Solar thermal collectors at Brainerd Airport

Heating air with solar thermal at Brainerd Lakes Regional Airport

Updated July 12, 2013 with system performance and savings over the 2012-2013 winter heating season.

Located just three miles outside of Brainerd, Minnesota, the unassuming Brainerd Lakes Regional Airport has instituted a solar energy heating system that will serve as an example to the region for decades to come. Utilizing nine 4 foot by 10 foot solar thermal air heat collectors affixed side-by-side on the south wall of one of the airport’s larger storage buildings, the airport saved over $500 in heating costs in the 2011-2012 winter, and an additional $1,400 in the 2012-2013 winter.

Unlike solar photovoltaic technology, the airport’s solar thermal system has nothing to do with electricity production. Rather, the solar thermal system’s collectors heat the air inside the building by absorbing solar energy. Once sufficient heat has been collected, a simple fan system moves the warm air into a building’s HVAC system. Airport officials are pleased with the system and look forward to documenting further energy savings in future winters.

Project Formation/Planning:

In February 2011, the Rural Renewable Energy Alliance (RREAL), in partnership with the Region 5 Development Commission, conducted a series of solar thermal site assessments to gauge solar thermal project potential for various local governments in central Minnesota. One such assessment was conducted at the Brainerd Regional Airport, which revealed a favorable situation for a solar thermal system on the airport’s vehicle storage building. After considering the project economics and relatively favorable return on investment, airport officials decided to move forward with the system.

Project Construction:

Construction for the system went very smoothly. Roger Garton, project manager from RREAL, reported the installation took only two and a half days, where similar projects might take up to five days to install. The construction process was accelerated by a relatively simple building layout. Because the interior of the storage building is one big room, the system didn’t need to be configured to any particular venting system, allowing a simple hot air dump at three different points along the building. The collectors were installed on the south wall of the building standing on end, one next to another. Because the storage building was covered in sheet metal, a bit of additional structural support was added to hold the system, though additional time and cost were limited, as indicated by the efficient install time.

System Specifications:

The system utilizes nine solar collectors, each measuring 4 ft. by 10 ft. The collectors are ducted in parallel configuration. Two supply ducts run across the side of the building, three different registers distribute heat in the building, and one return duct recirculates the air to the solar collectors. A 14 inch fan pushes 780 cfm (cubic feet per minute) through the system when it is activated. The system is controlled by a simple off the shelf warm air controller. After completing construction of the project, RREAL also installed a datalogger on the system that allows RREAL to track the performance of the system in five minute increments. This monitoring system will allow the project team to get a realistic report of exactly how much energy the system is producing, and how reliably it produces high quality heat for the building.

Since the system is using solar energy, there’s virtually no daily maintenance. Further, because solar thermal systems utilize common HVAC components, any experienced facilities operator should be able to perform any required maintenance to the fan, controller, or venting.

Project Insights:

Brainerd Lakes Regional Airport Manager Rick Adair stated he has been pleasantly surprised with the performance of his newly installed solar thermal system. Adair stated that, when the sun is out and shining, he rarely hears the storage building’s supplemental propane heater running, and the building is kept at a good comfortable temperature. The project team was also pleased with the easy installation process. They noted that with an insulated steel building like the one involved in this project, they didn’t have to worry about hiding any ductwork, as leaving it in the open fit well into the buildings industrial aesthetic. This turned out to be a big positive in terms of ease of installation, and limiting any building modifications. Locating a solar thermal project on a building with a similar layout would present a real positive benefit.

Costs & Savings:

Brainerd Lakes Regional Airport’s Solar Thermal heating system cost $23,468. This price included all parts, labor, and installation costs. At the time the project was proposed, the system was projected to save the airport approximately 501 gallons of propane heat every year. Using calculated system performance and fuel price trends (adjusted for inflation and fuel cost escalation) from the U.S. Department of Energy, the system was expected to pay for itself in energy savings alone over the course of a 14 year period. All energy produced after that point in time would be money that would have otherwise been spent on heating fuel costs. Over the course of the systems conservatively estimated 30 year life span, the system was expected to produce a savings of over $84,000.

Utilizing the newly installed solar thermal system’s datalogger, RREAL was able to produce its first true data report from the system in June 2012. The datalogger reported that the system went online on February 3, 2012 and delivered heat to the building through a small part of May 2012. During that shortened heating period, the system provided over 16 million BTUs—the solar energy source saved the Brainerd Lakes Regional Airport approximately 208 gallons of heating propane. Results were even more significant during the full 2012-2013 heating season, with nearly 41 million BTUs provided and just over 527 gallons of heating propane saved. Click here to download a report from RREAL with more specific system performance details.

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