at University of Illinois, UC

By Katie Fletcher | February 02, 2017

Around the beginning of December, a biomass boiler arrived at the University of Illinois at Urbana-Champaign’s energy farm. Currently, the university is busy installing the boiler, along with the required plumbing and electrical work, and in mid-to-late February, the unit will replace propane as the primary heat source for the energy farm’s main research greenhouse.

Manufactured by the German-based company Heizomat GmbH, the 198-kilowatt (kW) (675,000 Btu per hour) boiler will combust biomass, initially Miscanthus x giganteus, to heat water distributed across the research complex as the primary energy source for heating.

The University of Illinois at Urbana-Champaign’s 320-acre energy research farm focuses on second-generation biofuel crops, primarily on perennial grasses, fast-growing woody crops and some annual crops that can be considered a biofuel crop. The energy farm has also added sustainability projects, including looking into sustainable food production, however, the main focus has been on perennial feedstocks for biofuels.

Now, the university has the opportunity to take a portion of its energy crop and use it as a biomass fuel to heat the very greenhouse that helps grow it. After project funding was secured in July 2016, the greenhouse was retrofitted from forced air propane heat. Hot water heating will now be used through aluminum fin tubes around the parameter and forced air hydronic heaters that were placed next to the existing propane heating source. The propane heating assets will be kept in place as a backup. After retrofitting the greenhouse during the summer months, this past fall, the university prepared for the arrival of the biomass boiler by constructing the groundwork for the boiler house. In addition to the boiler, the boiler house will contain a Järnforsen cyclone particulate separator for flue gases and two, 1,000-gallon thermal storage tanks.

According to Tim Mies, director of the university’s energy farm, there is a little bit of a learning curve associated with converting the boiler from European standards to meet those in the U.S. System features include an auto-feeding fuel system to control burn rate, de-ashing and self-cleaning systems for more efficient burning, and electronics within the pumps, which allow for data tracking of supply and return temperatures, flow, electrical energy consumption and calculated energy. This data will be transmitted over a SCADA network to a centralized server for real-time display and analysis.

Once operational, boiler operators will also have to work with the boiler to run on miscanthus, as the boiler was built to burn wood chips. “We have seen installations where it has used miscanthus, but there will be small tweaks required to combust our grasses efficiently,” Mies said. “Initially, we’re going to configure it to burn miscanthus, but after that, this boiler is really designed to be a test bed for different feedstocks—it could burn wood chips, pelletized material—it’s really not designed to be a single-source feedstock only.”

The miscanthus the university is initially using is allowed to field dry through the fall and winter prior to combustion. “Basically, we wait for a killing frost to where the plant starts to dry down and the nutrients translocate back into the rhizomes, and we allow that to all happen naturally in the field with the plant standing,” Mies said. “As far as the harvest, initially we’re going to be working with just a standard forage chopper that will chop the material into approximately one-inch pieces and that will be fed directly into the boiler.”

Down the road, Mies said, the university wants to explore different practices, such as using bale processors or other material handling equipment to either improve upon the feed supply or bring the cost down, all in an effort to see what is the most user friendly in regards to the time spent managing the boiler.

Based on the university’s propane use over the last four years, the project team is able to estimate the amount of Btus needed to heat for a winter season. Based upon this, around 60 tons of biomass will be used to heat the greenhouse per year, which replaces 8,000 gallons of propane on an approximate Btu basis, equivalent to saving some 50 tons of CO2 from being released into the atmosphere.

Initially, the biomass boiler will run throughout the heating season, but Mies said, one option they’re looking into is to expand the number of months that boiler research can occur. “We might look at alternate uses for the heat where we can run in the non-critical months, testing different biomass sources,” he said.

Although the boiler will initially just heat the greenhouse, “down the road, we may look at adding additional heating loads to it that might expand upon the capability of the boiler, but for our initial project, it’s just this individual building,” Mies explained.

The university’s energy farm produces more than 500 tons of biomass each year, and expansion of biomass crops on the farm could easily top 1,000 tons per day, displacing 650 tons of coal currently used on campus. According to the university, this project lays the foundation for larger biomass projects that could directly supply renewable energy to the Urbana-Champaign campus through the Abbott power plant or other plants that feed energy to campus.

This project is the first biomass energy initiative on campus, and it will contribute to low-carbon energy targets laid out in the Illinois Climate Action Plan. The University of Illinois at Urbana-Champaign also has installed a solar farm that produces about 7,800 MWh of electricity per year and it’s recently entered into a wind power purchase agreement. “All of these are different ways we are looking at achieving our carbon neutrality goals,” Mies said. “We still have a long way to go.”

The purchase of the boiler and its installation were supported by grants from the Illinois Clean Energy Community Foundation, the Student Sustainability Committee, the Dudley Smith Initiative and proceeds from the 2015 campus sale of verified carbon credits to Chevrolet.