The City of Franklin (population 510), located in Renville county in southwest Minnesota, has quickly become an area leader in renewable energy with the installation of its 250,000 Btu biomass boiler heating system. Utilizing funding from an American Recovery and Reinvestment Act (ARRA) grant received through the Minnesota Department of Commerce, Division of Energy Resources, the city was able to build its current two boiler system, which heats three primary city buildings: city hall, the fire hall, and the city maintenance shop.
The three buildings, whose footprints combine to encompass almost 6,000 square feet, receive 100% of their heat from the biomass system, which has burned a variety of wood and agricultural residue-based biomass pellets since coming online in February 2011.
Project Formation:
A few years ago, the city was approached by a group of individuals who wanted to bring a biomass pellet production facility to town. Though that project never materialized, the idea of utilizing locally-sourced fuel (wood and agricultural residues) for the city’s heating needs remained. Once made aware of the ARRA funding opportunity, the city decided to attempt to put together a biomass heating project, with the idea of sourcing local biomass as its primary fuel. The city selected Dan Reek of Rural Energy Connections in Eden Prairie to be the project’s manager and submit the bid to the Minnesota Department of Commerce for an Energy Efficiency and Conservation Block Grant (EECBG).
A strong working relationship between Reek and city planning officials was a key part of the planning process that allowed the team to efficiently address any project design issues. For instance, biomass heating projects like these often incorporate storage bins to house the biomass pellets used for fuel in the boilers. However, city officials made Reek aware of the zoning ordinance that prohibited storage bins within Franklin city limits. As such, the project team was able to design a two-tiered roof design for the boiler building which included extra space for biomass pellet storage, meeting both project needs and city requirements.
Project Construction:
After all system design issues were handled, project construction moved along quickly. The City of Franklin made a concerted effort to use local contractors and materials whenever possible and was pleased with the level of service provided. However, efficient execution of the construction required a high degree of coordination between Rural Energy Connections and the local contractors. Franklin city officials noted that enabling a clear working relationship between these two sets of professionals should be a high priority for other cities considering a project like this.
System Specifications:
Franklin’s biomass heating system utilizes an open-loop, water-based system that carries water heated by the biomass boilers to a plate-style heat exchanger, where the water exchanges its heat with a separate closed-loop system that feeds into each of the three city buildings. Water leaves the biomass boiler at 190 degrees Fahrenheit and, after making its way through the heat exchanger, returns to the biomass boiler at approximately 160 degrees. A total of 521 feet of underground piping (laid within tile tubing) connects the three city buildings to the heat exchanger in the boiler building. Each heated city building has its own thermostat and distribution system, which disperses heat carried in the closed loop system by blower fan (city hall and the shop) or zoned radiators (fire hall). The system was integrated into each building’s existing heat distribution system.
During its first year of operation, the city’s public works director spent a short period of time checking the system every day to ensure it was functioning properly. The city manager now checks the system every 3 to 4 days, with the primary task being removal of ash from the spent fuel collector. Very little additional maintenance has been required since the system was installed.
Project Insights:
The city has been very pleased with the system performance, noting that the biomass boiler produces even heat across the entirety of each of the buildings. The city has had good luck with wood biomass pellets, noting their high-efficiency burn rate, which results in little ash. The city continues to search for a low-ash pellet made from agricultural residue. With operation and maintenance a virtual non-issue, the city’s primary focus is on securing a consistent low-cost fuel supply, preferably from a local producer, and a low-cost means of pellet transportation to save on shipping costs. The project team has been very happy with the system, and has no complaints about its heating capabilities or minimal O&M requirements.
Costs:
Franklin’s biomass heating project cost approximately $64,200. This cost included the installation of a second 250k BTU biomass boiler (approximately $7,600) to ensure sufficient heating capability and reliability. There were also added costs related to the unique two-tiered boiler/storage building that was required for the city’s zoning code. Finally, an additional $10,612 was needed for the purchase and installation of energy-efficient overhead doors located in the shop and fire department buildings. This increased the insulation of the building envelope, thereby reducing the city’s overall heating need/costs. Project Manager Dan Reek estimates that a similar biomass heating project, without the second boiler, special building (substituted for a used grain storage bin), or overhead doors would cost approximately $39,700.
The old propane-based heating system cost the City of Franklin approximately $7,077 per year to keep each of the buildings at their desired temperature. Using its new biomass-based heating system, the same heating load will cost the city less than half of its previous level, at $3,022 per year. With the added efficiency gained through the installation of the new overhead doors, the city’s annual heating costs were reduced even further, to approximately $2,210 per year! As demonstrated in Franklin, energy efficiency and renewable energy can be valuable in any local government’s energy project planning.
Without even factoring in that the cost of propane will continue to rise at rate much higher than biomass pellets, Franklin’s biomass heating project presents an estimated payback of about 14.5 years. Alluding to the increased costs that Franklin allowed for their project, Dan Reek estimated that a similar project—without the second boiler, special building, or overhead doors—would likely result in an energy savings payback of approximately 10 years.
Other Local Government Energy Action Renewables Stories:
- Brainerd Lakes Regional Airport solar thermal air heating system
- Renewable heating projects: biomass, wastewater, and solar thermal
- Untapped wastewater energy in Brainerd
About the Local Government Energy Action Series:
This year-long effort tells the stories of nearly 50 Minnesota municipalities, counties, and schools and the tangible results of their energy-saving efforts to inspire others to take their own actions.
Local Government Energy Action is brought to you by the Clean Energy Resource Teams (CERTs) in partnership with the Minnesota Department of Commerce, Division of Energy Resources.
