Sustainable Year-Round Growing in High Tunnels Utilizing Waste Vegetable Oil in Conjunction with a Subterranean Geothermal and Solar Heating and Cooling System

Final Report for FNC06-622

Project Type: Farmer/Rancher
Funds awarded in 2006: $6,000.00
Projected End Date: 12/31/2008
Region: North Central
State: Missouri
Project Coordinator:
Ivan’s Fig Farm
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Project Information


My Farm is located on ~10 acres in Dittmer, MO, ~30 miles south of St. Louis, MO, off HWY 30.

The major efforts are focused on growing Figs but a variety of heirloom vegetables are successfully grown on the farm. Currently one whole High Tunnel, equipped with a solar panel for automatic opening and closing of side curtains and a Clean burn Furnace for heating with waste cooking oil, is dedicated to growing several varieties of Figs. A second High Tunnel with an underground geothermal and solar heating and cooling systems is under experimental testing of new alternative energy sources for growing in High Tunnels. It was demonstrated that it is possible to grow year round figs, tomatoes, peppers, strawberries and other vegetables using a Geo-Solar system coupled with a used oil CleanBurn furnace.

I developed a method for sustainable growing of Figs in Missouri in a High Tunnel, as well as outside by using leaf mulch for protection from the winter freezing conditions. I grow organically figs, tomatoes, peppers and other vegetables using composted manure for fertilization, drip irrigation, organic mulching, crop rotation etc.

Goals: Despite the enormous beneficial effect for extension of the growing season, High Tunnels are either not used in the cold winter season or their use is limited to only growing low temperature resistant crops. The high cost of heating with propane, natural gas or other fossil fuels is one of the major limiting factors.

The goal of this project was to solve the problems of growing Figs and other high temperature requiring plants and vegetables in High Tunnels through the challenging cold winter season in Missouri, using alternative energy sources in a sustainable, profitable and environmentally friendly way.

Process: The Plan for achieving the goal consisted of utilizing the results of the Subterranean Geothermal and Solar Heating and Cooling System (SGSHCS) or Geo-Solar system, in conjunction with a used oil furnace. The Geo-Solar system installed within the perimeter of the High Tunnel consists of ~4500 feet of 4” pipes, running parallel at 2' off center, in three parallel layers above each other, within 1’ off center. The system was enclosed in a 4” thick, insulation box, running up to 2’outside the perimeter of the tunnel, constructed from 2’x 8’x 4” blue foam insulation panels. The box is 2’ deep on the upward slope and 4’ deep on the more exposed downward slope.

In order to evaluate the input of the two components of the System (the Geo-Solar system and the used oil furnace), the testing of each component was carried out in parallel in two consequent winters. During the first winter season, a 175,000 BTU/h furnace, purchased from Clean Burn was installed for the comparison studies of heating a High Tunnel with and without a Geo-Solar system. The furnace was installed in a used walk-in cooler and ducted directly into the High Tunnel with the Figs.

When the temperature outside dropped to –4 F on the coldest night in January of 2008, the temperature between the two High Tunnels was only within 3-4 F different and barely above freezing. The temperature of the air blowing from under the ground did not drop below 48 F, even on that coldest night of the season, when it was –4F outside.

It was established that it takes at least 1500 gallons of waste cooking oil, when keeping the thermostat inside the High Tunnel at 55F during the winter season, which is barely enough to keep it from freezing at
0 F and subzero outside temperatures. A college of mine, who grows hydroponic greens used 3,500 gallons of propane to keep her Greenhouse at 58 F, before she switched to using wood furnace, being no longer able to afford the propane prices.

During the second winter, a 250,000 Btu/h CleanBurn furnace, generously donated for the project by CleanBurn Inc, was coupled with the Geo-Solar system of the second High Tunnel. On December 17th, one week to Christmas, I had not started the furnace yet this winter, using only the Geo-Solar system. The temperatures had already dropped down to12 F, with windshield of 0 F on the 15th. Amazingly I was still picking figs and peppers, and my late fall planted tomatoes were growing ready for the harsh months of January and February. It turned out that the furnace would be spared for the coldest nights only, when the temperatures outside dropped in the single digits or subzero temps. It was amazing to see my tomatoes and strawberries blooming in the middle of January and a kumquat tree in a pot loaded with bright orange fruits. And last but not least exciting was to see my micro-algae cultures proliferating in deep green colors on the background of the 4’of snow piled against the sidewalls of the High Tunnel. I will stop here because the results speak for themselves.

