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Homesteading and Livestock

Self-reliance and sustainability in the 21st century.

Year-Round Food Production: So Much More Than a Greenhouse

For anyone eating on a budget, or living in a food desert where it is difficult to get to the grocery store, protein and fresh vegetables become luxuries. Without protein and fresh vegetables human health is compromised. Access is particularly limited where fresh vegetables cannot be grown outdoors during the winter. Carbohydrates like beans, rice, potatoes and pastas come cheap in bulk and store easily but animal protein and vegetables are best eaten fresh. A greenhouse is an option for winter vegetables but any savings can be lost if you have to heat the greenhouse.

We are developing ways to address these issues by designing for a relatively inexpensive structure that can be attached to the south side of a building to produce protein and fresh vegetables year round. To avoid the expense of gas or electric heat we are enclosing enough thermal mass to absorb extra heat when the sun is shining and release it when the sun goes down. The formula from the passive-solar greenhouse literature is that we need between 2 and 5 gallons of water, or equivalent, (masonry gives you about ¼ of the heat storage as the same volume of water) for every square foot of glazing. It also turns out that the type of glazing is less important than how well we are able to seal the structure against air leaks. We also get credit if the wall to which we attach the structure is heated from the other side.

We are not purists so we do not mind adding “active” elements to the system and we like to have each element serve multiple purposes. We like to try things and see how they work. Also, this structure is a part of our wider explorations into how we can work with nature and use natural processes to reduce our work load.

Integrated Closed Loop Production Systems

Nature works in cycles that have no cost and produce no waste. That is what makes natural systems sustainable. To reduce our cost of inputs to zero we have to close the loops and produce all of our inputs as a part of the production cycle. To reduce our waste to zero we have to integrate the processes and find a use for all the byproducts of each process. Those parts of the cycle that cannot survive freezing can be enclosed in a shell designed to retain the sun's heat during the day and release it at night.

Our first prototype is attached to the south wall of an occupied residential dwelling. We used two layers of greenhouse film over 2-by-4 framing. The north wall of our structure is constantly 65 to 70 degrees Fahrenheit and we have no heat loss in that direction. We built raised beds 3 feet wide and 3 feet deep in order to increase the ratio of thermal mass to air space. In the raised beds we installed a pipe attached to a fan that takes air from the top of the structure and blows it through the growing medium to actively transfer heat into and out of the growing medium. The growing medium is wood chips and horse manure like our outside gardens. The fan runs all winter long pumping heat into the bed when the sun is shining and pumping heat out of the bed at night. This heat storage system is called a climate battery and is based on designs developed at the Central Rocky Mountain Research Institute in Basalt, Colorado.

We next installed an aquaponics system built from three food grade 55 gallon drums. We built a tray lined with pond liner 3-feet-by-11-feet-by-1-foot (deep water culture). We cut one of the drums in half vertically and suspended the halves over the deep water culture. In those halves we installed a bell siphon so that the containers would flood and drain and then filled them with river rock (media beds). The rock hosts the bacteria that change the ammonia the fish produce into the nitrates that plants need. The two remaining barrels that hold the fish were plumbed to overflow into the media beds. We pump water from the deep water culture into the fish barrels. We plant directly into the river rock in the media bed and float insulation panels on the deep water culture to hold additional plants.

In the floor of the structure we set cinder blocks to support a walk way about 8” above the ground level. In the space under the walkway, we use worms to process chicken waste from our deep litter chicken operation. Nine weeks after adding chicken waste to the worm bed we can sift the worms out of the worm castings. We feed the worms to the fish and the chickens and we use the worm castings as a planting medium in our gardens.

A Food Cell: More Than a Greenhouse

In integrated closed loop production (ICLP) systems the primary design requirement is balance. We cannot produce more of any one thing than we can process all the products. Systems designed to produce a product for sale in the market are generally designed to produce as much of one thing as possible. That lowers costs through economies of scale but leaves an imbalance of by products that are not cycled in the design. ICLP can achieve economies of integration, meaning zero costs and zero waste, but there may never be enough of any one product to justify taking it to market. Instead, there is a constant production of a small amount of many products. That is perfect then for providing a varied diet of protein and fresh vegetables to the humans who are integrated into the system.

We have yet to reduce our input costs to zero. We still purchase chicken food and small amounts of fish food and some of our seeds. We are buying a small amount of electricity from the grid to run the water and air pumps and fan. We believe it is possible to close the loops but we have to integrate more processes. Still, in a structure 9-feet X 24-feet plus the space for our chickens, we can produce enough protein and fresh vegetables for maybe 8 families year round. That is not all the required calories, that is what you are missing if you are eating on a budget or live in a food desert.

Consider that taking care of chickens is easier than caring for a dog. Feeding the chicken waste to the worms is more pleasant than picking up after a dog. If you ever had a fish tank, this one even cleans itself. Growing plants in this structure is no more difficult than growing house plants. You will have to spend some time each evening picking a salad for dinner but you will spend much less time in the produce aisle at the grocery store.

Now think about dividing the necessary tasks among the members of eight families. How much of a time commitment are we really talking about? The more people involved the less any one person has to do. Everyone can still do all the other things they like to do and keep their jobs. That makes this structure much more than a greenhouse. We call it a food cell as it is a membrane with enclosed metabolic processes.

The Food Cell Challenge

We have spent maybe $2,500 on the entire system. We have done all the work with volunteer labor and we keep changing things as we experiment with different approaches. With the right design we could be talking about a reasonable investment spread over 8 families that results in essentially free food for the indefinite future. Any 8 families with jobs can certainly afford one. People in greater need may be able to apply for grants to build these systems.

What we have been able to accomplish to date is just the beginning. In a stand alone system we might want to add a supplemental heat source, such as a rocket mass heater, for those polar vortex days. We want to incorporate a sprouted barley feeding system for our chickens that will allow us to go 100 percent organic and GMO free. If I had sufficient time I would be looking to integrate raising insects as both animal and human food. We can do a better job of processing the byproducts from butchering the chickens and fish. We can work to incorporate more of the waste streams generated in our community such as the food scraps from a restaurant.

We are interested in sharing what we know with anyone willing to collaborate in the design, prototyping and testing process. If you would like to build one and share your results we are interested in working with you. You can start with information about a Basic Food Production System on our web site and we have a more advanced stand alone design we can share.

Combined with a neighborhood habitat improvement project using a deep mulch gardening system and incorporating seed saving and line breeding we begin to prepare for the potential of economic collapse and climate change while making important strides toward healing nature and ending poverty. This is how we will end hunger in the world.

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