Linking Nutrient Reduction Practices with Biomass Energy: Quantifying Thermal Energy Demand and Supply Capacity for Representative Farms in Eastern Iowa
According to the Iowa Nutrient Reduction Strategy, changing land use from row crops to perennial vegetation such as CRP or energy crops can reduce nitrate losses by 72-85 percent and phosphorus losses by 34-35 percent. Contour prairie strips can reduce surface nutrient runoff as effectively, and for about the same cost as cover crops. While perennial vegetation does not involve the uncertainty of replanting every year, they do reduce a landowner’s options for switching crops or management techniques in response to market conditions.
Increasing the number of farmers who adopt diverse, native perennial vegetation will require attractive conservation incentives, viable economic uses or some combination. This project is designed to quantify the barriers and the financial incentives for perennial vegetation used for both soil/water conservation and renewable energy.
Researchers will estimate the potential biomass energy produced per acre by prairie contour strips and other perennial vegetation based on existing data; document the types and quantity of thermal energy needs, and the seasonal pattern of demand, for several farms and/or rural businesses in eastern Iowa; model the quantity of thermal energy that could be produced with proper management of perennial biomass adopted for nutrient reduction purposes; research the harvest, processing, transport, storage methods and timing that will best meet the needs of the farms studied; identify the most cost-effective processing and conversion equipment for one farm or rural neighborhood; and calculate the payback period for a range of likely scenarios.
The final publication was provided as the project outcome: Giddens, E., L. Jackson, K. Enshayan. 2017. “Linking Nutrient Reduction Practices with Biomass Energy: Quantifying Thermal Energy Demand and Supply Capacity for Representative Farms in Eastern Iowa.” Tallgrass Prairie Center, University of Northern Iowa. PDF at: https://tallgrassprairiecenter.org/sites/default/files/2018_biomass_report_1.pdf
Team members distributed the white paper to various biomass energy-related organizations for dissemination.
Graphic design work was done to package the details of this project into a white paper format. Co-PI Laura Jackson shared a draft of the white paper at the Green Lands Blue Waters annual conference at the University of Wisconsin-Madison in November. Also during the conference, she discussed the project with the Green Lands Blue Waters Biomass Working Group.
Work on a white paper based on this project is ongoing, and the draft was reviewed this quarter by a key partner. An undergraduate student was hired to assist with graphic design and communications work, packaging the white paper’s content into multiple formats for dissemination to various audiences.
This quarter, work continued on developing the white paper for this study. Packaging the paper’s content into multiple formats for dissemination to various audiences also is underway.
During this reporting period, an additional rural facility that uses propane as a heating fuel and could potentially benefit from converting to a prairie biomass heating system was identified and analyzed. The facility is a typical hog confinement operation with four buildings in Howard County. Full conversion to prairie biomass heat would require approximately 10 acres of prairie. If 10 percent of row crop ag land were converted to prairie strips as a conservation practice, only 100 total acres would be needed to supply the prairie biomass to heat this facility.
During this reporting period, more rural facilities that currently use propane as a heating fuel and could potentially benefit from converting to prairie biomass heating systems were identified and analyzed. In addition to animal confinement buildings identified previously, rural commercial greenhouses also are potential candidates for prairie biomass heating systems. One example is a large commercial greenhouse operation in central Iowa that uses approximately 200,000 gallons of propane every year for heating. This operation has 45 heating units, some forced air and some boiler units. Full conversion to prairie biomass heat would require approximately 440 acres of prairie. For this facility, conversion could be done in stages by replacing a few heating units at a time as prairie is planted in the region to supply biomass feedstock for the heaters.
A spreadsheet to calculate the payback period for a new biomass boiler installation has been developed. It calculates an estimate of the number of acres of prairie that would be needed to provide adequate feedstock for the biomass heating system, and payback periods for a range of biomass feedstock costs and propane costs. A 2009 Iowa State University study estimated an average of 2.45 gallons of propane are used annually to heat each pig space in Iowa hog confinements. For a 5,000 hog confinement, this equates to an average of 12,250 gallons of propane annually. Displacing that amount of propane with prairie biomass could require as little as 28.5 acres of prairie, and could take less than 10 years to pay off the equipment premium.
A review was done of projects across the United States that have tested grass-based biomass heating equipment. A group of collaborators in Vermont are focused on small-scale applications, similar to this Iowa project. They selected and installed appropriate equipment, tested it with a variety of feedstocks, monitored stack emissions, and released a report May 2016. This report will provide valuable information as this project moves forward. Biomass heating systems make the most economic sense in commercial or institutional buildings that need to be heated throughout the winter, and currently are heated by propane. Buildings in northeast Iowa near Prairie on Farms installations that would be good candidates for this study are being investigated.
A meeting was held with the owner of Renew Energy Systems, a biomass densification business in St. Ansgar. Renew does densification of various types of biomass into briquettes. Plans are being made to have the company do a densification test run with one large square bale of the project’s prairie material. Maps of the Tallgrass Prairie Center’s Prairie on Farms program demonstration sites are being used, plus the land area of the prairie strips at each site, to develop a model of the quantity of thermal energy that can be produced with proper management of the prairie strips on each of these farms. Investigation of d
Meetings were held with two farmers who have installed prairie strips on their land, with both interested in the idea of using harvested prairie vegetation as a heating fuel. Discussion at a meeting of the Green Lands Blue Waters Perennial Biomass Working Group led to agreement that it’s first important to identify biomass heating units appropriate for burning prairie feedstocks before any further investigation of potential end users. A Minnesota farmer was visited who makes biomass pellets on site and burns them in pellet boilers to heat his greenhouse operation.