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helping Minnesota communities determine their energy future

CASE STUDY: SOLAR - CENTRAL REGION

Heating Things Up on the Farm: Crop Dryingwith Solar Air Heat in Central MinnesotaBy Kathleen McCarthy • August 2011

Since 2000, the Rural Renewable Energy Alliance(RREAL) has been serving low income communitiesin Central Minnesota by developing, manufacturing,and installing solar hot water and air heaters to helpfamilies reduce their heating fuel dependence andlower their energy bills. Now, RREAL is exploringother applications for sustainable energy.

Traditionally, agricultural crop drying uses a lot ofelectricity to run high heated fans. Crop drying isone of the most energy intensive operations of grainfarming. RREAL believes that using solar thermalfor air heating could significantly reduce the amountof electricity needed for this process. Farmers inMinnesota are feeling the cost of crop drying and arelooking for alternatives that are less energy intensiveand more cost effective.

“Having changed dramatically in the past century,crop drying today is an energy intensive process,heavily dependent on fossil fuels. Our state’s foodand energy security are somewhat vulnerable to thevagaries of fuel supply and expense,” explains JasonEdens, one of RREAL’s researchers for this project.

In 2008, RREAL decided to research solar air heat asa crop drying method and “outline the benefits ofusing this appropriate technology in an applicationthat has great potential to significantly contribute toMinnesota’s goals of reduced fossil fuel dependencyand resulting improved environment,” explainsEdens.

The project was spearheaded by Edens and thenRREAL’s research coordinator, Sarah Hayden. Theywere motivated to find the appropriate role for solarhot air technology in the crop drying process.“Although it would certainly benefit us if we discovered our technology were appropriate for cropdrying, our motivation was to determine the applicability and appropriateness for the technologyas a whole, not just our collector in particular.”

To begin, the team consulted with both theUniversity of Minnesota Extension Service and theNorth Dakota State University Extension Servicebecause both institutions had literature andresources regarding agricultural crop drying andsolar crop drying, in particular. “Dr. KennethHellevang, of NDSU, was particularly helpful inguiding us to relevant documentation,” said Edens.

Project Snapshot

Project: Research on the use of solar air heating for cropdrying

Benefits of Solar Air Heating:Decrease use of fossil fuels, reduce emissions,build resilience against rising fuel prices, economic savings

Conclusions:Supplemental solar crop drying in Minnesota canbe an economically and technically feasible technology

Partners:University of Minnesota Extension Service andthe North Dakota State University ExtensionService

Grant:$5,000 from Central CERT

RREAL is located in central MN in Pine River. They share acampus with the Hunt Utilities Group (HUG).CERTs PARTNERS

University of MinnesotaExtension and RegionalSustainableDevelopmentPartnerships

Eureka Recycling

Southwest RegionalDevelopmentCommission

The Minnesota Project

Minnesota Departmentof Commerce, Division of Energy Resources

“The literature revealed that a great many farmers throughout the world have been, are andwill continue to utilize solar air heat as part of their agricultural processing. In addition toagricultural crops, there are a great many folks in Minnesota who are using solar heat for silvicultural crop drying processes,” explains Edens. Yet because the upfront cost ofinstalling a solar air heat panel is often higher than a traditional crop drying machine, manyfarmers see the cost as prohibitive and are not willing to give it a try.

Despite the upfront costs, many long term economic, environmental, and social benefits canarise from utilizing a solar crop drying method, Edens argues. “Farmers employing solarcrop drying methods would experience economic savings, with a specific payback period tobe determined by the end of this project. Should we discover crop drying to be an appropriate application for solar, as we suspect, this project would have significant economic impact in central Minnesota through sales of locally manufactured solar collectorsspecifically designed for that application.”

Additionally, reducing the amount of electricity needed to crop drying by incorporatingsolar air heat to the process will significantly decrease the amount of unsustainable fossilfuels being burned.

Edens also identifies social benefits of renewable crop drying. “It will also make small agricultural communities and farmers more resilient against the impact of rising fossil fuelcosts. Energy crises will make crop drying financially challenging. At a time when smallfarmers are struggling to maintain their way of life, renewable and sustainable farmingmethods make sense for the individual farmer and state.”

With the help of a CERTs grant, RREAL was able to dedicate staff time to investigating solarthermal crop drying and ways to engage farms with the technology. The conclusion of theliterature review revealed that “generally, the literature is positive about the use of solar heatin crop drying applications in diverse settings throughout the world. In Minnesota, solarcrop drying was determined to be technically feasible in a supplemental setting whenexcluding the costs and benefits of externalities. In summary, supplemental solar crop drying in Minnesota can be an economically and technically feasible technology when usedin combination with a low temperature crop dryer.”

The research team plans to continue this project by developing ways to implement the practice in Minnesota.

For more information about the report, please contact Jason Edens at info@rreal.org or bycalling 218-587-4753.

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One of RREAL’s solar-powered furnaces

RREAL solar furnaces used in a series for commercial heating

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