An extensive data of temperature parameters had to be collected during the project, including the extreme points of the coldest nights or hottest days of the year. To generate all the data measurements was a challenging and time consuming job but was of enormous importance to understand the performance of the Geo-Solar system in conjunction with the used oil furnace.

The grant funds were used to purchase and install the CleanBurn furnaces as well as to pay for the waste oil supply and delivery, blue foam insulation around the perimeter of the Tunnel and polycarbonate end walls for better insulation and stability to high winds and storms.

• Fred Phillips, Director Research and Development at Clean Burn got interested in the project and helped by convincing the Management of Clean Burn Inc of the importance of the project. As a result, CleanBurn Inc generously provided a free 250,000 BTU furnace, worth $6500. Thanks to this it was possible to equip both High Tunnels with furnaces and perform the parallel testing experiments with and without Geo-Solar System.

• Willibald Pfeiffer, my neighbor poured the concrete foundation for the walk-in cooler to be used as a furnace box, helped with the technical and maintenance projects associated with the furnace, compressor and Geo-Solar system.

• Henry Rentz from Missouri Valley Renewable Energy Installed the polycarbonate end walls of the High Tunnels for better insulation and resistance to wind and storms.

• Dean Wilson, Agriculture and Rural Development Specialist, University of Missouri Extension, who coordinates a Program called “Grow Your Farm”, organized field trips to my farm to get the class participants acquainted with the new technology. It is a financial planning program for people who are serious about starting or changing ag enterprises.

• One of the program participants, Jason Hirtz, a young beginning farmer is currently taking an internship on my farm on growing organically with High Tunnels using alternative energy sources.

The project was successfully completed and the results were amazing. The results of testing with the Geo-Solar system encouraged me to plant tomatoes and peppers in early February without any additional heating or row covers, with just the Geo-Solar system. My risk was rewarded, by being the first farmer to bring tomatoes to market in May. When the restaurants found out, they bought me out for $5/Lb of heirloom tomatoes like Cherokee Purple, Zebra and Bulgarian varieties and I could not even get to the market.

On, December 17th, one week to Christmas, the temperatures had already dropped down to12F with wind chill of 0F on Monday night, the 15th. I had not started the furnace yet this winter using only the Geo-Solar system. Amazingly I was still picking figs and peppers, my late fall planted tomatoes were growing ready for the harsh January and February. It turned out that the furnace would be spared for the coldest nights only when the temperatures outside drop in the single digits or subzero temps. And depending on what I want to grow I can regulate the temperature inside much easier and cheaper, thanks to the Geo-Solar system. This saves me a lot of heating fuel now, when it is really important with the background of the economic and energy crisis. Prices of used cooking oil also went up double and triple earlier this year, due to the big demand for bio-diesel, when diesel prices were ~$4/gal. And although fuel prices have dropped 70% since then, OPEC is announcing today (March 16, 2009) a dramatic cut of 2 billion barrels/day. So prices will be up again: it’s not a matter of if, but when. And even if there is oil for another 20 years, the sustainable Geo-Solar will keep working as long as the sun keeps shining and the earth keeps warming.

The major result achieved was the possibility to grow year round in a High Tunnel in a sustainable, lower cost and ecologically cleaner way, which was achieved by utilization of the Geo-Solar System in conjunction with a used oil furnace. It became possible to have figs till Christmas, without using any heating, have tomatoes and strawberries blooming in the middle of January when the temperatures dropped to a low of -6F and a wind chill of -20F. The efficient performance of the system allowed for a savings of > 85% of the fuel necessary for heating a greenhouse during the winter season. The used oil is renewable. Burning used vegetable oil utilizes the stored solar energy, which otherwise, if not used to make bio-diesel, will be dumped and used by fungi and bacteria to release the energy and the CO2 in the air.

