Using Renewable Energy to Expand Opportunities for Regional Farmers

Joel Tallaksen, Renewable Energy Scientist

November 2016

In the distant past, Minnesota had a thriving agricultural economy based on both the grains we see grown today, but also a wide range of produce that fed those in cities without gardens.  With the development of refrigeration and advanced transportation systems, produce began to be grown in warmer regions of the world and shipped to northern climates such as Minnesota.  However, this transportation requires energy that is becoming more costly.  In addition, water scarcity is beginning to limit production in some of the areas where two and three seasons of outdoor production is possible.  Consumers are also beginning to express preferences for more diverse selection of produce that may not ship well.

A small number of farmers and gardeners in Minnesota have begun to use season extending low and high tunnels and deep winter greenhouses (DWG) to produce a variety of fruits and vegetables in non-traditional growing seasons.  A very committed University of Minnesota Extension group has been working with deep winter greenhouses to develop a standard suite of building designs for beginning growers. They are working to fully develop the technical, economic, and plant production aspects of these systems.

The systems are inexpensive and can be built by someone handy with tools and having access to a hardware store or building center. They are designed to collect and store heat from the sun, thus little fossil fuel is required for supplemental heating. These initial small-scale deep winter greenhouses demonstrate the potential for produce production in winter.  However, there are limitations to these systems.  The largest is the narrow variety of crops that can grow at 50 degrees in December and January, typically leafy greens, such as lettuce and spinach.  Another factor with the current designs is that the greenhouses are fairly small, both to reduce cost and maximize the ability to store heat.  Therefore, they are primarily used for as personal greenhouses or for supplemental income generation.

As a renewable energy researcher and amateur gardener, I began to consider how renewable energy technologies could enhance these growing systems.  Here at the West Central Research and Outreach Center, we have successfully been using sunlight to heat part of our facility for the last 6 years.  We have added over 50 kW of photovoltaic energy generation.  We are currently adding 20 kW of small scale wind production.  Including solar and wind energy in deep winter greenhouse systems could remove the temperature barriers for growing more diverse crops, as well as, provide power for advance LED lighting to plants that need longer growing days.  Also, the scale of the systems could be increased, which would improve the economics and allow for stand-alone greenhouse enterprises.

Over the last few months, I have had the opportunity to talk with the U of M Extension team about their systems and how renewable energy could be added to them.  We both feel that the capabilities of this systems can be expanded. Developing this technology would allow Minnesota to once again supply more of its produce and provide off-season opportunities to rural Minnesota.  Developing these opportunities for rural Minnesota using renewable energy is a key aspect of WCROC’s renewable energy team.  We hope that funds can be secured to work with the Extension Deep Winter Greenhouse team to more formally research the integration of renewable energy technology in greenhouse design.