Agroecological Design

Problems in modern food systems

• 17% of all fossil fuel used in the U.S. is consumed by the food production system.1

• The average U.S. farm uses an estimated 3 calories to produce 1 calorie of food. 1

• Food and agricultural products are transported 556 billion ton-miles within U.S. borders each year.2

• Local greenhouse production uses fossil fuels for heating and CO2 enrichment.3,4

Problems in waste handling

• A large fraction of compostible and recyclable materials are landfilled every year.

• Landfills contribute to global climate change through methane or carbon dioxide production.

• Large areas are centralized and mass transport and fossil fuels are needed to process this waste.

Problems in composting

• Compost production releases tons of heat energy, CO2, N, and H2O into the atmosphere every day.

• Water content, airflow, temperature, and odor emissions have to be controlled in composting operations.

• Runoff and groundwater pollution are issues as well.

Conventional Nutrient Management

Off-gassing from handling

and storage

Off-gassing of NH3, CO2, H20, SO2, heat, and

pathogens from housing

Some nutrient recovery

More off-gassing and

runoff to adjacent waters

Gradual nutrient

loss througho

ut the system

Ecological Solutions

Take wisdom from nature: What would nature do?

• Utilize all nutrients and energy in niches – no waste

• Identify cycles and relationships

• See the forest for the humus!

The biothermal alternative

Can we combine composting and greenhouse technologies to reduce scarce resource use, utilize waste resources, and create production niches?

The history of biological energy

• The use of manure for the incubating of crops dates back as far as 2000 years.

• Various systems have been attempted with mixed success.

• A technology has not been developed to utilize waste from large composting operations.

Jean Pain’s Hydronic System

-Wood chip based systems lasted longer

-50-ton heap

-Water temperature entering at 50F leaving at 140F at 4 liters/minute

-6 months without interfering with the decomposition process

-Circulated by thermosiphon

Composting Greenhouse (NAI)

•Three low-wattage fans,

consuming in total 140 watt

hours daily.

•Biofiltration through soil

•CO2 delivered below crop

canopy

•NH3 delivered to soil

•On a clear winter night:

outside 2F, inside 34F,

upper bed 79F, lower bed 62F,

compost 142F.

•Six person-hours per week

•Compost loading every four

or five days with 5 yd3 of

manure.

Solviva Greenhouse

•Transferred animal house exhaust to a horticultural greenhouse

•“Earthlung Filter” of leaf mold, sand, and soil that

filtered NH3 from air

•12 inch layer was skimmed and used.

•Radiated an estimated 432,000 BTU’s per day (400 chickens and 100 rabbits)

•18782.6 liters of Co2

•CO2 levels of 1400 ppm in the crop area

The Complexity of Biological Technology

• As in natural ecosystems, contained ecosystems have complex cycling and feedback relationships.

• Biothermal energy is not a steady-state resource, an engineering nightmare!

• Combining with conventional operations is a challenge.

• Variability and complexity dictate modeling as a design step.

STELLA!

• A systems model has been created to simulate the functioning of the structure

• Data for equations taken from peer-review literature

• Simulation is run against “best source” local whether data

Dairy Greenhouse

• Suspended Grow Beds constructed from PVC and waste twine.

• Beds 9’ in air so cows cannot disturb.

• Accessed with scaffolding on stalls.

• Irrigation drawn across ceiling.

• Compost produces irrigation water at 90 F.

• When mostly closed, barn is normally 15 degrees warmer than outside depending on wind, sun, and time of day.

• Humidity and ammonia have been acceptable so far.

• Cows produce water vapor, heat (390Kw/hr), and CO2 (950l/hr) (approximate) at average winter temperatures (10 F).

Ecological Nutrient Management

Filtration of house off-gassing

(recovery of CO2, H2O, N2 and heat.)

Anaerobic digestion of slurry (recovery of NH4 and CO2)

Contained aerobic composting (filtration, recovery of nutrients )

Field Application of stabilized compost

Minimal nutrient loss and energy production

Agroecological Design in the Fossil Fuel-less Future

• Energy and Nutrient flows will be utilized and waste will be minimized.

• Community scale will reflect available resources as in nature.

• Farms can be the community dumps of the future: look at the Intervale.

• Integrated farming systems will be prevalent and resources, skills, and space shared.

Agroecological Design in the Fossil Fuel-less Future

References1. Horrigan, Leo, Lawrence, Robert S. and Polly Walker. “How Sustainable

Agriculture Can Address the Environmental and Human Health Harms of Industrial Agriculture.” Environmental Health Perspectives. Vol 110, May 2002.

2. Norberg-Hodge, Helena , Merrifield, Todd and Gorelick, Steven. “Bringing The Food Economy Home: Local Alternatives to Global Agribusiness.” Bloomfield , CT : Kumarian Press. 2002.

3. Enoch, Herbert and Kimball, Bruce. “CO2 Enrichment of Greenhouse Crops” U.S: CRC Press, 1986.

4. Nelson, Paul V. “Greenhouse Operation and Management.” New Jersey: Prentice Hall, 1998.

5. Anna Edey “Solviva”6. Louis Albright “Env. Control for Animals and Plants”7. Howard Odum “Env., Power, and Society”8. Robert Huag “Compost Engineering”9. NAI composting greenhouse: http://www.fuzzylu.com/greencenter/home.htm10. Jean Pain info: http://journeytoforever.org/biofuel_library/methane_pain.html,

http://www.motherearthnews.com/arc/2032/, 11. Biocycle and Compost Science and Utilization.