I learned again and again that if the necessary support is provided to realize an idea, the pay off is enormous. This is particularly true in critical times like now with today’s energy and global warming issues putting pressure on the economy and sustainability.

The advantages of implementing the use of alternative and sustainable sources of energy in this efficient system are: saving energy, reducing pollution for a cleaner environment and the possibility to grow year-round fruits and vegetables during cold winter seasons. This can secure fresh locally produced fruits and vegetables, satisfying the fast growing sector of the local organic market.

This overcomes the barrier of using High Tunnels for growing year-round instead of staying empty. The high cost of heating with propane or other fuels of fossil origin is eliminated with a renewable fuel thus not contributing CO2 to global warming.

One unexpected result was the enormous spike of temperature during clear sunny days at mid day hours during the hot summer days. The heat build up turned out to be greater than what the capacity of the system can absorb. This requires additional venting of the heat in excess of 95F that the Geo-Solar system cannot quench. This can be readily achieved by installing oil pressure regulated vents or side curtains.

The general opinion in the literature is that earth tubes are more efficient for cooling than for heating. The results of this project although demonstrating the cooling capability of the system, showed that it is much more beneficial as a source for storing sun energy for heating at night, particularly in the early spring and late fall. Taping into the geothermal free energy occurs for a much smaller interval of time during the very cold winter and is limited to the maximum of 55-60 F constant subterranean temperature.

The system however has big potential that can be further expanded by increasing the capacity of the underground pipe system by length and depth and by better conserving the heat generated by the Geo-Solar System by increasing the insulation of the High Tunnel. One way would be by blowing surfactant foam between the two layers of polyethylene cover, which is known to increase R value with one unit per every inch of foam. The goal is to achieve a system that does not use any fuel for growing some tropical fruits. Such a system will be of significant importance for growing algae for bio-fuels (Please see my 2008 Farmers/Ranchers Grant project, FNC07-680 for details).

Presentations at meetings:
• Great Plains Vegetable Growers Meeting, St Joseph, MO, 2007 ~500 people
• Slow Food Presentation at Schlafly Bottleworks, August 2008 ~ 80 people

Publications and Other Media:
• Article in St Louis Post Dispatch 09/03/2008
• Interviews regarding the new alternative energy system: Channel 2 and Channel 5, St.
Louis TV and KHTS Public Radio.
• Provided information on the project by participation in the High Tunnel on-line communication and discussion.

Project events or activities:
• Organized field trips and presentations at the farm regarding the new alternative energy system.
• Worked with intern young growers on teaching use and applications for growing with the new system.

I had the wonderful opportunity to be invited by Ted Carey, Extension Specialist Food Crops, Kansas State University as a plenary speaker at the Great Plains Vegetable Growers Conference in 2007 in St. Joseph, MO. The one hour presentation allowed me to present my ideas about using alternative energies and automation for growing in High Tunnels and for growing Figs in particular. The presentation covered the use of automatic curtain control powered by a solar panel, the Subterranean Solar and Geothermal Heating and Cooling System and the Clean Burn's waste cooking oil automated heating system.

The successful growing of figs in the High Tunnels has excited many growers and several have already started growing them in High Tunnels on their farms. I have provided them with detailed instructions on the aspects of growing the figs and the technical knowledge for operating the systems. I even supplied them with rooted fig plants ready for planting in their High Tunnels. Several groups of interested farmers visited the operation during the summer of 2007. Among them was a group of five from the Missouri State University, State Fruit Experiment Station with Patrick Byers, Fruit grower advisor and Marilyn Odneel; the extension specialist from the University of Missouri at Columbia Dr Lewis Jett; 12 people from the St. Louis Botanical Garden Club, many individual local farmers, neighbors and friends. Another group of 25 growers, members of the Great Plains Growers Association from Columbia, Missouri with Dr James Quinn, the Extension Specialist for the University of MO, Columbia visited on a Field trip on April 19, 2008.

In September of 2008 Dean Wilson, Extension Specialist at the University of Missouri made a field trip with his class on Sustainable Agriculture.


Participation Summary
Any opinions, findings, conclusions, or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of the U.S. Department of Agriculture or SARE.