Saturday, December 15, 2012


No Winter at Whitewater Gardens Farm: Geothermal Greenhouse Project in Altura, MN

by Jenna Lewein • August 2011
Sandy and Lonny Dietz in their greenhouse
As residents of the Midwest know, the growing season is painfully short. When it’s twenty below, what else can you do besides go to the supermarket and buy tomatoes shipped from thousands of miles away? Whitewater Farms in Altura, Minnesota has found a solution. The farm, owned and operated by Sandy and Lonny Dietz, contains a geothermal greenhouse that allows them to produce fresh vegetables year-round.
The Dietzs plant up to eight acres every growing season and the resulting produce is eagerly gobbled up by local community members, co-ops, and restaurants. Sandy and Lonny saw the potential in exploring renewable energy options to expand the growing season into the winter months by powering a greenhouse and operating a cold cell storage unit to keep produce grown in the greenhouse from spoiling.
In order to find the best possible combination of renewable energies, the Dietzs turned to the Southeast CERT for a grant that would allow them to research methods they thought had the most potential, namely, ground source heat pumps, wood boiler systems, wind turbines, and photovoltaic cells. In 2007, Sandy and Lonny were awarded $4,000 by CERTs, which allowed them to conduct a feasibility study and hire a board of advisors to help them engineer solutions that could be applied to their greenhouse.
Ultimately, it was decided that geothermal energy, by way of ground source heat pumps, was the most feasible for heating the soil within the greenhouse and also for cooling the cold storage area. Ground source heat pumps work by using the temperature of the soil to heat or cool something. While the surface temperature of the soil will vary wildly depending upon the time of year, the soil a few feet below the surface remains unaffected.
Ground temperature in winter is always warmer than the air temperature around it, and cooler than the air temperature in the summer. By using this difference in temperatures to regulate and guide heating and cooling with a ground source heat pump, the Dietzs could use a renewable type of energy to offset their conventional energy usage.

1 comment:

Jackie Champion said...

Hi there! Keep it up! This is a good read. I will be looking forward to visit your page again and for your other posts as well. Thank you for sharing your thoughts about geothermal in your area. I am glad to stop by your site and know more about geothermal.
Geothermal electric plants were traditionally built exclusively on the edges of tectonic plates where high temperature geothermal resources are available near the surface. The development of binary cycle power plants and improvements in drilling and extraction technology enable enhanced geothermal systems over a much greater geographical range. Demonstration projects are operational in Landau-Pfalz, Germany, and Soultz-sous-ForĂȘts, France, while an earlier effort in Basel, Switzerland was shut down after it triggered earthquakes. Other demonstration projects are under construction in Australia, the United Kingdom, and the United States of America.
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